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Proposed Rule

Control of Air Pollution From Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards

Action

Proposed Rule.

Summary

This action would establish more stringent vehicle emissions standards and reduce the sulfur content of gasoline beginning in 2017, as part of a systems approach to addressing the impacts of motor vehicles and fuels on air quality and public health. The proposed gasoline sulfur standard would make emission control systems more effective for both existing and new vehicles, and would enable more stringent vehicle emissions standards. The proposed vehicle standards would reduce both tailpipe and evaporative emissions from passenger cars, light-duty trucks, medium-duty passenger vehicles, and some heavy-duty vehicles. This would result in significant reductions in pollutants such as ozone, particulate matter, and air toxics across the country and help state and local agencies in their efforts to attain and maintain health-based National Ambient Air Quality Standards. Motor vehicles are an important source of exposure to air pollution both regionally and near roads. These proposed vehicle standards are intended to harmonize with California's Low Emission Vehicle program, thus creating a federal vehicle emissions program that would allow automakers to sell the same vehicles in all 50 states. The proposed vehicle standards would be implemented over the same timeframe as the greenhouse gas/fuel efficiency standards for light-duty vehicles, as part of a comprehensive approach toward regulating emissions from motor vehicles.

Unified Agenda

Control of Air Pollution From Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards

3 actions from May 21st, 2013 to December 2013

  • May 21st, 2013
  • July 1st, 2013
    • NPRM Comment Period End
  • December 2013
    • Final Rule
 

Table of Contents Back to Top

Tables Back to Top

DATES: Back to Top

Comments. Comments must be received on or before June 13, 2013.

Public Hearing: The public hearings were held on April 24, 2013 in Philadelphia, PA and April 29, 2013 in Chicago, IL.

ADDRESSES: Back to Top

Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2011-0135, by one of the following methods:

  • www.regulations.gov: Follow the on-line instructions for submitting comments.
  • Email: A-and-R-Docket@epamail.epa.gov.
  • Mail: Air and Radiation Docket and Information Center, Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania Ave. NW., Washington, DC 20460. In addition, please mail a copy of your comments on the information collection provisions to the Office of Information and Regulatory Affairs, Office of Management and Budget (OMB), Attn: Desk Officer for EPA, 725 17th St. NW., Washington, DC 20503.
  • Hand Delivery: EPA Docket Center, EPA West Building, Room 3334, 1301 Constitution Ave. NW., Washington, DC 20460. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. EPA-HQ-OAR-2011-0135. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at www.regulations.gov, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through www.regulations.gov or email. The www.regulations.gov Web site is an “anonymous access” system, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an email comment directly to EPA without going through www.regulations.gov your email address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional information about EPA's public docket visit the EPA Docket Center homepage at http://www.epa.gov/epahome/dockets.htm. For additional instructions on submitting comments, go to Section I.B of the SUPPLEMENTARY INFORMATION section of this document.

Docket: All documents in the docket are listed in the www.regulations.gov index. Although listed in the index, some information is not publicly available, e.g., CBI or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, will be publicly available only in hard copy. Publicly available docket materials are available either electronically in www.regulations.gov or in hard copy at the Air and Radiation Docket and Information Center, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave. NW., Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Air Docket is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT: Back to Top

JoNell Iffland, Office of Transportation and Air Quality, Assessment and Standards Division (ASD), Environmental Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105; Telephone number: (734) 214-4454; Fax number: (734) 214-4816; Email address: iffland.jonell@epa.gov.

SUPPLEMENTARY INFORMATION: Back to Top

I. General Information Back to Top

A. Does this action apply to me?

Entities potentially affected by this proposed rule include gasoline refiners and importers, ethanol producers, gasoline additive manufacturers, transmix processors, terminals and fuel distributors, light-duty vehicle manufacturers, independent commercial importers, alternative fuel converters, and manufacturers and converters of vehicles between 8,500 and 14,000 lbs gross vehicle weight rating (GVWR).

Potentially regulated categories include:

Category NAICSaCode SICbCode Examples of potentially affected entities
aNorth American Industry Classification System (NAICS).
bStandard Industrial Classification (SIC).
Industry 324110 2911 Petroleum refineries (including importers).
Industry 325110 2869 Butane manufacturers.
Industry 325193 2869 Ethyl alcohol manufacturing.
Industry 211112 1321 Natural gas liquids extraction and fractionation.
Industry 325199 2869 Other basic organic chemical manufacturing.
Industry 486910 4613 Natural gas liquids pipelines, refined petroleum products pipelines.
Industry 424690 5169 Chemical and allied products merchant wholesalers.
Industry 325199 2869 Manufacturers of gasoline additives.
Industry 424710 5171 Petroleum bulk stations and terminals. E51-83 manufacturers.
Industry 493190 4226 Other warehousing and storage-bulk petroleum storage.
Industry 336111, 336112 3711 Light-duty vehicle and light-duty truck manufacturers.
Industry 811111, 811112, 811198 7538, 7533, 7534 Independent commercial importers.
Industry 335312, 336312, 336322, 336399, 811198 3621, 3714, 3519, 3599, 7534 Alternative fuel converters.
Industry 333618, 336120, 336211, 336312 3699, 3711, 3713, 3714 On-highway heavy-duty engine & vehicle (>8,500 lbs GVWR) manufacturers.

This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by this proposed action. This table lists the types of entities that EPA is now aware could potentially be regulated by this proposed action. Other types of entities not listed in the table could also be regulated. To determine whether your activities would be regulated by this proposed action, you should carefully examine the applicability criteria in 40 CFR parts 79, 80, 85, 86, 1065, and 1066 and the referenced regulations. If you have any questions regarding the applicability of this proposed action to a particular entity, consult the person listed in the preceding FOR FURTHER INFORMATION CONTACT section.

B. What should I consider as I prepare my comments for EPA?

1. Submitting CBI

Do not submit this information to EPA through www.regulations.gov or email. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD ROM that you mail to EPA, mark the outside of the disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2.

2. Tips for Preparing Your Comments

When submitting comments, remember to:

  • Identify the rulemaking by docket number and other identifying information (subject heading, Federal Register date and page number).
  • Follow directions—The agency may ask you to respond to specific questions or organize comments by referencing a Code of Federal Regulations (CFR) part or section number.
  • Explain why you agree or disagree, suggest alternatives, and substitute language for your requested changes.
  • Describe any assumptions and provide any technical information and/or data that you used.
  • If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced.
  • Provide specific examples to illustrate your concerns, and suggest alternatives.
  • Explain your views as clearly as possible, avoiding the use of profanity or personal threats.
  • Make sure to submit your comments by the comment period deadline identified.

C. Did EPA conduct a peer review before issuing this notice?

This regulatory action was supported by influential scientific information. Therefore, EPA conducted peer reviews in accordance with OMB's Final Information Quality Bulletin for Peer Review. Specifically, EPA conducted six peer reviews in connection with data supporting the proposed Tier 3 program, including new research on the effects of fuel properties changes (including sulfur effects) on exhaust and evaporative emissions of Tier 2 vehicles. The refinery-by-refinery cost model was also peer reviewed. The peer review reports are located in the docket for today's action, as well as the agency's response to the peer review comments.

Table of Contents Back to Top

I. Executive Summary and Overview of Proposed Program

A. Introduction

B. What are the basic components of the proposed program?

1. Proposed Standards for Light-Duty Vehicle, Light-Duty Truck, and Medium-Duty Passenger Vehicle Tailpipe Emissions

2. Proposed Heavy-Duty Vehicle Tailpipe Emissions Standards

3. Proposed Evaporative Emission Standards

4. Onboard Diagnostic Systems (OBD)

5. Emissions Test Fuel

6. Fuel Standards

7. Regulatory Streamlining and Technical Amendments

C. What would the impacts of the proposed standards be?

II. Why is EPA making this proposal?

A. Basis for Action Under the Clean Air Act

1. Clean Air Act Section 202

2. Clean Air Act Section 211

B. Overview of Public Health Impacts of Motor Vehicles and Fuels

1. Ozone

2. Particulate Matter

3. Nitrogen Oxides and Sulfur Oxides

4. Carbon Monoxide

5. Mobile Source Air Toxics

6. Near-Roadway Pollution

7. Environmental Impacts of Motor Vehicles and Fuels

III. How would this proposal reduce emissions and air pollution?

A. Effects of the Proposed Vehicle and Fuel Changes on Mobile Source Emissions

1. How do vehicles produce the emissions addressed in this proposal?

2. How would the proposed changes to gasoline sulfur content affect vehicle emissions?

B. How would emissions be reduced?

1. NO X

2. VOC

3. CO

4. Direct PM 2.5

5. Air Toxics

6. SO 2

7. Greenhouse Gases

C. How would air pollution be reduced?

1. Ozone

2. Particulate Matter

3. Nitrogen Dioxide

4. Air Toxics

5. Visibility

6. Nitrogen and Sulfur Deposition

7. Environmental Justice

IV. Proposed Vehicle Emissions Program

A. Tailpipe Emission Standards for Light-Duty Vehicles, Light-Duty Trucks, and Medium-Duty Passenger Vehicles

1. Overview

2. Summary of Proposed FTP and SFTP Tailpipe Standards

3. Proposed FTP Standards

4. Proposed SFTP Standards

5. Feasibility of the Proposed NMOG+NO X and PM Standards

6. Impact of Gasoline Sulfur Control on the Feasibility of the Proposed Vehicle Emission Standards

7. Other Provisions

B. Tailpipe Emissions Standards for Heavy-Duty Vehicles

1. Overview

2. HDV Exhaust Emissions Standards

3. Supplemental FTP Standards for HDVs

4. HDV Emissions Averaging, Banking, and Trading

5. Feasibility of HDV Standards

6. Other HDV Provisions

C. Evaporative Emissions Standards and Onboard Diagnostic System Requirements

1. Tier 3 Evaporative Emission Standards

2. Evaporative Emissions Program Structure and Implementation Flexibilities

3. Heavy-Duty Gasoline Vehicle (HDGV) Requirements

4. Test Procedures and Certification Test Fuel

5. Improvements to In-Use Performance of Fuel Vapor Control Systems

6. Other Initiatives

D. Emissions Test Fuel

1. Proposed Changes to Gasoline Emissions Test Fuel

2. Proposed Flexible Fuel Vehicle Test Fuel

3. Proposed Implementation Schedule

4. Potential Implications on CAFE Standards, GHG Standards, and Fuel Economy Labels

5. Consideration of Nonroad, Motorcycle, and Heavy-Duty Engine Emissions Test Fuel

6. Consideration of CNG and LPG Emissions Test Fuel

E. Small-Business Provisions

1. Lead Time for Exhaust and Evaporative Emission Standards

2. Assigned Deterioration Factors

3. Reduced Testing Burden

4. Hardship

5. Applicability of Flexibilities

F. Compliance Provisions

1. Exhaust Emission Test Procedures

2. Reduced Test Burden

3. Miscellaneous Provisions

4. Manufacturer In-Use Verification Testing (IUVP) Requirements

V. Proposed Fuel Program

A. Proposed Tier 3 Gasoline Sulfur Standards

1. Overview

2. Proposed Annual Average Sulfur Standard

3. Per-Gallon Sulfur Caps

B. Refinery Air Permitting Interactions

1. Background on New Source Review Programs

2. Background on NSR Experience Under the Tier 2 Fuel Program

3. Changes in the NSR Permitting Program since Tier 2 Final Rule

4. Assessment of Tier 3 Refinery Changes and Permitting Implications

5. New Source Performance Standards and National Emission Standards for Hazardous Air Pollutants for Refineries

6. Steps for Streamlining the Permitting Process

C. Standards for Denatured Fuel Ethanol and Other Oxygenates

D. Standards for Fuel Used in Flexible Fueled Vehicles

1. Standards for E51-83

2. Standards for Mid-Level Ethanol Blends (E16-50)

E. Proposed Program Flexibilities

1. Averaging, Banking, and Trading Program

2. Regulatory Flexibility Provisions

3. Provisions for Refiners Facing Hardship Situations

F. Compliance Provisions

1. Registration, Reporting, and Recordkeeping Requirements

2. Sampling and Testing Requirements

3. Small Refiner Compliance

4. Small Volume Refinery Compliance

5. Attest Engagements, Violations, and Penalties

6. Special Fuel Provisions and Exemptions

G. Statutory Authority for Proposed Tier 3 Fuel Controls

1. Section 211(c)(1)(A)

2. Section 211(c)(1)(B)

VI. Technical Amendments and Regulatory Streamlining

A. Amendments to 40 CFR Parts 79 and 80

1. Regulatory Streamlining

2. Subpart I Technical Amendments

3. Performance-Based Measurement Systems (PBMS)

4. Downstream Pentane Blending

B. Engine, Vehicle and Equipment Programs

1. Fuel Economy Labeling

2. Removing Obsolete Regulatory Text

3. Motorcycle Driving Schedules

4. Updating Reference Procedures

VII. What are the cost impacts of the proposed rule?

A. Estimated Costs of the Vehicle Standards

B. Estimated Costs of the Fuel Program

1. Overview

2. Methodology

3. Summary of Costs Without ABT Program

4. Summary of Costs With ABT Program

5. Other Cost Estimates

C. Summary of Proposed Program Costs

D. Cost per Ton of Emissions Reduced

VIII. What are the estimated benefits of the proposed rule?

A. Overview

B. Quantified Human Health Impacts

C. Monetized Benefits

D. What are the limitations of the benefits analysis?

E. Illustrative Analysis of Monetized Impacts Associated With the Proposal in 2017

IX. Alternatives Analysis

A. Vehicle Emission Standards

1. Shorter NMOG+NO X Standard Phase-in

2. Longer NMOG+NO X Standards Phase-in Due to Early Credits

3. Shorter PM Standards Phase-in

4. NMOG+NO X Standards

5. PM Standards

B. Fuel Sulfur Standards

X. Economic Impact Analysis

A. Introduction

B. Vehicle Sales Impacts

C. Impacts on Petroleum Refinery Sector Production

D. Employment Impacts

1. Employment Impacts in the Auto Sector

2. Refinery Employment Impacts

XI. Public Participation

A. How do I submit comments?

B. How should I submit CBI to the Agency?

C. What should I consider as I prepare my comments for EPA?

D. Will there be a public hearing?

XII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review and Executive Order 13563: Improving Regulation and Regulatory Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

1. Overview

2. Background

3. Reason for Today's Proposed Rule

4. Legal Basis for Agency Action

5. Summary of Potentially Affected Small Entities

6. Potential Reporting, Recordkeeping, and Compliance

7. Related Federal Rules

8. Summary of SBREFA Panel Process and Panel Outreach

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments

G. Executive Order 13045: Protection of Children From Environmental Health Risks and Safety Risks

H. Executive Order 13211: Actions Concerning Regulations That Significantly Affect Energy Supply, Distribution, or Use

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations

XIII. Statutory Provisions And Legal Authority

I. Executive Summary and Overview of Proposed Program Back to Top

A. Introduction

In this action, EPA is proposing a major program designed to reduce air pollution from passenger cars and trucks. This program includes new standards for both vehicle emissions and the sulfur content of gasoline, considering the vehicle and its fuel as an integrated system. We refer to this proposed program as the “Tier 3” vehicle and fuel standards.

This proposed rule is part of a comprehensive approach to address the impacts of motor vehicles on air quality and public health. Over 158 million Americans are currently experiencing unhealthy levels of air pollution, which are linked with respiratory and cardiovascular problems and other adverse health impacts that lead to increased medication use, hospital admissions, emergency department visits, and premature mortality. [1] Motor vehicles are a particularly important source of exposure to air pollution, especially in urban areas. By 2014 we project that in many nonattainment areas, cars and light trucks will contribute 30-45 percent of total nitrogen oxides (NO X) emissions, 20-25 percent of total volatile organic compound (VOC) emissions, and 5-10 percent of total direct particulate matter (PM 2.5) emissions. [2] These compounds form ozone, PM, and other air pollutants, whose health and environmental effects are described in more detail in Section II. Cars and light trucks also continue to be a significant contributor to air pollution directly near roads, with gasoline vehicles accounting for more than 50 percent of near-road concentrations of some criteria and toxic pollutants. [3] More than 50 million people live, work, or go to school in close proximity to high-traffic roadways, and the average American spends more than one hour traveling along roads each day. 4 5 Almost 90 percent of daily trips use personal vehicles. [6]

The standards set forth in this proposed rule would significantly reduce levels of multiple air pollutants (such as ambient levels of ozone, PM, nitrogen dioxide (NO 2), and mobile source air toxics (MSATs)) across the country, with immediate impacts expected due to the proposed sulfur control standards starting in 2017. These reductions would help state and local agencies in their effort to attain and maintain health-based National Ambient Air Quality Standards (NAAQS). Few other national strategies exist that would deliver the same magnitude of multi-pollutant reductions projected to result from the proposed Tier 3 standards. In the absence of additional controls, many areas will continue to have ambient ozone concentrations exceeding the NAAQS in the future. See Section III.C for more details.

The Clean Air Act authorizes EPA to establish emissions standards for motor vehicles to address air pollution that may reasonably be anticipated to endanger public health or welfare (section 202). EPA also has authority to establish fuel controls to address such air pollution (section 211). These statutory authorities are described in Section II.A.

The vehicle and gasoline sulfur standards we are proposing represent a “systems approach” to reducing vehicle-related exhaust and evaporative emissions by addressing the vehicle and fuel as a system. The systems approach enables emission reductions that are both technologically feasible and cost-effective beyond what would be possible looking at vehicle and fuel standards in isolation. We first applied such an approach with our Tier 2 vehicle/gasoline sulfur standards (finalized in 2000). [7] We believe that a similar approach for the proposed Tier 3 standards would be a cost-effective way to achieve substantial additional emissions reductions.

The proposed Tier 3 standards include new light- and heavy-duty vehicle emission standards for exhaust emissions of VOC (specifically, non-methane organic gases, or NMOG), NO X, and PM, as well as evaporative emissions standards. The proposed standards for light-duty vehicle, light-duty truck, and medium-duty passenger vehicle tailpipe emissions are an 80 percent reduction in fleet average NMOG+NO X compared to current standards, and a 70 percent reduction in per-vehicle PM standards. The proposed Tier 3 heavy-duty vehicle tailpipe emissions standards provide reductions in both NMOG+NO X and PM that are on the order of 60 percent, compared to current standards. The proposed evaporative emissions standards represent a 50 percent reduction from current standards.

The vehicle emission standards, combined with the proposed reduction of gasoline sulfur content from the current 30 parts per million (ppm) average down to a 10-ppm average, would result in dramatic emissions reductions for NO X, VOC, direct PM 2.5, carbon monoxide (CO) and air toxics. For example, in 2030, when Tier 3 vehicles would make up the majority of the fleet as well as vehicle miles travelled, NO X and VOC emissions from on-highway vehicles would be reduced by about one quarter, and CO emissions would be reduced by about 30 percent. Emissions of many air toxics would also be reduced by 10 to nearly 40 percent of national emissions from on-highway vehicles. Reductions would continue beyond 2030 as more of the fleet is composed of Tier 3 vehicles. For example, the Tier 3 program would reduce on-highway emissions of NO X and VOC nearly 40 percent by 2050, when Tier 3 vehicles would comprise almost the entire fleet.

Gasoline vehicles depend to a great degree on catalytic converters to reduce levels of pollutants in their exhaust, including NMOG and NO X, as well as PM (specifically, the volatile hydrocarbon fraction), CO, and most air toxics. The catalytic converters become significantly less efficient when sulfur from the gasoline is deposited (adsorbed) onto the precious metals that catalyze the reactions to reduce the emissions. The Tier 2 rulemaking required refiners to take steps to reduce sulfur levels in gasoline by approximately 90 percent, to an average of 30 ppm. As discussed in Section IV.A.6, subsequent research provides a compelling case that even this level of sulfur not only degrades the emission performance of vehicles on the road today, but also inhibits necessary further reductions in vehicle emissions performance to reach the proposed Tier 3 standards. Thus, the proposed Tier 3 10-ppm average sulfur standard is significant in two ways: it enables vehicles designed to the proposed Tier 3 tailpipe exhaust standards to meet these standards in-use for the duration of their useful life, and it facilitates immediate emission reductions from all the vehicles on the road at the time the sulfur controls are implemented. Lower sulfur gasoline also facilitates the development of lower-cost technologies to improve fuel economy. Sulfur in the fuel quickly causes the fuel economy benefits of lean-burn technologies to disappear due to its effect on NOx adsorber operation requiring more fuel to be burned. We are not the first regulatory agency to recognize the need for lower-sulfur gasoline. Agencies in Europe and Japan have already imposed gasoline sulfur caps of 10 ppm, and the State of California is already averaging 10 ppm sulfur with a per gallon cap of 20 ppm. Other states are preempted by the Clean Air Act from adopting new fuel programs to meet air quality objectives. Consequently, they could not receive the air quality benefits of lower sulfur gasoline without federal action.

This proposal is one aspect of a comprehensive national program regulating emissions from motor vehicles. EPA's recent final rule for reducing greenhouse gas (GHG) emissions from light-duty (LD) vehicles starting with model year (MY) 2017 (referred to here as the “2017 LD GHG” standards) is another aspect of this comprehensive program. [8] The Tier 3 proposal addresses interactions with the 2017 LD GHG rule in a manner that aligns implementation of the two actions, to achieve significant criteria pollutant and GHG emissions reductions while providing regulatory certainty and compliance efficiency. As vehicle manufacturers introduce new vehicle platforms for compliance with the GHG standards, they will be able to design them for compliance with the Tier 3 standards at the same time. The proposed Tier 3 standards are also closely coordinated with California's Low Emission Vehicle (LEV III) program to create a vehicle emissions program that would allow automakers to sell the same vehicles in all 50 states. (In December 2012 EPA approved a waiver of Clean Air Act preemption for the California Air Resources Board's (CARB's) LEV III program with compliance beginning in 2015. Ten states have adopted the LEV III program under Section 177 of the Clean Air Act. [9] ) We have worked closely with individual vehicle manufacturers and their trade associations, who have emphasized the importance of a harmonized national program. Together, the Tier 3, 2017 LD GHG, and LEV III standards would maximize reductions in GHGs, criteria pollutants and air toxics from motor vehicles while streamlining programs and enabling manufacturers to design a single vehicle for nationwide sales, thus reducing their costs of compliance. In this way, the Tier 3 proposal responds to the May 21, 2010 Presidential Memorandum that requested that EPA develop a comprehensive approach toward regulating motor vehicles, including consideration of non-GHG emissions standards. [10]

As part of the systems approach to this program, we are considering the future fuels on which vehicles will be operating. In particular, the renewable fuels mandate that was revised by the Energy Independence and Security Act (EISA) and is being implemented through the Renewable Fuel Standards program (RFS2) [11] will result in significant amounts of ethanol-blended gasoline in the implementation timeframe of the proposed Tier 3 program. We are proposing to update the specifications of the certification test fuel with which vehicles demonstrate compliance with emissions standards, in order to better reflect the ethanol content and other properties of gasoline that will be in use.

This section provides an overview of the vehicle- and fuel-related standards we are proposing as well as the impacts of the proposed standards. The public health issues and statutory requirements that have prompted this proposal are described in Section II, and our discussion of how the proposal would reduce emissions and air pollution is presented in Section III. Details of proposed standards and how they would be implemented can be found in Sections IV through VI. Sections VII through X contain our discussion of the proposed standards' technological feasibility and cost, benefits, alternatives and economic impacts.

B. What are the basic components of the proposed program?

In the more than 10 years since EPA finalized the Tier 2 Vehicle Program, manufacturers of light-duty vehicles have continued to develop a wide range of improved technologies capable of reducing key exhaust emissions, especially VOC, NO X, and PM. The California LEV II program has been instrumental in the continuous technology improvements by requiring year after year reductions in the fleet average hydrocarbon levels, in addition to requiring the introduction of advanced exhaust and evaporative emission controls in partial zero emission vehicles (PZEVs). This progress in vehicle technology has made it possible for manufacturers to achieve emission reductions well beyond the requirements of the Tier 2 program if gasoline sulfur levels are lowered further.

As a result, we are proposing new standards for exhaust emissions of NMOG, NO X, and PM, as well as evaporative emissions standards. These standards would phase in beginning with MY 2017. The proposed Tier 3 standards are very similar in structure to those in the existing Tier 2 program. As with the Tier 2 program, the proposed standards would apply to all light-duty vehicles (LDVs, or passenger cars), light-duty trucks (LDT1s, LDT2s, LDT3s, and LDT4s) and Medium-Duty Passenger Vehicles (or MDPVs). We are also proposing separate but closely related standards for heavy-duty vehicles up to 14,000 lbs Gross Vehicle Weight Rating (GVWR). These vehicles were not included in Tier 2 but were made subject to new standards in a final rule that covered the broad heavy-duty sector (66 FR 5002, January 18, 2001). We have concluded that the proposed vehicle emissions standards, in conjunction with the reductions in fuel sulfur also proposed in this action, are feasible across the fleet in the proposed time frame.

In the discussions of the various elements of our proposed program for light- and heavy-duty vehicles throughout this preamble, we describe how the provisions would be consistent with the California Air Resources Board (CARB) LEV III program. Auto manufacturers have stressed to us the importance of their being able to design and produce a single fleet of vehicles in all 50 states that would comply with requirements under the Tier 3 program and the LEV III program, as well as greenhouse gas/Corporate Average Fuel Economy (CAFE) requirements in the same timeframe. Consistency among the federal and California programs means that special versions of vehicles with different emission control hardware and calibrations would not be necessary for different geographic areas. This would allow manufacturers to avoid the additional costs of parallel design, development, calibration, and manufacturing. Consistency among programs would also eliminate the need to supply aftermarket parts for repair of multiple versions of a vehicle. To that end, we worked closely with CARB and with the vehicle manufacturers, both with individual companies and with their trade associations, to align the two programs in most respects.

We have also designed the proposed Tier 3 program to be implemented in the same timeframe as the federal and California GHG emissions and fuel economy standards for model years 2017-2025. We expect that in response to these programs, manufacturers will be developing entirely new powertrains for most of their vehicles. Because the Tier 3 standards would phase in over the same timeframe, manufacturers would be in a position to simultaneously respond to all of these requirements.

1. Proposed Standards for Light-Duty Vehicle, Light-Duty Truck, and Medium-Duty Passenger Vehicle Tailpipe Emissions

We are proposing a comprehensive program that would include new fleet-average standards for the sum of NMOG and NO X tailpipe emissions (presented as NMOG+NO X) and for PM. [12] These proposed standards, when applied in conjunction with reduced gasoline sulfur content, would result in very significant improvements in vehicle emissions from the levels of the Tier 2 program. For these pollutants, we are proposing standards as measured on test procedures that represent a range of vehicle operation, including the Federal Test Procedure (or FTP, simulating typical driving) and the Supplemental Federal Test Procedure (or SFTP, a composite test simulating higher temperatures, higher speeds, and quicker accelerations). In addition to the standards, we are also proposing to extend the regulatory useful life period during which the standards apply and to make test fuel more representative of expected real-world fuel (see Section I.B.5 below).

As discussed in Section IV.A.6., the impact of gasoline sulfur poisoning on exhaust catalyst performance provides a compelling argument, particularly for larger vehicles and trucks, that these vehicle standards would be achievable only with a reduction of gasoline sulfur content from the current 30-ppm average down to a 10-ppm average. Sulfur is a well-known catalyst poison. The nature of sulfur's interactions with active catalytic materials is complex and varies with catalyst composition, exhaust gas composition and exhaust temperature. Thus, even if a manufacturer were able to certify a new vehicle to the proposed new stringent standards, the manufacturer's ability to maintain the emission performance of that vehicle in-use is greatly jeopardized if the vehicle is being operated on gasoline sulfur levels greater than 10 ppm. Vehicle manufacturers, both individually and through their trade associations, have emphasized that reduced gasoline sulfur would be required to meet the proposed standards. 13 14 Due to the variation in actual vehicle operation, any amount of gasoline sulfur will deteriorate catalyst efficiency. However, we believe that a 10-ppm average sulfur level is sufficiently low to enable compliance with these proposed Tier 3 vehicle standards, and as described below and in Section V, reducing sulfur levels further would cause sulfur control costs to quickly escalate.

The proposed FTP and SFTP NMOG+NO X standards would be fleet-average standards, meaning that a manufacturer would calculate the average emissions of the vehicles it sells in each model year and compare that average to the applicable standard for that model year. The manufacturer would certify each of its vehicles to a per-vehicle “bin” standard (see Section IV.A.2) and sales-weight these values to calculate its fleet-average NMOG+NO X emissions for each model year. The proposed fleet average standards for NMOG+NO X evaluated over the FTP are summarized in Table I-1. The standards for light-duty vehicles would begin in MY 2017 at a level representing a 46 percent reduction from the current Tier 2 requirements. (For vehicles over 6000 lbs GVWR, the standards would apply beginning in MY 2018). As shown, these proposed fleet-average standards would decline during the first several years of the program, becoming increasingly stringent until ultimately reaching an 81 percent reduction when the transition is complete. The proposed FTP NMOG+NO X program includes two separate sets of declining fleet-average standards, with LDVs and small light trucks (LDT1s) in one grouping and heavier light trucks (LDT2s, LDT3s, LDT4s) and MDPVs in a second grouping, that would converge at 30 milligram per mile (mg/mi) in MY 2025 and later. [15]

Manufacturers could also earn credits for fleet average NMOG+NO X levels below the applicable standard in any model year. Credits that were previously banked or obtained from other manufacturers could be used, or credits could be transferred to other manufacturers (see Section IV.A.7.a). Unused credits would expire after 5 model years. Manufacturers would also be allowed to carry deficits in their credit balance for up to 3 model years.

Table I-1—Proposed LDV, LDT, and MDPV Fleet Average NMOG+NO X FTP Standards Back to Top
Model year
2017a 2018 2019 2020 2021 2022 2023 2024 2025 and later
[mg/mi]
aFor vehicles above 6000 lbs GVWR, the fleet average standards would apply beginning in MY 2018.
bThese proposed standards would apply for a 150,000 mile useful life. Manufacturers could choose to certify all of their LDVs and LDT1s to a useful life of 120,000 miles. If any of these families are certified to the shorter useful life, a proportionally lower numerical fleet-average standard would apply, calculated by multiplying the respective 150,000 mile standard by 0.85 and rounding to the nearest mg. See Section IV.A.7.b.
LDV/LDT1b 86 79 72 65 58 51 44 37 30
LDT2,3,4 and MDPV 101 92 83 74 65 56 47 38 30

Similarly, the proposed NMOG+NO X standards measured over the SFTP would be fleet-average standards, declining from MY 2017 until MY 2025, as shown in Table I-2. In this case, the same standards would apply to both lighter and heavier vehicles. In MY 2025, the SFTP NMOG+NO X standard would reach its final fleet average level of 50 mg/mi.

Table I-2—Proposed LDV, LDT, and MDPV Fleet Average NMOG+NO X SFTP Standards Back to Top
Model year
2017a 2018 2019 2020 2021 2022 2023 2024 2025 and later
[mg/mi]
aFor vehicles above 6000 lbs GVWR, the fleet average standards would apply beginning in MY 2018.
NMOG + NO X 103 97 90 83 77 70 63 57 50

We are also proposing PM standards as part of this Tier 3 program, both on the FTP and US06 cycles (US06 is a component of the SFTP test). Research has demonstrated that the level of PM from gasoline light-duty vehicles is more significant than previously thought. [16] Although many vehicles today are performing at or near the levels of the proposed standards, the data indicate that improvements, especially in high-load fuel control and in the durability of engine components, are possible.

Under typical driving, as simulated by the FTP, the PM emissions of most current-technology gasoline vehicles are fairly low at certification and in use, well below the Tier 2 p.m. standards. At the same time we see considerable variation in PM emissions among vehicles of various makes, models, and designs. As a result, we are proposing a new FTP PM standard that is set to ensure that all new vehicles perform at the level already being achieved by well-designed Tier 2 emission control technologies. The proposed PM standards would apply to each vehicle separately (i.e., not as a fleet average). Also, in contrast to the declining NMOG+NO X standards, the proposed PM standard on the FTP for certification testing is 3 mg/mi for all vehicles and for all model years. As for the NMOG+NO X standards, for vehicles over 6000 lbs GVWR, the FTP PM standard would apply beginning in MY 2018. Manufacturers could phase in their vehicle models as a percent of U.S. sales through MY 2022. Most vehicles are already performing at this stringent PM level, and the primary intent of the proposed standard is to bring all light-duty vehicles to the typical level of PM performance being demonstrated by the current light-duty fleet.

The proposed program also includes a separate in-use FTP PM standard of 6 mg/mi for the testing of in-use vehicles that would apply during the percent phase-in period only. This in-use standard would address the uncertainties that accompany the introduction of new technologies, and then expire. Table I-3 presents the FTP certification and in-use PM standards and the phase-in percentages. The proposed standards represent a significant numerical reduction from the Tier 2 p.m. emission standards of 10 mg/mi for light-duty vehicles.

Table I-3—Phase-In for Proposed FTP PM Standards Back to Top
2017a 2018 2019 2020 2021 2022 and later
aFor vehicles above 6000 lbs GVWR, the proposed FTP PM standards would apply beginning in MY 2018.
Phase-In (percent of U.S. sales). 20 20 40 70 100 100
Certification Standard (mg/mi) 3 3 3 3 3 3
In-Use Standard (mg/mi). 6 6 6 6 6 3

Finally, the proposed Tier 3 program includes certification PM standards evaluated over the SFTP (specifically the US06 component of the SFTP procedure) at a level of 10 mg/mi for lighter vehicles and 20 mg/mi for heavier vehicles. PM levels over the SFTP are typically higher than the PM emitted over the FTP due to the increased load on the vehicle. Test data show that most current light-duty vehicles are already performing in the range of the proposed standard. As in the case of the FTP PM standards, the intent of the proposed standard is to bring the emission performance of all vehicles to that already being demonstrated by many vehicles in the current light-duty fleet.

As with the FTP PM standard, we propose separate in-use US06 p.m. standards during the percent phase-in only, of 15 and 25 mg/mi for vehicles up to and above 6,000 lbs (lbs) GVWR, respectively. The US06 p.m. standards would also phase in on the same schedule as the FTP PM standards, reaching 100 percent of each company's U.S. sales by MY 2022.

2. Proposed Heavy-Duty Vehicle Tailpipe Emissions Standards

As discussed in detail in Section IV.B, we are proposing Tier 3 exhaust emissions standards for complete heavy-duty vehicles (HDVs) between 8,501 and 14,000 lb GVWR. Vehicles in this GVWR range are often referred to as Class 2b (8,501-10,000 lb) and Class 3 (10,001-14,000 lb) vehicles, and are typically full-size pickup trucks and work vans. Most are built by companies with even larger light-duty truck markets, and as such they frequently share major design characteristics and potential emissions control technologies with their LDT counterparts. However, in contrast to the largely gasoline-fueled LDT fleet, roughly half of the HD pickup and van fleet in the U.S. is diesel-fueled, which is a consideration in setting emissions standards, as diesel engine emissions and control strategies differ from those of gasoline engines.

The key elements of the proposed Tier 3 program for HDVs would parallel those proposed for passenger cars and LDTs, with adjustments in standards levels, emissions test requirements, and implementation schedules, appropriate to this sector. These key elements include a combined NMOG+NO X declining fleet average standard, new stringent PM standards phasing in on a separate schedule, adoption of a 15 percent ethanol by volume (E15) certification test fuel for gasoline-fueled vehicles, extension of the regulatory useful life to 150,000 miles or 15 years (whichever occurs first), and a new requirement to meet standards over an SFTP that would address real-world driving modes not well-represented by the FTP cycle alone.

We are proposing the separate Class 2b and Class 3 fleet average NMOG+NO X standards shown in Table I-4. The proposed standards would become more stringent in successive model years from 2018 to 2022, with voluntary standards made available in 2016 and 2017, all of which would be set at levels that match those of California's LEV III program for these classes of vehicles. Each covered HDV sold by a manufacturer in each model year would contribute to this fleet average based on the mg/mi NMOG+NO X level of the emission level (“bin”) declared for it by the manufacturer. Manufacturers could also earn credits for fleet average NMOG+NO X levels below the standard in any model year. Tier 3 credits that were previously banked, obtained from other manufacturers, or transferred across the Class 2b/Class 3 categories could be used to help demonstrate compliance. Unused credits would expire after 5 model years. Manufacturers would also be allowed to carry deficits in their credit balance for up to 3 model years.

Table I-4—Proposed HDV Fleet Average NMOG+NO X Standards Back to Top
[mg/mi]
Voluntary Required program.
Model Year 2016 2017 2018 2019 2020 2021 2022 and later.
Class 2b 333 310 278 253 228 203 178.
Class 3 548 508 451 400 349 298 247.

We are proposing PM standards of 8 mg/mi and 10 mg/mi for Class 2b and Class 3 HDVs, respectively, phasing in as an increasing percentage of a manufacturer's sales per year. We are proposing the same phase-in schedule as proposed for the light-duty sector during model years 2018-2019-2020-2021: 20-40-70-100 percent, respectively, and a more flexible but equivalent alternative PM phase-in is also being proposed. Tier 3 HDVs would also be subject to more stringent CO and formaldehyde exhaust emissions standards.

Finally, we are proposing first-ever SFTP standards for HDVs to ensure a robust overall control program that precludes high off-FTP cycle emissions by having vehicle designers consider them in their choice of compliance strategies. As for light-duty vehicles, we are proposing that SFTP compliance be based on a weighted composite of measured emissions from testing over the FTP cycle, the SC03 cycle, and an aggressive driving cycle, with the latter tailored to various HDV sub-categories: the US06 cycle for most HDVs, the highway portion of the US06 cycle for low power-to-weight Class 2b HDVs, and the LA-92 (or “Unified”) cycle for Class 3 HDVs. The proposed SFTP standards are the same as those adopted for California LEV III vehicles, and would apply to NMOG+NO X, PM, and CO emissions.

Overall, we expect the Tier 3 program we are proposing for HDVs to result in substantial reductions in harmful emissions from this large fleet of work trucks and vans. The final Tier 3 standards levels for NMOG+NO X and PM are on the order of 60 percent lower than the current stringent standards that took full effect in the 2009 model year.

3. Proposed Evaporative Emission Standards

Gasoline vapor emissions from vehicle fuel systems occur when a vehicle is in operation, when it is parked, and when it is being refueled. These evaporative emissions, which occur on a daily basis from gasoline-powered vehicles, are primarily functions of temperature, fuel vapor pressure, and activity. EPA first instituted evaporative emission standards in the early 1970s to address emissions when vehicles are parked after being driven. These are commonly referred to as hot soak plus diurnal emissions. Over the subsequent years the test procedures have been modified and improved and the standards have become more numerically stringent. We have addressed emissions which arose from new fuel system designs by putting in place new requirements such as running loss emission standards and test procedure provisions to address permeation emissions. Subsequently standards were put in place to control refueling emissions from all classes of gasoline-powered motor vehicles up to 10,000 lbs GVWR. Even though evaporative and refueling emission control systems have been in place for most of these vehicles for many years, they still contribute about 30-40 percent of the summer on-highway mobile source hydrocarbon inventory. These fuel vapor emissions are ozone and PM precursors, and also contain air toxics such as benzene.

To control evaporative emissions, EPA is proposing more stringent standards that would require covered vehicles to have essentially zero fuel vapor emissions in use. These include more stringent evaporative emissions standards, new test procedures, and a new fuel/evaporative system leak emission standard. The program also includes refueling emission standards for a portion of heavy-duty gasoline vehicles (HDGVs) over 10,000 lbs GVWR. EPA is proposing phase-in flexibilities as well as credit and allowance programs. The proposed standards, harmonized with California's “zero evap” standards, are designed to essentially allow for a use of common technology in vehicle models sold throughout the U.S. The level of the standard remains above zero to account for nonfuel background emissions from the vehicle hardware itself.

Requirements to meet the Tier 3 evaporative emission regulations would phase-in over a six model year period. We are proposing two options for the 2017 model year, but after that the sales percentage requirements are 60 percent for MYs 2018 and 2019, 80 percent for model years 2020 and 2021, and 100 percent for model years 2022 and later. In Table I-5 we present the proposed evaporative diurnal plus hot soak emission standards by vehicle class. The standards are approximately a 50 percent reduction from the existing standards. To enhance flexibility and reduce costs, EPA is proposing a program that would allow manufacturers to generate allowances through early certifications (basically before the 2017 model year) and to demonstrate compliance using averaging concepts. Manufacturers may comply on average within each of the four vehicle categories, but not across these categories. EPA is not proposing any changes to the existing light-duty running loss or refueling emission standards, with the exception of the certification test fuel requirement discussed in Section I.B.5 below.

Table I-5—Proposed Evaporative Emission Standards Back to Top
Vehicle class Highest diurnal + hot soak level (over both 2-day and 3-day diurnal tests)
[g/test]
LDV, LDT1 0.300
LDT2 0.400
LDT3, LDT4, MDPV 0.500
HDGVs 0.600

EPA is proposing a new testing requirement referred to as the bleed emission test procedure to help ensure fuel vapor emissions are eliminated. Under this proposal, manufacturers would be required to measure diurnal emissions over the 2-day diurnal test procedure from just the fuel tank and the evaporative emission canister and comply with a 0.020 gram per test (g/test) standard for all LDVs, LDTs, and MDPVs, without averaging. The corresponding canister bleed test standard for HDGVs would be 0.030 g/test. The proposed Tier 3 evaporative emission standards would be phased in over a period of six model years between MY 2017 and MY 2022, with the leak test phasing in beginning in 2018.

Data from in-use evaporative emissions testing indicates that vapor leaks from vehicle fuel/evaporative systems are found in the fleet and that even very small leaks have the potential to make relatively significant contributions to the mobile source VOC inventory. To help address this issue, we are also proposing to add a new emission standard and test procedure to control vapor leaks from vehicle fuel and vapor control systems. The standard would prohibit leaks with a cumulative equivalent diameter of 0.02 inches or greater. We are proposing to add this simple and inexpensive test and emission standard to help ensure vehicles maintain zero fuel vapor emissions over their full useful life. New LDV, LDT, MDPV, and HDGV equal to or less than 14.000 lbs GVWR meeting the proposed Tier 3 evaporative emission regulations would also be required to meet the leak emission standard beginning in the 2018 model year. The requirement to meet the leak emission standard would phase-in on the same percentage of sales schedule as the proposed Tier 3 evaporative emission standard. Manufacturers would comply with the leak emission standard during certification and in use. EPA is not proposing that the leak emission standard apply to HDGVs above 14,000 lbs GVWR.

EPA is also proposing new refueling emission control requirements for all HDGVs equal to or less than 14,000 lbs GVWR (i.e., Class 2b/3 HDGVs), starting in the 2018 model year. EPA is proposing to include these vehicles as part of the same basic implementation scheme used for LDVs and LDTs. The current refueling emission control requirements apply to complete Class 2b HDGVs, and EPA is proposing to extend those requirements to Class 3 HDGVs as well, since the fuel and evaporative control systems on these vehicles are very similar to those on their slightly lighter-weight Class 2b counterparts.

4. Onboard Diagnostic Systems (OBD)

EPA and CARB both have OBD regulations applicable to the vehicle classes covered by the proposed Tier 3 emission standards. In the past the requirements have been very similar, so most manufacturers have met CARB OBD requirements and, as permitted in our regulations, EPA has generally accepted compliance with CARB's OBD requirements as satisfying EPA's OBD requirements. Over the past several years CARB has upgraded its requirements to help improve the effectiveness of OBD in ensuring good in-use exhaust and evaporative system emissions performance. We have reviewed these provisions and agree with CARB that these revisions will help to improve in-use emissions performance, while at the same time harmonizing with the CARB program. Toward that end, we are proposing to adopt and incorporate by reference the current CARB OBD regulations effective for the 2017 MY. We are also proposing two specific additions to enhance the implementation of the leak emission standard. EPA would retain the provision that certifying with CARB's program would permit manufacturers to seek a separate EPA certificate on that basis.

5. Emissions Test Fuel

In-use gasoline has changed considerably since EPA's test fuel specifications were first set and last revised. Gasoline sulfur and benzene have been reduced and, perhaps most importantly, gasoline containing 10 percent ethanol by volume (E10) has replaced clear gasoline (E0) across the country. This has had second-order effects on other gasoline properties. In-use fuel is projected to continue to change with the implementation of the RFS2 program (e.g., the potential expansion of the number of retailers that offer gasoline containing 15 percent ethanol by volume (E15)) as well as today's proposed Tier 3 gasoline sulfur program.

As a result, we are proposing to update our federal emissions test fuel to better match today's in-use gasoline and also to be forward-looking with respect to future ethanol and sulfur content. The new test fuel specifications would apply to new vehicle certification, assembly line, and in-use testing. EPA is also proposing changes consistent with CARB's LEV III emissions test fuel specifications. Key changes include:

  • Moving away from “Indolene” (E0) to an E15 test fuel;
  • Lowering octane to match regular-grade gasoline (except for premium-required vehicles);
  • Adjusting distillation temperatures, aromatics, and olefins to better match today's in-use fuel and to be consistent with anticipated E15 composition; and
  • Lowering the existing sulfur specification and setting a benzene specification to be consistent with proposed Tier 3 gasoline sulfur requirements and recent MSAT2 gasoline benzene requirements. [17]

The proposed E15 emissions test fuel specifications are detailed in Section IV.D.1 as well as § 1065.710 of the proposed regulations. For more information on how we arrived at the proposed fuel parameters and ASTM test methods, refer to Chapter 3 of the draft Regulatory Impact Analysis (RIA).

In addition to proposing a new E15 emissions test fuel, we are also proposing for the first time detailed specifications for the E85 emissions test fuel used for flexible fuel vehicle (FFV) certification, as discussed in Section IV.D.2. [18] This is intended to avoid uncertainty and confusion in the certification of FFVs designed to operate on ethanol levels up to 83 percent. Furthermore, we are proposing to allow vehicle manufacturers to request approval for an alternative certification fuel such as a high-octane 30 percent ethanol by volume (E30) blend for vehicles they might design or optimize for use on such a fuel. This could help manufacturers that wish to raise compression ratios to improve vehicle efficiency, as a step toward complying with the 2017 and later light-duty greenhouse gas and CAFE standards (2017 LD GHG). This in turn could help provide a market incentive to increase ethanol use beyond E10 by overcoming the disincentive of lower fuel economy associated with increasing ethanol concentrations in fuel, and enhance the environmental performance of ethanol as a transportation fuel by using it to enable more fuel efficient engines.

In addition to seeking comment on all aspects of the proposed new emission test fuel requirements, we also seek comment on whether there are other aspects of today's proposed standards that, if modified, might provide an incentive for, or remove obstacles to, the development of highly efficient vehicles optimized for use on higher level ethanol blends.

6. Fuel Standards

Under the Tier 3 fuel program, we are proposing that gasoline and any ethanol-gasoline blend contain no more than 10 ppm sulfur on an annual average basis by January 1, 2017. Similar to the Tier 2 gasoline program, the proposed Tier 3 program would apply to gasoline in the U.S. and the U.S. territories of Puerto Rico and the Virgin Islands, excluding California. The proposed program would result in gasoline that contains, on average, two-thirds less sulfur than it does today. In addition, following discussions with numerous refiners and other segments of the fuel market (e.g., pipelines, terminals, marketers, ethanol industry representatives, transmix processors, additive manufacturers), we are proposing a Tier 3 fuel program that contains considerable flexibility to ease both initial and long-term implementation of the program. We are proposing an averaging, banking, and trading (ABT) program that would allow refiners and importers to spread out their investments through an early credit program and rely on ongoing nationwide averaging to meet the 10-ppm sulfur standard. We are also proposing a three-year delay for small refiners and “small volume refineries” processing less than or equal to 75,000 barrels of crude oil per day. As a result of the early credit program, even considering the proposed ABT program and flexibilities offered to small refiners and small volume refineries, we anticipate considerable reductions in gasoline sulfur levels prior to 2017, with final refinery control to the 10-ppm average occurring by January 1, 2020. For more on the proposed gasoline sulfur program flexibilities, refer to Section V.D.

Under today's Tier 3 gasoline sulfur program, we are proposing to either maintain the current 80-ppm refinery gate and 95-ppm downstream per-gallon caps or lower them to 50 and 65 ppm, respectively. We also evaluated and are seeking comment on the potential of lowering the per-gallon caps to as low as 20 and 25 ppm. There are advantages and disadvantages with each of the various sulfur cap options (explained in more detail in Section V.A.3), but under all scenarios, the stringency of the 10-ppm annual average standard would result in reduced gasoline sulfur levels nationwide. A summary of the proposed Tier 3 sulfur standards is provided in Table I-6.

Table I-6—Proposed Tier 3 Gasoline Sulfur Standards Back to Top
Proposed Tier 3 gasoline sulfur standards Cap Option 1 Cap Option 2
Limit Effective Limit Effective
aEffective January 1, 2020 for eligible small refiners and small volume refineries.
Refinery annual average standard 10 ppm January 1, 2017a 10 ppm January 1, 2017.a
Refinery gate per-gallon cap 80 ppm Already 50 ppm January 1, 2020.
Downstream per-gallon cap 95 ppm Already 65 ppm March 1, 2020.

We are proposing that manufacturers of gasoline additives that are used downstream of the refinery at less than 1 volume percent must limit the sulfur contribution to the finished gasoline from the use of their additive to less than 3 ppm when the additive is used at the maximum recommended treatment rate.

The proposed vehicle emissions standards are fuel neutral (i.e. they are applicable regardless of the type of fuel that the vehicle is designed to use). The sulfur content of highway diesel fuel is already required to meet a 15ppm sulfur cap. Thus, no further action is needed to enable diesel fuel vehicles to meet the proposed emissions standards. There currently are no sulfur standards for the fuel used in compressed natural gas (CNG) and liquid propane gas (LPG) vehicles. We request comment on whether it is necessary for EPA to establish sulfur standards for CNG and LPG, and whether a 15 ppm sulfur cap similar to that established for highway diesel fuel would be appropriate. Comment is also requested on whether and how to address the sulfur contribution from odorants and other additives used in CNG and LPG.

As the number of flex-fuel vehicles (FFVs) in the in-use fleet increases, it is now becoming increasingly important that all fuels used in FFVs, not just gasoline, meet fuel quality standards. A lack of clarity regarding the standards that apply to fuels used in FFVs could act to impede the further expansion of ethanol blended fuels with concentrations greater than 15 volume percent, which is important to satisfying the requirements of the RFS2 program. For these reasons, we believe it is important that our gasoline quality standards for not only sulfur, but also benzene, RVP, detergency, and chemical composition (i.e., contains only carbon, hydrogen, oxygen, nitrogen, and sulfur) apply to any fuel used in an FFV. At the same time, it is not necessarily clear how we should implement such standards within the context of our existing regulations as these fuels tend to be produced downstream of the petroleum refinery. For this reason we are seeking comment on both the need to extend our gasoline standards to all gasoline-ethanol blends, as well as the appropriate regulatory mechanisms for doing so.

7. Regulatory Streamlining and Technical Amendments

We are proposing and requesting comment in this action on a number of items to help streamline the in-use fuels regulations at 40 CFR part 80. The majority of items involve clarifying vague or inconsistent language, removal or updating of outdated provisions, and decrease in frequency and/or volume of reporting burden where data are no longer needed or are redundant with other EPA fuels programs. In general, we believe that these changes would reduce burden on industry and allow us to achieve the standards and resulting environmental benefits as early as possible with no expected loss in environmental control. In some cases, these regulatory streamlining items are non-substantive amendments that correct minor errors or inconsistencies in the regulations.

The regulatory streamlining items that we are proposing for the in-use fuels regulations are changes that we believe are straightforward and should be made quickly. In addition, there are a number of items that we believe need further consideration and discussion on which we are seeking comment.

The proposal also includes a variety of technical amendments to certification-related requirements for engine and vehicle emission standards. We are proposing to revise the fuel economy labeling requirements to correspond to the new Tier 3 standards. We are also proposing to remove obsolete regulatory text and make several minor corrections and clarifications.

Please refer to Section VI for a complete discussion of technical amendments and regulatory streamlining provisions and issues.

C. What would the impacts of the proposed standards be?

The proposed Tier 3 vehicle and fuel standards together would reduce dramatically emissions of NO X, VOC, PM 2.5, and air toxics. The gasoline sulfur standards, which would take effect in 2017, would provide large immediate reductions in emissions from existing gasoline vehicles and engines. NO X emissions would be reduced by about 284,000 tons, or about 8 percent of emissions from on-highway vehicles, in 2017 alone. The emission reductions would increase over time as newer vehicles become a larger percentage of the fleet. In 2030, when 80 percent of the light-duty fleet (and 90 percent of the vehicle miles travelled) consists of Tier 3 vehicles, we expect the NO X and VOC emissions to be reduced by about 525,000 tons and 226,000 tons, respectively, or one quarter of emissions from on-highway vehicles compared to their 2030 levels without the Tier 3 program. Emissions of CO would decrease by almost 6 million tons, or 30 percent of emissions from on-highway vehicles. Emissions of many air toxics would also be reduced, including benzene, 1,3-butadiene, acetaldehyde, formaldehyde, acrolein and ethanol, with reductions ranging from 10 to nearly 40 percent of national emissions from on-highway vehicles. We expect these reductions to continue beyond 2030 as more of the fleet continues to turn over to Tier 3 vehicles; for example, by 2050, when nearly all of the fleet would have turned over to Tier 3 standards, we estimate the Tier 3 program would reduce on-highway emissions of NO X and VOC nearly 40 percent from the level of emissions projected without Tier 3 controls. [19]

These reductions in emissions of NO X, VOC, PM 2.5 and air toxics from the proposed Tier 3 standards are projected to lead to significant decreases in ambient concentrations of ozone, PM 2.5 and air toxics (including notable nationwide reductions in benzene concentrations) by 2030, and would immediately reduce ozone in 2017 when the proposed sulfur controls take effect. Additional information on the emission and air quality impacts of the proposed Tier 3 program is presented in Sections III.B and C.

Exposure to ambient concentrations of ozone, PM 2.5, and air toxics is linked to adverse human health impacts such as premature deaths as well as other important public health and environmental effects (see Section II.B). The proposed Tier 3 standards would reduce these adverse impacts and yield significant benefits, including those we can monetize and those we are unable to quantify. We estimate that by 2030, the annual emission reductions of the Tier 3 standards would annually prevent between 670 and 1,700 PM-related premature deaths, between 160 and 710 ozone-related premature deaths, 81,000 work days lost, and approximately 1.4 million minor restricted-activity days. The estimated annual monetized health benefits of the proposed Tier 3 standards in 2030 (2010$) would be between $8.0 and $23 billion, assuming a 3-percent discount rate (or between $7.4 billion and $21 billion assuming a 7-percent discount rate). [20] The proposed fuel standards are projected to cost on average less than one cent per gallon of gasoline, and the proposed light-duty vehicle standards would have an average cost that increases in proportion to the increase in stringency from $50 per vehicle in 2017 to $134 per vehicle when the standards are fully phased in 2025. The annual cost of the overall program in 2030 would be approximately $3.4 billion. [21] The 2030 benefits are 2 to 7 times the costs of the program.

The benefits in Table I-7 include all of the human health impacts we are able to quantify and monetize at this time. However, the full complement of human health and welfare effects associated with PM, ozone and air toxics remain unquantified because of current limitations in methods and/or available data. As a result, the health benefits quantified in this section are likely underestimates of the total benefits attributable to the proposed standards. See Sections VII and VIII for detailed descriptions of the costs and benefits of this proposal.

Table I-7—Summary of Annual Benefits and Costs Associated With the Proposed Tier 3 Program Back to Top
Description 2030
[Billions, 2010$]a
aAll estimates represent annual benefits and costs anticipated for the year 2030. Totals are rounded to two significant digits and may not sum due to rounding.
bThe calculation of annual costs does not require amortization of costs over time. Therefore, the estimates of annual cost do not include a discount rate or rate of return assumption (see Section VII of the preamble for more information on vehicle and fuel costs). The program costs include the costs associated with the Tier 3 vehicle and fuel standards in all states except California.
cThe benefits presented in this table have been adjusted to remove benefits of the Tier 3 program in California.
dTotal includes ozone and PM 2.5 benefits. Range was developed by adding the estimate from the Bell et al., 2004 ozone premature mortality function to PM 2.5-related premature mortality derived from the American Cancer Society cohort study (Pope et al., 2002) for the low estimate and ozone premature mortality derived from the Levy et al., 2005 study to PM 2.5-related premature mortality derived from the Six-Cities (Laden et al., 2006) study for the high estimate.
eAnnual benefits analysis results reflect the use of a 3 percent and 7 percent discount rate in the valuation of premature mortality and nonfatal myocardial infarctions, consistent with EPA and OMB guidelines for preparing economic analyses.
fValuation of premature mortality based on long-term PM exposure assumes discounting over the SAB recommended 20-year segmented lag structure described in the Regulatory Impact Analysis for the 2006 PM National Ambient Air Quality Standards (September, 2006).
gNot all possible benefits are quantified and monetized in this analysis; the total monetized benefits presented here may therefore be underestimated. Potential benefit categories that have not been quantified and monetized, due to current limitations in methods and/or data availability, are listed in Table VIII-2. For example, we have not quantified a number of known or suspected health and welfare effects linked with reductions in ozone and PM (e.g., reductions in heart rate variability, reduced material damage to structures and cultural monuments, and reduced eutrophication in coastal areas). We are also unable to quantify health and welfare benefits associated with reductions in air toxics.
Vehicle Program Costs $2.1
Fuels Program Costs 1.3
Total Estimated Costsb 3.4
Total Estimated Health Benefits c d e f g
3 percent discount rate $8.0-$23
7 percent discount rate 7.4-21
Annual Net Benefits (Total Benefits—Total Costs):
3 percent discount rate 4.6-20
7 percent discount rate 4.0-18

II. Why is EPA making this proposal? Back to Top

The Clean Air Act authorizes EPA to establish emissions standards for motor vehicles to address air pollution that may reasonably be anticipated to endanger public health or welfare. EPA also has authority to establish fuel controls to address such air pollution. These statutory requirements are described in Section II.A.

Emissions from motor vehicles and their fuels contribute to ambient levels of ozone, PM, NO 2, sulfur dioxide (SO 2) and CO, which are all pollutants for which EPA has established health-based NAAQS. These pollutants are linked with respiratory and/or cardiovascular problems and other adverse health impacts leading to increased medication use, hospital admissions, emergency department visits, and premature mortality. Over 158 million people currently live in areas designated nonattainment for one or more of the current NAAQS. [22]

Motor vehicles also emit air toxics, and the majority of Americans continue to be exposed to ambient concentrations of air toxics at levels which have the potential to cause adverse health effects, including cancer, immune system damage, and neurological, reproductive, developmental, respiratory, and other health problems. [23] A more detailed discussion of the health and environmental effects of these pollutants is included in Section II.B.

Cars and light trucks also continue to be a significant contributor to air pollution directly near roads, with gasoline vehicles accounting for more than 50 percent of near-road concentrations of some criteria and toxic pollutants. [24] More than 50 million people live, work, or go to school in close proximity to high-traffic roadways, and the average American spends more than one hour traveling each day, with nearly 90 percent of daily trips occurring by personal vehicle. 25 26 27 Exposure to traffic-related pollutants has been linked with adverse health impacts such as respiratory problems (particularly in asthmatic children) and cardiovascular problems.

In the absence of additional controls such as Tier 3 standards, many areas will continue to have ambient ozone and PM 2.5 concentrations exceeding the NAAQS in the future. States and local areas are required to adopt control measures to attain the NAAQS and, once attained, to demonstrate that control measures are in place sufficient to maintain the NAAQS for ten years (and eight years later, a similar demonstration is required for another ten-year period). The proposed Tier 3 standards would be a critical part of areas' strategies to attain and maintain the standards. Maintaining the standards has been challenging in the past, particularly for areas where high population growth rates lead to significant annual increases in vehicle trips and vehicle miles traveled. Our air quality modeling for this proposal, which is described in more detail in Section III.C, projects that in 2017 a significant number of counties outside CA will be within 10 percent of the 2008 ozone NAAQS, in the absence of additional controls. These counties in particular would benefit from the proposed Tier 3 standards as they work to ensure long-term maintenance of the NAAQS.

Section III provides more detail on how this proposal would reduce motor vehicle emissions and ambient levels of pollution. The proposed rule would meaningfully reduce ozone concentrations as early as 2017 (the first year of the program), and even more significantly in 2030. The reductions are of significant enough magnitude to bring ozone levels in some counties from above the standard to below the standard, even without any additional controls. We also project that the Tier 3 standards would reduce ambient PM 2.5 concentrations.

Without this proposal to reduce nationwide motor vehicle emissions, areas would have to adopt other measures to reduce emissions from other sources under their state or local authority. Few other measures exist for providing multi-pollutant reductions of the same magnitude and cost-effectiveness as those expected from the proposed Tier 3 standards. Furthermore, states outside California do not have the authority to lower the sulfur in gasoline, which is needed to immediately reduce emissions from the existing fleet and also enable new vehicles to meet the proposed Tier 3 emissions standards throughout their useful life.

The reductions in ambient ozone and PM 2.5 that would result from the proposed Tier 3 standards would provide significant health benefits. By 2030, the standards would annually prevent between 670 and 1,700 PM-related premature deaths, between 160 and 710 ozone-related premature deaths, 81,000 work days lost, and approximately 1.4 million minor restricted-activity days (see Section VIII for more details). This proposal would also reduce air toxics; for example, we project that in 2030, the proposal would decrease ambient benzene concentrations by 10-25 percent in some urban areas. Furthermore, the proposed Tier 3 standards would reduce traffic-associated pollution near major roads. EPA is proposing Tier 3 vehicle and fuel standards as part of a comprehensive nationwide program for regulating all types of air pollution from motor vehicles. EPA recently finalized standards to reduce GHG emissions from light-duty vehicles, starting with model year 2017. [28] The Tier 3 standards in this proposal, which address non-GHGs, would be implemented on the same timeframe, thus allowing manufacturers to optimize their vehicle redesigns over both sets of standards. Furthermore, the Tier 3 vehicle and fuel standards are also closely aligned with California's LEV III program, in such a way that manufacturers could design a single vehicle for nationwide sales. This reduces the cost of compliance for auto manufacturers.

This Tier 3 proposal responds to the President's request in his May 2010 memorandum for EPA to review the adequacy of its existing non-GHG standards for new motor vehicles and fuels, and to promulgate new standards, if necessary, as part of a comprehensive approach to regulating motor vehicles. [29] Based on our review, we have concluded that improved vehicle technology, combined with lower sulfur gasoline, make it feasible and cost-effective to reduce emissions well below the current Tier 2 levels. These emission reductions are necessary to reduce air pollution that is (and projected to continue to be) at levels that endanger public health and welfare.

A. Basis for Action Under the Clean Air Act

1. Clean Air Act Section 202

We are proposing to set motor vehicle emission standards under the authority of section 202 of the Clean Air Act. Section 202(a) provides EPA with general authority to prescribe vehicle standards, subject to any specific limitations elsewhere in the Act. EPA is also setting standards for larger light-duty trucks and MDPVs under the general authority of section 202(a)(1) and under section 202(a)(3), which requires that standards applicable to emissions of hydrocarbons, NO X, CO and PM from heavy-duty vehicles [30] reflect the greatest degree of emission reduction available for the model year to which such standards apply, giving appropriate consideration to cost, energy, and safety. In addition, section 202(k) provides EPA with authority to issue and revise regulations applicable to evaporative emissions of hydrocarbons from all gasoline-fueled motor vehicles during: (1) Operation, and (2) over 2 or more days of nonuse; under ozone-prone summertime conditions. Regulations under section 202(k) shall take effect as expeditiously as possible and shall require the greatest degree of emission reduction achievable by means reasonably expected to be available for production during any model year to which the regulations apply, giving appropriate consideration to fuel volatility, and to cost, energy, and safety factors associated with the application of the appropriate technology. Further, section 206 and in particular section 206(d) of the Clean Air Act authorizes EPA to establish methods and procedures for testing whether a motor vehicle or motor vehicle engine conforms with section 202 requirements.

2. Clean Air Act Section 211

We are proposing to adopt gasoline sulfur controls pursuant to our authority under section 211(c)(1) of the CAA. This section allows EPA to establish a fuel control if at least one of the following two criteria is met: (1) The emission products of the fuel cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare; or (2) the emission products of the fuel will impair to a significant degree the performance of any emissions control device or system which is either in general use or which the Administrator finds has been developed to a point where in a reasonable time it will be in general use were the fuel control to be adopted. We are proposing gasoline sulfur controls based on both of these criteria. Under the first criterion, we believe that gasoline with current levels of sulfur contributes to ambient levels of air pollution that endanger public health and welfare, as described in Section II.B. Under the second criterion, we believe that gasoline sulfur impairs the emissions control systems of vehicles, as discussed in Section III.A.2.

B. Overview of Public Health Impacts of Motor Vehicles and Fuels

Motor vehicles emit pollutants that contribute to ambient levels of ozone, PM, NO 2, SO 2, CO, and air toxics. Motor vehicles are significant contributors to emissions of VOC and NO X, which contribute to the formation of both ozone and PM 2.5. Approximately 159 million people currently live in counties designated nonattainment for one or more of the NAAQS, and this figure does not include the people living in areas with a risk of exceeding the NAAQS in the future. [31] The majority of Americans continue to be exposed to ambient concentrations of air toxics at levels which have the potential to cause adverse health effects. [32] In addition, populations who live, work, or attend school near major roads experience elevated exposure concentrations to a wide range of air pollutants. [33]

EPA has already adopted many emission control programs that are expected to reduce ambient pollution levels. As a result of these programs, the number of areas that continue to violate the ozone and PM 2.5 NAAQS or have high levels of air toxics is expected to continue to decrease. However, the baseline air quality modeling completed for this proposed rule predicts that without additional controls there will continue to be a need for reductions in ozone, PM 2.5 and air toxics concentrations in the future. Section III.C of this preamble presents the air quality modeling results for this proposed rule.

1. Ozone

a. Background

Ground-level ozone pollution is typically formed through reactions involving VOC and NO X in the lower atmosphere in the presence of sunlight. These pollutants, often referred to as ozone precursors, are emitted by many types of pollution sources, such as highway and nonroad motor vehicles and engines, power plants, chemical plants, refineries, makers of consumer and commercial products, industrial facilities, and smaller area sources.

The science of ozone formation, transport, and accumulation is complex. Ground-level ozone is produced and destroyed in a cyclical set of chemical reactions, many of which are sensitive to temperature and sunlight. When ambient temperatures and sunlight levels remain high for several days and the air is relatively stagnant, ozone and its precursors can build up and result in more ozone than typically occurs on a single high-temperature day. Ozone and its precursors can be transported hundreds of miles downwind from precursor emissions, resulting in elevated ozone levels even in areas with low local VOC or NO X emissions.

b. Health Effects of Ozone

The health and welfare effects of ozone are well documented and are assessed in EPA's 2006 Air Quality Criteria Document and 2007 Staff Paper. 34 35 People who are more susceptible to effects associated with exposure to ozone can include children, the elderly, and individuals with respiratory disease such as asthma. Those with greater exposures to ozone, for instance due to time spent outdoors (e.g., children and outdoor workers), are of particular concern. Ozone can irritate the respiratory system, causing coughing, throat irritation, and breathing discomfort. Ozone can reduce lung function and cause pulmonary inflammation in healthy individuals. Ozone can also aggravate asthma, leading to more asthma attacks that require medical attention and/or the use of additional medication. Thus, ambient ozone may cause both healthy and asthmatic individuals to limit their outdoor activities. In addition, there is suggestive evidence of a contribution of ozone to cardiovascular-related morbidity and highly suggestive evidence that short-term ozone exposure directly or indirectly contributes to non-accidental and cardiopulmonary-related mortality, but additional research is needed to clarify the underlying mechanisms causing these effects. In a report on the estimation of ozone-related premature mortality published by the National Research Council (NRC), a panel of experts and reviewers concluded that short-term exposure to ambient ozone is likely to contribute to premature deaths and that ozone-related mortality should be included in estimates of the health benefits of reducing ozone exposure. [36] Animal toxicological evidence indicates that with repeated exposure, ozone can inflame and damage the lining of the lungs, which may lead to permanent changes in lung tissue and irreversible reductions in lung function. The respiratory effects observed in controlled human exposure studies and animal studies are coherent with the evidence from epidemiologic studies supporting a causal relationship between acute ambient ozone exposures and increased respiratory-related emergency room visits and hospitalizations in the warm season. In addition, there is suggestive evidence of a contribution of ozone to cardiovascular-related morbidity and non-accidental and cardiopulmonary mortality.

c. Current and Projected Ozone Levels

Concentrations that exceed the level of the ozone NAAQS occur in many parts of the country, including many major population centers. In addition, our modeling without the proposed Tier 3 controls projects that in the future we will continue to have many areas that will have ambient ozone concentrations above the level of the NAAQS (see Section III.C.1). States will need to meet the standard in the 2015-2032 timeframe. The emission reductions and significant ambient ozone improvements from this proposed rule, which would take effect starting in 2017, would be helpful to states as they work to attain and maintain the ozone NAAQS.

The primary and secondary NAAQS for ozone are 8-hour standards with a level of 0.075 ppm. The most recent revision to the ozone standards was in 2008; the previous 8-hour ozone standards, set in 1997, had a level of 0.08 ppm. In 2004, the U.S. EPA designated nonattainment areas for the 1997 8-hour ozone NAAQS. 37 38 As of December 14, 2012, there were 41 ozone nonattainment areas for the 1997 ozone NAAQS composed of 221 full or partial counties with a total population of over 118 million. Nonattainment designations for the 2008 ozone standard were finalized on April 30, 2012 and May 31, 2012. [39] These designations include 46 areas, composed of 227 full or partial counties, with a population of over 123 million. As of December 14, 2012, over 138 million people are living in ozone nonattainment areas. [40]

States with ozone nonattainment areas are required to take action to bring those areas into attainment. The attainment date assigned to an ozone nonattainment area is based on the area's classification. Most ozone nonattainment areas are required to attain the 1997 8-hour ozone NAAQS in the 2007 to 2013 time frame and then to maintain it thereafter. [41] The attainment dates for areas designated nonattainment for the 2008 8-hour ozone NAAQS are in the 2015 to 2032 timeframe, depending on the severity of the problem in each area. In addition, EPA is working to complete the current review of the ozone NAAQS by mid-2014. If EPA revises the ozone standards in 2014 pursuant to that review, the attainment dates associated with areas designated nonattainment for that NAAQS would likely be in the 2019 to 2036 timeframe, depending on the severity of the problem in each area.

EPA has already adopted many emission control programs that are expected to reduce ambient ozone levels. As a result of these and other federal, state and local programs, 8-hour ozone levels are expected to improve in the future. However, even with the implementation of all current state and federal regulations, there are projected to be counties violating the ozone NAAQS well into the future. Thus additional federal control programs, such as Tier 3, can assist areas with attainment dates in 2017 and beyond in attaining the NAAQS as expeditiously as practicable and may relieve areas with already stringent local regulations from some of the burden associated with adopting additional local controls.

2. Particulate Matter

a. Background

Particulate matter is a highly complex mixture of solid particles and liquid droplets distributed among numerous atmospheric gases which interact with solid and liquid phases. Particles range in size from those smaller than 1 nanometer (10 −9 meter) to over 100 micrometer (μm, or 10 −6 meter) in diameter (for reference, a typical strand of human hair is 70 μm in diameter and a grain of salt is about 100 μm). Atmospheric particles can be grouped into several classes according to their aerodynamic and physical sizes, including ultrafine particles (<0.1 μm), accumulation mode or `fine' particles (< 1 to 3 μm), and coarse particles (>1 to 3 μm). For regulatory purposes, fine particles are measured as PM 2.5 and inhalable or thoracic coarse particles are measured as PM 10-2.5, corresponding to their size (diameter) range in micrometers and referring to total particle mass under 2.5 and between 2.5 and 10 micrometers, respectively. The EPA currently has standards that measure PM 2.5 and PM 10. [42]

Particles span many sizes and shapes and consist of hundreds of different chemicals. Particles are emitted directly from sources and are also formed through atmospheric chemical reactions; the former are often referred to as “primary” particles, and the latter as “secondary” particles. Particle pollution also varies by time of year and location and is affected by several weather-related factors, such as temperature, clouds, humidity, and wind. A further layer of complexity comes from particles' ability to shift between solid/liquid and gaseous phases, which is influenced by concentration and meteorology, especially temperature.

Fine particles are produced primarily by combustion processes and by transformations of gaseous emissions (e.g., sulfur oxides (SO X), nitrogen oxides (NO X), and volatile organic compounds (VOC)) in the atmosphere. The chemical and physical properties of PM 2.5 may vary greatly with time, region, meteorology, and source category. Thus, PM 2.5 may include a complex mixture of different components including sulfates, nitrates, organic compounds, elemental carbon and metal compounds. These particles can remain in the atmosphere for days to weeks and travel hundreds to thousands of kilometers.

b. Health Effects of PM

Scientific studies show ambient PM is associated with a series of adverse health effects. These health effects are discussed in detail in EPA's Integrated Science Assessment (ISA) for Particulate Matter. [43] Further discussion of health effects associated with PM can also be found in the draft RIA. The ISA summarizes health effects evidence associated with both short-term and long-term exposures to PM 2.5, PM 10-2.5, and ultrafine particles.

The ISA concludes that health effects associated with short-term exposures (hours to days) to ambient PM 2.5 include mortality, cardiovascular effects, such as altered vasomotor function and myocardial ischemia, and hospital admissions and emergency department visits for ischemic heart disease and congestive heart failure, and respiratory effects, such as exacerbation of asthma symptoms in children and hospital admissions and emergency department visits for chronic obstructive pulmonary disease and respiratory infections. [44] The ISA notes that long-term exposure (months to years) to PM 2.5 is associated with the development/progression of cardiovascular disease, premature mortality, and respiratory effects, including reduced lung function growth in children, increased respiratory symptoms, and asthma development. [45] The ISA concludes that the currently available scientific evidence from epidemiologic, controlled human exposure, and toxicological studies supports a causal association between short- and long-term exposures to PM 2.5 and cardiovascular effects and premature mortality. Furthermore, the ISA concludes that the collective evidence supports likely causal associations between short- and long-term PM 2.5 exposures and respiratory effects. The ISA also concludes that the scientific evidence is suggestive of a causal association for reproductive and developmental effects including respiratory-related infant mortality, and cancer, mutagenicity, and genotoxicity and long-term exposure to PM 2.5. [46]

For PM 10−2.5, the ISA concludes that the current evidence is suggestive of a causal relationship between short-term exposures and premature mortality, cardiovascular effects, and respiratory effects. Data are inadequate to draw conclusions regarding the health effects associated with long-term exposure to PM 10−2.5. [47]

For ultrafine particles, the ISA concludes that there is suggestive evidence of a causal relationship between short-term exposures and cardiovascular effects, such as changes in heart rhythm and blood vessel function. It also concludes that there is suggestive evidence of association between short-term exposure to ultrafine particles and respiratory effects. Data are inadequate to draw conclusions regarding the health effects associated with long-term exposure to ultrafine particles. [48]

c. Current and Projected PM 2.5 Levels

There are many areas of the country that are currently in nonattainment for the annual and 24-hour PM 2.5 NAAQS. Our modeling without the proposed Tier 3 controls projects that in the future we will continue to have many areas that will have ambient PM 2.5 concentrations above the level of the NAAQS (see Section III.C.2). States will need to meet the 24-hour standard in the 2015-2019 timeframe and the annual standard in the 2021-2025 timeframe. The emission reductions and improvements in ambient PM 2.5 from this proposed rule, which would take effect starting in 2017, would be helpful to states as they work to attain and maintain the PM 2.5 NAAQS.

There are two NAAQS for PM 2.5: an annual standard (12 micrograms per cubic meter (μg/m [3] )) and a 24-hour standard (35 μg/m [3] ). The most recent revisions to these standards were in 1997, 2006 and in December 2012. The December 2012 rule revised the level of the annual PM 2.5 standard from 15 μg/m [3] to 12 μg/m [3] . [49]

In 2005 EPA designated nonattainment areas for the 1997 PM 2.5 NAAQS. [50] As of December 14, 2012, over 91 million people lived in the 35 areas that are designated as nonattainment for the 1997 PM 2.5 NAAQS. These PM 2.5 nonattainment areas are comprised of 191 full or partial counties. On October 8, 2009, the EPA issued final nonattainment area designations for the 2006 24-hour PM 2.5 NAAQS. [51] These designations include 32 areas composed of 121 full or partial counties with a population of over 70 million. In total, there are 50 PM 2.5 nonattainment areas with a population of over 105 million people. [52]

States with PM 2.5 nonattainment areas will be required to take action to bring those areas into attainment in the future. Most 1997 PM 2.5 nonattainment areas are required to attain the 1997 PM 2.5 NAAQS in the 2010 to 2015 time frame and then required to maintain the 1997 PM 2.5 NAAQS thereafter. [53] The 2006 24-hour PM 2.5 nonattainment areas will be required to attain the 2006 24-hour PM 2.5 NAAQS in the 2014 to 2019 time frame and then be required to maintain the 2006 24-hour PM 2.5 NAAQS thereafter. [54] The 2012 PM 2.5 nonattainment areas will likely be required to attain the 2012 PM 2.5 NAAQS in the 2020 to 2025 time frame, depending on the severity of an area's fine particle pollution problems and the availability of pollution controls. The standards proposed here begin taking effect in 2017.

EPA has already adopted many mobile source emission control programs that are expected to reduce ambient PM levels. As a result of these and other federal, state and local programs, the number of areas that fail to meet the PM 2.5 NAAQS in the future is expected to decrease. However, even with the implementation of all current state and federal regulations, there are projected to be counties violating the PM 2.5 NAAQS well into the future. Thus additional federal control programs, such as Tier 3, can assist areas with attainment dates in 2017 and beyond in attaining the NAAQS as expeditiously as practicable and may relieve areas with already stringent local regulations from some of the burden associated with adopting additional local controls.

3. Nitrogen Oxides and Sulfur Oxides

a. Background

Nitrogen dioxide (NO 2) is a member of the NO X family of gases. Most NO 2 is formed in the air through the oxidation of nitric oxide (NO) emitted when fuel is burned at a high temperature. Sulfur dioxide (SO 2), a member of the sulfur oxide (SO X) family of gases, is formed from burning fuels containing sulfur (e.g., coal or oil derived), extracting gasoline from oil, or extracting metals from ore.

SO 2 and NO 2 and their gas phase oxidation products can dissolve in water droplets and further oxidize to form sulfuric and nitric acid which react with ammonia to form sulfates and nitrates, both of which are important components of ambient PM. The health effects of ambient PM are discussed in Section II.B.2.b of this preamble. NO X and VOC are the two major precursors of ozone. The health effects of ozone are covered in Section II.B.2.1.b.

b. Health Effects of NO 2

Information on the health effects of NO 2 can be found in the EPA Integrated Science Assessment (ISA) for Nitrogen Oxides. [55] The EPA has concluded that the findings of epidemiologic, controlled human exposure, and animal toxicological studies provide evidence that is sufficient to infer a likely causal relationship between respiratory effects and short-term NO 2 exposure. The ISA concludes that the strongest evidence for such a relationship comes from epidemiologic studies of respiratory effects including symptoms, emergency department visits, and hospital admissions. Based on both short- and long-term studies, the ISA concludes that associations of NO 2 with respiratory health effects are stronger among a number of groups; these include individuals with preexisting pulmonary conditions (e.g., asthma or COPD), children and older adults. The ISA also draws two broad conclusions regarding airway responsiveness following NO 2 exposure. First, the ISA concludes that NO 2 exposure may enhance the sensitivity to allergen-induced decrements in lung function and increase the allergen-induced airway inflammatory response following 30-minute exposures of asthmatics to NO 2 concentrations as low as 0.26 ppm. Second, exposure to NO 2 has been found to enhance the inherent responsiveness of the airway to subsequent nonspecific challenges in controlled human exposure studies of asthmatic subjects. Small but significant increases in non-specific airway hyperresponsiveness were reported following 1-hour exposures of asthmatics to 0.1 ppm NO 2. Enhanced airway responsiveness could have important clinical implications for asthmatics since transient increases in airway responsiveness following NO 2 exposure have the potential to increase symptoms and worsen asthma control. Together, the epidemiologic and experimental data sets form a plausible, consistent, and coherent description of a relationship between NO 2 exposures and an array of adverse health effects that range from the onset of respiratory symptoms to hospital admission.

Although the weight of evidence supporting a causal relationship is somewhat less certain than that associated with respiratory morbidity, NO 2 has also been linked to other health endpoints. These include all-cause (nonaccidental) mortality, hospital admissions or emergency department visits for cardiovascular disease, and decrements in lung function growth associated with chronic exposure.

c. Health Effects of SO 2

Information on the health effects of SO 2 can be found in the EPA Integrated Science Assessment for Sulfur Oxides. [56] SO 2 has long been known to cause adverse respiratory health effects, particularly among individuals with asthma. Other potentially sensitive groups include children and the elderly. During periods of elevated ventilation, asthmatics may experience symptomatic bronchoconstriction within minutes of exposure. Following an extensive evaluation of health evidence from epidemiologic and laboratory studies, the EPA has concluded that there is a causal relationship between respiratory health effects and short-term exposure to SO 2. Separately, based on an evaluation of the epidemiologic evidence of associations between short-term exposure to SO 2 and mortality, the EPA has concluded that the overall evidence is suggestive of a causal relationship between short-term exposure to SO 2 and mortality.

d. Current Levels of NO 2

Between 2003 and 2005, national mean concentrations of NO 2 were about 15 parts per billion (ppb) for averaging periods ranging from a day to a year. [57] There are two NAAQS for NO 2: an annual standard (53 ppb) and a 1-hour standard (100 ppb). The primary NAAQS for NO 2 was revised in January 2010. EPA completed area designations in January 2012 and there are currently no nonattainment areas. The designations were based on the existing community-wide monitoring network. Once the expanded network of NO 2 monitors is fully deployed and three years of air quality data have been collected, EPA intends to redesignate areas, as appropriate, based on the air quality data from the new monitoring network. 58 59

4. Carbon Monoxide

Carbon monoxide (CO) is a colorless, odorless gas emitted from combustion processes. Nationally and, particularly in urban areas, the majority of CO emissions to ambient air come from mobile sources.

a. Health Effects of Carbon Monoxide

Information on the health effects of CO can be found in the EPA Integrated Science Assessment (ISA) for Carbon Monoxide. [60] The ISA concludes that ambient concentrations of CO are associated with a number of adverse health effects. [61] This section provides a summary of the health effects associated with exposure to ambient concentrations of CO. [62]

Human clinical studies of subjects with coronary artery disease show a decrease in the time to onset of exercise-induced angina (chest pain) and electrocardiogram changes following CO exposure. In addition, epidemiologic studies show associations between short-term CO exposure and cardiovascular morbidity, particularly increased emergency room visits and hospital admissions for coronary heart disease (including ischemic heart disease, myocardial infarction, and angina). Some epidemiologic evidence is also available for increased hospital admissions and emergency room visits for congestive heart failure and cardiovascular disease as a whole. The ISA concludes that a causal relationship is likely to exist between short-term exposures to CO and cardiovascular morbidity. It also concludes that available data are inadequate to conclude that a causal relationship exists between long-term exposures to CO and cardiovascular morbidity.

Animal studies show various neurological effects with in-utero CO exposure. Controlled human exposure studies report inconsistent neural and behavioral effects following low-level CO exposures. The ISA concludes the evidence is suggestive of a causal relationship with both short- and long-term exposure to CO and central nervous system effects.

A number of epidemiologic and animal toxicological studies cited in the ISA have evaluated associations between CO exposure and birth outcomes such as preterm birth or cardiac birth defects. The epidemiologic studies provide limited evidence of a CO-induced effect on preterm births and birth defects, with weak evidence for a decrease in birth weight. Animal toxicological studies have found associations between perinatal CO exposure and decrements in birth weight, as well as other developmental outcomes. The ISA concludes these studies are suggestive of a causal relationship between long-term exposures to CO and developmental effects and birth outcomes.

Epidemiologic studies provide evidence of effects on respiratory morbidity such as changes in pulmonary function, respiratory symptoms, and hospital admissions associated with ambient CO concentrations. A limited number of epidemiologic studies considered copollutants such as ozone, SO 2, and PM in two-pollutant models and found that CO risk estimates were generally robust, although this limited evidence makes it difficult to disentangle effects attributed to CO itself from those of the larger complex air pollution mixture. Controlled human exposure studies have not extensively evaluated the effect of CO on respiratory morbidity. Animal studies at levels of 50-100 ppm CO show preliminary evidence of altered pulmonary vascular remodeling and oxidative injury. The ISA concludes that the evidence is suggestive of a causal relationship between short-term CO exposure and respiratory morbidity, and inadequate to conclude that a causal relationship exists between long-term exposure and respiratory morbidity.

Finally, the ISA concludes that the epidemiologic evidence is suggestive of a causal relationship between short-term exposures to CO and mortality. Epidemiologic studies provide evidence of an association between short-term exposure to CO and mortality, but limited evidence is available to evaluate cause-specific mortality outcomes associated with CO exposure. In addition, the attenuation of CO risk estimates which was often observed in copollutant models contributes to the uncertainty as to whether CO is acting alone or as an indicator for other combustion-related pollutants. The ISA also concludes that there is not likely to be a causal relationship between relevant long-term exposures to CO and mortality.

5. Mobile Source Air Toxics

Light-duty vehicle emissions contribute to ambient levels of air toxics known or suspected as human or animal carcinogens, or that have noncancer health effects. The population experiences an elevated risk of cancer and other noncancer health effects from exposure to the class of pollutants known collectively as “air toxics.” [63] These compounds include, but are not limited to, benzene, 1,3-butadiene, formaldehyde, acetaldehyde, acrolein, polycyclic organic matter, and naphthalene. These compounds were identified as national or regional risk drivers or contributors in the 2005 National-scale Air Toxics Assessment and have significant inventory contributions from mobile sources. [64]

a. Health Effects of Air Toxics

i. Benzene

The EPA's IRIS database lists benzene as a known human carcinogen (causing leukemia) by all routes of exposure, and concludes that exposure is associated with additional health effects, including genetic changes in both humans and animals and increased proliferation of bone marrow cells in mice. 65 66 67 EPA states in its IRIS database that data indicate a causal relationship between benzene exposure and acute lymphocytic leukemia and suggest a relationship between benzene exposure and chronic non-lymphocytic leukemia and chronic lymphocytic leukemia. EPA's IRIS documentation for benzene also lists a range of 2.2 × 10 −6 to 7.8 × 10 −6 as the unit risk estimate (URE) for benzene. 68 69 The International Agency for Research on Carcinogens (IARC) has determined that benzene is a human carcinogen and the U.S. Department of Health and Human Services (DHHS) has characterized benzene as a known human carcinogen. 70 71

A number of adverse noncancer health effects including blood disorders, such as preleukemia and aplastic anemia, have also been associated with long-term exposure to benzene. 72 73 The most sensitive noncancer effect observed in humans, based on current data, is the depression of the absolute lymphocyte count in blood. 74 75 EPA's inhalation reference concentration (RfC) for benzene is 30 µg/m [3] . The RfC is based on suppressed absolute lymphocyte counts seen in humans under occupational exposure conditions. In addition, recent work, including studies sponsored by the Health Effects Institute (HEI), provides evidence that biochemical responses are occurring at lower levels of benzene exposure than previously known. 76 77 78 79 EPA's IRIS program has not yet evaluated these new data. EPA does not currently have an acute reference concentration for benzene. The Agency for Toxic Substances and Disease Registry (ATSDR) Minimal Risk Level (MRL) for acute exposure to benzene is 29 µg/m [3] for 1-14 days exposure. 80 81

ii. Formaldehyde

In 1991, EPA concluded that formaldehyde is a carcinogen based on nasal tumors in animal bioassays. [82] An Inhalation Unit Risk for cancer and a Reference Dose for oral noncancer effects were developed by the Agency and posted on the Integrated Risk Information System (IRIS) database. Since that time, the National Toxicology Program (NTP) and International Agency for Research on Cancer (IARC) have concluded that formaldehyde is a known human carcinogen. 83 84 85

The conclusions by IARC and NTP reflect the results of epidemiologic research published since 1991 in combination with previous animal, human and mechanistic evidence. Research conducted by the National Cancer Institute reported an increased risk of nasopharyngeal cancer and specific lymphohematopoietic malignancies among workers exposed to formaldehyde. 86 87 88 A National Institute of Occupational Safety and Health study of garment workers also reported increased risk of death due to leukemia among workers exposed to formaldehyde. [89] Extended follow-up of a cohort of British chemical workers did not report evidence of an increase in nasopharyngeal or lymphohematopoietic cancers, but a continuing statistically significant excess in lung cancers was reported. [90] Finally, a study of embalmers reported formaldehyde exposures to be associated with an increased risk of myeloid leukemia but not brain cancer. [91]

Health effects of formaldehyde in addition to cancer were reviewed by the Agency for Toxics Substances and Disease Registry in 1999 [92] and supplemented in 2010, [93] and by the World Health Organization. [94] These organizations reviewed the literature concerning effects on the eyes and respiratory system, the primary point of contact for inhaled formaldehyde, including sensory irritation of eyes and respiratory tract, pulmonary function, nasal histopathology, and immune system effects. In addition, research on reproductive and developmental effects and neurological effects were discussed.

EPA released a draft Toxicological Review of Formaldehyde—Inhalation Assessment through the IRIS program for peer review by the National Research Council (NRC) and public comment in June 2010. [95] The draft assessment reviewed more recent research from animal and human studies on cancer and other health effects. The NRC released their review report in April 2011. [96] The EPA is currently revising the draft assessment in response to this review.

iii. Acetaldehyde

Acetaldehyde is classified in EPA's IRIS database as a probable human carcinogen, based on nasal tumors in rats, and is considered toxic by the inhalation, oral, and intravenous routes. [97] The URE in IRIS for acetaldehyde is 2.2 × 10 −6 per µg/m [3] . [98] Acetaldehyde is reasonably anticipated to be a human carcinogen by the U.S. DHHS in the 12th Report on Carcinogens and is classified as possibly carcinogenic to humans (Group 2B) by the IARC. 99 100 EPA is currently conducting a reassessment of cancer risk from inhalation exposure to acetaldehyde.

The primary noncancer effects of exposure to acetaldehyde vapors include irritation of the eyes, skin, and respiratory tract. [101] In short-term (4 week) rat studies, degeneration of olfactory epithelium was observed at various concentration levels of acetaldehyde exposure. 102 103 Data from these studies were used by EPA to develop an inhalation reference concentration of 9 µg/m [3] . Some asthmatics have been shown to be a sensitive subpopulation to decrements in functional expiratory volume (FEV1 test) and bronchoconstriction upon acetaldehyde inhalation. [104] The agency is currently conducting a reassessment of the health hazards from inhalation exposure to acetaldehyde.

iv. Acrolein

EPA most recently evaluated the toxicological and health effects literature related to acrolein in 2003 and concluded that the human carcinogenic potential of acrolein could not be determined because the available data were inadequate. No information was available on the carcinogenic effects of acrolein in humans and the animal data provided inadequate evidence of carcinogenicity. [105] The IARC determined in 1995 that acrolein was not classifiable as to its carcinogenicity in humans. [106]

Lesions to the lungs and upper respiratory tract of rats, rabbits, and hamsters have been observed after subchronic exposure to acrolein. [107] The Agency has developed an RfC for acrolein of 0.02 µg/m [3] and an RfD of 0.5 µg/kg-day. [108] EPA is considering updating the acrolein assessment with data that have become available since the 2003 assessment was completed.

Acrolein is extremely acrid and irritating to humans when inhaled, with acute exposure resulting in upper respiratory tract irritation, mucus hypersecretion and congestion. The intense irritancy of this carbonyl has been demonstrated during controlled tests in human subjects, who suffer intolerable eye and nasal mucosal sensory reactions within minutes of exposure. [109] These data and additional studies regarding acute effects of human exposure to acrolein are summarized in EPA's 2003 IRIS Human Health Assessment for acrolein. [110] Studies in humans indicate that levels as low as 0.09 ppm (0.21 mg/m [3] ) for five minutes may elicit subjective complaints of eye irritation with increasing concentrations leading to more extensive eye, nose and respiratory symptoms. Acute exposures in animal studies report bronchial hyper-responsiveness. Based on animal data (more pronounced respiratory irritancy in mice with allergic airway disease in comparison to non-diseased mice [111] ) and demonstration of similar effects in humans (e.g., reduction in respiratory rate), individuals with compromised respiratory function (e.g., emphysema, asthma) are expected to be at increased risk of developing adverse responses to strong respiratory irritants such as acrolein. EPA does not currently have an acute reference concentration for acrolein. The available health effect reference values for acrolein have been summarized by EPA and include an ATSDR MRL for acute exposure to acrolein of 7 µg/m [3] for 1-14 days exposure; and Reference Exposure Level (REL) values from the California Office of Environmental Health Hazard Assessment (OEHHA) for one-hour and 8-hour exposures of 2.5 µg/m [3] and 0.7 µg/m [3] , respectively. [112]

v. 1,3-Butadiene

EPA has characterized 1,3-butadiene as carcinogenic to humans by inhalation. 113 114 The IARC has determined that 1,3-butadiene is a human carcinogen and the U.S. DHHS has characterized 1,3-butadiene as a known human carcinogen. 115 116 117 There are numerous studies consistently demonstrating that 1,3-butadiene is metabolized into genotoxic metabolites by experimental animals and humans. The specific mechanisms of 1,3-butadiene-induced carcinogenesis are unknown; however, the scientific evidence strongly suggests that the carcinogenic effects are mediated by genotoxic metabolites. Animal data suggest that females may be more sensitive than males for cancer effects associated with 1,3-butadiene exposure; there are insufficient data in humans from which to draw conclusions about sensitive subpopulations. The URE for 1,3-butadiene is 3 × 10 −5 per µg/m [3] . [118] 1,3-butadiene also causes a variety of reproductive and developmental effects in mice; no human data on these effects are available. The most sensitive effect was ovarian atrophy observed in a lifetime bioassay of female mice. [119] Based on this critical effect and the benchmark concentration methodology, an RfC for chronic health effects was calculated at 0.9 ppb (approximately 2 µg/m [3] ).

vi. Ethanol

EPA is planning to develop an assessment of the health effects of exposure to ethanol, a compound which is not currently listed on EPA's IRIS database. Extensive health effects data are available for ingestion of ethanol, while data on inhalation exposure effects are sparse. In developing the assessment, EPA is evaluating pharmacokinetic models as a means of extrapolating across species (animal to human) and across exposure routes (oral to inhalation) to better characterize the health hazards and dose-response relationships for low levels of ethanol exposure in the environment.

vii. Polycyclic Organic Matter

The term polycyclic organic matter (POM) defines a broad class of compounds that includes the polycyclic aromatic hydrocarbon compounds (PAHs). One of these compounds, naphthalene, is discussed separately below. POM compounds are formed primarily from combustion and are present in the atmosphere in gas and particulate form. Cancer is the major concern from exposure to POM. Epidemiologic studies have reported an increase in lung cancer in humans exposed to diesel exhaust, coke oven emissions, roofing tar emissions, and cigarette smoke; all of these mixtures contain POM compounds. 120 121 Animal studies have reported respiratory tract tumors from inhalation exposure to benzo[a]pyrene and alimentary tract and liver tumors from oral exposure to benzo[a]pyrene. [122] In 1997 EPA classified seven PAHs (benzo[a]pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, dibenz[a,h]anthracene, and indeno[1,2,3-cd]pyrene) as Group B2, probable human carcinogens. [123] Since that time, studies have found that maternal exposures to PAHs in a population of pregnant women were associated with several adverse birth outcomes, including low birth weight and reduced length at birth, as well as impaired cognitive development in preschool children (3 years of age). 124 125 These and similar studies are being evaluated as a part of the ongoing IRIS assessment of health effects associated with exposure to benzo[a]pyrene.

viii. PAN

PAN (peroxy acetyl nitrate) has not been evaluated by EPA's IRIS program. Information regarding the potential carcinogenicity of PAN is limited. As noted in the EPA air quality criteria document for ozone and related photochemical oxidants, cytogenetic studies indicate that PAN is not a potent mutagen, clastogen (a compound that can cause breaks in chromosomes), or DNA-damaging agent in mammalian cells either in vivo or in vitro. Some studies suggest that PAN may be a weak bacterial mutagen at concentrations much higher than exist in present urban atmospheres. [126]

Effects of ground-level smog causing intense eye irritation have been attributed to photochemical oxidants, including PAN. [127] Animal toxicological information on the inhalation effects of the non-ozone oxidants has been limited to a few studies on PAN. Acute exposure to levels of PAN can cause changes in lung morphology, behavioral modifications, weight loss, and susceptibility to pulmonary infections. Human exposure studies indicate minor pulmonary function effects at high PAN concentrations, but large inter-individual variability precludes definitive conclusions. [128]

ix. Naphthalene

Naphthalene is found in small quantities in gasoline and diesel fuels. Naphthalene emissions have been measured in larger quantities in both gasoline and diesel exhaust compared with evaporative emissions from mobile sources, indicating it is primarily a product of combustion. Acute (short-term) exposure of humans to naphthalene by inhalation, ingestion, or dermal contact is associated with hemolytic anemia and damage to the liver and the nervous system. [129] Chronic (long term) exposure of workers and rodents to naphthalene has been reported to cause cataracts and retinal damage. [130] EPA released an external review draft of a reassessment of the inhalation carcinogenicity of naphthalene based on a number of recent animal carcinogenicity studies. [131] The draft reassessment completed external peer review. [132] Based on external peer review comments received, a revised draft assessment that considers all routes of exposure, as well as cancer and noncancer effects, is under development. The external review draft does not represent official agency opinion and was released solely for the purposes of external peer review and public comment. The National Toxicology Program listed naphthalene as “reasonably anticipated to be a human carcinogen” in 2004 on the basis of bioassays reporting clear evidence of carcinogenicity in rats and some evidence of carcinogenicity in mice. [133] California EPA has released a new risk assessment for naphthalene, and the IARC has reevaluated naphthalene and re-classified it as Group 2B: possibly carcinogenic to humans. [134]

Naphthalene also causes a number of chronic non-cancer effects in animals, including abnormal cell changes and growth in respiratory and nasal tissues. [135] The current EPA IRIS assessment includes noncancer data on hyperplasia and metaplasia in nasal tissue that form the basis of the inhalation RfC of 3 µg/m [3] . [136] The ATSDR MRL for acute exposure to naphthalene is 0.6 mg/kg/day.

x. Other Air Toxics

In addition to the compounds described above, other compounds in gaseous hydrocarbon and PM emissions from light-duty vehicles would be affected by this proposal. Mobile source air toxic compounds that would potentially be impacted include ethylbenzene, propionaldehyde, toluene, and xylene. Information regarding the health effects of these compounds can be found in EPA's IRIS database. [137]

b. Current Levels of Air Toxics

The majority of Americans continue to be exposed to ambient concentrations of air toxics at levels which have the potential to cause adverse health effects. [138] The levels of air toxics to which people are exposed vary depending on where people live and work and the kinds of activities in which they engage, as discussed in detail in U.S. EPA's most recent Mobile Source Air Toxics Rule. [139] According to the National Air Toxic Assessment (NATA) for 2005, [140] mobile sources were responsible for 43 percent of outdoor toxic emissions and over 50 percent of the cancer risk and noncancer hazard associated with primary emissions. Mobile sources are also large contributors to precursor emissions which react to form secondary concentrations of air toxics. Formaldehyde is the largest contributor to cancer risk of all 80 pollutants quantitatively assessed in the 2005 NATA. Mobile sources were responsible for over 40 percent of primary emissions of this pollutant in 2005, and are major contributors to formaldehyde precursor emissions. Benzene is also a large contributor to cancer risk, and mobile sources account for over 70 percent of ambient exposure. Over the years, EPA has implemented a number of mobile source and fuel controls which have resulted in VOC reductions, which also reduced formaldehyde, benzene and other air toxic emissions.

6. Near-Roadway Pollution

Locations in close proximity to major roadways generally have elevated concentrations of many air pollutants emitted from motor vehicles. Hundreds of such studies have been published in peer-reviewed journals, concluding that concentrations of CO, NO, NO 2, benzene, aldehydes, particulate matter, black carbon, and many other compounds are elevated in ambient air within approximately 300-600 meters (about 1,000-2,000 feet) of major roadways. Highest concentrations of most pollutants emitted directly by motor vehicles are found at locations within 50 meters (about 165 feet) of the edge of a roadway's traffic lanes.

A recent large-scale review of air quality measurements in vicinity of major roadways between 1978 and 2008 concluded that the pollutants with the steepest concentration gradients in vicinities of roadways were CO, ultrafine particles, metals, elemental carbon (EC), NO, NO X, and several VOCs. [141] These pollutants showed a large reduction in concentrations within 100 meters downwind of the roadway. Pollutants that showed more gradual reductions with distance from roadways included benzene, NO 2, PM 2.5, and PM 10. In the review article, results varied based on the method of statistical analysis used to determine the trend.

For pollutants with relatively high background concentrations relative to near-road concentrations, detecting concentration gradients can be difficult. For example, many aldehydes have high background concentrations as a result of photochemical breakdown of precursors from many different organic compounds. This can make detection of gradients around roadways and other primary emission sources difficult. However, several studies have measured aldehydes in multiple weather conditions, and found higher concentrations of many carbonyls downwind of roadways. 142 143 These findings suggest a substantial roadway source of these carbonyls.

In the past 15 years, many studies have been published with results showing that populations who live, work, or go to school near high-traffic roadways experience higher rates of numerous adverse health effects, compared to populations far away from major roads. [144] In addition, numerous studies have found adverse health effects associated with spending time in traffic, such as commuting or walking along high-traffic roadways. The health outcomes with the strongest evidence linking them with traffic-associated air pollutants are respiratory effects, particularly in asthmatic children, and cardiovascular effects.

Numerous reviews of this body of health literature have been published as well. In 2010, an expert panel of the Health Effects Institute (HEI) published a review of hundreds of exposure, epidemiology, and toxicology studies. [145] The panel rated how the evidence for each type of health outcome supported a conclusion of a causal association with traffic- associated air pollution as either “sufficient,” “suggestive but not sufficient,” or “inadequate and insufficient.” The panel categorized evidence of a causal association for exacerbation of childhood asthma as “sufficient.” The panel categorized evidence of a causal association for new onset asthma as between “sufficient” and as “suggestive but not sufficient.” “Suggestive of a causal association” was how the panel categorized evidence linking traffic-associated air pollutants with exacerbation of adult respiratory symptoms and lung function decrement. It categorized as “inadequate and insufficient” evidence of a causal relationship between traffic-related air pollution and health care utilization for respiratory problems, new onset adult asthma, chronic obstructive pulmonary disease (COPD), nonasthmatic respiratory allergy, and cancer in adults and children. Other literature reviews have been published with conclusions similar to the HEI panel's. 146 147 148 Health outcomes with few publications suggest the possibility of other effects still lacking sufficient evidence to draw definitive conclusions. Among these outcomes with a small number of positive studies are neurological impacts (e.g., autism and reduced cognitive function) and reproductive outcomes (e.g., preterm birth, low birth weight). 149 150 151 152

In addition to health outcomes, particularly cardiopulmonary effects, conclusions of numerous studies suggest mechanisms by which traffic-related air pollution affects health. Numerous studies indicate that near-roadway exposures increase systemic inflammation, affecting organ systems, including blood vessels and lungs. 153 154 155 156 Long-term exposures in near-road environments have been associated with inflammation-associated conditions, such as atherosclerosis and asthma. 157 158 159

.

Several studies suggest that some factors may increase susceptibility to the effects of traffic-associated air pollution. Several studies have found stronger respiratory associations in children experiencing chronic social stress, such as in violent neighborhoods or in homes with high family stress. 160 161 162

The risks associated with residence, workplace, or schools near major roads are of potentially high public health significance due to the large population in such locations. According to the 2009 American Housing Survey, over 22 million homes (17.0 percent of all U.S. housing units) were located within 300 feet of an airport, railroad, or highway with four or more lanes. This corresponds to a population of more than 50 million U.S. residents in close proximity to high-traffic roadways or other transportation sources. As discussed in Section III, populations near major roads have higher fractions of minority residents and lower socioeconomic status. Furthermore, on average, Americans spend more than an hour traveling each day, bringing nearly all residents into a high-exposure microenvironment for part of the day.

EPA continues to research near-road air quality, including the types of pollutants found in high concentrations near major roads and health problems associated with the mixture of pollutants near roads.

7. Environmental Impacts of Motor Vehicles and Fuels

a. Plant and Ecosystem Effects of Ozone

Elevated ozone levels contribute to environmental effects, with impacts to plants and ecosystems being of most concern. Ozone can produce both acute and chronic injury in sensitive species depending on the concentration level and the duration of the exposure. Ozone effects also tend to accumulate over the growing season of the plant, so that even low concentrations experienced for a longer duration have the potential to create chronic stress on vegetation. Ozone damage to plants includes visible injury to leaves and impaired photosynthesis, both of which can lead to reduced plant growth and reproduction, resulting in reduced crop yields, forestry production, and use of sensitive ornamentals in landscaping. In addition, the impairment of photosynthesis, the process by which the plant makes carbohydrates (its source of energy and food), can lead to a subsequent reduction in root growth and carbohydrate storage below ground, resulting in other, more subtle plant and ecosystems impacts.

These latter impacts include increased susceptibility of plants to insect attack, disease, harsh weather, interspecies competition and overall decreased plant vigor. The adverse effects of ozone on forest and other natural vegetation can potentially lead to species shifts and loss from the affected ecosystems, resulting in a loss or reduction in associated ecosystem goods and services. Lastly, visible ozone injury to leaves can result in a loss of aesthetic value in areas of special scenic significance like national parks and wilderness areas. The final 2006 Ozone Air Quality Criteria Document presents more detailed information on ozone effects on vegetation and ecosystems.

b. Visibility

Visibility can be defined as the degree to which the atmosphere is transparent to visible light. [163] Visibility impairment is caused by light scattering and absorption by suspended particles and gases. Visibility is important because it has direct significance to people's enjoyment of daily activities in all parts of the country. Individuals value good visibility for the well-being it provides them directly, where they live and work, and in places where they enjoy recreational opportunities. Visibility is also highly valued in significant natural areas, such as national parks and wilderness areas, and special emphasis is given to protecting visibility in these areas. For more information on visibility see the final 2009 PM ISA. [164]

EPA is pursuing a two-part strategy to address visibility impairment. First, EPA developed the regional haze program which was put in place in July 1999 to protect the visibility in Mandatory Class I Federal areas. [165] There are 156 national parks, forests and wilderness areas categorized as Mandatory Class I Federal areas. [166] These areas are defined in CAA section 162 as those national parks exceeding 6,000 acres, wilderness areas and memorial parks exceeding 5,000 acres, and all international parks which were in existence on August 7, 1977. Second, EPA has concluded that PM 2.5 causes adverse effects on visibility in other areas that are not protected by the Regional Haze Rule, depending on PM 2.5 concentrations and other factors that control their visibility impact effectiveness such as dry chemical composition and relative humidity (i.e., an indicator of the water composition of the particles). EPA revised the PM 2.5 standards in December 2012 and established a target level of protection that is expected to be met through attainment of the existing secondary standards for PM 2.5.

i. Current Visibility Levels

As mentioned in Section II.B.2.c, millions of people live in nonattainment areas for the PM 2.5 NAAQS. These populations, as well as large numbers of individuals who travel to these areas, are likely to experience visibility impairment. In addition, while visibility trends have improved in mandatory class I federal areas, the most recent data show that these areas continue to suffer from visibility impairment. In summary, visibility impairment is experienced throughout the U.S., in multi-state regions, urban areas, and remote mandatory class I federal areas.

c. Atmospheric Deposition

Wet and dry deposition of ambient particulate matter delivers a complex mixture of metals (e.g., mercury, zinc, lead, nickel, aluminum, cadmium), organic compounds (e.g., polycyclic organic matter, dioxins, furans) and inorganic compounds (e.g., nitrate, sulfate) to terrestrial and aquatic ecosystems. The chemical form of the compounds deposited depends on a variety of factors including ambient conditions (e.g., temperature, humidity, oxidant levels) and the sources of the material. Chemical and physical transformations of the compounds occur in the atmosphere as well as the media onto which they deposit. These transformations in turn influence the fate, bioavailability and potential toxicity of these compounds. Atmospheric deposition has been identified as a key component of the environmental and human health hazard posed by several pollutants including mercury, dioxin and PCBs. [167]

Adverse impacts on water quality can occur when atmospheric contaminants deposit to the water surface or when material deposited on the land enters a waterbody through runoff. Potential impacts of atmospheric deposition to waterbodies include those related to both nutrient and toxic inputs. Adverse effects to human health and welfare can occur from the addition of excess nitrogen via atmospheric deposition. The nitrogen-nutrient enrichment contributes to toxic algae blooms and zones of depleted oxygen, which can lead to fish kills, frequently in coastal waters. Deposition of heavy metals or other toxics may lead to the human ingestion of contaminated fish, impairment of drinking water, damage to freshwater and marine ecosystem components, and limits to recreational uses. Several studies have been conducted in U.S. coastal waters and in the Great Lakes Region in which the role of ambient PM deposition and runoff is investigated. 168 169 170 171 172

Atmospheric deposition of nitrogen and sulfur contributes to acidification, altering biogeochemistry and affecting animal and plant life in terrestrial and aquatic ecosystems across the United States. The sensitivity of terrestrial and aquatic ecosystems to acidification from nitrogen and sulfur deposition is predominantly governed by geology. Prolonged exposure to excess nitrogen and sulfur deposition in sensitive areas acidifies lakes, rivers and soils. Increased acidity in surface waters creates inhospitable conditions for biota and affects the abundance and nutritional value of preferred prey species, threatening biodiversity and ecosystem function. Over time, acidifying deposition also removes essential nutrients from forest soils, depleting the capacity of soils to neutralize future acid loadings and negatively affecting forest sustainability. Major effects include a decline in sensitive forest tree species, such as red spruce (Picea rubens) and sugar maple (Acer saccharum), and a loss of biodiversity of fishes, zooplankton, and macro invertebrates.

In addition to the role nitrogen deposition plays in acidification, nitrogen deposition also leads to nutrient enrichment and altered biogeochemical cycling. In aquatic systems increased nitrogen can alter species assemblages and cause eutrophication. In terrestrial systems nitrogen loading can lead to loss of nitrogen sensitive lichen species, decreased biodiversity of grasslands, meadows and other sensitive habitats, and increased potential for invasive species. For a broader explanation of the topics treated here, refer to the description in Section 6.3.2 of the RIA.

Adverse impacts on soil chemistry and plant life have been observed for areas heavily influenced by atmospheric deposition of nutrients, metals and acid species, resulting in species shifts, loss of biodiversity, forest decline, damage to forest productivity and reductions in ecosystem services. Potential impacts also include adverse effects to human health through ingestion of contaminated vegetation or livestock (as in the case for dioxin deposition), reduction in crop yield, and limited use of land due to contamination.

Atmospheric deposition of pollutants can reduce the aesthetic appeal of buildings and culturally important articles through soiling, and can contribute directly (or in conjunction with other pollutants) to structural damage by means of corrosion or erosion. Atmospheric deposition may affect materials principally by promoting and accelerating the corrosion of metals, by degrading paints, and by deteriorating building materials such as concrete and limestone. Particles contribute to these effects because of their electrolytic, hygroscopic, and acidic properties, and their ability to adsorb corrosive gases (principally sulfur dioxide).

i. Current Nitrogen and Sulfur Deposition

Over the past two decades, the EPA has undertaken numerous efforts to reduce nitrogen and sulfur deposition across the U.S. Analyses of long-term monitoring data for the U.S. show that deposition of both nitrogen and sulfur compounds has decreased over the last 17 years. The data show that reductions were more substantial for sulfur compounds than for nitrogen compounds. In the eastern U.S., where data are most abundant, total sulfur deposition decreased by about 44 percent between 1990 and 2007, while total nitrogen deposition decreased by 25 percent over the same time frame. [173] These numbers are generated by the U.S. national monitoring network and they likely underestimate nitrogen deposition because neither ammonia nor organic nitrogen is measured. Although total nitrogen and sulfur deposition has decreased over time, many areas continue to be negatively impacted by deposition. Deposition of inorganic nitrogen and sulfur species routinely measured in the U.S. between 2005 and 2007 were as high as 9.6 kilograms of nitrogen per hectare (kg N/ha) averaged over three years and 20.8 kilograms of sulfur per hectare (kg S/ha) averaged over three years. [174]

d. Environmental Effects of Air Toxics

Emissions from producing, transporting and combusting fuel contribute to ambient levels of pollutants that contribute to adverse effects on vegetation. Volatile organic compounds, some of which are considered air toxics, have long been suspected to play a role in vegetation damage. [175] In laboratory experiments, a wide range of tolerance to VOCs has been observed. [176] Decreases in harvested seed pod weight have been reported for the more sensitive plants, and some studies have reported effects on seed germination, flowering and fruit ripening. Effects of individual VOCs or their role in conjunction with other stressors (e.g., acidification, drought, temperature extremes) have not been well studied. In a recent study of a mixture of VOCs including ethanol and toluene on herbaceous plants, significant effects on seed production, leaf water content and photosynthetic efficiency were reported for some plant species. [177]

Research suggests an adverse impact of vehicle exhaust on plants, which has in some cases been attributed to aromatic compounds and in other cases to nitrogen oxides. 178 179 180

III. How would this proposal reduce emissions and air pollution? Back to Top

A. Effects of the Proposed Vehicle and Fuel Changes on Mobile Source Emissions

The vehicle and fuel standards that EPA is proposing would significantly reduce the tailpipe and evaporative emissions of light- and heavy-duty vehicles in several ways, as described in this section. In addition, the proposed gasoline sulfur standard would reduce emissions of SO 2 from existing gasoline-powered vehicles and equipment. As described in Section II, all of these emission reductions would in turn improve air quality nationwide and reduce the health effects associated with air pollution from mobile sources.

As with the Tier 2 program, EPA is proposing to implement closely-coordinated requirements for both automakers and refiners in the same rulemaking action. The proposed vehicle emission standards and gasoline sulfur standards represent a “systems approach” to reducing vehicle-related exhaust and evaporative emissions. By recognizing the relationships among the various sources of emissions addressed by this proposed rule, we have been able to integrate the provisions into a single, coordinated program.

1. How do vehicles produce the emissions addressed in this proposal?

The degree to which vehicles produce exhaust and evaporative emissions depends on the design and functionality of the engine and the associated exhaust and evaporative emission controls, in concert with the properties of the fuel on which the vehicle is operating. In the following paragraphs, we discuss how light- and heavy-duty vehicles produce each of these types of emissions, both from the tailpipe and from the fuel system.

a. Tailpipe (Exhaust) Emissions

Which pollutants are emitted at the vehicle's tailpipe and their quantities depend on how the fuel is combusted in the engine and how the resulting gases are treated in the exhaust system. Historically, much of tailpipe emission control has focused on hydrocarbon compounds (HC) and NO X. The portion of hydrocarbons that is methane is minimally reactive in forming ozone. Thus, for emission control purposes, the focus is generally on non-methane hydrocarbons (NMHC), which are also expressed as non-methane organic gases (NMOG) in order to account for oxygenates (usually ethanol) now usually present in the fuel.

Tailpipe hydrocarbon emissions also include several toxic pollutants, including benzene, acetaldehyde, and formaldehyde. To varying degrees, the mass emissions of these pollutants are reduced along with other hydrocarbons by the catalytic converter and improved engine controls.

Light- and heavy-duty gasoline vehicles also emit PM and CO. PM forms directly as a combustion product (primarily as elemental carbon, usually called soot) and also indirectly as semi-volatile hydrocarbon compounds that form particles in the exhaust system or soon after exiting the tailpipe. CO is a product of incomplete fuel combustion.

When operating properly, modern exhaust emission controls (centering on the catalytic convertor) can reduce much of the HC (including toxics), NO X and CO exiting the engine. However, tailpipe emissions are increased during periods of vehicle startup, as catalytic convertors must warm up to be effective; during subsequent operation due to the interference of sulfur in the gasoline; during high load operating events, as the catalyst is overwhelmed or its operation is modified to protect against permanent damage; and as a vehicle ages, as the catalyst degrades in performance due to the effects of high temperature operation and contaminants in the fuel and lubricating oil.

b. Evaporative Emissions

Gasoline vehicles also produce vapors in the fuel tank and fuel system that can be released as evaporative emissions. These vapors are primarily the lighter, more volatile hydrocarbon compounds in the gasoline, which, like exhaust hydrocarbons, contribute to concentrations of VOCs in the atmosphere.

As discussed in Section IV below, vehicle evaporative (“evap”) control systems are designed to block or capture vapors as they are generated. Vapors are generated in the vehicle fuel tank and fuel system (and released to the atmosphere if not adequately controlled) as fuel heats up due to ambient temperature increase and/or vehicle operation. Fuel vapors are also released when they permeate through hose material, when they leak at connections or due to damaged components, and during refueling events.

In general, the evap emission controls on current vehicles (and that would be improved under this proposed rule) consist of a canister filled with activated charcoal and connected by hoses to the fuel system. The hoses direct generated vapors to the canister, which collects the vapors on the carbon and stores them until the system experiences a “purge” event. During purge, the engine draws fresh air through the canister, carrying vapors released by the carbon to the engine to be combusted and restoring the capacity of the canister. Evaporative emissions occur when vapors are emitted to the atmosphere because the evap system is compromised, the carbon canister is overwhelmed, or vapors permeate or leak. As such, evaporative emission controls also involve proper material selection for fuel system components, careful design of these components, and onboard diagnostics to check the system for failure.

2. How would the proposed changes to gasoline sulfur content affect vehicle emissions?

Gasoline vehicles depend to a great degree on catalytic converters to reduce levels of pollutants in their exhaust, including NMOG and NO X, as well as PM (specifically, the volatile hydrocarbon fraction), CO, and most air toxics. The presence of sulfur in gasoline has a strong impact on these emissions, particularly NO X, due to its impact on proper catalyst operation.

Sulfur naturally occurs in crude oil and thus in gasoline. In vehicle catalytic converters, the precious metals that catalyze the reactions that convert the pollutants become significantly less efficient when sulfur is deposited (adsorbed) onto them. The Tier 2 rulemaking required refiners to take steps to reduce sulfur levels in gasoline by approximately 90 percent, to an average of 30 ppm. At the time there were indications that sulfur reductions below 30 ppm may continue to provide additional emission benefits. However, the data was insufficient to quantify the benefits to the existing fleet, and the Tier 2 vehicle standards could be achieved without lowering sulfur further. As a result, to minimize the cost of the Tier 2 program, the sulfur standard was not further reduced below 30 ppm.

As discussed in Section IV.A.6, subsequent research provides a compelling case that even this level of sulfur degrades the emission performance of vehicles on the road today, and inhibits necessary further reductions in vehicle emissions performance, which depend on optimum catalyst performance to reach emission targets. A study conducted by EPA and the auto industry in support of the Mobile Source Air Toxics (MSAT) rule found significant reductions in NO X, CO and total HC when nine Tier 2 vehicles were tested on low sulfur fuel, relative to 32-ppm fuel. [181] In particular, the study found a nearly 50 percent increase in NO X when sulfur was increased from 6 ppm to 32 ppm. Another recent study by Umicore showed reductions of 41 percent for NO X and 17 percent for HC on a PZEV operating on fuel with 33-ppm and 3-ppm fuel. [182]

A larger study recently completed by EPA confirmed these results, showing significant reductions in FTP-composite NO X (23 percent), CO (12 percent) and total HC (13 percent) on the 5-ppm fuel, relative to 28-ppm fuel. For NO X, the majority of overall reductions were driven by large reductions on warmed-up periods of the test cycle (Bag 2), which showed a 59 percent reduction between 28 and 5-ppm fuel, consistent with the role of sulfur in catalyst degradation discussed above. Applying individual bag reductions to in-use activity patterns from EPA emission models suggests an overall NO X reduction of nearly 40 percent on the road.

Based on these studies, the benefits of the proposed Tier 3 sulfur standard are significant in two ways: they enable vehicles designed to the proposed Tier 3 tailpipe exhaust standards to meet these standards for the duration of their useful life, and they facilitate immediate emission reductions from all the vehicles on the road at the time the sulfur controls are implemented.

B. How would emissions be reduced?

The proposed standards would reduce emissions of VOC, NO X (including NO 2), direct PM 2.5, CO, SO 2, and air toxics. The proposed sulfur standards would reduce emissions from the on-road fleet immediately upon implementation, so to reflect these early reductions, we present emission reductions in calendar year 2017. The proposed vehicle standards would begin to reduce emissions as the cleaner cars and trucks begin to enter the fleet in model year 2017. The magnitude of reduction would grow as more Tier 3 vehicles enter the fleet. Therefore, we also present emission reductions in calendar year 2030, when model year 2017 and later cars and trucks contribute nearly 90 percent of fleet-wide vehicle miles travelled. Although 2030 is the farthest year that is feasible for air quality modeling, the full reduction of the vehicle program would be realized after 2030, when the fleet has fully turned over to Tier 3 vehicles. In Chapter 7 of the RIA, we present emission reductions projected in 2050, as well as additional calendar years between 2017 and 2030.

Emission reductions are estimated on an annual basis, for all 50 U.S. states plus the District of Columbia, Puerto Rico and the U.S. Virgin Islands. The reductions were estimated using a version of EPA's MOVES model updated for this analysis, as described in detail in Chapter 7 of the RIA. This version of MOVES includes our most recent data on how vehicle emissions are affected by changes in sulfur, ethanol, and other fuel properties. We estimated emission reductions compared to a reference case that assumed partial RFS2 implementation by 2017, with full implementation in 2022 and beyond. The ethanol scenarios used for the reference and control cases were the “post-EPAct/EISA” scenario defined in Chapter 7 of the RIA, reflecting a mix of E10 and E15 in 2017, and E15 only in 2030. The reference case also assumed continuation of the Tier 2 vehicle program indefinitely, and an average sulfur level of 30 ppm (10 ppm in California).

As discussed throughout this preamble, implementation of the proposed Tier 3 standards is aligned with the 2017 LD GHG standards to achieve significant criteria pollutant and GHG emissions reductions while providing regulatory certainty and compliance efficiency to the auto and oil industries. The 2017 LD GHG standards were still in a preliminary state of development (pre-proposal) at the time we finalized our assumptions for the Tier 3 emissions, air quality, and cost analyses, so we were not able to reflect them in these analyses. However, we continue to expect vehicle criteria pollutant performance to be neutral under the GHG program, because exhaust and evaporative emissions are not proportional to the amount of fuel burned; rather, our standards are expressed on a per-mile basis, not on a per-gallon basis. Vehicle criteria emissions are almost exclusively controlled by a vehicle's emissions aftertreatment system and not by the efficiency of the engine.

The majority of the NMOG that is emitted from a gasoline engine is generated during cold start, before the catalyst is lit off, and NO X is often created during higher load operation. Optimizing catalyst efficiency, minimizing thermal parasitics, minimizing fuel system leaks, and lower gasoline sulfur will be key enablers for all vehicles to meet the Tier 3 standards, regardless of the vehicle's fuel efficiency. Because we do not expect the increase in fuel efficiency to result in lower criteria pollutant emissions, we did not claim in the 2017 LD GHG rule any reductions attributable to the ability of vehicles to meet lower criteria emission levels (see 77 FR 62899-62901, October 15, 2012). In other words, in the 2017 LD GHG rule, we assumed that, absent the proposed Tier 3 standards, the light-duty fleet would continue to meet the Tier 2 standards. Thus, we believe that the inclusion of the light-duty GHG standards in our cost and benefit analyses for the proposed Tier 3 standards would have had little or no impact on the results or our conclusions, as discussed in Sections 7.1.2 and 7.1.3.2.1 of the draft RIA. Nevertheless, for the final rulemaking we will include the LD GHG requirements in the analysis.

The analysis described here does account for the following national onroad rules:

  • Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements (65 FR 6698, February 10, 2000)
  • Heavy-Duty Engine and Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements (66 FR 5002, January 18, 2001)
  • Mobile Source Air Toxics Rule (72 FR 8428, February 26, 2007)
  • Regulation of Fuels and Fuel Additives: Changes to Renewable Fuel Standard Program (75 FR 14670, March 26, 2010)
  • Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards for 2012-2016 (75 FR 25324, May 7, 2010)

The analysis also accounts for many other national rules and standards. In addition, the modeling accounts for state and local rules including local fuel standards, Inspection/Maintenance programs, Stage II refueling controls, the National Low Emission Vehicle Program (NLEV), and the section 177 states LEV and LEVII programs. See the Tier 3 emissions modeling TSD for more detail.

A summary of emission reductions projected to result from Tier 3, relative to the reference case, is shown in calendar years 2017 and 2030 for NO X, VOC, direct PM 2.5, CO, SO 2, and total air toxics in Table III-1. For many pollutants, the immediate reductions in 2017 are significant; for example, combined NO X and VOC emissions would be reduced by over 300,000 tons. By 2030, combined NO X and VOC emissions would be reduced by roughly 750,000 tons, one quarter of the onroad inventory. Many of the modeled air toxics would be significantly reduced as well, including benzene, 1,3-butadiene, acetaldehyde, acrolein and ethanol (ranging from 20 to nearly 40 percent of the national onroad inventory by 2030). The relative reduction in overall emissions would continue to increase beyond 2030 as more of the fleet continues to turn over to Tier 3 vehicles; for example, by 2050, when nearly all of the fleet would have turned over to Tier 3 standards, we estimate the Tier 3 program would reduce onroad emissions of NO X and VOC nearly 40 percent from the level of emissions projected without Tier 3 controls.

Table III-1—Estimated Emission Reductions from the Proposed Tier 3 Standards Back to Top
2017 2030
Tons Percent of onroad inventory Tons Percent of onroad inventory
[Annual U.S. short tons]a
aThis analysis assumed emissions reductions from the Tier 3 vehicle standards would occur in all states. For the final rule we will account for LEV III vehicle standards in states that have subsequently adopted it.
NO X 284,381 8 524,790 28
VOC 44,782 3 226,028 23
CO 746,683 4 5,765,362 30
Direct PM 2.5 121 0.1 7,458 10
Benzene 1,625 4 8,582 36
SO 2 16,261 51 17,267 51
1,3-Butadiene 322 5 1,087 37
Formaldehyde 727 3 2,707 12
Acetaldehyde 762 3 4,414 26
Acrolein 23 1 184 15
Ethanol 2,684 2 27,821 24

Reductions for each pollutant are discussed in the following sections, focusing on the contribution of program elements to the total reductions summarized above.

1. NO X

The proposed sulfur standards would significantly reduce NO X emissions immediately upon implementation of the program. As discussed above, recent research on the impact of sulfur on Tier 2 technology vehicles shows the potential for significant reductions in NO X emissions from the existing fleet of Tier 2 vehicles by lowering sulfur levels to 10 ppm. Prior research shows that NO X emissions would also be expected to decrease from the fleet of older (pre-Tier 2) light-duty vehicles as well as heavy-duty gasoline vehicles, [183] although at to a lesser extent than for Tier 2 vehicles.

Table III-2 shows the reduction in NO X emissions, in annual short tons, projected in calendar years 2017 and 2030. The reductions are split into those attributable to the introduction of low sulfur fuel in the pre-Tier 3 fleet (defined for this analysis as model years prior to 2017); and reductions attributable to vehicle standards enabled by low sulfur fuel (model year 2017 and later). As shown, upon implementation of the proposed sulfur standards, total onroad NO X emissions are projected to drop 8 percent. This is primarily due to large reductions from Tier 2 gasoline vehicles, which contribute about one-quarter of the NO X emissions from the on-road fleet in 2017. The relative reduction grows as cleaner vehicles turn over into the fleet. By 2030, we project that the reduction in overall onroad NO X inventory would be close to 30 percent.

Table III-2—Projected NO X Reductions From Tier 3 Program Back to Top
2017 2030
[Annual U.S. Tons]a
aThis analysis assumed emissions reductions from the Tier 3 vehicle standards would occur in all states. For the final rule we will account for LEV III vehicle standards in states that have subsequently adopted it.
Total reduction 284,381 524,790
Reduction from pre-Tier 3 fleet due to sulfur standard 264,653 66,286
Reduction from Tier 3 fleet due to vehicle and sulfur standards 19,728 458,504
Percent reduction in onroad NO X emissions 8% 28%

2. VOC

Table III-3 shows the reduction in VOC emissions, in annual short tons, projected in calendar years 2017 and 2030 resulting from the proposed standards. In 2017, as with NO X, we project reductions from the pre-Tier 3 fleet with the proposed fuel standards. By 2030 the reduction in overall onroad VOC emissions would be over 20 percent, the majority of this from the Tier 3 fleet. The proposed evaporative standards are projected to account for roughly one quarter of the overall vehicle program reduction in 2030.

Table III-3—Projected VOC Reductions From Tier 3 Program Back to Top
2017 2030
[Annual U.S. tons]a
aThis analysis assumed emissions reductions from the Tier 3 vehicle standards would occur in all states. For the final rule we will account for LEV III vehicle standards in states that have subsequently adopted it.
Total reduction 44,782 226,028
Reduction from pre-Tier 3 fleet due to sulfur standard 39,561 13,739
Reduction from Tier 3 fleet due to vehicle and sulfur standards 5,222 212,289
Exhaust 41,433 168,264
Evaporative 3,349 57,764
Percent reduction in onroad VOC emissions 3% 23%

3. CO

Table III-4 shows the reductions for CO, broken down by pre- and post-Tier 3 in the manner described for NO X and VOC above. Based on research showing sizeable CO reductions from lower sulfur fuel, the immediate reductions in the onroad fleet from sulfur control are also significant. The CO exhaust standards are projected to reduce onroad CO emissions 30 percent by 2030.

Table III-4—Projected CO Reductions From Tier 3 Program Back to Top
2017 2030
[Annual U.S. tons]
aThis analysis assumed emissions reductions from the Tier 3 vehicle standards would occur in all states. For the final rule we will account for LEV III vehicle standards in states that have subsequently adopted it.
Total reduction 746,683 5,765,362
Reduction from pre-Tier 3 fleet due to sulfur standard 608,502 139,074
Reduction from Tier 3 fleet due to vehicle and sulfur standards 138,181 5,626,288
Percent reduction in onroad CO emissions 4% 30%

4. Direct PM 2.5

Reductions in direct emissions of PM 2.5 are projected to result solely from the proposed vehicle tailpipe standards, so meaningful reductions are realized mainly as the fleet turns over. By 2030, we project a reduction of about 7,500 tons annually, which represents approximately 10 percent of the onroad direct PM 2.5 inventory. However, since the PM standards are mainly focused on improving engine durability through the end of a vehicle's useful life, the relative reduction in onroad emissions is projected to grow to 17 percent with full fleet turnover in 2050. Reductions in NO X and VOC emissions would also reduce secondary PM formation, which is quantified as part of the air quality analysis described in Section III.C.

5. Air Toxics

Emissions of air toxics also would be reduced by the proposed sulfur, exhaust and evaporative standards. Air toxics are generally a subset of compounds making up VOC, so the reduction trends tend to track the VOC reductions presented above. Table III-5 presents reductions for certain key air toxics, and Table III-6 presents reductions for the sum of 71 different toxic compounds.

Table III-5—Reductions for Certain Individual Compounds Back to Top
Tons reduced in 2017 Percent reduction in onroad emissions Tons reduced in 2030 Percent reduction in onroad emissions
[Annual U.S. tons]
aThis analysis assumed emissions reductions from the Tier 3 vehicle standards would occur in all states. For the final rule we will account for LEV III vehicle standards in states that have subsequently adopted it.
Acetaldehyde 762 3 4,414 26
Formaldehyde 727 3 2,707 12
Acrolein 23 1 184 15
1,3-Butadiene 322 5 1,087 37
Benzene 1,625 4 8,581 36
Naphthalene 96 2 420 17
Ethanol 2,684 2 27,821 24

The totals shown in Table III-6 represent the sum of 71 species including the toxics in Table III-5, 15 polycyclic aromatic hydrocarbon (PAH) compounds in gas and particle phase, and additional gaseous compounds such as toluene, xylenes, styrene, hexane, 2,2,4-trimethylpentane, n-hexane, and propionaldehyde (Appendix 7A in the draft RIA). As shown, in 2030 the overall onroad inventory of total toxics would be reduced by over 20 percent, with nearly one third of the vehicle program reductions coming from the proposed evaporative standards.

Table III-6—Reductions in Total Mobile Source Air Toxics Back to Top
2017 2030
[Annual U.S. Tons]
aThis analysis assumed emissions reductions from the Tier 3 vehicle standards would occur in all states. For the final rule we will account for LEV III vehicle standards in states that have subsequently adopted it.
Total reduction 15,156 89,685
Reduction from pre-Tier 3 fleet due to sulfur standard 12,452 5,022
Reduction from Tier 3 fleet due to vehicle and sulfur standards 2,683 84,663
Exhaust 13,748 64,144
Evaporative 1,408 25,541
Percent reduction in onroad toxics emissions 3% 23%

6. SO 2

SO 2 emissions from mobile sources are a direct function of sulfur in the fuel, and reducing sulfur in gasoline would result in immediate reductions in SO 2 from the on and off-road fleet. The reductions, shown in Table III-7, are a function of the sulfur level and fuel consumption. This is reflected in the relative contribution of on-road vehicles and off-road equipment, where off-road gasoline consumption accounts for approximately 5 percent of overall gasoline use. [184]

Table III-7—Projected SO 2 Reductions From Tier 3 Program Back to Top
2017 2030
[Annual U.S. Tons]
Total reduction 16,261 17,267
Reduction from onroad vehicles due to sulfur standard 15,494 16,370
Reduction from off-road equipment due to sulfur standard 767 897
Percent reduction in onroad SO 2 emissions 51% 51%

7. Greenhouse Gases

Reductions in nitrous oxide (N 2 O) emissions and methane (CH 4) emissions, both potent greenhouse gas emissions, are projected for gasoline cars and trucks due to the proposed sulfur and tailpipe standards. A study conducted by the University of California at Riverside found a 29 percent reduction in N 2 O emissions over the FTP when sulfur was reduced from 30 to 5 ppm, [185] while EPA research described in Section IV.A on sulfur effects found a 25 percent reduction in CH 4 emissions when sulfur was reduced from 28 to 5 ppm. Several studies have established correlations between reductions in tailpipe NO X emissions and reductions in N 2 O from gasoline cars and trucks, 186 187 188 as well as correlations between reductions in tailpipe HC emissions and reductions in CH 4. 189 190 One such study (Behrentz et al.) reported an N 2 O: NO X ratio of 0.095 ± 0.035, and supported the application of N 2 O: NO X ratios to NO X emissions as a reasonable method for estimating N 2 O emission inventories. As detailed in RIA Chapter 7.3, a range of N 2 O reductions is bounded by applying this ratio to NO X reductions projected for this proposal (from Table III-1), and applying the UC Riverside sulfur results to MOVES N 2 O inventories for pre-Tier 3 vehicles. Using a 100-year global warming potential of 298 for N 2 O according to the 2007 IPCC AR4, [191] the range of reductions calculated for N 2 O is from 2.9 to 7.3 million metric tons of carbon dioxide equivalent (MMTCO 2 e) in 2017, growing to 12.3 to 13.5 MMTCO 2 e in 2030. MOVES can be used to directly estimate CH 4 reductions from the sulfur and vehicle standards, estimating an additional 0.1 MMTCO 2 e reduction in 2017, growing to 0.5 MMTCO2e in 2030. The range of total GHG reductions from the Tier 3 rule is 3.0 to 7.4 MMTCO 2 e in 2017, growing to 12.8 to 14.0 MMTCO 2 e in 2030.

These reductions would be offset to some degree by CO 2 emissions associated with higher energy use required in the process of removing sulfur within the refinery. To assess the potential refinery permitting implications of the Tier 3 proposal, we calculated the CO 2 emission impacts on a refinery-by-refinery basis. We used the projected refinery-specific changes from our refinery-by-refinery modeling (see Chapter 5 of the draft RIA) to estimate changes in process energy and then applied emission factors that correspond to those changes. The results showed an increase of up to 4.6 MMTCO 2 e in 2017 for all U.S. refineries complying with the lower sulfur standards assuming that the proposed sulfur standards are fully phased-in. [192] The actual increase is expected to be considerably lower, since this is a permitting analysis and refineries will not be operating at their permit capacity. The actual increase will also be a function of several factors, including technology options selected by the refineries and the projected use of averaging, banking and trading in avoiding the need for investments at some refineries. As a result, 4.6 MMTCO 2 e represents an upper-bound estimate of the possible increase in refinery CO 2 emissions due to the need for additional process heat and hydrogen production to enable the additional hydrotreating required.

In 2017, the range of potential decrease in CH 4 and N 2 O emissions overlaps with the range of projected increase in CO 2 from refinery processes, suggesting that a net increase or decrease in GHG emissions cannot be quantified with certainty. However, we estimate the program would result in net GHG reductions as the program continues into the future, as shown by our 2030 estimates.

We do not expect the Tier 3 vehicle standards to result in any discernible changes in vehicle CO 2 emissions or fuel economy. Emissions of the pollutants that we have designed the program to address—NMOG, NO X, and PM—are not a function of the amount of fuel consumed, since manufacturers need to design their catalytic emission control systems to reduce these emissions regardless of their engine-out levels. However, there may be some slight reduction of vehicle mass if manufacturers explore lighter exhaust manifold materials in order to reduce thermal mass and promote earlier catalyst light-off. EPA invites comments on any potential impacts of the proposed Tier 3 program on vehicle CO 2 emissions and fuel economy.

C. How would air pollution be reduced?

Reductions in emissions of NO X, VOC, PM 2.5 and air toxics expected as a result of the proposed Tier 3 standards are projected to lead to significant decreases in ambient concentrations of ozone, PM 2.5, and air toxics. The results of our air quality modeling of the impacts of the Tier 3 proposal are summarized in the following section. The air quality modeling predicts significant improvements in ozone concentrations due to the proposed Tier 3 standards. Ambient PM 2.5 and NO 2 concentrations are also expected to improve as a result of the proposed Tier 3 program. Decreases in ambient concentrations of air toxics are projected with the proposed standards, including notable nationwide reductions in benzene concentrations. Our air quality modeling also predicts improvements in visibility and sulfur deposition, as well as substantial decreases in nitrogen deposition as a result of the proposed standards.

1. Ozone

The air quality modeling done for this proposal projects that in 2017, with all current controls in effect but excluding the emissions changes expected to occur as a result of this proposed action or any other additional controls, at least 40 counties, with a projected population of almost 50 million people, would have projected design values above the level of the 2008 8-hour ozone standard of 75 ppb. Even in 2030 the modeling projects that in the absence of additional controls there would be 12 counties with a population of almost 32 million people with projected design values above the level of the 2008 8-hour ozone standard of 75 ppb. Since the emission changes from this proposal go into effect during the period when some areas are still working to attain the ozone NAAQS, the projected emission changes would help state and local agencies in their effort to attain and maintain the ozone standard.

Air quality modeling indicates ozone design value concentrations would decrease dramatically in many areas of the country as a result of this action and in some places those decreases would be enough to change the projected design values from being above the NAAQS to being below the NAAQS. The decreases in ozone design values are likely due to projected tailpipe reductions in NO X and VOCs from reductions in fuel sulfur and engine controls.

In 2017, the majority of the design value decreases are between 0.5 and 1.0 ppb. The projected population-weighted average design value concentration without the proposed rule is 71.3 ppb in 2017. The proposed rule would also reduce the projected ozone design values in three counties from above the level of the standard to below. These three counties are Bucks County in Pennsylvania, Arlington County in Virginia and St Louis County in Missouri. The projected population in these three counties in 2017 is almost 2 million people. In 2030, the proposed rule would result in larger decreases in ozone design values, with the majority of counties projecting decreases of between 1.0 and 1.5 ppb, and over 200 more counties with decreases greater than 1.5 ppb. The projected population-weighted average design value concentration without the proposed rule is 66.7 ppb in 2030. There are also two more counties whose projected design values would be reduced from above the level of the ozone standard to below by the proposed rule in 2030. These counties are Hudson County in New Jersey and Brazoria County in Texas. The projected population in these two counties in 2030 is over 1 million people.

Table III-8 and Table III-9 show the average change in 2017 and 2030 8-hour ozone design values for: (1) All counties with 2005 baseline design values, (2) counties with 2005 baseline design values that exceeded the 2008 ozone standard, (3) counties with 2005 baseline design values that did not exceed the 2008 standard, but were within 10 percent of it, (4) counties with 2017/2030 design values that exceeded the 2008 ozone standard, and (5) counties with 2017/2030 design values that did not exceed the standard, but were within 10 percent of it. Counties within 10 percent of the standard are intended to reflect counties that although not violating the standards, will also be impacted by changes in ozone as they work to ensure long-term maintenance of the ozone NAAQS. All of these metrics show a decrease in 2017 and 2030, indicating in five different ways the overall improvement in air quality.

On a population-weighted basis, the average modeled future-year 8-hour ozone design values are projected to decrease by 0.47 ppb in 2017 and 1.55 ppb in 2030. On a population-weighted basis design values in those counties that are projected to be above the 2008 ozone standard in 2017 and 2030 are projected to decrease by 0.30 and 1.62 ppb respectively due to the proposed standards.

Table III-8—Average Change in Projected 8-Hour Ozone Design Value in 2017 c Back to Top
Averagea Number of U.S. counties 2020 populationb Change in 2017 design value (ppb)
aAverages are over counties with 2005 modeled design values.
bPopulation numbers based on Woods & Poole data. Woods & Poole Economics, Inc. 2001. Population by Single Year of Age CD.
cThis analysis assumed emissions reductions from Tier 3 vehicle standards would occur in all states and did not account for emission reductions associated with LEV III vehicle standards in California and other states that have subsequently adopted it. The analysis for the final rule will account for LEV III vehicle standards.
All 676 238,026,106 −0.50
All, population-weighted −0.47
Counties whose 2005 base year is violating the 2008 8-hour ozone standard 393 176,910,535 −0.56
Counties whose 2005 base year is violating the 2008 8-hour ozone standard, population-weighted −0.51
Counties whose 2005 base year is within 10 percent of the 2008 8-hour ozone standard 201 40,516,171 −0.47
Counties whose 2005 base year is within 10 percent of the 2008 8-hour ozone standard, population-weighted −0.42
Counties whose 2017 control case is violating the 2008 8-hour ozone standard 37 47,659,433 −0.35
Counties whose 2017 control case is violating the 2008 8-hour ozone standard, population-weighted −0.30
Counties whose 2017 control case is within 10 percent of the 2008 8-hour ozone standard 124 68,625,934 −0.51
Counties whose 2017 control case is within 10 percent of the 2008 8-hour ozone standard, population-weighted −0.49
Table III-9—Average Change in Projected 8-Hour Ozone Design Value in 2030 c Back to Top
Averagea Number of U.S. counties 2030 populationb Change in 2030 design value (ppb)
aAverages are over counties with 2005 modeled design values.
bPopulation numbers based on Woods & Poole data. Woods & Poole Economics, Inc. 2001. Population by Single Year of Age CD.
cThis analysis assumed emissions reductions from Tier 3 vehicle standards would occur in all states and did not account for emission reductions associated with LEV III vehicle standards in California and other states that have subsequently adopted it. The analysis for the final rule will account for LEV III vehicle standards.
All 676 261,497,900 −1.35
All, population-weighted −1.55
Counties whose 2005 base year is violating the 2008 8-hour ozone standard 393 194,118,748 −1.54
Counties whose 2005 base year is violating the 2008 8-hour ozone standard, population-weighted −1.69
Counties whose 2005 base year is within 10 percent of the 2008 8-hour ozone standard 201 44,436,103 −1.18
Counties whose 2005 base year is within 10 percent of the 2008 8-hour ozone standard, population-weighted −1.25
Counties whose 2030 control case is violating the 2008 8-hour ozone standard 10 30,619,714 −1.49
Counties whose 2030 control case is violating the 2008 8-hour ozone standard, population-weighted −1.62
Counties whose 2030 control case is within 10 percent of the 2008 8-hour ozone standard 40 21,541,863 −1.37
Counties whose 2030 control case is within 10 percent of the 2008 8-hour ozone standard, population-weighted −1.50

2. Particulate Matter

The air quality modeling conducted for this proposal projects that in 2030, with all current controls in effect but excluding the emissions changes expected to occur as a result of this proposal or any other additional controls, at least 14 counties, with a projected population of over 28 million people, would have projected design values above the level of the annual standard of 12 µg/m 3 and at least 21 counties, with a projected population of over 31 million people, would have projected design values above the level of the 24-hour standard of 35 μg/m 3. [193] Since the emission changes from this proposed action would go into effect during the period when some areas are still working to attain the PM 2.5 NAAQS, the projected emission changes would be useful to state and local agencies in their effort to attain and maintain the PM 2.5 standard.

The proposed rule would reduce 24-hour and annual PM 2.5 design values in 2030. Annual PM 2.5 design values in the majority of modeled counties would decrease by between 0.01 and 0.05 µg/m 3 and in over 100 additional counties design values are projected to decrease by greater than 0.05 μg/m 3. The projected population-weighted average design value concentration without the proposed rule is 9.5 µg/m 3 in 2030. The average modeled future-year annual PM 2.5 design values in 2030 decrease by 0.06 µg/m 3 on a population-weighted basis. Design values in those counties that are projected to be above the annual PM 2.5 standard in 2030 decrease even more, by 0.11 µg/m [3] on a population-weighted basis, due to the proposed standards. In addition, the average modeled future-year 24-hour PM 2.5 design values in 2030 decrease by 0.20 µg/m 3 on a population-weighted basis. The projected population-weighted average design value concentration without the proposed rule is 24.3 µg/m 3 in 2030. The decreases in PM 2.5 design values are likely due to the projected tailpipe reductions in primary PM 2.5, NO X and VOCs. The proposed rule has little impact on PM 2.5 design values for the majority of counties in 2017, although our air quality modeling underestimated the PM decreases that would result from this proposal (see Section 7.4.2.3 of the draft RIA for more detail).

Table III-10 and Table III-11 present the average change in 2030 annual and 24-hour PM 2.5 design values for: (1) All counties with 2005 baseline design values, (2) counties with 2005 baseline design values that exceeded the PM 2.5 standard, (3) counties with 2005 baseline design values that did not exceed the standard, but were within 10 percent of it, (4) counties with 2030 design values that exceeded the PM 2.5 standard, and (5) counties with 2030 design values that did not exceed the standard, but were within 10 percent of it. Counties within 10 percent of the standard are intended to reflect counties that although not violating the standards, will also be impacted by changes in PM 2.5 as they work to ensure long-term maintenance of the annual and/or 24-hour PM 2.5 NAAQS. All of these metrics show a decrease in 2030. On a population-weighted basis, there is a 0.06 µg/m 3 decrease in the average modeled future-year annual PM 2.5 design values in 2030 and a decrease of 0.11 µg/m [3] in those counties that are projected to be above the annual PM 2.5 standard in 2030. In addition, the average population-weighted modeled future-year 24-hour PM 2.5 design values are projected to decrease by 0.20 µg/m 3 due to the proposed standards and design values in those counties that are projected to be above the 24-hour PM 2.5 standard in 2030 would decrease by 0.32 µg/m 3.

Table III-10—Average Change in Projected Annual PM 2.5 Design Values in 2030 c Back to Top
Averagea Number of U.S. counties 2030 Population Change in 2030 design value (μg/m3)
aAverages are over counties with 2005 modeled design values.
bPopulation numbers based on Woods & Poole data. Woods & Poole Economics, Inc. 2001. Population by Single Year of Age CD.
cThis analysis assumed emissions reductions from Tier 3 vehicle standards would occur in all states and did not account for emission reductions associated with LEV III vehicle standards in California and other states that have subsequently adopted it. The analysis for the final rule will account for LEV III vehicle standards.
dEight of these counties are in California, see Table 7-35 in the DRIA.
All 576 247,415,381 −0.05
All, population-weighted −0.06
Counties whose 2005 base year is violating the annual PM 2.5 standard 314 152,109,569 −0.05
Counties whose 2005 base year is violating the annual PM 2.5 standard, population-weighted −0.07
Counties whose 2005 base year is within 10 percent of the annual PM 2.5 standard 83 31,863,376 −0.05
Counties whose 2005 base year is within 10 percent of the annual PM 2.5 standard, population-weighted −0.05
Counties whose 2030 control case is violating the annual PM 2.5 standardd 14 28,624,758 −0.11
Counties whose 2030 control case is violating the annual PM 2.5 standard, population-weightedd −0.10
Counties whose 2030 control case is within 10 percent of the annual PM 2.5 standard 28 23,840,272 −0.07
Counties whose 2030 control case is within 10 percent of the annual PM 2.5 standard, population-weighted −0.09
Table III-11—Average Change in Projected 24-hour PM 2.5 Design Values in 2030 c Back to Top
Averagea Number of U.S. counties 2030 Populationb Change in 2030 design value (μg/m3)
aAverages are over counties with 2005 modeled design values.
bPopulation numbers based on Woods & Poole data. Woods & Poole Economics, Inc. 2001. Population by Single Year of Age CD.
cThis analysis assumed emissions reductions from Tier 3 vehicle standards would occur in all states and did not account for emission reductions associated with LEV III vehicle standards in California and other states that have subsequently adopted it. The analysis for the final rule will account for LEV III vehicle standards.
dEleven of these counties are in California, see Table 7-37 in the DRIA.
All 569 245,111,480 −0.16
All, population-weighted −0.20
Counties whose 2005 base year is violating the 2006 24-hour PM 2.5 standard 108 91,474,036 −0.29
Counties whose 2005 base year is violating the 2006 24-hour PM 2.5 standard, population-weighted −0.27
Counties whose 2005 base year is within 10 percent of the 2006 24-hour PM 2.5 standard 140 53,990,060 −0.18
Counties whose 2005 base year is within 10 percent of the 2006 24-hour PM 2.5 standard, population-weighted −0.21
Counties whose 2030 control case is violating the 2006 24-hour PM 2.5 standardd 21 31,002,272 −0.50
Counties whose 2030 control case is violating the 2006 24-hour PM 2.5 standard, population-weightedd −0.32
Counties whose 2030 control case is within 10 percent of the 2006 24-hour PM 2.5 standard 7 4,212,913 −0.37
Counties whose 2030 control case is within 10 percent of the 2006 24-hour PM 2.5 standard, population-weighted −0.50

3. Nitrogen Dioxide

Although our modeling indicates that by 2030 the majority of the country will experience decreases of less than 0.1 ppb in their annual NO 2 concentrations due to this proposal, annual NO 2 concentrations are projected to decrease by more than 0.3 ppb in most urban areas. These emissions reductions would also likely decrease 1-hour NO 2 concentrations and help any potential nonattainment areas to attain and maintain the standard. Additional information on the emissions reductions that are projected with this proposal is available in Section 7.2.1 of the draft RIA.

4. Air Toxics

Our modeling indicates that the impacts of proposed Tier 3 standards include generally small decreases in ambient concentrations of air toxics, especially in urban areas, with notable nationwide reductions in benzene. Although reductions are greater in 2030 (when Tier 3 cars and trucks would contribute nearly 90 percent of fleet-wide vehicle miles travelled) than in 2017 (the first year of the proposed program), our modeling projects there would be small immediate reductions in ambient concentrations of air toxics due to the proposed sulfur controls in 2017. Furthermore, the full reduction of the vehicle program would be realized after 2030, when the fleet has fully turned over to Tier 3 vehicles. Air toxics pollutants dominated by primary emissions (or a decay product of a directly emitted pollutant) have the largest impacts, rather than air toxics that primarily result from photochemical transformation. Specifically, in 2030, our modeling projects that the proposal would decrease ambient benzene concentrations across much of the country on the order of 1 to 5 percent, with reductions ranging from 10 to 25 percent in some urban areas. Our modeling also shows reductions of 1,3-butadiene and acrolein concentrations in 2030 ranging between 1 and 25 percent, with 1,3-butadiene decreases of at least 0.005 μg/m [3] in urban areas. These toxics are national risk drivers and the reductions in ambient concentrations from this proposed rule would result in reductions in risks from cancer and noncancer health effects. In some parts of the country (mainly urban areas), ethanol and formaldehyde concentrations are projected to decrease on the order of 1 to 5 percent in 2030 as a result of the proposal. Decreases in ethanol concentrations are expected due to reductions in VOC as a result of the proposed standards. Changes in ambient acetaldehyde concentrations are generally less than 1 percent across the U.S., although the proposal may decrease acetaldehyde concentrations in some urban areas by 1 to 2.5 percent in 2030.

Although the reductions in ambient air toxics concentrations expected from the proposed Tier 3 standards are generally small, they are projected to benefit the majority of the U.S. population. As shown in Table III-12, over 80 percent of the total U.S. population is projected to experience a decrease in ambient benzene and acrolein concentrations of at least 2.5 percent, with more than 90 percent of the populations projected to experience 1,3-butadiene concentrations of similar magnitude. Over 80 percent of the U.S population is projected to experience at least a 1 percent decrease in ambient ethanol concentrations, and over 60 percent would experience a similar decrease in ambient formaldehyde concentrations with the proposed standards.

Table III-12—Percent of Total Population Experiencing Changes in Annual Ambient Concentrations of Toxic Pollutants in 2030 as a Result of the Proposed Standards a Back to Top
Percent change Benzene (percent) Acrolein (percent) 1,3-Butadiene (percent) Formaldehyde (percent) Ethanol (percent) Acetaldehyde (percent)
aThis analysis assumed emissions reductions from Tier 3 vehicle standards would occur in all states and did not account for emission reductions associated with LEV III vehicle standards in California and other states that have subsequently adopted it. The analysis for the final rule will account for LEV III vehicle standards.
≤ −50
> −50 to ≤ −25 0.1
> −25 to ≤ −10 2.8 0.7 56.8
> −10 to ≤ −5 23.7 36.8 30.8
> −5 to ≤ −2.5 54.5 43.7 7.1 1.2 33.0 0.3
> −2.5 to ≤ −1 17.7 15.3 3.4 63.2 55.3 25.1
> −1 to < 1 1.4 3.5 1.7 35.6 11.6 74.6
≥ 1 to < 2.5 0.0
≥ 2.5 to < 5
≥ 5 to < 10
≥ 10 to < 25
≥ 25 to < 50
≥ 50

5. Visibility

Air quality modeling conducted for this proposed action was used to project visibility conditions in 139 mandatory class I federal areas across the U.S. The results show that in 2030 all the modeled areas would continue to have annual average deciview levels above background and the proposed rule would improve visibility in all these areas. [194] The average visibility at all modeled mandatory class I federal areas on the 20 percent worst days is projected to improve by 0.04 deciviews, or 0.28 percent, in 2030. Section 7.2.5.5 of the draft RIA contains more detail on the visibility portion of the air quality modeling.

6. Nitrogen and Sulfur Deposition

Our air quality modeling projects substantial decreases in nitrogen deposition as a result of the proposed standards. The standards would result in annual percent decreases of greater than 5 percent in most major urban areas and greater than 7 percent in a few areas. In addition, smaller decreases, in the 1 to 1.5 percent range, would occur over most of the rest of the country. The impacts of the proposed standards on sulfur deposition are smaller, ranging from no change to decreases of over 2 percent in some areas. For maps of 2030 deposition impacts and additional information on these impacts see Section 7.2.5.6 of the draft RIA.

7. Environmental Justice

Environmental justice (EJ) is a principle asserting that all people deserve fair treatment and meaningful involvement with respect to environmental laws, regulations, and policies. EPA seeks to provide the same degree of protection from environmental health hazards for all people. As referenced below, numerous studies have found that some environmental hazards are more prevalent in areas with high population fractions of racial/ethnic minorities and people with low socioeconomic status (SES), as would be expected on the basis of those areas' share of the general population.

As discussed in Section II of this document, concentrations of many air pollutants are elevated near high-traffic roadways. If minority populations and low-income populations disproportionately live near such roads, then an issue of EJ may be present. Such disparities may be due to multiple factors. [195]

People with low SES often live in neighborhoods with multiple stressors and health risk factors, including reduced health insurance coverage rates, higher smoking and drug use rates, limited access to fresh food, visible neighborhood violence, and elevated rates of obesity and some diseases such as asthma, diabetes, and ischemic heart disease. Although questions remain, several studies find stronger associations between air pollution and health in locations with such chronic neighborhood stress, suggesting that populations in these areas may be more susceptible to the effects of air pollution. 196 197 198 199 Household-level stressors such as parental smoking and relationship stress also may increase susceptibility to the adverse effects of airpollution. 200 201

To address the existing conditions in areas near major roadways, in comparison with other locations, we reviewed existing scholarly literature examining the topic, and conducted our own evaluation of two national datasets: the U.S. Census Bureau's American Housing Survey for calendar year 2009 and the U.S. Department of Education's database of school locations.

Existing publications that address EJ issues generally report that populations living near major roadways (and other types of transportation infrastructure) tend to be composed of larger fractions of nonwhite residents. People living in neighborhoods near such sources of air pollution also tend to be lower in income than people living elsewhere. Numerous studies evaluating the demographics and socioeconomic status of populations or schools near roadways have found that they include a greater percentage of minority residents, as well as lower SES (indicated by variables such as median household income). Locations in these studies include Los Angeles, CA, Seattle, WA, Wayne County, MI, Orange County, FL, and the State of California 202 203 204 205 206 207

We analyzed two national databases that allowed us to evaluate whether homes and schools were located near a major road. One database, the American Housing Survey (AHS), includes descriptive statistics of over 70,000 housing units across the nation. The study is conducted every two years by the U.S. Census Bureau. We analyzed data from the 2009 AHS. The second database we analyzed was the U.S. Department of Education's Common Core of Data, which includes enrollment and location information for schools across the U.S.

In analyzing the 2009 AHS, we focused on whether or not a housing unit was located within 300 feet of “4-or-more lane highway, railroad, or airport.” [208] We analyzed whether there were differences between houses and householders in such locations and those not in them. [209] We found that houses with a nonwhite householder were 22-34 percent more likely to be located within 300 feet of these large transportation facilities, while houses with a Hispanic householder were 17-33 percent more likely. Households near large transportation facilities were, on average, lower in income and educational attainment, more likely to be a rental property and located in an urban area.

In examining schools near major roadways, we examined the Common Core of Data (CCD) from the U.S. Department of Education, which includes information on all public elementary and secondary schools and school districts nationwide. [210] To determine school proximities to major roadways, we used a geographic information system (GIS) to map each school and roadways based on the U.S. Census's TIGER roadway file. [211] We found that minority students were overrepresented at schools within 200 meters of the largest roadways, and that schools within 200 meters of the largest roadways also had higher than expected numbers of students eligible for free or reduced-price lunches. For example, Black students represent 21.57 percent of students at schools located within 200 meters of a primary road, whereas Black students represent 16.62 percent of students in all U.S. schools. Hispanic students represent 30.13 percent of students at schools located within 200 meters of a primary road, whereas Hispanic students represent 21.93 percent of students in all U.S. schools.

Overall, there is substantial evidence that people who live or attend school near major roadways are more likely to be of a minority race, Hispanic ethnicity, and/or low SES. The reduction of near-roadway concentrations of many pollutants, discussed above, is likely to help in mitigating this disparity in racial, ethnic, and economically-based exposures.

IV. Proposed Vehicle Emissions Program Back to Top

In the more than 10 years since EPA finalized the Tier 2 Vehicle Program, manufacturers of light-duty vehicles have continued to develop a wide range of improved technologies capable of reducing key exhaust emissions, especially hydrocarbons, nitrogen oxides (NO X), and particulate matter (PM). The California LEV II program has been instrumental in the continuous technology improvements by requiring year after year reductions in fleet average hydrocarbon levels in addition to requiring the introduction of advanced exhaust and evaporative emission controls in partial zero emission vehicles (PZEVs). This progress in vehicle technology has made it possible for manufacturers to achieve emission reductions well beyond the requirements of the Tier 2 program if gasoline sulfur levels are lowered further.

Extensive data from existing Tier 2 (and California LEV II) vehicles show the opportunity for further reductions, especially in addressing emissions produced at start-up, emissions under high-speed, high-load conditions, the effects of sulfur in gasoline, the effects of increased oil consumption, and the effects of vehicle and control systems age. For these reasons, we are proposing more stringent standards designed to reduce emissions, primarily non-methane organic gases (NMOG), NO X, and PM from new vehicles. As discussed in detail below and in the draft RIA, we have concluded that, in conjunction with the reductions in fuel sulfur proposed in this action, the proposed vehicle emissions standards are feasible and cost-effective across the fleet in the proposed timeframe. We believe that simultaneous reductions in fuel sulfur would be a key factor in enabling the entire fleet of light-duty vehicles to meet the proposed emission standards in-use, throughout the life of the vehicle.

This section describes in detail the proposed program for reducing tailpipe and evaporative emissions from light-duty vehicles (LDVs, or passenger cars), light-duty trucks (LDT1s, 2s, 3s, and 4s), Medium-Duty Passenger Vehicles (MDPVs), and heavy-duty vehicles (HDVs). Sections IV.A and B discuss the proposed tailpipe emission standards and time lines, and other provisions for new light-duty vehicles and MDPVs and for new heavy-duty vehicles up to 14,000 lbs Gross Vehicle Weight Rating (GVWR). Section IV.C presents the proposed evaporative emissions standards and program as well as proposed improvements to the existing Onboard Diagnostics (OBD) provisions. In Section IV.D, we describe our proposal to update our federal certification fuel to better match today's in-use fuel and to be forward-looking with respect to potential future gasoline ethanol and sulfur content. We also discuss in this section proposed compliance flexibilities for small companies and small-volume manufacturers (IV.E) and test procedure and other compliance provisions (IV.F).

A. Tailpipe Emission Standards for Light-Duty Vehicles, Light-Duty Trucks, and Medium-Duty Passenger Vehicles

1. Overview

The proposed Tier 3 standards are very similar in structure to those in the Tier 2 program. As with the Tier 2 program, the proposed standards would apply to all LDVs and LDTs below 8,500 lbs GVWR, and MDPVs (8,500 to 10,000 lbs GVWR). (We discuss the proposed standards for heavy-duty vehicles up to 14,000 lbs GVWR other than MDPVs, in Section IV.B below.) Also as with Tier 2, manufacturers would select from several “bins” of emission standards such that the average of their vehicles' emissions complies with the proposed fleet-average standards.

In the discussions of the various elements of our proposed program for light- and heavy-duty vehicles throughout this preamble, we describe how the provisions would be consistent with the California Air Resources Board (CARB) LEV III program. [212] Auto manufacturers have stressed to us the importance of their being able to design and produce a single fleet of vehicles in all 50 states that would comply with requirements under the Tier 3 program and the LEV III program, as well as greenhouse gas/CAFE requirements in the same timeframe. Consistency among the federal and California programs means that special versions of vehicles with different emission control hardware and calibrations would not be necessary for different geographic areas. This would allow manufacturers to avoid the additional costs of parallel design, development, calibration, and manufacturing. Consistency among programs would also eliminate the need to supply aftermarket parts for repair of multiple versions of a vehicle. We believe that the most cost-effective national program will result from close coordination of CARB LEV III and federal Tier 3 program elements and their implementation. To that end, we worked closely with CARB and the vehicle manufacturers, both individually and through their trade associations, to align the two programs.

The Tier 3 program we are proposing is identical to LEV III in most major respects for both light-duty and heavy-duty vehicle exhaust and evaporative emissions requirements, as discussed in detail below in this section. The levels and the timing of the light-duty and heavy-duty declining fleet-average NMOG+NOx standards that we are proposing would be identical to those in LEV III. Also, the Tier 3 emissions bins to which manufacturers would certify individual vehicle models in order to comply with the average standards, for both light- and heavy-duty vehicles, would also be identical to those in LEV III. Similarly, the proposed Tier 3 per-vehicle PM standards match LEV III standards through MY 2024. In addition, our proposed primary evaporative emissions standards and onboard diagnostics requirements are also identical to the LEV III requirements.

We note there are a few proposed Tier 3 provisions that CARB and EPA understand would be different, for reasons discussed below. Specifically, these include the LEV III program and our proposed Tier 3 program would have different light-duty PM requirements late in the program (i.e., after MY 2024 (IV.A.3.b.)), would require different test fuels (E10 and E15, respectively (IV.A.3.c)), and only EPA would have an evaporative leak test (IV.C.5.b). EPA and CARB will continue to work toward additional consistency between our programs whenever practicable as both programs are implemented. Beyond these three provisions, the differences between the programs would not be major and would exist only in the early transitional years of the Tier 3 program. These differences would result from the fact that the LEV III requirements begin slightly earlier and that a limited phase-in of some provisions would be necessary for a smooth transition to overall aligned programs. These temporary differences would include the process for how early compliance credits would be generated and used (e.g., Section IV.A.7.a); how quickly manufacturers would need move toward certifying all of their vehicle models to longer useful-life values (e.g., Section IV.A.7.b) and on the new test fuel (e.g., Section IV.A.7.c); and transitional emissions bins to facilitate the transition from Tier 2 to Tier 3 (IV.A.7.m). Similarly, the primary Tier 3 evaporative standards would have a brief phase in period, temporarily resulting in requirements that would be slightly different from those in LEV III.

The proposed Tier 3 program is designed primarily to reduce exhaust and evaporative emissions during summer ambient temperature conditions when NMOG, NO X and PM emissions contribute to air quality concerns. We are not proposing new emission requirements for any vehicle or fuel over the cold temperatures test cycles (i.e., the 20 °F cold CO and NMHC tests). However, we seek comment on the need for doing so, including vehicles operating on E85 fuel, and on the appropriate form and level for any such cold-temperature requirements.

2. Summary of Proposed FTP and SFTP Tailpipe Standards

We are proposing a comprehensive program that would address the key pollutants of concern. We are proposing new standards for the sum of NMOG and NO X emissions, presented as NMOG+NO X, and PM. As discussed in Section III above, these proposed standards would result in very significant improvements in vehicle emissions from the levels of the Tier 2 program. For these pollutants, we are proposing standards as measured on test procedures that represent a range of vehicle operation, including the Federal Test Procedure (FTP) and the Supplemental Federal Test Procedure (SFTP). Unless otherwise specified, the proposed FTP and SFTP standards would apply to vehicles operating on gasoline, diesel, and alternative fuels, including both flexible fuel and dedicated alternative fuel vehicles.

The proposed FTP and SFTP NMOG+NO X standards would be fleet-average standards, meaning that the manufacturer would calculate the average emissions of the vehicles it sells in each model year and compare that average to the applicable standard for that model year. The proposed fleet average standards for NMOG+NO X evaluated over the FTP are summarized in Table I-1. (For comparison, the average NMOG and NO X standard for the Tier 2 program, when added together, equal 160 mg/mi). The standards would begin in MY 2017 at a level representing a 46 percent reduction from the current Tier 2 requirements for lighter vehicles and would become increasingly stringent, culminating in an 81 percent reduction in MY 2025. The proposed FTP NMOG+NO X program includes separate fleet average standards for lighter and heavier vehicles that would converge at 30 milligrams per mile (mg/mi) in MY 2025 and later. 213 214

Manufacturers would determine their fleet average FTP NMOG+NO X emission values based on the per-vehicle “bin standards” to which they certified each vehicle model. As with the Tier 2 program, manufacturers would be free to choose to certify vehicles to any of the bins, so long as the sales-weighted average of the NMOG+NO X values from the selected bins met the fleet average standard for that model year. Table IV-1 presents the per-vehicle bin standards. Similarly, the proposed fleet average NMOG+NO X standards measured over the SFTP are summarized in Table I-2. The proposed SFTP NMOG+NO X fleet average standards decline from MY 2017 until MY 2025. In this case, the same standards would apply to both lighter and heavier vehicles. In MY 2025, the SFTP NMOG+NO X standard would reach its fully phased-in fleet average level of 50 mg/mi. We are also proposing PM standards as part of this Tier 3 program. The proposed PM standards would apply to each vehicle separately (i.e., not as a fleet average). Also, in contrast to the declining NMOG+NO X standards, the proposed certification PM standard on the FTP is 3 mg/mi for all vehicles and for all model years, but phasing in beginning in MY 2017 for vehicles at or below 6,000 lbs GVWR and in MY 2018 for vehicles above 6,000 lbs GVWR. Based on EPA and CARB test programs, most current light duty vehicles are already performing at or below this level. However, some vehicles are emitting above this level, due to such factors as combustion chamber designs, and fuel and oil consumption controls that are not optimized for low PM emissions. The intent of the proposed 3 mg/mi standard is to bring all light-duty vehicles to the PM level typical of that being demonstrated by most light-duty vehicles today.

To address the uncertainties that will accompany the introduction of new technologies, the proposed program also includes a separate in-use FTP PM standard of 6 mg/mi for the testing of in-use vehicles during the phase-in period, as described in more detail below. As presented in Table I-3, for vehicles at or below 6000 lbs GVWR, these FTP certification and in-use standards would be phased in beginning with a requirement that at least 20 percent of a company's U.S. sales meet the standards in MY 2017 and reaching a 100 percent compliance requirement in MY 2021. The proposed standards represent a significant numerical reduction from the Tier 2 PM emission standards of 10 mg/mi for light-duty vehicles. Finally, the proposed Tier 3 program includes PM standards evaluated over the US06 cycle (a component of the SFTP test, discussed further below) at a level of 10 mg/mi for vehicles at or below 6,000 lbs GVWR and 20 mg/mi for heavier vehicles. We are proposing separate standards for different sizes of vehicles because PM generation typically increases when vehicles are carrying heavier loads and/or when they are pulling trailers. The US06 PM standards would phase in on the same schedule as the FTP PM standards, reaching 100 percent of each company's U.S. sales by MY 2022. These US06 standards would apply to the same vehicle models that a manufacture chose to certify to the FTP PM standard during the percent phase in period. PM levels over the US06 are typically higher than the PM emitted over the FTP due to the increased load on the vehicle. As in the case of the FTP PM standards, the intent of the proposed standard is to bring the emission performance of all vehicles to that already being demonstrated by many vehicles in the current light-duty fleet.

As with the FTP PM standard, we propose a separate in-use US06 PM standard during the percent phase-in period of 15 and 25 mg/mi for vehicles of 6000 lbs GVWR and less, and for vehicles above 6,000 lbs GVWR, respectively.

The next subsections describe in more detail the proposed standards, how they would be implemented over time, and the technological approaches that we believe will be available to manufacturers in order to comply.

3. Proposed FTP Standards

As summarized above, we propose new standards for the primary pollutants of concern for this rule (NMOG, NO X, and PM) as measured on the FTP. The following paragraphs describe in more detail these FTP standards for NMOG+NO X and PM, as well as for carbon monoxide (CO) and formaldehyde (HCHO).

a. FTP NMOG+NO X Standards

We propose that the Tier 3 NMOG and NO X standards, both of which are important to reduce ambient ozone concentrations, be expressed in terms of the sum of the two pollutants, or as NMOG+NO X in mg/mi. [215] This approach contrasts with the Tier 2 standards, which were expressed as separate NMOG and NO X standards. We believe that the combined standard is appropriate for this proposed program for several reasons. At the stringent proposed emission levels, combining NMOG and NO X would provide a small amount of compliance flexibility, while at the same time significantly reducing both NMOG and NO X emission levels. For example, the combined standard would allow a gasoline vehicle manufacturer to have slightly higher NMOG if it were offset by lower NO X, or allow a diesel vehicle manufacturer to have slightly higher NO X if offset by lower NMOG. This approach still ensures major reductions in both pollutants compared to today's levels. This is because the very stringent level of the fully phased-in proposed combined standard (30 mg/mi NMOG+NO X) means that even with a degree of allowed trading off of one pollutant for the other, the maximum emissions of either pollutant would need to be well below current levels. The standards of the California LEV III program would also be expressed as NMOG+NO X; aligning Tier 3 with LEV III in this respect would facilitate an important element of a national program.

We believe that a fully phased-in level for the proposed fleet-average standard of 30 mg/mi is the most stringent level that we could reasonably propose in the context of our proposed 10-ppm average standard for gasoline sulfur. As discussed in the feasibility Section IV.A.5 below, when necessary margins of compliance are considered, this proposed standard is very close to zero. We request comment on this level for the proposed standard, as well as the declining standards during the transition years (see Table IV-3 below). EPA is proposing compliance mechanisms for the new Tier 3 FTP standards that are the same in most respects as those of the Tier 2 program. Using the Tier 2 approaches as much as possible would streamline the implementation of the program by maintaining most of the compliance processes that manufacturers are familiar with today.

A key compliance mechanism adapted from the Tier 2 program is a “bin” structure for the proposed emission standards. For these purposes, a bin is a set of several standards that are intended to be complied with as a group. Thus each Tier 3 bin would have an NMOG+NO X standard and a PM standard, as well as CO and HCHO standards. A manufacturer choosing to certify a vehicle to a certain bin would need to meet each of that bin's standards for the full useful life of the vehicle. In this approach, manufacturers could certify vehicles to any of the bins, but they would have to ensure that average NMOG+NO X of the bins to which all of its vehicles were certified met the fleet average standard specific to the vehicle category (i.e., LDV/LDT1 and LDT2/3/4/MDPVs) for that model year. That is, a manufacturer would comply by ensuring that the sales-weighted average of the NMOG+NO X values of the bins to which each of its vehicle models was certified was lower than the fleet average standard that applied for that model year.

For each proposed bin, we are including CO and HCHO standards at levels intended to prevent new engine and emission control designs that would result in increases in today's CO and HCHO emissions. The standards are based on the comparable current LEV II and Tier 2 bin standards for these pollutants. The current standards do not appear to be technology-forcing, and we believe that this would continue to be the case as Tier 3 technologies are developed.

The bin structure that we are proposing for light duty vehicles, light-duty trucks, and MDPVs standards is presented in Table IV-1.

Table IV-1—Proposed FTP Standards for LDVs, LDTs and MDPVs (mg/mi) Back to Top
Bin NMOG+NO X (mg/mi) PMa (mg/mi) CO (g/mi) HCHO (mg/mi)
aIn MYs 2017-20, the PM standard applies only to that segment of a manufacturer's vehicles covered by the percent of sales phase-in for that model year.
Bin 160 160 3 4.2 4
Bin 125 125 3 2.1 4
Bin 70 70 3 1.7 4
Bin 50 50 3 1.7 4
Bin 30 30 3 1.0 4
Bin 20 20 3 1.0 4
Bin 0 0 0 0 0

Consistent with the Tier 2 principle of vehicle and fuel neutrality, we are proposing that the same standards apply to LDVs, LDTs, or MDPVs, regardless of the fuel they use. That is, vehicles certified to operate on any fuel (e.g., gasoline, diesel fuel, E85, CNG, LNG, hydrogen, and methanol) would all be subject to the same standards.

We propose to maintain the fleet-average approach of the Tier 2 standards. Unlike Tier 2, the proposed Tier 3 fleet-average standards would decline annually to a fully phased-in level of 30 mg/mi NMOG+NO X. (The Tier 2 program, after a period of transition, established a single fleet average standard for all model years.) Specifically, we are proposing NMOG+NO X standards as measured on the FTP that would reduce the combined fleet-average emissions gradually from MY 2017 through 2025, as shown in Table IV-2 below. Beginning in MY 2017, we propose separate fleet average standards for lighter and heavier vehicles that would both decline annually, converging in MY 2025. These proposed declining average standards are identical to CARB's LEV III standards. [216]

The declining fleet-average NMOG+NO X standard requirement would begin in 2017 for light-duty vehicles and light-duty trucks with a GVWR up to and including 6,000 lbs and in 2018 for all other light-duty vehicles and light-duty trucks (i.e., those with a GVWR greater than 6,000 lbs). The standards would apply to the heavier vehicles a year later to facilitate the transition to a 50-state program for all manufacturers. During this transition period, there would be two fleet-average NMOG+NO X standards for each model year, one for LDVs and LDT1s and a second fleet-average standard for all other LDTs (LDT2s, LDT3s, and LDT4s) and for MDPVs. We are proposing that the fleet-average standards decline in a linear way from MY 2017 through MY 2025, at which point the two fleet-average standards would converge and stabilize for later model years at the same level, 30 mg/mi, as shown in Table IV-2. Note that these fleet average standards are for LDT2 and larger vehicles, and for LDVs and LDT1s that manufacturers certify to the 150,000 mile useful life value. Section IV.A.7.b discusses how the Clean Air Act defines the useful life values for certification purposes and how EPA proposes to also provide for certification to slightly lower emissions standards to a useful life value of 120,000 miles, representing a level of stringency that is equivalent to that of the emission standards corresponding to the 150,000 mile useful life, for LDVs and LDT1s.

Table IV-2—Proposed LDV, LDT, and MDPV Fleet Average FTP NMOG+NO X Standards Back to Top
Model Year
2017a 2018 2019 2020 2021 2022 2023 2024 2025 and later
[mg/mi]
aFor vehicles above 6,000 lbs GVWR, the fleet average standards would apply beginning in MY 2018.
bThese proposed standards apply for a 150,000 mile useful life. Manufacturers could choose to certify all of their LDVs and LDV1s to a useful life of 120,000 miles. If any of these families are certified to the shorter useful life, a proportionally lower numerical fleet average standard would apply, calculated by multiplying the respective 150,000 mile standard by 0.85 and rounding to the nearest mg.
LDV/LDT1b 86 79 72 65 58 51 44 37 30
LDT2,3,4 and MDPV 101 92 83 74 65 56 47 38 30

EPA is also proposing an alternative phase-in of the 30 mg/mi FTP NMOG+NO X standard that would be available if a manufacturer prefers a stable standard and four full years of lead time, as specified in the Clean Air Act for vehicles above 6,000 lbs GVWR. For MYs 2017 and 2018, a manufacturer would certify vehicles up to 6,000 lbs GVWR to the primary declining FTP fleet average standards, as in the primary program. Then, beginning in MY 2019, a stable fleet average standard of 30 mg/mi would apply to an increasing percentage of a manufacturer's light-duty vehicles, light-duty trucks, and MDPVs, both up to and above 6,000 lbs GVWR. The percent phase-in would match the proposed PM percent phase-in schedule, as discussed below—specifically 40 percent of sales in MY 2019, 70 percent in MY 2020, and 100 percent in MY 2021 and later model years. A manufacturer choosing to certify any vehicle to this alternative phase-in would need to use this approach for all its models in MYs 2019 and later; certifying part of its fleet to the declining fleet average after MY 2018 would not be permitted, since the structures of the two approaches, including the early credits provisions of the NMOG+NOx fleet average program, would not be consistent. A manufacturer certifying to this alternative phase-in would also need to comply with the alternative SFTP NMOG+NOx phase-in and the alternative FTP PM and US06 PM phase-ins as described below. Vehicles covered by the alternative phase-in programs would be considered “final Tier 3” vehicles and thus would also comply with the Tier 3 certification fuel and full useful life provisions. EPA requests comment on this alternative phase-in approach as well as on the primary option above.

b. FTP PM Standards

We also propose new FTP standards for PM emissions, as summarized in Table IV-3 below. For many years, EPA's focus for mobile source PM was on diesel engine emissions. In recent years, the very effective controls on PM exhaust emissions that manufacturers have developed for heavy-duty diesel engines have been successfully applied to light-duty diesel engines as well. At the same time, attention to gasoline engine PM emissions has increased as research has demonstrated that the level of PM from gasoline light duty vehicles is more significant than had been previously thought. [217]

Under typical driving, as simulated by the FTP, the PM emissions of most current-technology gasoline vehicles are fairly low, well below the Tier 2 PM standards. At the same time we see considerable variation in PM emissions among vehicle models not consistently associated with any specific engine or emission control technology (Section 1.5.1 of the draft RIA). As a result, we are proposing a new FTP PM standard that is set to ensure that all new vehicles would perform at a level representing what is already being achieved by well-designed Tier 2 emission control technologies.

PM emissions over the FTP are generally attributed to the cold start, when PM formation from combustion of the fuel is facilitated by the operating conditions, including a cold combustion chamber and fuel enrichment. During cold start, PM control via oxidation of semi-volatile organic compounds from the lubricating oil by catalytic converters is less effective. We believe that the proposed FTP PM standard can be achieved with improvements to the fuel controls during the cold start without the need for any new technology or hardware. Improvements in cold-start exhaust catalyst performance for NMOG+NOx control will also reduce emissions of semi-volatile organic PM. As such, cold start PM levels are relatively independent of vehicle application and therefore we are proposing a single FTP PM standard for all light-duty and MDPV vehicles. The PM standard level we are proposing would ensure that future PM performance is consistent with current well-performing Tier 2 vehicles. Unlike the NMOG+NO X FTP standard, the PM standard would not decline over time, since most manufacturers are already producing vehicles that would meet the proposed new standards.

Although we believe it is important that the proposed FTP PM standard apply from the beginning of the Tier 3 program, we are proposing several provisions to provide a degree of flexibility for manufacturers in how many vehicle models would need to meet that standard in the early years of the program. Manufacturers have raised several issues that we believe these provisions would address.

In meetings with EPA, several manufacturers have expressed concerns about how a PM standard in the range of the proposed 3 mg/mi standard would be implemented. One concern related to the initial uncertainties about PM emissions performance that will accompany the development of new engine technologies, including those that may be introduced to address the GHG emissions/fuel economy standards that EPA and NHTSA recently finalized for these vehicles. Also, manufacturers expressed concerns related to the testing of PM on the FTP, particularly about potential updates to the test procedures required to accurately measure PM at very low levels. Finally, related to the concerns about the new test procedures are the current limitations that exist for some manufacturers regarding the capacity of their test facilities to perform a significant volume of gasoline vehicle PM testing.

For these reasons, we are proposing a percent-of-sales phase-in during the first 5 years of the program to address these concerns. Beginning in MY 2017 (and in MY 2018 for vehicles over 6,000 lbs GVWR), manufacturers would comply with the PM standard with a minimum of 20 percent of their U.S. sales. As shown in Table IV-3, the percentage of the manufacturer's sales that would need to comply would increase each year, reaching 100 percent in MY 2021. In addition to this percent phase-in, we are proposing a separate PM standard of 6 mg/mi that would apply only for in-use testing of vehicles certified to the new standards, and only during the percent phase-in period.

Due to the MY 2018 start date for vehicles over 6,000 lbs GVWR, manufacturers that have few or no vehicle models over 6,000 lbs GVWR would be required to certify a larger percentage of their total light-duty sales in MY 2017 than full line manufacturers. While we believe that most manufacturers would likely choose a single large-volume durability group to meet the 2017 requirements, we seek comment on an option to comply with the MY 2017 PM requirements by allowing manufactures to certify 10 percent of all their light-duty vehicle sales in MY 2017 to the new PM standards, including light-duty vehicles over 6,000 lbs GVWR and MDPVs. This approach would be consistent with the CARB LEVIII program, which requires that 10 percent of all light-duty vehicle sales meet the new PM standards in MY 2017.

Because of the expected time and expense of performing emission tests on the improved PM test procedures, we are proposing to limit the number of tests using the new procedures that a manufacturer would need to perform at certification and during in-use testing. Specifically, manufacturers would be required to test vehicles representing a minimum of 25 percent of a model's durability test groups during certification each model year (and a minimum of 2 durability groups). [218] Manufacturers could select which durability groups to test, but would need to rotate the groups tested each year to eventually cover their whole fleet. Similarly, manufacturers performing in-use testing under the In-Use Verification Program could limit their testing to 50 percent of their low- and high-mileage test vehicles. Again, manufacturers would need to rotate their vehicle models so that each model would be tested every other year. Overall, we believe that the flexibility that these proposed provisions would provide would facilitate the expeditious implementation of the proposed program, with no significant impact on the potential benefits of the program.

The PM standards that we are proposing are the most stringent technically feasible standards within the implementation timeframe of this proposal. Although the CARB LEV III program includes a 1 mg/mi standard which will begin phasing in starting in MY 2025, they acknowledge that there is a need for continuing PM measurement method development prior to implementing this standard. [219] In order for EPA to propose a standard at this level, there must be established methods to reliably and consistently measure PM below that standard, for compliance purposes.

We request comment on all of the proposed FTP standards, their structure, and their implementation schedules.

Table IV-3—Summary of Proposed FTP Standards Back to Top
aFor vehicles above 6,000 lbs GVWR, the proposed FTP PM would apply beginning in MY 2018.
bThe percent phase-in would not apply to the declining fleet average standards.
cManufacturers would be required to test 25 percent of each model year's durability groups, minimum of 2.
dManufacturers would be required to test 50 percent of their low and high mileage in-use vehicles.
Program Element Units Model Year Notes  
a2017 2018 2019 2020 2021 2022 2023    
NMOG+NO X Standard (fleet average) mg/mi Per declining fleet average for cars and trucks (see Table IV-2)b  
PM Standards    
Phase-in % 20 20 40 70 100 100 100  
FTP Certification mg/mi 3 3 3 3 3 3 3 Note c
In-use mg/mi 6 6 6 6 6 3 3 Note d

As with the proposed FTP NMOG+NO X standards, EPA is also proposing an alternative phase-in of the 3 mg/mi FTP PM standard that would be available if a manufacturer prefers 4 full years of lead time for vehicles above 6,000 lbs GVWR. A manufacturer that chooses the alternative phase-in for the FTP NMOG+NO X program above could also postpone the beginning of the phase-in for PM compliance for vehicles above 6,000 lbs GVWR until MY 2019. For MYs 2017 and 2018, a manufacturer would certify vehicles up to 6,000 lbs GVWR to the 3 mg/mi FTP PM standard (and have a 6 mg/mi in-use PM standard) for 20 percent of its sales in each of those years, as with the primary PM percent phase-in schedule. Then, for MYs 2019 and later, it would comply with the 3 mg/mi (and 6 mg/mi in-use) PM standards for their LDVs, LDTs, and MDPVs, both up to and above 6,000 lbs GVWR. For MYs 2019 and 2020 (i.e., before the phase-in is fully implemented in MY 2021), manufacturers choosing this alternative would be required to meet the PM standard on the same segment of their fleet vehicles being used to meet the NMOG+ NO X fleet average standard, and at the applicable phase-in percentage of sales for the given model year. Manufacturers certifying to the alternative PM phase-in standard would also need to comply with the alternative US06 PM phase-in as described below, as well as the NMOG+ NO X FTP and SFTP phase-ins. EPA requests comment on this alternative phase-in approach as well as on the primary PM phase-in option above.

4. Proposed SFTP Standards

In addition to the proposed FTP standards, we are proposing NMOG+NO X and PM standards as measured on the SFTP. The SFTP (and specifically the US06 component of the test) is designed to simulate higher speeds and higher acceleration rates (and thus higher loads) when substantially more heat can be generated during the combustion process. It is during these kinds of operation that engines can go into a fuel “enrichment” mode, where the engine's controls may temporarily create a rich air/fuel mixture to protect exhaust components from thermal damage. Enrichment can increase emissions of NMOG+NO X and PM, primarily due to the incomplete combustion that occurs under rich conditions and the diminished effectiveness of the catalyst in these circumstances. However, enrichment can be minimized or eliminated in current and future engines, where components can be thermally protected even under high-load conditions by careful electronic management of the air/fuel mixture and the combustion process. To reduce emissions caused by excessive enrichment, we are proposing new SFTP standards. Further, as described in Section IV.A.4.c below, we are proposing limitations on the magnitude of enrichment that could be commanded by the vehicle operator. We describe the proposed SFTP standards in the following paragraphs.

We are also proposing an SFTP composite CO standard of 4.2 g/mi for all model years 2017 (or 2018) and later. This standard represents no effective change from the current Tier 2 SFTP CO standard, which we believe is already at a level that is sufficiently stringent.

a. SFTP NMOG+NO X Standards

We have reviewed certification and in-use NMOG and NO X data on a wide range of recent vehicles as tested on the US06 cycle. See Chapter 1 of the draft RIA for an analysis of this data. It is clear that most current vehicles are generally avoiding significant enrichment events during high-load operation and thus achieve relatively low NMOG+NO X emissions on the US06 test. The data shows that with minor (if any) improvements to engine calibrations and with no significant loss of performance, manufacturers are able to essentially eliminate enrichment events and their emissions consequences. Thus, as presented in Table IV-5 below, we are proposing new composite SFTP standards for NMOG+NO X at levels that would be more stringent than those required by the existing Tier 2 program. We believe that the new standards would require emission performance at levels currently achieved today by most vehicles under high-load operation, and we do not believe that significant additional reductions would result from SFTP standards more stringent than the proposed 50 mg/mi fully phased-in level. The SFTP emissions value for certification of gaseous pollutants would continue to be calculated as a weighted composite value of emissions on three cycles (0.35 × FTP + 0.28 × US06 + 0.37 × SC03), as is done for the Tier 2 SFTP standards.

We believe that the proposed standards could be more challenging in the early years of the program. Thus, we propose a declining fleet average standard that would become increasingly stringent from MY 2017 to MY 2025. Manufacturers would comply with a declining NMOG+NO X fleet-average SFTP standard for each year beginning in MY 2017 (MY 2018 for vehicles over 6000 lbs GVWR) and culminating for MY 2025 and later with a fleet-average standard of 50 mg/mi.

To provide flexibility in meeting the fleet-average standards, manufacturers would determine for themselves what the specific SFTP composite standard would be for an individual vehicle family and report that self-selected standard and the measured emission performance. (These self-selected standards are analogous to “family emission limits,” or “FELs,” used in other programs (e.g., heavy-duty highway engine standards).) For each family, a manufacturer would choose any composite NMOG+NO X standard, up to 180 mg/mi, in even 10 mg/mi increments. The manufacturer would then calculate the sales-weighted average of all the selected standards of the families across its fleet and compare that emissions value to the applicable fleet-average standards for that model year. Table IV-4 presents the proposed declining fleet-average SFTP NMOG+NO X standards.

As with the proposed FTP NMOG+NO X and PM standards, EPA is also proposing an alternative phase-in of the 50 mg/mi SFTP NMOG+NO X standard that would be available if a manufacturer prefers a stable standard and four full years of lead time for vehicles above 6,000 lbs GVWR. For MYs 2017 and 2018, a manufacturer would certify vehicles up to 6,000 lbs GVWR to the primary SFTP declining fleet average standards, as in the primary program. Then, beginning in MY 2019, a stable fleet average standard of 50 mg/mi would apply to an increasing percentage of a manufacturer's light-duty vehicles, light-duty trucks, and MDPVs, both up to and above 6,000 lbs GVWR. The percent phase-in would match the proposed PM percent phase-in schedule, as discussed below. A manufacturer certifying to this alternative phase-in would also need to comply with the alternative FTP NMOG+NO X phase-in and the alternative FTP PM and US06 PM phase-ins, as described elsewhere in this section. EPA requests comment on this alternative phase-in approach as well as on the primary option above.

b. US06 PM Standards

Our proposed approach to addressing PM emissions on the US06 test (a component of the composite SFTP standard) is somewhat different from the SFTP standards that we are proposing for NMOG and NO X emissions. In the case of PM, US06 data on recent vehicles shows that current gasoline vehicles can have very low PM emissions, but US06 PM emission levels vary depending on many factors. In some cases, manufacturer emission control strategies that are sensitive to variations in operating conditions (e.g., variation due to driver behavior or automatic transmission shift points) appear to result in very low PM levels during some tests and yet higher PM on other tests on the same vehicle when driven slightly differently. We also believe that some of the observed high PM emissions may be partly due to increasing oil consumption in vehicles as they age, especially under higher-load conditions or hard closed-throttle deceleration conditions. Thus, we now believe that more focus on vehicles as they age is important.

We have designed the proposed US06 PM standards in light of all of these factors, which relate to PM emission formation under relatively extreme driving conditions. For these standards, we are proposing to focus on the US06 cycle component of the composite SFTP, since most of our concern about PM formation and sensitivity of engine controls arises from high-speed, high-load driving conditions. Similarly, the quantity of PM emissions from warmed-up engines is closely related to engine load, since the higher rate of fuel consumption results in more opportunities for PM to form. For this reason, we propose that heavier vehicles, which face high-load conditions more frequently than lighter vehicles, comply with a higher US06 standard and lighter vehicles comply with a lower standard. The proposed US06 PM standard would be 10 mg/mi for vehicles at or below 6,000 lbs GVWR and 20 mg/mi for heavier vehicles.

EPA is seeking comment on the use of vehicle weight to establish separate US06 PM standards for cars and trucks. The data presented in Chapter 1 of the draft RIA demonstrate that today's heavier vehicles are already achieving PM emission levels well below our proposed 20 mg/mi standard and are approximately equivalent to the performance of lighter vehicles. According to our data, manufacturers appear to be controlling PM emissions in heavier vehicles over severe duty cycles. Thus, EPA seeks comment on the proposed US06 PM standards in general, including whether EPA should adopt a common US06 standard of 10 mg/mi for all light-duty vehicles.

As is the case for the proposed FTP PM standards, we are proposing a single per-vehicle maximum standard to apply in each model year, with an allowable percentage phase-in schedule identical to the FTP PM phase-in.

Finally, as with the FTP PM standard (and for the same reasons), we propose a slightly less stringent in-use US06 PM standard that would apply during the percent phase-in period only. The proposed in-use SFTP PM standards would be 15 mg/mi for vehicles at or below 6,000 lbs GVWR and 25 mg/mi for heavier vehicles.

As with the proposed FTP and SFTP NMOG+NO X standards and FTP PM standards, EPA is also proposing an alternative phase-in of the 20 mg/mi PM standard as measured on the US06 cycle, that would be available if a manufacturer prefers 4 full years of lead time for vehicles above 6,000 lbs GVWR. A manufacturer that chooses the alternative phase-in for the FTP NMOG+NO X program above could also postpone the beginning of the phase-in for US06 PM compliance for vehicles above 6,000 lbs GVWR until MY 2019. For MYs 2017 and 2018, a manufacturer would certify vehicles up to 6,000 lbs GVWR to the 10 mg/mi FTP PM standard (and have a 15 mg/mi in-use standard) for 20 percent of its sales in each of those years, as with the primary PM percent phase-in schedule. Then, for MYs 2019 and later, it would comply with the respective standards for vehicles up to and above 6,000 lbs GVWR for their LDVs, LDTs, and MDPVs (i.e., 10 mg/mi and 15 mg/mi (in-use) for vehicles up to 6,000 lbs GVWR, and 20 mg/mi and 25 mg/mi (in-use) for vehicles above 6,000 lbs GVWR.) For MYs 2019 and 2020, manufacturers choosing this alternative would be required to meet both the FTP PM and the US06 PM standards on the same segment of their fleet vehicles being used to meet the 30 mg/mi fleet average NMOG+NO X standards, at the applicable percent phase-in requirement for the given model year. Manufacturers certifying to the alternative US06 PM phase-in standard would also need to comply with the alternative FTP PM phase-in as described above, as well as the NMOG+NO X FTP and SFTP phase-ins. EPA requests comment on this alternative phase-in approach as well as on the primary US06 phase-in option above.

All of the proposed SFTP/US06 standards are shown in Table IV-4 and Table IV-5.

Table IV-4—Proposed LD and MDPV SFTP Composite Fleet Average Standards Back to Top
Model year
2017 2018 2019 2020 2021 2022 2023 2024 2025 and later
aFor vehicles above 6,000 lbs GVWR, the NMOG+NO X and CO standards would apply beginning in MY 2018.
NMOG+NO X (mg/mi) a103 97 90 83 77 70 63 57 50
CO (g/mi) a4.2
Table IV-5—Summary of Proposed SFTP Standards Back to Top
Program element Units Model year Notes
a2017 2018 2019 2020 2021 2022 2023
aFor vehicles above 6,000 lbs GVWR, the standards would apply beginning in MY 2018.
bThe percent phase-in would not apply to the declining fleet average standards.
cManufacturers would be required to test 25 percent of each model year's durability groups, minimum of 2.
dManufacturers would be required to test 50 percent of their low and high mileage in-use vehicles.
NMOG+NO X Standard (fleet average) mg/mi Per declining fleet average for cars and trucks (see Table IV-4)b
PM Standards:                  
Phase-in % 20 20 40 70 100 100 100  
US06:                  
LDV, LDT1&2 Certification mg/mi 10 10 10 10 10 10 10 Note c.
LDV, LDT1&2 In-use mg/mi 15 15 15 15 15 10 10 Note d.
US06:                  
LDT3&4, MDPV Certification mg/mi 20 20 20 20 20 20 20 Note c.
LDT3&4, MDPV In-use mg/mi 25 25 25 25 25 20 20 Note d.

We request comment on our proposed SFTP NMOG+NO X and PM standards, their structure, and their implementation schedules.

c. Enrichment Limitation for Spark-Ignition Engines

To prevent emissions from excessive enrichment during operating conditions represented by the SFTP cycles, we are proposing limitations on the magnitude of enrichment that could be commanded, including enrichment episodes encountered during in-use operation. During conditions where enrichment was demonstrated to be present on the SFTP, the nominal air to fuel ratio could not be richer at any time than the leanest air to fuel ratio required to obtain maximum torque (lean best torque or LBT). An air to fuel ratio of LBT plus a tolerance of 4 percent additional enrichment would be allowed in actual vehicle testing to protect for any in-use variance in the air to fuel ratio from the nominal LBT air to fuel determination, for such reasons as air or fuel distribution differences from production variances or aging.

LBT is defined as the leanest air to fuel ratio required at a speed and load point with a fixed spark advance to make peak torque. Specifically, an increase in fuel would not result in an increase in torque while maintaining a fixed spark advance. LBT is determined by setting the spark advance to a setting that is less than or equal to the spark advance required for best torque (MBT) and maintaining that spark advance when sweeping the air to fuel ratio. This fixed spark advance requirement is intended to prevent torque changes related to spark changes masking true LBT. Manufacturers may request approval of an alternative LBT definition for a unique technology or control strategy. The Agency could determine that an enrichment amount was excessive or not necessary and therefore deem that the approach did not meet the air to fuel ratio requirements.

Enrichment required for thermal protection would continue to be allowed upon demonstration of necessity to the Agency, based upon temperature limitations of the engine or exhaust components. Manufacturers would be required to provide descriptions of all components requiring thermal protection, temperature limitations of the components, how the enrichment strategy will detect over-temperature conditions and correct them, and a justification regarding why the enrichment is the minimum necessary to protect the specific components. The Agency may determine that the enrichment is not justified or is not the minimum necessary based on the use of engineering judgment using industry-reported thermal protection requirements.

5. Feasibility of the Proposed NMOG+NO X and PM Standards

In this section, with additional support in Chapter 1 of the draft RIA, we describe how we reached our conclusion that the proposed Tier 3 standards would be technologically feasible in the time frame of the program. For each of the proposed emission standards, the lead time provided by the proposed program is more than sufficient for all manufacturers to comply. First, manufacturers in many cases are already adopting complying technologies for reasons other than this proposed rulemaking. For example, many of the technologies that manufacturers will begin to develop as early as MY 2014 in response to the CARB LEV III FTP and SFTP NMOG+NO X standards for the California market will likely represent steps toward compliance with this proposed national program. Similarly, manufacturers are already building some vehicles that comply with our proposed evaporative emissions standards in response to the CARB LEV III evaporative standards. In addition, as described above, our proposed program incorporates a number of phase-in provisions that would ease the transition to compliance, including time some manufacturers would need to install PM testing capability and to ramp up production on a national scale. We invite comment on our conclusions relating to the feasibility of the proposed program for each of the standards, as discussed below, including our overall conclusion that technological lead time is not a driving factor in complying with any of the proposed standards.

This feasibility assessment is based on a variety of complementary technical data, studies, and analyses. As described below, these include our analysis of the stringency of the proposed standards as compared to current Tier 2 emission levels. We also discuss below our observation that manufacturers are currently certifying several vehicle models under the California LEV II program that could likely achieve the proposed Tier 3 NMOG+NO X and PM standards or similar levels. EPA has assessed the emissions control challenges manufacturers would generally face (e.g., cold start NMOG reductions and running (warmed-up) NO X emissions under typical and more aggressive driving conditions) and the corresponding technologies that we expect to be available to manufacturers to meet these challenges. Our feasibility assessment accounts for the fact that the proposed Tier 3 program would apply to all types of new vehicles, ranging from small cars to large pick-up trucks and MDPVs and representing a wide diversity in applications and in specific engine designs.

It is important to note that our primary assessment of the feasibility of engine and emission control technologies is based on the assumption that vehicles would be certified on gasoline with a fuel sulfur content of 10 ppm and operated on in-use gasoline with 10 ppm sulfur or less. [220] Therefore, our primary assessment does not incorporate the degradation of emission control system caused by higher levels of sulfur content, as is discussed in Section IV.6 below and in the draft RIA. This assessment reinforces the critical role of gasoline sulfur control, as proposed in Section V below, in making it possible for EPA to propose emission standards at these very stringent levels. See Section IV.6 below for a full discussion of our current knowledge of the effects of gasoline sulfur on current vehicle emissions as well as our projections of how we expect that sulfur would affect compliance with standards in the range of the proposed Tier 3 standards.

Since there are multiple aspects to the Tier 3 program, it is necessary to consider technical feasibility in light of the different program requirements and their interactions with each other. In many cases, manufacturers would be able to address more than one requirement with the same general technological approach (e.g., faster catalyst light-off can improve both FTP NMOG+NO X and PM emissions). At the same time, the feasibility assessment must consider that different technologies may be needed on different types of vehicle applications (i.e., cars versus trucks) and must consider the relative effectiveness of these technologies in reducing emissions for the full useful life of the vehicle while operating on expected in-use fuel. For example, certain smaller vehicles with correspondingly small engines may be less challenged to meet FTP standards than larger vehicles with larger engines. Conversely, these smaller vehicles may have more difficulty meeting the more aggressive SFTP requirements than vehicles with larger and more powerful engines. Additionally, the ability to meet the proposed SFTP emission requirements can also be impacted by the path taken to meet the FTP requirements (e.g., larger volume catalysts for US06 emissions control vs. smaller catalysts for improved FTP cold-start emissions control). Throughout the following discussion, we address how these factors, individually and in interaction with each other, affect the feasibility of the proposed program. We invite comment on our assessments of these or any other such potential interactions. Also, although we are not aware of any technological reasons that vehicle emission controls responding to new Tier 3 requirements should affect vehicle CO 2 emissions or fuel economy in any significant way, it is possible that such interactions could occur. For example, there may be some slight change in vehicle mass if manufacturers explore lighter exhaust manifold materials in order to reduce thermal mass and promote earlier catalyst light-off or add emissions control equipment such as hydrocarbon adsorbers. We invite comment on any such potential effects as well.

a. FTP NMOG+NO X Standards

The proposed new emission requirements include stringent NMOG+NO X standards on the FTP that would require new vehicle hardware in order to achieve the 30 mg/mi fleet average level in 2025. The type of new hardware that would be required would vary depending on the specific application and emission challenges. Smaller vehicles with corresponding smaller engines would generally need less new hardware while larger vehicles may need additional hardware and improvements beyond what would be needed for the smaller vehicles. While some vehicles, especially larger light trucks, may face higher costs in meeting the proposed standards, it is important to remember that not every vehicle needs to meet the standard. The proposed program has been structured to provide higher emission standard “bins” (see Table IV-1 above) to which manufacturers may certify more challenged vehicles, so long as these vehicles are offset with vehicles certified in lower emission bins such that the fleet-wide average meets the standard. We believe that the availability of the proposed less-stringent bins would allow for feasible and cost-effective compliance for all vehicles. In the Tier 2 program, manufacturers took advantage of this flexibility, especially in the early years of the program. Then, as technologies improved and/or became less expensive and the need for averaging diminished, manufacturers began certifying all or most of their fleets to the average bin (Tier 2 Bin 5). We anticipate that manufacturers will follow a similar trend with the proposed Tier 3 standards, relying on fleet averaging more significantly in the transitional years but certifying increasing numbers of their vehicles to the final fleet average standard of 30 mg/mi in the later years of the program.

In order to assess the technical feasibility of a 30 mg/mi NMOG+NO X national fleet average FTP standard, EPA conducted two supporting analyses. The initial analyses performed were of the current Tier 2 and LEV II fleets. This provided a baseline for the current federal fleet emissions performance, as well as the emissions performance of the California LEV II fleet. The second consideration was a modal analysis of typical vehicle emissions under certain operating conditions. In this way EPA determined the specific emissions performance challenges that vehicle manufacturers would face in meeting the lower fleet average emission standards. Each of these considerations is described in greater detail below.

The current federal fleet is certified to an average of Tier 2 Bin 5, equivalent to 160 mg/mi NMOG+NO X. [221] For MY 2009, 92 percent of LDVs and LDT1s were certified to Tier 2 Bin 5 and 91 percent of LDT2s through LDT4s were certified to Tier 2 Bin 5. This was not an unexpected result as there is currently no motivation for vehicle manufacturers to produce a federal fleet that over-complies with respect to the current Tier 2 standards. By comparison, in the California fleet, where compliance with the “PZEV” program encourages manufacturers to certify vehicles to cleaner levels, only 30 percent of the LDVs and LDT1s are certified to Tier 2 Bin 5 and 60 percent are certified to Tier 2 Bin 3. The situation regarding the truck fleet in California is similarly stratified, with 37 percent of the LDT2s through LDT4s being certified to Tier 2 Bin 5 and 55 percent being certified to Tier 2 Bin 3. In many cases identical vehicles are being certified to a lower standard in California and a higher standard federally. We note that vehicles certified to a lower standard in California are operated on gasoline with an average sulfur content of 10 ppm and thereby are able to maintain their emissions performance in-use. Based on these patterns of federal and California certification, EPA believes that much of the existing Tier 2 fleet could be certified to a lower federal fleet average immediately, with no significant feasibility concerns, if lower sulfur gasoline were made available nationwide.

Regardless of the Tier 2 bin standards at which manufacturers choose to certify their vehicles, actual measured emissions performance of these vehicles is typically well below the numerical standards. This difference is referred to as “compliance margin” and is a result of manufacturers' efforts to address all the sources of variability, including:

  • Test-to-test variability (within one test site and lab-to-lab)
  • Build variation expectations
  • Manufacturing tolerances and stack-up
  • Vehicle operation (for example: driving habits, ambient temperature, etc.)
  • Fuel composition
  • The effects of fuel sulfur on exhaust catalysts and oxygen sensors
  • The effects of other fuel components, including ethanol and gasoline additives
  • Oil consumption
  • The impact of oil additives and oil ash on exhaust catalysts and oxygen sensors

For MY 2009, the compliance margin for a Tier 2 Bin 5 vehicle averaged approximately 60 percent. In other words, actual vehicle emissions performance was on average about 40 percent of a 160 mg/mi NMOG+NO X standard, or about 64 mg/mi. By comparison, for California-certified vehicles, the average Super Ultra Low Emission Vehicle (SULEV) compliance margin was somewhat less for the more stringent standards, approximately 50 percent. We believe that the recent California experience is a likely indicator of compliance margins that manufacturers would design for in order to comply with the proposed Tier 3 FTP standards. Thus, a typical Tier 2 Bin 5 vehicle, performing at 40 percent of the current standard (i.e., at about 64 mg/mi) would need improvements sufficient to reach about 15 mg/mi (50 percent of a 30 mg/mi standards).

To understand how the several currently-used technologies described below could be used by manufacturers to reach the stringent proposed Tier 3 NMOG+NO X standards, it is helpful to consider emissions formation in common modes of operation for gasoline engines, or modal analysis. [222] The primary challenge faced by manufacturers for producing Tier 3 compliant light-duty gasoline vehicle powertrains would be to reduce the emissions during cold-start operation which, based on modal analysis of a gasoline powered vehicle being operated on the FTP cycle, occurs during about the first 50 seconds after engine start. Thus, effective control of these cold-start emissions would be the primary technological goal of manufacturers complying with the proposed Tier 3 FTP standards. As discussed below, light-duty manufacturers are already applying several technologies capable of significant reductions in these cold start emissions to vehicles currently on the road.

b. SFTP NMOG+NO X Standards

The increase in the stringency of the SFTP NMOG+NO X standards, specifically across the US06 cycle, would generally only require additional focus on fuel control of the engines and diligent implementation of new technologies that manufacturers are already introducing or are likely to introduce in response to the current and 2017 LD GHG emission standards. These include downsized gasoline direct injection (GDI) and turbocharged engines, which may also include improvements to the engine and emission control hardware to tolerate higher combustion and exhaust temperatures expected in these future GHG-oriented engine designs. The upgraded materials or components would enable manufacturers to rely less on fuel enrichment during high-speed/high-load operation to protect components from overheating. This fuel enrichment is currently the source of elevated VOC, NO X, and PM emissions seen in a subset of the current Tier 2 fleet.

With respect to enrichment, changes to the fuel/air mixture by increasing the fuel fraction has historically been the primary method available to manufacturers to protect the catalyst and other exhaust components from over-temperature conditions. Changing the fuel/air mixture is no longer the only tool available to manufacturers for this purpose. With the application of electronic throttle controls, variable valve timing, exhaust gas recirculation and other exhaust temperature influencing technologies on nearly every light-duty vehicle, the manufacturer has the ability to systematically control the operation and combustion processes of the engine to minimize or altogether avoid areas and modes of operation where thermal issues can occur. While some of these solutions could in some cases result in a small and temporary reduction in vehicle performance (absolute power levels), we believe that it could be an effective way to reduce NMOG+NO X emissions over the SFTP test.

Additionally, some components, especially catalysts, can experience accelerated thermal deterioration that occurs when operating at higher temperatures for more time than expected under normal operation (e.g., trailer towing, mountain grades). Some upgrades of existing vehicle emission control technology, like catalyst substrates and washcoats may be required to limit thermal deterioration and ensure vehicle emissions compliance throughout the useful life of the vehicle.

In order to assess the technical feasibility of a 50 mg/mi NMOG+NO X national fleet average SFTP standard, EPA conducted an analysis of SFTP levels of Tier 2 and LEV II vehicles. The analysis was performed on the US06 results from current Tier 2 and LEV II vehicles tested in the in-use verification program (IUVP) by manufacturers and submitted to EPA. This analysis provided a baseline for the current Tier 2 and LEV II fleet emissions performance, as well as the SFTP emissions performance capability of the cleanest vehicles meeting the proposed Tier 3 FTP standards. The analysis concluded that most vehicles in the IUVP testing program are already capable of meeting the composite SFTP standard of 50 mg/mi when the Tier 3 FTP standard levels are factored into the composite calculation. With the technological improvements already underway as discussed above, we believe all 2017 and later vehicles would be able to comply with the proposed SFTP standards, directly, or through the flexibility of the averaging, banking and trading program. For further information on the analysis see Chapter 1 of the draft RIA.

c. FTP and SFTP PM Standards

As described above for NMOG+NO X over the SFTP, the increase in the stringency of the FTP and SFTP PM standards would generally also only require additional focus on fuel control of the engines and diligent implementation of new technologies like gasoline direct injection (GDI) and turbocharged engines. Some upgrades of existing vehicle emission control technology may be required to ensure vehicle emissions performance is maintained throughout the useful life of the vehicle. These upgrades may include improvements to the engine to control wear that could result in increased PM from oil consumption and selection of GDI systems that would be capable of continuing to perform optimally even as the systems age.

We based our conclusions about the ability of manufacturers to meet the proposed PM standards largely on the PM performance of the existing fleet, both on the FTP and SFTP. In the case of FTP testing of current vehicles, data on both low and high mileage light-duty vehicles demonstrate that the majority of vehicles are currently achieving levels at or below the proposed Tier 3 FTP standards.

The testing results can be found in Chapter 1 of the draft RIA. A small number of vehicles are at or just over the proposed FTP PM standard at low mileage and could require calibration changes and/or catalyst changes to meet the new standards. It is our expectation that the same calibration and catalyst changes required to address NMOG would also provide the necessary PM control. Vehicles that currently have higher PM emissions over the FTP or SFTP at higher mileages would likely be required to control oil consumption and combustion chamber deposits.

We also analyzed PM test data on US06 emissions for current Tier 2 vehicles. The data show that many vehicles are already at or below the proposed standards on the US06. Vehicles that have high PM emission rates on the US06 would likely need to control enrichment, and oil consumption particularly later in life. As described above for SFTP NMOG+NO X control, enrichment can be more accurately managed through available electronic engine controls. The strategies for reducing oil consumption are similar to those described above for controlling oil consumption on the FTP. However, given the higher engine speeds experienced on the US06 and the increase in oil consumption that can accompany this kind of operation, manufacturers would most likely focus on oil sources stemming from the piston to cylinder interface and positive crankcase ventilation (PCV).

Manufacturers have informed us that they have already reduced or are planning to reduce the oil consumption of their engines by improved sealing of the paths of oil into the combustion chamber and improved piston-to-cylinder interfaces. They are already taking or considering these actions to address issues of customer satisfaction and cost of ownership. In addition, many vehicle manufacturers acknowledge the relationship between combustion chamber deposits and PM formation and are actively pursuing design changes to mitigate fuel impingement within the combustion chamber and its commensurate PM effects. Both types of controls are being widely applied by manufacturers today.

d. Technologies Manufacturers Are Likely To Apply

Most of the technologies expected to be applied to light-duty vehicles to meet the stringent proposed standards would address the emissions control system's ability to control emission during cold start. The effectiveness of current vehicle emissions control systems depends in large part on the time it takes for the catalyst to light off, which is typically defined as the catalyst reaching a temperature of 250 °C. In order to improve catalyst light-off, we expect that manufacturers would add technologies that provide heat from combustion more readily to the catalyst or improve the catalyst efficiency at lower temperatures. These technologies include calibration changes, thermal management, close-coupled catalysts, catalyst platinum group metals (PGM) loading and strategy, and secondary air injection, all which generally improve emission performance of all pollutants. In some cases where the catalyst light-off and efficiency are not enough to address the cold start NMOG emissions, hydrocarbon adsorbers may be applied to trap hydrocarbons until such time that the catalyst is lit off. Note that with the exception of hydrocarbon adsorbers each of these technologies addresses NMOG, NO X, and PM performance. The technologies are described in greater detail below. Additional information on these technologies can also be found in Chapter 1 of the RIA.

  • Engine Control Calibration Changes—These include changes to retard spark and/or adjust air/fuel mixtures such that more combustion heat is created during the cold start. Control changes may include injection strategies in GDI applications, unique cold-start variable valve timing and lift, and other available engine parameters. Engine calibration changes can affect NMOG, NO X and PM emissions.
  • Catalyst PGM Loading—Additional PGM loading, increased loading of other active materials, and improved dispersion of PGM and other active materials in the catalyst provide a greater number of sites available to catalyze emissions and addresses NMOG, NO X and PM emissions. Catalyst PGM loading, when implemented in conjunction with low sulfur gasoline, will effectively eliminate NO X emissions under warmed-up conditions.
  • Thermal Management—This category of technologies includes all design attributes meant to conduct the combustion heat into the catalyst with minimal cooling. This includes insulating the exhaust piping between the engine and the catalyst, reducing the wetted area of the exhaust path, reducing the thermal mass of the exhaust system, and/or using close-coupled catalysts (i.e., the catalysts are packaged as close as possible to the engine's cylinder head to mitigate the cooling effects of longer exhaust piping). Thermal management technologies primarily address NMOG emissions, but also affect NO X and PM emissions.
  • Secondary Air Injection—By injecting air directly into the exhaust stream, close to the exhaust valve, combustion can be maintained within the exhaust, creating additional heat by which to increase the catalyst temperature. The air/fuel mixture must be adjusted to provide a richer exhaust gas for the secondary air to be effective.
  • Hydrocarbon Adsorber—Traps hydrocarbons during a cold start until the catalyst lights off, and then releases the hydrocarbons to be converted by the catalyst.
  • Gasoline Sulfur—The relative effectiveness for NMOG and NO X control of the exhaust-catalyst related technologies are constrained by gasoline fuel sulfur levels. Thus, reduced sulfur in gasoline is an enabling technology to achieve the standards and maintain this performance during in-use operation. We discuss the relationship between gasoline sulfur and emissions in greater detail in Section IV.6 below and in the draft RIA.

Discussions between EPA, CARB, vehicle manufacturers, and major component suppliers indicated that large light-duty trucks (e.g., pickups and full-size sport utility vehicles (SUVs) in the LDT3 and LDT4 categories) would be the most challenging light-duty vehicles to bring into compliance with the proposed Tier 3 NMOG+NO X standards at the 30 mg/mi corporate average emissions level. A similar challenge was addressed when large light-duty trucks were brought into compliance with the Tier 2 standards over the past decade. Figure IV-1 provides a graphical representation of the effectiveness of Tier 3 technologies for large light-duty truck applications. A compliance margin is shown in both cases. Note that the graphical representation of the effectiveness of catalyst technologies on NO X and NMOG when going from Tier 2 to Tier 3 levels also includes a reduction in gasoline sulfur levels from 30 ppm to 10 ppm.

6. Impactof Gasoline Sulfur Control on the Feasibility of the Proposed Vehicle Emission Standards

a. Fuel Sulfur Impacts on Exhaust Catalysts

Modern three-way catalytic exhaust systems utilize platinum group metals (PGM), metal oxides and other active materials to selectively oxidize organic compounds and carbon monoxide in the exhaust gases. These systems simultaneously reduce nitrogen oxides when air-to-fuel ratio control operates in a condition of relatively low amplitude/high frequency oscillation about the stoichiometric point. Sulfur is a well-known catalyst poison. There is a large body of work demonstrating sulfur inhibition of the emissions control performance of PGM three-way exhaust catalyst systems. 224 225 226 227 228 229 230 231 232 233 The nature of sulfur interactions with washcoat materials, active catalytic materials and catalyst substrates is complex and varies with catalyst composition and exhaust gas composition and exhaust temperature. The variation of these interactions with exhaust gas composition and temperature means that the operational history of a vehicle is an important factor; continuous light-load operation, throttle tip-in events and enrichment under high-load conditions can all impact sulfur interactions with the catalyst.

Sulfur from gasoline is oxidized during spark-ignition engine combustion primarily toSO 2 and, to a much lesser extent, SO 3 −2.Sulfur oxides selectively chemically bind (chemisorb) with, and in some cases react with, active sites and coating materials within the catalyst, thus inhibiting the intended catalytic reactions. Sulfur oxides inhibit pollutant catalysis chiefly by selective poisoning of active PGM, ceria sites, and alumina washcoatings (see Figure IV-2). [234] The amount of sulfur retained by the catalyst is primarily a function of its operating temperature, the active materials and coatings used within the catalyst, the concentration of sulfur oxides in the incoming exhaust gases, and air-to-fuel ratio feedback and control by the engine management system.

Selective sulfur poisoning of platinum (Pt) and rhodium (Rh) is primarily from surface-layer chemisorption. Sulfur poisoning of palladium (Pd) and ceria appears to be via chemisorption combined with formation of more stable metallic sulfur compounds, e.g. PdS and Ce 2 O 2 S, present in both surface and bulk form (i.e., below the surface layer. 235 236 237 238 Ceria, zirconia and other oxygen storage components (OSC) play an important role that is crucial to NO X reduction over Rh as the engine air-to-fuel ratio oscillates about the stoichiometric closed-loop control point. [239] Water-gas-shift reactions are important for NO X reduction over catalysts combining Pd and ceria. This reaction can be blocked by sulfur poisoning and may be responsible for observations of reduced NO X activity over Pd/ceria catalysts even with exposure to fairly low levels of sulfur (equivalent to 15 ppm in gasoline). 240 241 Pd is also of increased importance for meeting Tier 3 standards due to its unique application in the closed-coupled-catalysts location required for vehicles certifying to very stringent emission standards. Pd is required in closed-coupled catalysts due to its resistance to high temperature thermal sintering. Sulfur removal from Pd requires rich operation at higher temperatures than required for sulfur removal from other PGM catalysts. [242]

In addition to its interaction with catalyst materials, sulfur can also react with the washcoating itself to form alumina sulfate, which in turn can block coating pores and reduce gaseous diffusion to active materials below the coating surface. [243] This may be a significant mechanism for the observed storage of sulfur compounds at light and moderate load operation with subsequent, rapid release as sulfate particulate matter when high-load, high-temperature conditions are encountered. [244]

Operating the catalyst at a sufficiently high temperature under net reducing conditions (e.g., air-to-fuel equivalence that is net fuel-rich of stoichiometry) can effectively release the sulfur oxides from the catalyst components. Thus, regular operation at sufficiently high temperatures at rich air-to-fuel ratios can minimize the effects of fuel sulfur levels on catalyst active materials and catalyst efficiency. However, it cannot completely eliminate the effects of sulfur poisoning. A study of Tier 2 vehicles in the in-use fleet recently completed by EPA shows that emission levels immediately following high speed/load operation is still a function of fuel sulfur level, suggesting that lower fuel sulfur levels will bring emission benefits unachievable by catalyst regeneration procedures alone. [245] Furthermore, regular operation at these temperatures and at rich air-to-fuel ratios is not desirable, for several reasons. The temperatures necessary to release sulfur oxides are high enough to lead to thermal degradation of the catalyst over time via thermal sintering of active materials. Sintering reduces the surface area available to participate in reactions. Additionally, it is not always possible to maintain these catalyst temperatures (because of cold weather, idle conditions, light load operation) and the rich air-to-fuel ratios necessary can result in increased PM, NMOG and CO emissions. Thus, reducing fuel sulfur levels has been the primary regulatory mechanism to minimize sulfur contamination of the catalyst and ensure optimum emissions performance over the useful life of a vehicle. The impact of gasoline sulfur has become even more important as vehicle emission standards have become more stringent. Some studies have suggested an increase in catalyst sensitivity to sulfur (in terms of percent conversion efficiency) when standards increase in stringency and emissions levels decrease. Emission standards under the programs that preceded the Tier 2 program (Tier 0, Tier 1 and National LEV, or NLEV) were high enough that the impact of sulfur was considered negligible. The Tier 2 program recognized the importance of sulfur and reduced the sulfur levels in the fuel from around 300 ppm to 30 ppm in conjunction with the new emission standards. [246] At that time, very little work had been done to evaluate the effect of further reductions in fuel sulfur, especially on in-use vehicles that may have some degree of catalyst deterioration due to real-world operation.

In 2005, EPA and several automakers jointly conducted a program that examined the effects of sulfur and other gasoline properties, benzene, and volatility on emissions from a fleet of nine Tier 2 compliant vehicles. Section 1.2.3 of the draft RIA provides details of the Mobile Source Air Toxics (MSAT) Study. [247] The study found significant reductions in NO X, CO and total hydrocarbons (HC) when the vehicles were tested on low sulfur fuel, relative to 32 ppm fuel. [248] In particular, the study found a nearly 50 percent increase in NO X over the FTP when sulfur was increased from 6 ppm to 32 ppm. Given the prep procedures related to catalyst clean-out and loading used by these studies, these results may represent a “best case” scenario relative to what would be expected under more typical driving conditions. Nonetheless, these data suggested the effect of sulfur loading was reversible for Tier 2 vehicles, and that there were likely to be significant emission reductions possible with further reductions in gasoline sulfur level. For more discussion of the impact of gasoline fuel sulfur on the current light-duty vehicle fleet, see Section III.A.

b. EPA Gasoline Sulfur Effects Testing

Both the MSAT and Umicore studies showed the emission reduction potential of lower sulfur fuel on Tier 2 and later technology vehicles over the FTP cycle. However, assessing the potential for reduction on the in-use fleet requires understanding how sulfur exposure over time impacts emissions, and what the state of loading is for the typical vehicle in the field. In response to these data needs, EPA conducted a new study to assess the emission reductions expected from the in-use Tier 2 fleet with a reduction in fuel sulfur level from current levels. It was designed to take into consideration what was known from prior studies on sulfur build-up in catalysts over time and the effect of periodic regeneration events that may result from higher speed and load operation over the course of day-to-day driving.

The study sample described in this analysis consisted of 81 cars and light trucks recruited from owners in southeast Michigan, covering model years 2007-9 with approximately 20,000-40,000 odometer miles. The makes and models targeted for recruitment were chosen to be representative of high sales vehicles covering a range of types and sizes. Test fuels were two non-ethanol gasolines with properties typical of certification test fuel, one at a sulfur level of 5 ppm and the other at 28 ppm. A nominal concentration of approximately 25 ppm was targeted for the high level to be representative of retail fuel available to the public in the vehicle recruiting area. All emissions data was collected using the FTP cycle at a nominal temperature of 75 °F.

Using the 28 ppm test fuel, emissions data were collected from vehicles in their as-received state as well as following a high-speed/load “clean-out” procedure consisting of two back-to-back US06 cycles intended to reduce sulfur loading in the catalyst. A statistical analysis of this data showed highly significant reductions in several pollutants including NO X and hydrocarbons, suggesting that reversible sulfur loading exists in the in-use fleet and has a measurable effect on aftertreatment performance (Table IV-6). For example, Bag 2 NO X emissions dropped 32 percent between the pre- and post-cleanout tests on 28 ppm fuel.

Table IV-6—Average Clean-Out Effect on In-Use Emissions Using 28 ppm Test Fuel a Back to Top
NO X (p-value) THC (p-value) CO (p-value) NMHC (p-value) CH 4 (p-value) PM (p-value)
aThe clean-out effect is not significant at α = 0.10 when no reduction estimate is provided.
Bag 1 4.7%(0.0737) 15.4%(<0.0001)
Bag 2 31.9%(0.0009) 16.5%(0.0024) 17.8%(0.0181) 15.3%(0.0015)
Bag 3 38.3%(<0.0001) 21.4%(<0.0001) 19.5%(0.0011) 27.8%(<0.0001) 12.0%(<0.0001) 24.5%(<0.0001)
FTP Composite 11.4%(<0.0001) 4.1%(0.0187) 7.6%(0.0008) 3.0%(0.0751) 6.9%(0.0003) 13.7%(<0.0001)
Bag 1-Bag 3 4.2%(0.0714)

To assess the impact of lower sulfur fuel on in-use emissions, further testing was conducted on a representative subset of vehicles on 28 ppm and 5 ppm fuel with accumulated mileage. A first step in this portion of the study was to assess differences in the effectiveness of the clean-out procedure when done using different fuel sulfur levels. Table IV-7 presents a comparison of emissions immediately following (<50 miles) the clean-out procedures at the low vs. high sulfur level. These results show significant emission reductions for the 5 ppm fuel relative to the 28 ppm fuel immediately after this clean-out; for example, Bag 2 NO X emissions were 47 percent lower on the 5 ppm fuel vs. the 28 ppm fuel. This indicates that the catalyst is not fully desulfurized, even after a clean out procedure, as long as there is sulfur in the fuel.

Table IV-7—Percent Reduction in Exhaust Emissions When Going From 28 ppm to 5 ppm Sulfur Gasoline for the First Three Repeat FTP Tests Immediately Following Clean-Out Back to Top
NO X (p-value) THC (p-value) CO (p-value) NMHC (p-value) CH 4 (p-value) PMa
aSulfur level not significant at α = 0.10.
Bag 1 5.9%(0.0896) 5.4%(0.0118) 7.3%(0.0023) 4.6%(0.0465) 11.1%(<0.0001)
Bag 2 47.3%(0.0010) 40.2%(<0.0001) a 34.4%(0.0041) 53.6%(<0.0001)
Bag 3 51.2%(<0.0001) 35.0%(<0.0001) 10.1%(0.0988) 45.0%(<0.0001) 25.4%(<0.0001)
FTP Composite 17.7%(0.0001) 11.2%(<0.0001) 8.3%(0.0003) 8.8%(0.0003) 21.4%(<0.0001)
Bag 1-Bag 3 a a 5.8%(0.0412) a a

To assess the overall in-use reduction between high and low sulfur fuel, a mixed model analysis of all data as a function of fuel sulfur level and miles driven after cleanout was performed. This analysis found highly significant reductions for several pollutants, as shown in Table IV-8. Reductions for Bag 2 NO X were particularly high, estimated at 59 percent between 28 ppm and 5 ppm overall. For some pollutants, such as Bag 2 NO X, the model fitting did not find a significant miles-by-sulfur interaction, suggesting the relative differences were not dependent on miles driven after clean-out. Other results, such as Bag 1 hydrocarbons, did show a significant miles-by-sulfur interaction. In this case, determination of a sulfur level effect for the in-use fleet required estimation of a miles-equivalent level of sulfur loading, which was determined by the cleanout results obtained from the baseline testing on the vehicles as-received.

Table IV-8—Summary of Mixed Model Results for Emission Reductions When Going From 28 ppm to 5 ppm Sulfur Gasoline, Adjusted for In-Use Sulfur Loading (Mileage Accumulation) Where Appropriate Back to Top
NO X (p-value) THC (p-value) CO (p-value) NMHC (p-value) CH 4 (p-value) NO X+NMOG (p-value) PMa
aSulfur level not significant at α = 0.10. For THC Bag 1 and CH 4 Bag 1, because the effect of clean-out was not statistically significant, the reduction estimates are based on the estimates of least squares means.
bModel with significant sulfur and mileage interaction term.
Bag 1 10.7%(0.0033) b8.5%(0.0382) b7.5%(0.0552) 7.5%(< 0.0001) b13.9%(<0.0001) N/A
Bag 2 59.2%(<0.0001) 48.8%(<0.0001) a b44.8%(0.0260) 49.9%(<0.0001) N/A
Bag 3 62.1%(<0.0001) 40.2%(<0.0001) 20.1%(<0.0001) 49.9%(<0.0001) 29.2%(<0.0001) N/A
FTP Composite b23.0%(0.0180) b13.0%(0.0027) b11.9%(0.0378) b10.6%(0.0032) b25.8%(<0.0001) 17.3%(0.0140)
Bag 1-Bag 3 a 5.2%(0.0063) 4.3%(0.0689) 5.1%(0.0107) 4.6%(0.0514) N/A

Major findings from this study include:

  • Reversible sulfur loading is occurring in the in-use fleet of Tier 2 vehicles and has a measureable effect on emissions of NO X, hydrocarbons, and other pollutants of interest.
  • The effectiveness of high speed/load procedures in restoring catalyst efficiency is limited when operating on higher sulfur fuel.
  • Reducing fuel sulfur levels from current levels to levels in the range of the proposed gasoline sulfur standards would be expected to achieve significant reductions in emissions of NO X, hydrocarbons, and other pollutants of interest in the in-use fleet.

The overall reductions found in this study are in agreement with other low sulfur studies conducted on Tier 2 vehicles. The magnitude of NO X and HC reductions found in this study when switching from 28 ppm to 5 ppm fuel are consistent with those found in MSAT and Umicore studies mentioned above. For further details regarding the Tier 2 In-Use Gasoline Sulfur Effects Study, see the draft report on this work. [249]

c. Fuel Sulfur Impacts on Vehicles at the Proposed Tier 3 Levels

As discussed in previous sections, the Tier 3 Program would reduce fleet average NMOG+NO X emissions by over 80 percent. The feasibility of the proposed 30 mg/mi NMOG+NO X fleet average standard depends on a degree of emissions control from exhaust catalyst systems that will require gasoline at 10 ppm sulfur or lower. The most likely control strategies would involve using exhaust catalyst technologies and powertrain calibration primarily focused on reducing cold-start emissions of NMOG and on both cold-start and warmed-up (running) emissions of NO X. An important part of this strategy, particularly for larger vehicles having greater difficulty achieving cold-start NMOG emissions control, would be to reduce NO X emissions to near-zero levels. This would allow sufficient NMOG compliance margin to allow vehicles to meet the combined NMOG+NO X emissions standards for their full useful life.

Achieving the proposed Tier 3 emission standards would require very careful control of the exhaust chemistry and exhaust temperatures to ensure high catalyst efficiency. The impact of sulfur on OSC components in the catalyst makes this a challenge even at relatively low (10 ppm) gasoline sulfur levels. NO X conversion by exhaust catalysts is strongly influenced by the OSC components like ceria. Ceria sulfation may play an important role in the degradation of NO X emission control with increased fuel sulfur levels observed in the MSAT, Umicore and EPA Tier 2 In-Use Gasoline Sulfur Effects studies. [250]

Light-duty vehicles certified to CARB SULEV and federal Tier 2 Bin 2 exhaust emission standards accounted for approximately 3.1 percent and 0.4 percent, respectively of vehicle sales for MY2009. Light-duty vehicles certified to SULEV under LEV II are more typically certified federally to Tier 2 Bin 3, Bin 4 or Bin 5, and vehicles certified to SULEV and Tier 2 Bins 3-5 comprised approximately 2.5 percent of sales for MY2009. In particular, nonhybrid vehicles certified in California as SULEV are not certified to federal Tier 2 Bin 2 emissions standards even though the numeric limits for NO X and NMOG are shared between the California LEV II and federal Tier 2 programs for SULEV and Bin 2. Confidential business information shared by the auto companies indicate that the primary reason is an inability to demonstrate compliance with SULEV/Bin 2 emission standards after vehicles have operated in-use on gasoline with greater than 10 ppm sulfur and with exposure to gasoline up to the Tier 2 80 ppm gasoline sulfur cap. While vehicles certified to the SULEV and Tier 2 Bin 2 standards both demonstrate compliance using certification gasoline with 15-40 ppm sulfur content, in-use compliance of SULEV vehicles in California occurs after operation on gasoline with an average of 10 ppm sulfur and a maximum cap of 30 ppm sulfur while federally certified vehicles operate on gasoline with an average of 30 ppm sulfur and a maximum cap of 80 ppm sulfur. Although the SULEV and Tier 2 Bin 2 standards are numerically equivalent, the increased sulfur exposure of in-use vehicles certified under the federal Tier 2 program results in a need for a higher emissions compliance margin to take into account the impact of in-use gasoline sulfur on full useful life vehicle emissions. As a result, vehicles certified to California SULEV typically certify to emissions standards under the federal Tier 2 program that are 1-2 certification bins higher (e.g., SULEV certified federally as Tier 2 Bin 3 or Bin 4) in order to ensure in-use compliance with emissions standards out to the full useful life of the vehicle when operating on higher-sulfur gasoline.

Emissions of vehicles certified to the SULEV standard of the California LEV II program, or the equivalent Tier 2 Bin 2 standards, can provide some insight into the impact of fuel sulfur on vehicles at the very low proposed Tier 3 emissions levels. Vehicle testing by Toyota of LEV I, LEV II ULEV and prototype SULEV vehicles showed larger percentage increases in NO X and HC emissions for SULEV vehicles as gasoline sulfur increased from 8 ppm to 30 ppm, as compared to other LEV vehicles they tested. Testing of a SULEV-certified PZEV vehicle by Umicore showed a pronounced, progressive trend of increasing NO X emissions (referred to as “NO X creep”) when switching from a 3 ppm sulfur gasoline to repeated, back-to-back FTP tests using 33 ppm sulfur gasoline. [251] The PZEV Chevrolet Malibu, after being aged to an equivalent of 150,000 miles, demonstrated emissions at a level equivalent to the compliance margin for the Tier 3 Bin 30 NMOG+NO X standard when operated on 3 ppm sulfur fuel and for at least one FTP test after switching to 33 ppm certification fuel. Following operation over 2 FTP cycles on 33 ppm sulfur fuel, NO X emissions alone were more than double the proposed Tier 3 30 mg/mi NMOG+NO X standard. [252] This represents a NO X percentage increase that is approximately 2-3 times of what has been reported for similar changes in fuel sulfur level for Tier 2 and older vehicles over a similar difference in fuel sulfur. 253 254 There are no LDTs larger than LDT2 and no larger non-hybrid LDVs. We expect that additional catalyst technologies, for example increasing catalyst surface area (volume or substrate cell density) and/or increased PGM loading, would need to be applied to larger vehicles in order to achieve the catalyst efficiencies necessary to comply with the proposed Tier 3 standards. Any sulfur impact on catalyst efficiency would have a larger impact on vehicles and trucks that rely more on very high catalyst efficiencies in order to achieve very low emissions.

The negative impact of gasoline sulfur on catalytic activity and the resultant loss of exhaust catalyst effectiveness to chemically reduce NO X and oxidize NMOG and air toxic emissions occurs across all vehicle categories. However, the impact of gasoline sulfur on NO X emissions control of catalysts in the fully-warmed-up condition is particularly of concern for larger vehicles (the largest LDVs and LDT3s, LDT4s, and MDPVs). Manufacturers face the most significant challenges in reducing cold-start NMOG emissions for these vehicles. Because of the need to reach near-zero NO X levels, any significant degradation in NO X emissions control over the useful life of the vehicle would likely prevent some if not most larger vehicles from reaching a combined NMOG+NO X low enough to comply with the 30 mg/mi fleet-average standard. These vehicles represent a sufficiently large segment of light-duty vehicle sales now and in the foreseeable future that their emissions could not be offset (and thus the fleet-average standard achieved) by certifying vehicles to bins below the fleet average. Any degradation in catalyst performance due to gasoline sulfur would reduce or eliminate the margin necessary to ensure in-use compliance with the proposed Tier 3 emissions standards. Certifying to a useful life of 150,000 miles versus the current 120,000 miles would further add to manufacturers' compliance challenge for Tier 3 large light trucks (See Section IV.7.b below for more on the useful life requirements.)

d. Gasoline Sulfur Control Required To Meet Tier 3 Emissions Standards

The impact of gasoline sulfur poisoning on exhaust catalyst performance and the relative stringency of the Tier 3 standards, particularly for larger vehicles and trucks, when considered together make a compelling argument for the virtual elimination of sulfur from gasoline. As discussed in Section V.A.2, the proposed 10-ppm standard for sulfur in gasoline represents the lowest practical limit from a standpoint of fuel production, handling and transport. While lowering gasoline sulfur to levels below 10 ppm would further help ensure in-use vehicle compliance with the Tier 3 standards, the Agency believes that a gasoline sulfur standard of 10 ppm would allow compliance by gasoline-fueled engines with a national fleet average of 30 mg/mi NMOG+NO X. The level of the proposed Tier 3 standards was considered in light of a 10-ppm average sulfur level for gasoline. Not only should a 10-ppm sulfur standard enable vehicle manufacturers to certify their entire product line of vehicles to the Tier 3 fleet average standards, but based on the results of testing both Tier 2 vehicles and SULEV vehicles as discussed above, reducing gasoline sulfur to 10 ppm should enable these vehicles to maintain their emission performance in-use over their full useful life. It is important to note that while the preceding discussion focused on gasoline sulfur control, spark ignition engines operating on other fuels (i.e., CNG, LPG, E85) and utilizing a three way catalyst systems for control of emission are similarly affected by the sulfur levels in the fuel. We invite comment on all aspects of our analysis of gasoline sulfur effects and our conclusions, especially comments that include any additional relevant testing data.

7. Other Provisions

a. Early Credits

The California LEV III program is scheduled to begin at least two model years earlier than the proposed federal Tier 3 program. [255] As stated earlier, EPA proposes to implement the Tier 3 standards in MY 2017, for vehicles 6,000 lbs GVWR and less, and in MY 2018 for vehicles over 6,000 lbs GVWR. As a result, LEV III vehicles sold in California beginning in MY 2015 will be required to meet a lower fleet average NMOG+NO X level than the federal fleet is meeting at that time. In addition, the California NMOG+NO X standards will continue to decline resulting in the gap growing between the current federal program and LEV III. The early credit program we are proposing is designed to accomplish three goals: (1) Encourage manufacturers to produce a cleaner federal fleet earlier than otherwise required; (2) provide needed flexibility to the manufacturers to facilitate the “step down” from the current Tier 2 Bin 5 fleet average required in MY 2016 to the LEV III-based declining fleet average in MY 2017; and (3) create a Tier 3 program that is equivalent in stringency to the LEV III program such that manufacturers will be able to produce a 50-state fleet at the earliest opportunity.

The first provision that we are proposing to address these goals is to allow manufacturers to generate early federal credits against the current Tier 2 Bin 5 requirement [256] in MYs 2015 and 2016 for vehicles under 6,000 lbs GVWR and MYs 2016 and 2017 for vehicles greater than 6,000 lbs GVWR. (Early credits would only be available for manufacturers complying under the primary program (declining fleet average), not the alternative phase-in approach (Section IV.A.3.a above). In order to generate these credits, manufacturers would sum the NMOG and NO X certification standards for each federally certified Tier 2 vehicle and calculate an NMOG+NO X fleet average. Credits would be based on the difference between the new, cleaner, fleet average and the Tier 2 Bin 5 requirement (160 mg/mi total of NMOG and NO X). We expect that manufacturers could accomplish this by certifying existing Tier 2 vehicles to a lower fleet average, mainly for the higher bins as the current sulfur content in gasoline would preclude them from certifying the cleanest bins federally (Our analysis, presented in Section IV.A.5 above and Chapter 1 of the draft RIA, shows that many vehicles currently certified to Tier 2 Bin 5 could likely be certified to a lower bin with some reduction in compliance margin; e.g., from Bin 5 to Bin 4 or Bin 3.) We expect to realize early environmental benefits, as the result of a cleaner federal fleet, that justify the credits generated.

We believe that this provision would help us realize both our first and our second goals. For example, a manufacturer certifying their federal fleet to Tier 2 Bin 4 would earn 50 mg/mi of NMOG+NO X credits per vehicle (i.e., 160 mg/mi minus 110 mg/mi) which should encourage manufacturers to certify a cleaner federal fleet and provide ample opportunity for credit generation to facilitate the “step down” in stringency. However, if we allowed excessive early credits to be generated it could allow manufacturers to delay their federal compliance with the same fleet average as California for several years. This would be in direct conflict with our third goal of creating a program of equal stringency to the California program as early as possible. In order to address this concern we are proposing that the application of the early federal credits be constrained under the following conditions:

  • Early federal credits generated under the provision described above could be used without limitation in MY 2017.
  • Credits used for compliance in MY 2018 and beyond would be capped at an amount equal to the lesser of the manufacturer's federal credits as calculated above or the manufacturer's LEV III credits multiplied by the ratio of 50-state sales to California only sales. Calculation of these credits would account for the fact that some LEV III credits may have begun to expire and would no longer be eligible as a basis for Tier 3 early credits.

By capping the available federal credits we believe that the two programs, LEV III and Tier 3 would be at parity starting in 2018 MY. In addition, because the number of federal early credits that could be used would be based on the number of LEV III credits that the manufacturer had generated, there may be additional motivation for manufacturers to over-perform in California during the initial model years.

We are proposing that early credit life be limited to 5 years with no discounting, consistent with the California LEV II and LEV III programs and similar to the basic credit carry-forward provisions of the recent light-duty and heavy-duty greenhouse gas rules. We are not proposing any carry-over of Tier 2 credits for use in the Tier 3 program. We seek comment on the 5-year credit life in the context of the programs goals of harmonization with California LEV III and whether the added flexibility would be advantageous relative to any added burden associated with corresponding record retention requirements.

b. Useful Life

The “useful life” of a vehicle is the period of time, in terms of years and miles, during which a manufacturer is responsible for the vehicle's emissions performance. [257] For LDVs and LDTs (including MDPVs) under the Tier 2 program, there have historically been both “full useful life” values, approximating the average life of the vehicle on the road, and “intermediate useful life” values, representing about half of the vehicle's life. For the Tier 3 program, we are proposing several changes to the current useful life provisions that are appropriate to the proposed standards described above.

Every vehicle manufacturer with which the EPA has met has expressed the desire for a single national vehicle fleet and has indicated an ability and willingness to certify their vehicles to a 150,000 mile, 15 year full useful life in support of that goal, since the LEV III program would apply a single 150,000 mile, 15 year useful life value for all of the new standards. However, the CAA, written at a time when vehicles did not last as long as today, precludes EPA from requiring a useful life value longer than the 120,000 mile (and 10 or 11 year, as applicable) value set in Tier 2, for all LDVs and for LDTs up to 3,750 lbs LVW and up to 6,000 lbs GVWR (LDT1s). For vehicles heavier than these limits (i.e., LDT2s, 3s, 4s, as well as MDPVs, representing a large fraction of the light-duty fleet) we are proposing a 150,000 mile, 15 year useful life value. For the lighter vehicles, we are proposing to continue to apply the 120,000 mile (and 10 or 11 year, as applicable) full useful life requirement from the Tier 2 program. Numerically, we are proposing 120,000 mile useful life NMOG+NO X standards that are 85 percent of the respective NMOG+ NO X 150,000 mile standards. (See Chapter 1 of the draft RIA for a description of our analysis of this relationship.) For the lighter vehicles, we propose that manufacturers be allowed to choose to certify to either useful life value in complying with the proposed fleet average and per-vehicle standards. [258] A manufacturer choosing to comply with the 120,000 mile useful life standards for any of their lighter vehicles would demonstrate compliance with the numerically lower fleet-average NMOG+ NO X standards for all LDV and LDT1 families. Standards for all other pollutants [259] would remain the same regardless of whether compliance was at the 120,000 mile or the 150,000 mile useful life periods. If a vehicle manufacturer chose to comply with the 120,000 mile useful life standards for their lighter vehicles, it would be required to separately demonstrate that its larger vehicles complied with the 150,000 mile fleet average standards.

Except for vehicles not required to meet a 150,000 miles useful life and for which a manufacturer chose to apply the 120,000 mile useful life value, we propose that manufacturers be required to certify vehicles to the 150,000 mile useful life beginning with the first model year that a vehicle model is certified to the FTP NMOG+NO X Bin 70 or lower. This useful-life requirement would apply beginning in MY 2017. Beginning in MY 2020, all vehicles would need to certify to the 150,000 mile useful life, regardless of NMOG+NO X certification bin, unless they are allowed and the manufacturer has chosen to remain at 120,000 mile useful life. (Note that the timing of the requirement to certify on the new test fuel would follow the same approach as for the useful life requirement (i.e., based on the first year a model is certified to Bin 70 or below) as described in Section IV.A.7.c below.)

We request comment on the proposed useful life provisions, including the 85 percent factor we propose to use to establish the standards for the 120,000 mile useful life.

c. Test Fuels

We recognize that test fuels are an important element of a national program. Vehicle manufacturers have emphasized the desire to reduce test burden by producing one vehicle that is tested to a single test procedure and a single fuel and meets both California and federal requirements. Although we have been able to reasonably align the proposed Tier 3 program with the LEV III program in most key respects, we recognize that there would still exist some differences in emissions performance between vehicles operated on the LEV III and Tier 3 certification fuels. The largest differences between the two fuels are the amount of ethanol they contain and the Reid Vapor Pressure (RVP). The proposed Tier 3 NMOG+NO X standards assume operation on federal certification fuel.

We propose that manufacturers begin to certify vehicles on the new Tier 3 fuels [260] beginning with the first model year that a vehicle model is certified to the FTP NMOG+NO X Bin 70 or lower, independent of its useful life. The new-fuel requirement would apply beginning in MY 2017. Beginning in MY 2020, all gasoline-fueled models would need to certify on the new fuel, regardless of their certification bin. [261] As discussed in Section IV.A.7.b above, manufacturers would also need to apply the 150,000 mile useful life value to these same vehicles as they begin to be certified to Bin 70 and lower.

During the transition period from Tier 2 fuel to the new Tier 3 and LEV III fuels, manufacturers have indicated a substantial workload challenge of developing and certifying a vehicle to the two new fuels simultaneously. To address this potential workload and certification challenge, we propose that vehicles certified in MY 2015 through 2019 to California LEV III standards using California LEV III certification fuels and test procedures could be used for certifying to EPA standards. (For example, for MY 2015 and 2016, EPA would consider such vehicles to be Tier 2 vehicles, although they could be tested on California LEV III fuel. [262] Similarly, for MY 2017 through 2019, EPA would consider such vehicles to be Interim Tier 3 vehicles, although they could be tested on California LEV III fuel.) For these vehicles only, we would not perform or require in-use exhaust testing on Tier 3 fuel.

California does not have fuel specifications for high altitude testing or cold CO and hydrocarbon testing. For this reason, we are proposing that for vehicles that manufacturers choose to certify using LEV III fuel and test procedures, they can use test fuels meeting either Tier 2 or Tier 3 fuel specifications to comply with these federal-only requirements. We would perform in-use testing for these vehicles on the same fuel as selected by the manufacturer at certification.

Certifications after MY 2019, however, would be required to use the Tier 3 fuel and carry-over certifications using LEV II, LEV III or Tier 2 certification fuels would not be allowed after MY 2019. CARB has indicated that they would accept Tier 3 test data (on federal certification fuel) to obtain a California certificate as early as MY 2015. In this manner manufacturers should be able to avoid compliance testing on more than one fuel as vehicles certified to LEV III using federal certification fuel could obtain Final Tier 3 status. [263]

d. High Altitude Requirements

FTP emission standards are historically designed to be applicable at all altitudes. Under Tier 2, the same FTP emission bin standards applied to vehicles tested at both low and high-altitude. However, fundamental physical challenges exist at high altitude resulting in typically higher emissions during cold starts compared with starts at lower altitudes (i.e., sea level). This expected increase in emissions is primarily due to the lower air density at higher altitudes. Due to the lower air density, the needed volume of the hot combustion exhaust required to quickly heat the catalyst in the first minute after a cold start is reduced. As a result, catalyst light-off is delayed and cold start emissions increase. Vehicles under the Tier 2 program typically had sufficient compliance margins to absorb this increase in emissions during testing under high-altitude conditions. However, given the near-zero standards we are proposing in Tier 3, vehicles will have less compliance margin with which to address the issue.

Under the Tier 3 program, we expect that the emission control technologies selected for low altitude performance would also provide very significant emission control at high altitude. [264] However, as explained above, unique emission challenges exist with operation at higher altitude. The stringency of the Tier 2 standards is such that manufacturers comply with the same standards at all altitudes without the need to design their emission control strategies specifically for the more challenging high altitude operation. The Tier 3 stringency may not allow manufacturers emission control strategies at lower altitude to maintain sufficient compliance margin when tested at higher altitude, therefore requiring manufacturers to design their emission controls specifically for higher altitude.

To avoid requiring special high-altitude emission control technologies, we propose to allow manufacturers the limited relief of complying with the next less-stringent bin for testing at high altitude for vehicles certified at sea level to Bin 20, 30, and 50 (e.g., certifying to Bin 50 for testing at high altitude versus Bin 30 at sea level). For vehicles certified at sea level to Bins 70 and 125, 35 mg/mi of relief will be provided. No relief is proposed for Bin 160.

We do not believe that the impact of the fairly small fraction of overall U.S. driving that occurs in high altitude locations warrants a requirement for additional technologies to be applied specifically for high-altitude conditions. In addition, this provision is intended to be applicable to all Final Tier 3 vehicles for the duration of the Tier 3 program.

While vehicles would need to meet the Tier 3 standards at all intermediate altitudes, the question remains as to what the value of the standard should be at a given intermediate altitude. We request comment on both the level of the proposed high altitude standards and the appropriate level of the standard at intermediate altitudes. In particular, we seek comment on whether this could be addressed by requiring that all emission control strategies remain in effect at altitudes that are in between the specific altitudes used for high and low altitude testing and that any altitude-related auxiliary emission control device (AECD) must be identified by the manufacturer and justified as not being defeat devices.

Table IV-9—Proposed High Altitude Standards Back to Top
Bin Sea level FTP standard (mg/mi NMOG+NO X) Altitude FTP standard (mg/mi NMOG+NO X)
Bin 160 160 160
Bin 125 125 160
Bin 70 70 105
Bin 50 50 70
Bin 30 30 50
Bin 20 20 30

e. Highway Test Standards

Sustained high-speed operation can result in NO X emissions that may not be represented on either the FTP or SFTP cycles. Although we are not aware of any serious issues with this mode of operation with current Tier 2 vehicles, we are interested in preventing increases in these NO X emissions as manufacturers develop new or improved engine and emission control technologies.

For this reason, we are proposing that the same FTP NMOG+NO X standards proposed above also apply on the Highway Fuel Economy Test (HFET), which is performed as a part of GHG and Fuel Economy compliance testing. Thus, the FTP NMOG+NO X standard for the bin at which a manufacturer has chosen to certify a vehicle would also apply on the HFET test. For example, if a manufacturer certifies a vehicle to Bin 70, the vehicle's NMOG+NO X performance over the HFET could not exceed 70 mg/mi. Manufacturers would simply need to ensure that the same emission control strategies implemented for the FTP and SFTP cycles were also effectively utilized during the highway test cycle. We believe that this proposed requirement would not require manufacturers to take any unique technological action, would not add technology costs, and would not add significantly to the certification burden. We request comment on this proposed provision.

f. Interim 4,000 mile SFTP Standards

During the period of the declining NMOG+NO X standards, we are proposing that interim Tier 3 vehicles meet 4,000 mile SFTP standards, consistent with the existing Tier 2 and LEV II program requirements. The 4,000 mile standards are designed to prevent excessive emission levels from a single vehicle or a single SFTP cycle, which can occur if only a composite approach is taken. Under the Tier 3 program, the proposed composite standards would be fleet average standards that would decline from 2017 until 2025, as described in Section IV.A.4. While this approach is expected to result in fleet-wide reductions in SFTP emissions during all years of the declining standard, the level of the fleet average requirement during the initial years provides an opportunity for backsliding of SFTP emissions on individual vehicles or on individual SFTP cycles. We believe it is appropriate to require any individual Interim Tier 3 vehicle to at a minimum meet the same requirements under the Tier 2 and LEV II programs. Table IV-10 below presents the proposed 4,000 mile SFTP standards for interim Tier 3 vehicles.

Table IV-10—Proposed 4,000 Mile SFTP Exhaust Standards for Interim Tier 3 Vehicles (Grams/mile) Back to Top
Vehicle category US06 NMOG+NO X US06 CO SC03 NMOG+NO X SC03 CO
LDV/LDT1 0.14 8.0 0.20 2.7
LDT2 0.25 10.5 0.27 3.5
LDT3 0.4 10.5 0.31 3.5
LDT4 0.6 11.8 0.44 4.0

We believe that vehicles considered to be Final Tier 3 (i.e., they meet the Tier 3 PM requirements, specifically the stringent SFTP PM standards) will have sufficiently robust designs that the 4,000 mile SFTP standards will no longer be necessary. Additionally, once the program reaches the fully phased-in fleet average composite standard of 50 mg/mi in 2025, high SFTP emissions even on a limited portion of a manufacturer's fleet should be effectively mitigated. We seek comment on this proposed 4,000 mile SFTP provision.

g. Phase-In Schedule

As described in Section IV.A.3, under the proposed Tier 3 program, manufacturers would be required to certify each vehicle model to an FTP bin, which would then be used to calculate the NMOG+NO X fleet average of all of its vehicles. Manufacturers would also need to determine the SFTP levels of each model and calculate the NMOG+NO X fleet average for the SFTP requirements as described in Section IV.A.4. These separate FTP and SFTP fleet average calculations would satisfy one aspect of certification under the Tier 3 program, specifically the standards associated with each model year.

As described in Sections IV.A.7.b and IV.A.7.c above, the longer (150,000 mile) useful life value, as applicable, and the new Tier 3 certification fuel for exhaust testing would be implemented as manufacturers certified vehicles to more stringent NMOG+NO X standards, with the threshold to implement both of these provisions being Bin 70. Beginning in MY 2017, any vehicle certified to Bin 70 or lower would be required to be certified on Tier 3 test fuel. In addition, any vehicle certified to Bin 70 or lower that would be required to meet the longer 150,000 mile useful life would be required to do so. Beginning in MY 2020 all vehicles would be required to be certified to on the Tier 3 test fuel, regardless of the bin they are certified to or the useful life they are required to meet.

Manufacturers would also be required to comply with more stringent PM standards on a percent phase-in schedule. Compliance with the PM standards, which is consistent with the CARB LEV III program, would be independent of the fleet average requirements described above. The PM emission standards for FTP and SFTP described in Section IV.A.3 and 4 respectively would be implemented as a percent phase-in requirement as described below under a basic phase-in schedule or under an optional phase-in schedule.

Vehicles certified to a Tier 3 bin, meeting the requirements of the PM phase-in schedule, and complying with the other Tier 3 requirements (i.e., 150,000 mile useful life (as applicable) and Tier 3 certification fuel, as applicable) would be considered “Final Tier 3” compliant vehicles. All other vehicles certified to Tier 3 bins but not yet meeting the PM and other Tier 3 requirements would be considered “Interim Tier 3” compliant vehicles. At the completion of the percent phase-in period for PM (2021 for the basic PM phase-in schedule and 2022 for the alternative PM phase-in schedule, as described below), 100 percent of vehicles would need to meet the all Tier 3 requirements and would be considered “Final Tier 3” vehicles.

For the PM requirements, each year manufacturers would be required to meet either the basic PM percent phase-in or alternative PM phase-in as described in the following subsections. The basic percent PM phase-in schedule is composed of fixed yearly minimum phase-in percentages that we expect that most manufacturers would meet to comply with the Tier 3 requirements. The alternative PM phase-in schedule provides additional flexibility for manufacturers with product offerings that may not provide sufficient vehicle model granularity to allow for a gradual transition into the Final Tier 3 requirements as described below. In either case, Interim Tier 3 vehicles not yet meeting the Tier 3 PM standards must at a minimum meet the Tier 2 PM full useful life FTP standard of 10 mg/mi and the SFTP weighted composite standard of 70 mg/mi.

i. Basic PM Percent Phase-In Schedule

It is important to note that the percent phase-in of the new Tier 3 standards that we are proposing and the declining fleet average standards to which a manufacturer's fleet is held are separate and independent elements of the Tier 3 program. “Phase-in” in this context means the fraction of a manufacturer's fleet that would be required to meet the new Tier 3 PM standards in a given model year. We expect manufacturer fleets to consist of a mix of vehicles certified to Tier 2, LEV II, LEV III and Tier 3 standards throughout the percent phase-in period.

As discussed above, vehicles originally certified to Tier 2, LEV II, and LEV III would be carried over into the Tier 3 program as Interim Tier 3 vehicles. A vehicle would be considered a “Final Tier 3 vehicle” when it is certified to one of the Tier 3 bins; meets the Tier 3 PM standards; certifies to the 150,000 useful life value (for LDT2s, LDT3s, LDT4s, and MDPVs); and certifies on the new certification test fuel. Table IV-11 below presents the proposed PM phase-in schedule for Final Tier 3 vehicles.

Table IV-11—PM Phase-In Schedule for Final Tier 3 Vehicles Back to Top
Model year 2017 2018 2019 2020 2021 2022 and later
aIn 2017 model year, a manufacturer may optionally include vehicles up to 8,500 lbs GVWR and/or MDPVs in its phase-in calculation.
Manufacturer's Fleet (%) 20a 20 40 70 100 100
Vehicle Types ≤ 6,000 lbs GVWR All vehicles ≤ 8,500 lbs GVWR and MDPVs

ii. Optional PM Phase-In

The proposed PM percent-of-sales phase-in schedule described above would allow manufacturers with multiple vehicle models to plan the phase-in of those models based on anticipated volumes of each vehicle model. However, manufacturers certifying only a few vehicle models might not benefit from this schedule. This is because, in order to satisfy the phase-in schedule percentages, they might have to over-comply with the required percentages earlier than would a manufacturer with many vehicle models available for the phase-in.

For instance, a manufacturer with only two models that each equally accounted for 50 percent of their sales would be required to introduce (at least) one of the models in MY 2017 meet the PM phase-in requirement of 20 percent in the first year. Because it represented 50 percent of the manufacturer's sales, this model would then also meet the requirements for MY 2018 (20 percent) and MY 2019 (40 percent). To meet the MY 2020 requirement of 70 percent of sales, however, the manufacturer would need to introduce the second Tier 3 vehicle that year. Thus the manufacturer would have introduced 100 percent of its Tier 3 models one year earlier than would have been required of a manufacturer that was able to delay the final 30 percent of its fleet until MY 2021 (by distributing its their models over the entire phase-in period).

To provide for more equal application of this benefit among all manufacturers in the early years of the program, we are proposing an optional “indexed” PM phase-in schedule that could be used by a manufacturer to meet its PM percent phase-in requirements. A manufacturer that exceeded the phase-in requirements in any given year would be allowed to, in effect, offset some of the phase-in requirements in a later model year. The optional phase-in schedule would be acceptable if it passes a mathematical test. The mathematical test is designed to provide manufacturers a benefit from certifying to the standards at higher volumes than obligated to under the normal phase-in schedule, while ensuring that significant numbers of vehicles are meeting the new Tier 3 requirements during each year of the optional phase-in schedule. In this approach, manufacturers would weight the earlier years by multiplying their percent phase-in by the number of years prior to MY 2022 (i.e., the second year of the 100 percent phase-in requirement).

The proposed mathematical equation for applying the optional PM phase-in is as follows:

(5 × APP2017) + (4 × APP2018) + (3 × APP2019) + (2 × APP2020) + (1 × APP2021) ≥540,

where APP is the anticipated phase-in percentage for the referenced model year.

The sum of the calculation would need to be greater than or equal to 540, which is the result when the optional phase-in equation is applied to the primary percent phase-in schedule (i.e., 5 × 20% + 4 × 20% + 3 × 40% + 2 × 70% + 1 × 100% = 540).

Applying the proposed optional PM phase-in equation to the hypothetical manufacturer in the example above, the manufacturer could postpone its model introductions by one year each, to MY 2018 and MY 2021. Its calculation would be (5 × 0% + 4 × 50% + 3 × 50% + 2 × 50% + 1 × 100% = 550, and thus the phase-in would be acceptable.

EPA requests comment on the proposed PM phase-in schedules.

h. In-Use Standards

i. NMOG+NO X

The proposed Tier 3 emission standards would require a substantial migration of emission control technology historically used only on a small percent of the fleet and typically limited to smaller vehicles and engines. While we believe that these technologies can generally be used on any vehicle and are applicable to the entire fleet, manufacturers have less experience with the in-use performance of these technologies across the fleet. For example, technologies that accelerate catalyst warm-up such as catalyst location close to the engine exhaust ports and other advanced thermal management approaches would be new to certain vehicle types, particularly larger vehicles (i.e., LDT3/4s), which have historically not relied on these technologies to meet emission standards.

To help manufacturers address the lack of in-use experience and associated challenges with the expanded introduction of these technologies particularly in the larger vehicles, we are proposing temporarily-relaxed in-use NMOG+NO X standards that would apply to all vehicles certified to Bins 70 and cleaner as Interim or Final Tier 3 vehicles. The in-use standards would apply during the entire percent phase-in period (i.e., through MY 2021). The proposed in-use standards would be 40 percent less stringent than the certification standards, providing a significant but reasonable temporary cushion for the uncertainties associated with new technologies (or new applications of existing technologies) over the life of the vehicle.

The proposed in-use NMOG+NO X standards are shown in Table IV-12.

Table IV-12—Proposed FTP In-Use Standards for Light Duty Vehicles and MDPVs Back to Top
Bin NMOG+NO X (mg/mi)
[mg/mi]
Bin 160 160
Bin 125 125
Bin 70 98
Bin 50 70
Bin 30 42
Bin 20 28

ii. PM

As with the proposed NMOG+NO X standards, the introduction of new emission control technologies or new applications of existing technologies (e.g., GDI, turbocharging, downsized engines) would create significant uncertainties for manufacturers about in-use performance over the vehicle's useful life. We are proposing a temporary in-use FTP standard for PM of 6 mg/mi for all light duty vehicles and MDPVs certified to the Tier 3 full useful life 3 mg/mi standard. Since the Tier 3 PM standard has a percent phase-in schedule spread over several years, starting in 2017 with full phase-in completed in 2022, we are proposing that the in-use standard apply to all vehicles certified to the new PM standards during the entire percent phase-in period (i.e., through MY 2021).

We are also proposing temporarily-relaxed in-use US06 PM standards. We propose in-use standards 5 mg/mi less stringent than the certification standards, or 15 mg/mi for all light duty vehicles up to and including 6,000 lbs GVWR and 25 mg/mi for all light duty vehicles and light-duty trucks over 6,000 lbs GVWR and MDPVs. Consistent with the FTP in-use standards, these in-use standards would apply to all vehicles certified to the new PM standards during the entire percent phase-in period (i.e., through MY 2021).

EPA requests comment on the proposed in-use standards.

i. FFVs

Because of the physical and chemical differences in how emissions are generated and controlled between vehicles operating on gasoline and ethanol, manufacturers of vehicles designed for high-percentage blends of ethanol (usually called Flexible Fuel Vehicles, or FFVs) may face unique compliance challenges under the proposed Tier 3 program. Historically, under the Tier 2 program, FFVs have only been required to meet all Tier 2 emission standards while operating on gasoline; when operating on the alternative fuel (generally this means a blend that is nominally 85 percent ethanol, or E85), they have only been required to meet the FTP emission standards.

However, E85 use may rise considerably in the future as ethanol use increases in response to the Renewable Fuels Standards (RFS). Thus, it is increasingly important that FFVs maintain their emission performance when operating on E85 across different operating conditions.

We believe that at standard test conditions, requiring manufacturers to meet the Tier 3 standards on any blend of gasoline and ethanol would not add technological feasibility concerns beyond compliance on gasoline alone (or low-level blends like E10 or E15). We are thus proposing that in addition to complying with the Tier 3 requirements when operating on gasoline, FFVs also comply with both the FTP and the SFTP emission standards when operating on E85. This would include the requirement to meet emission standards for both gasoline and E85 for the FTP, highway test, and SFTP emission standards at standard test temperatures (i.e., 68 °F to 86 °F). Since FFVs can operate on any blend of gasoline and ethanol (up to a nominal 85 percent ethanol), the emission requirements apply to operation at all levels of the alternative fuel that can be achieved with commercially available fuels. However, for emission compliance demonstration purposes, we will continue to test on gasoline and the highest available level ethanol.

EPA welcomes comment on this proposed approach to FFV compliance.

j. Credit for Direct Ozone Reduction (DOR) Technology

Since the late 1990s, technologies have been commercialized with which vehicles can remove ozone from the air that flows over the vehicle's coolant radiator. In such direct ozone reduction (DOR) technology, a catalytic coating on the radiator is designed to convert ambient ozone into gaseous oxygen, addressing the air quality concerns about ozone. Detailed technical analyses for the California LEV II and the federal Tier 2 programs showed that when properly designed these systems can remove sufficient ozone from the air to be equivalent to a quantifiable reduction in tailpipe NMOG emissions. In the earlier programs, both California and EPA provided methodologies through which a manufacturer could demonstrate the capability and effectiveness of the ozone-reducing technology and be granted an NMOG credit. A small number of vehicle models with DOR applications received credit under the LEV II program; no manufacturer formally applied for credits under the federal Tier 2 program.

Some manufacturers have expressed an interest in the continued availability of a DOR credit as a part of their potential LEV III and Tier 3 compliance strategies. EPA believes that when a DOR system is shown to be effective in reducing ozone, a credit toward Tier 3 compliance is warranted. We propose that manufacturers following the California methodology for demonstrating effectiveness and calculating a appropriate credit for a DOR system be granted a specific credit toward the NMOG portion of the NMOG+NO X standard. [265] As with the California program, such a credit could not exceed 5 mg/mi NMOG. We invite comment on the appropriateness of this proposed DOR credit approach, including the application of the California methodology to the federal Tier 3 program.

k. Credit for Adopting a 150,000-Mile Emissions Warranty

Under the Tier 3 standards proposed above manufacturers would be expected to design their emission control systems to continue to operate effectively for a useful life of 150,000 miles (120,000 miles for some smaller vehicles). However, as with the current Tier 2 program, manufacturers are only required to replace failed emission control components or systems on customers' vehicles for a limited time period, specified in the Clean Air Act (80,000 miles/8 years for key emission control components). EPA believes that voluntary extension of this warranty obligation by manufacturers would provide additional emission reductions by helping ensure that controls continue to operate effectively in actual operation through the full life of the vehicle.

We propose that a manufacturer providing its customers with a robust emission control system warranty of 15 years or 150,000 miles be eligible for a modest credit of 5 mg/mi NMOG+NO X. [266] Because of the significant liability that manufacturers would be accepting, we do not expect that the use of this credit opportunity would be widespread. However, based on our modeling of the expected deterioration of the emissions of future Tier 3 vehicles absent repair/replacement of failed emission controls, we anticipate that the value to the environment of long emissions warranties in terms of reduced real-world emissions would significantly exceed the 5 mg/mi NMOG+NO X credit. [267]

We propose to use the same criteria for approving such a credit as does the parallel California program. [268] Thus, in addition to committing to customers that failing emission controls would be repaired or replaced for 15 years/150,000 miles, manufacturers would also need to accept the liability that in the event that a specific emissions control device failed on greater than 4 percent of a vehicle model's production, they would recall the entire production of that model for repair. EPA requests comment on this optional credit opportunity.

l. Averaging, Banking, and Trading of Credits

An averaging, banking, and trading (ABT) program was established in the Tier 2 program to provide for credits to be generated by certifying vehicles that perform better than the standards, for those credits to be used to offset vehicles that perform worse than the standards, and for credits to be banked for later use or traded to other manufacturers. The ABT program is largely unchanged by this Tier 3 proposal. In some cases, especially during the transitional years, there would be specific restrictions on the generation of credits, as described above. Also, we are proposing that Tier 3 credits expire after 5 years, consistent with the LEV II and LEV III programs and similar to the basic credit carry-forward provisions in the recent light-duty and heavy-duty greenhouse gas rules. We invite comment on the ABT program in general, and specific comment on a longer Tier 3 credit life, including any flexibilities that this may provide and any implications for record retention requirements by manufacturers.

m. Tier 3 Transitional Emissions Bins

In discussions with manufacturers, EPA has become aware that some vehicles may continue to be produced as late as MY 2019 that could be certified to Tier 2 Bin 3 or Bin 4 standards. In order to provide manufacturers flexibility in meeting the fleet average standards and thus to further facilitate the transition from Tier 2 to Tier 3, we will allow manufacturers to certify to the combined NMOG+NO X levels of these bins through MY 2019. Two proposed transitional Tier 3 bins, Bin 110 and Bin 85, would have NMOG+NO X standards on the FTP of 110 mg/mi and 85 mg/mi, respectively (i.e., the sum of the NMOG and NO X values from the Tier 2 bins); the associated FTP standards for CO, PM, and HCHO corresponding to these bins would be identical to those for vehicles certified to the proposed Tier 3 Bin 125. Tier 3 SFTP standards would apply to these vehicles, and these vehicles would be included in the Tier 3 p.m. percent phase-in calculations.

n. Compliance Demonstration

In general, we are proposing that manufacturers demonstrate compliance with the proposed Tier 3 light-duty vehicle emission standards in a very similar manner to current Tier 2 vehicle compliance (see § 86.1860 of the proposed regulatory language). However, we propose for Tier 3 that manufacturers calculate their compliance with the fleet average standards and percent phase-in standards based on annual nationwide sales, including sales in California and Clean Air Act Section 177 states. We believe that this approach represents another step toward achieving the goal of an effectively nationwide program as early as possible, which has been a basic principle in EPA's development of this proposed program and broadly supported by vehicle manufacturers. We also believe that basing compliance on nationwide sales may reduce the need for manufacturers to project future sales and track past years' sales in a disaggregated way. Because the proposed Tier 3 provisions will become increasingly consistent with LEV III provisions as the Tier 3 program phases in, we believe that any disproportionate impacts of different mixes of vehicles in different states are unlikely to occur. We seek comment on this approach to compliance demonstration.

This proposed nationwide compliance calculation approach would apply to vehicles as they become subject to the Tier 3 provisions, either the declining fleet-average NMOG+NO X curves or the percent phase-in PM standards. Were any manufacturer to choose to use the alternative FTP and SFTP phase-ins, which are not a part of the LEV III program, the manufacturer would not include sales in California or in the Section 177 states in its compliance calculations. [269]

B. Tailpipe Emissions Standards for Heavy-Duty Vehicles

1. Overview

We are proposing Tier 3 exhaust emissions standards for heavy-duty vehicles (HDVs) between 8,501 and 14,000 lbs GVWR that are certified to gram per mile standards on a chassis dynamometer. Vehicles in this GVWR range are often referred to as Class 2b (8,501-10,000 lbs) and Class 3 (10,001-14,000 lbs) vehicles, and are typically full-size pickup trucks and work vans certified as complete vehicles. [270] Most are built by companies with even larger light-duty truck markets, and as such they frequently share major design characteristics and potential emissions control technologies with their LDT counterparts. However, in contrast to the largely gasoline-fueled LDT fleet, roughly half of the HD pickup and van fleet in the U.S. is diesel-fueled, which is a consideration in setting emissions standards, as diesel engine emissions and control strategies differ from those of gasoline engines.

Manufacturers of diesel-fueled complete HDVs have the option under existing EPA regulations to satisfy EPA criteria emissions requirements for these vehicles by using engines certified through engine dynamometer testing, but for the most part have chosen to certify whole vehicles on the chassis test. We are proposing to codify this common practice and require that diesel-fueled Class 2b and 3 complete Tier 3 vehicles, like their gasoline-fueled counterparts, be certified to the Tier 3 standards on the chassis test. The current prohibition in 40 CFR 86.1863-07(d) on averaging, banking, and trading (ABT) credit generation and use by chassis-certified diesel HDVs would be replaced by the proposed fleetwide averaging program. We are not proposing changes to the heavy-duty engine certification requirements at this time.

Manufacturers of incomplete HDVs that are sold to secondary manufacturers for subsequent completion (less than 10 percent of the Class 2b and 3 U.S. market) are also allowed under existing EPA regulations to certify via either the chassis or engine test, and those who choose to chassis-certify in the future would be subject to Tier 3 requirements. We are not proposing to mandate chassis certification of incomplete Class 2b and 3 vehicles, but we note that California's LEV III program does include such a requirement for Class 2b and we request comment on doing the same in the federal program. We further note that MDPVs are classified as HDVs under the Clean Air Act but, as in our current Tier 2 program, would be covered as part of our Tier 3 light-duty program discussed in Section IV.A, and not in the proposed program described here.

The key elements of the proposed Tier 3 program for HDVs parallel those proposed for passenger cars and LDTs, with adjustments in standards levels, emissions test requirements, and implementation schedules, appropriate to this sector. These key elements include a combined NMOG+NO X declining fleet average standard beginning in 2018 and reaching the final, fully phased-in level in 2022, creation of a bin structure for standards, new stringent PM standards phasing in on a separate schedule, changes to the test fuel for gasoline- and ethanol-fueled vehicles, extension of the regulatory useful life to 150,000 miles, and a new requirement to meet standards over the SFTP that would address real-world driving modes not well-represented by the FTP cycle alone. We believe that other requirements already in place for HDV testing and compliance remain appropriate. In particular, we believe the current HDV certification requirement to test at the adjusted loaded vehicle weight (ALVW), equal to vehicle curb weight plus one-half the payload weight, is more appropriate for these heavy-duty work trucks and vans than the LDT requirement to test at curb weight plus 300 lbs. These differences from light-duty requirements also factor into the evaluation of potential control technologies and subsequent choice of standards levels, as discussed below.

As with the proposed light-duty Tier 3 program, we are putting strong emphasis on coordinating this HDV Tier 3 proposal with California's LEV III program for Class 2b and 3 vehicles, referred to in LEV III as medium-duty vehicles (MDVs). The goal is to create a coordinated “national program” in which California would accept compliance with Tier 3 standards as sufficient to also satisfy LEV III requirements, thus allowing manufacturers to comply nationwide by marketing a single vehicle fleet. With this goal in mind, we discuss the relationship of the proposed HDV Tier 3 program provisions to LEV III throughout this section. As part of this effort, we are proposing that manufacturers of Tier 3 HDVs calculate compliance with the fleet average standards and percent phase-in standards discussed in this section based on annual nationwide sales, including sales in California and Clean Air Act Section 177 states. This would help to create an effectively nationwide program, which has been a basic principle in EPA's development of this proposed program and broadly supported by vehicle manufacturers. If this proposed approach to HDV fleet compliance calculations is not adopted, EPA could base compliance with the proposed Tier 3 requirements on U.S. sales outside of California and the Section 177 states.

Furthermore, in 2011 EPA and NHTSA set first-ever standards for GHGs and fuel consumption from HD pickups and vans (as well as other heavy-duty vehicles and engines). These standards phase in over 2014-2018, so in developing the Tier 3 HDV proposal we have carefully taken this new program into account to maximize the coordination between the two complementary heavy-duty regulatory programs and avoid inconsistencies.

2. HDV Exhaust Emissions Standards

a. Bin Standards

We are proposing that manufacturers certify HDVs to Tier 3 requirements by having them meet the standards for one of the bins listed in Table IV-13. Manufacturers would choose bins for their vehicles based on their product plans and corporate strategy for compliance with the fleet average standards discussed in Section IV.A.2.b, and once a vehicle's bin is designated, those bin standards apply throughout its useful life. Because the fleet average standards become more stringent over time, the bin mix would gradually shift from higher to lower bins. As in the past, we are proposing numerically higher standards levels for Class 3 vehicles than for Class 2b vehicles, reflective of the added challenge in reducing per-mile emissions from large work trucks designed to carry and tow heavier loads. Also, the proposed standards levels for both Class 2b and Class 3 HDVs are significantly higher than those being proposed for light-duty trucks due to marked differences in vehicle size and capability, and to our requirement to test HDVs in a loaded condition (at ALVW). By conducting emissions testing with loaded vehicles, the heavy-duty program ensures that emissions controls are effective when these vehicles are performing their core function: hauling heavy loads. This is a key difference between the heavy-duty and light-duty truck programs. The proposed bin structure and standards levels are consistent with those in the LEV III program. We request comment on the usefulness of creating additional bins between Bin 0 and the next lowest bin in each vehicle class, as a means of encouraging clean technologies and adding flexibility.

Table IV-13—Proposed FTP Standards for HDVs Back to Top
NMOG+NO X (mg/mi) NMOG (mg/mi) NO X (mg/mi) PM (mg/mi) CO (g/mi) Formaldehyde (mg/mi)
Class 2b (8,501-10,000 lbs GVWR)            
Bin 395 (interim) 195 200 8 6.4 6
Bin 340 (interim) 140 200 8 6.4 6
Bin 250 250 8 6.4 6
Bin 200 200 8 4.2 6
Bin 170 170 8 4.2 6
Bin 150 150 8 3.2 6
Bin 0 0 0 0 0
Class 3 (10,001-14,000 lbs GVWR)            
Bin 630 (interim) 230 400 10 7.3 6
Bin 570 (interim) 170 400 10 7.3 6
Bin 400 400 10 7.3 6
Bin 270 270 10 4.2 6
Bin 230 230 10 4.2 6
Bin 200 200 10 3.7 6
Bin 0 0 0 0 0

The proposed NMOG and NO X standards for the highest bins in each class (Class 2b Bin 395 and Class 3 Bin 630) are equal to the current non-methane hydrocarbon (NMHC) and NO X standards that took full effect in 2009, as well as to equivalent LEV standards in California's LEV II program. These bins are intended as carryover bins. That is, we would expect them to be populated with vehicles that are designed to meet the current standards, and that are being phased out as new lower-emitting vehicle designs phase in to satisfy the proposed Tier 3 fleet average NMOG+NO X standard. We also consider the next highest bins (Class 2b Bin 340 and Class 3 Bin 570) to be carryover bins, because they likewise can be readily achieved by vehicles designed for today's EPA and California LEV II emissions programs. As the 2018-2022 phase-in progresses, it would become increasingly difficult to produce vehicles in these bins and still meet the fleet average standard. Therefore vehicles in these bins (as well as some others not yet designed to meet Tier 3 PM standards described in Section IV.B.2.d) would be considered “interim Tier 3” vehicles, and the bins themselves would be considered “interim bins.”

To facilitate their use in this carryover function, we are proposing that the interim bins not include SFTP requirements, longer useful life requirements, or requirements to conduct exhaust emissions testing with the proposed new gasoline test fuel discussed in Section IV.D, although testing on this fuel would be allowed. For gasoline-fueled HDVs in all other bins, we are proposing that exhaust emissions testing be conducted with the new test fuel. (See Section IV.D.5 for discussion of our request for comment on extending this requirement to testing of gasoline-fueled heavy-duty engines as well.) In the context of these proposed accommodations for the interim bins, we propose two additional measures to help ensure these bins are focused on their function of helping manufacturers transition to Final Tier 3 vehicles. First, we propose that the interim bins be available only in the phase-in years of the program, that is, through MY 2021, as is appropriate to their interim status.

Second, we are proposing that vehicles in the interim bins meet separate NMOG and NO X standards, as indicated in Table IV-13, rather than combined NMOG+NO X standards. This proposed provision is intended to keep a manufacturer from redesigning or recalibrating a vehicle design under combined NMOG+NO X Tier 3 standards for such purposes as reducing fuel consumption, through means that result in higher NO X or NMOG emissions than exhibited by today's vehicles, contrary to the intended carryover function of the interim bins. We note that other, more stringent, proposed bins also carry this potential but to a lesser degree, and we feel their relatively low NMOG+NO X standards levels sufficiently mitigate this concern, whereas the interim bins have the potential to allow a doubling of emissions or more. We request comment on this issue and the proposed approach to addressing it.

b. Fleet Average NMOG+NO X Standards

As in the light-duty program, a key element of the Tier 3 program is a fleet average NMOG+NO X standard that becomes more stringent in successive model years: In the case of HDVs, from 2018 to 2022. Each HDV sold by a manufacturer in each model year contributes to this fleet average based on the mg/mi NMOG+NO X level of the bin declared for it by the manufacturer. For the interim bins, with separate NMOG and NO X standards, the NMOG+NO X level is the simple sum of the NMOG and NO X standards. Manufacturers may also earn or use credits for fleet average NMOG+NO X levels below or above the standard in any model year, as described in Section IV.B.4. We are proposing the separate Class 2b and Class 3 fleet average standards shown in Table IV-14, though a manufacturer could effectively average the two fleet classes using credits (see Section IV.B.4). We believe this split-curve approach is superior to a single HDV phase-in because it recognizes the different Class 2b/Class 3 fleet mixes among manufacturers and the different challenges in meeting mg/mi standards between Class 2b and Class 3 vehicles, while still allowing for a corporate compliance strategy based on a combined HDV fleet through the use of credits.

The proposed fleet average standards are consistent with those set for the MDV LEV III program in model years 2018 and later. Note that the LEV III program also sets standards for model years before 2018, something EPA is not requiring due to lead time considerations. However, we are proposing that manufacturers may voluntarily meet bin and fleet average standards in model years 2016 and 2017 that are consistent with the MDV LEV III standards, for the purpose of generating credits that can be used later or traded to others. These proposed voluntary standards are shown in Table IV-14. This proposed voluntary opt-in program serves the important purpose of furthering consistency between the federal and California programs, such that manufacturers who wish to can produce a single vehicle fleet for sale nationwide, with the opportunity for reciprocal certification in affected model years. It further incentivizes pulling ahead of Tier 3 technologies, with resulting environmental benefits, by providing for early compliance credits in this nationwide fleet.

Manufacturers choosing to opt into this early compliance program could start in either model year 2016 or 2017. They would have to meet the full complement of applicable bin standards and requirements, including SFTP standards, but not the Tier 3 PM FTP and SFTP standards discussed in Sections IV.B.2.d and IV.B.3.a, or the evaporative emissions standards discussed in Section IV.C, because these requirements phase in on a later schedule. We are also requesting comment on extending the voluntary compliance opportunity to the 2015 model year.

Table IV-14—Proposed HDV Fleet Average NMOG+NO X Standards Back to Top
[mg/mi]
Voluntary Required program
Model Year 2016 2017 2018 2019 2020 2021 2022 and later.
Class 2b 333 310 278 253 228 203 178.
Class 3 548 508 451 400 349 298 247.

We believe that offering this voluntary opt-in would benefit the environment, the regulated industry, and vehicle purchasers, because it has potential to accomplish early emissions reductions while maintaining the goal of a cost-effective, nationwide vehicle program in every model year going forward. We request comment on all facets of this proposed approach.

Although manufacturers would be allowed to meet the fleet average NMOG+NO X standard through whatever combination of bin-specific vehicles they choose, it is instructive to note that the fully phased in fleet average standard for model years 2022 and later would be the equivalent of a Class 2b fleet mix of 90 percent Bin 170 and 10 percent Bin 250 vehicles, and a Class 3 fleet mix of 90 percent Bin 230 and 10 percent Bin 400 vehicles. Therefore, it is appropriate to consider Bin 170 Class 2b vehicles and Bin 230 Class 3 vehicles to be representative of Tier 3-compliant HDVs in the long term.

The Tier 3 program we are proposing for HDVs would result in substantial reductions in harmful emissions from this large fleet of work trucks and vans, vehicles that are typically driven over high annual miles on every part of the nation's highway and urban roadway system. The Final Tier 3 standards levels for NMOG+NO X and PM are on the order of 60 percent lower than the current stringent standards that took full effect three years ago.

c. Alternative NMOG+NO X Phase-In

We believe that the program described in Sections IV.B.2.a and b above would provide manufacturers with a flexible and effective compliance path. However, as in the case of the light-duty standards discussed above, we are proposing to provide an alternative compliance path that would be available to any manufacturer who prefers a stable standard and four full years of lead time, as specified in the Clean Air Act. [271] This alternative approach would be equivalent to the primary approach that is based on NMOG+NO X declining fleet average standards and would apply during the program phase-in over the 2016-2022 model years, with the first three of those model year standards made voluntary and set at levels to align with the California LEVIII program. We are proposing an alternative phase-in structured to require an annually increasing percent-of-sales of HDVs certified to the fully phased in 178 mg/mi (Class 2b) and 247 mg/mi (Class 3) standards, as shown in Table IV-15.

Table IV-15—Proposed Percent-of-Sales Alternative NMOG+NO X Phase-in Back to Top
Voluntary Required program
Model Year 2016 2017 2018 2019 2020 2021 2022 and later.
Class 2b 29% 39% 54% 65% 77% 88% 100%.
Class 3 21% 32% 47% 60% 73% 87% 100%.

Under our alternative phase-in proposal, the availability of emissions averaging makes the two alternatives functionally equivalent, not just in the annual emissions reductions they achieve, but also in how manufacturers may design their mix of products to meet the phase-in standards. Although we are proposing to make the alternative approach available, we believe that the primary approach—the declining fleet average standard discussed above—is more consistent with the approach taken in California's LEV III program and in recent GHG reduction rules.

To help ensure that the percent-of-sales alternative is fully equivalent to the primary program in terms of fleet-wide emissions control and technology mix choices, we are proposing that it include some additional provisions. First, we are proposing that the Tier 3 vehicles being phased in under the percent-of-sales alternative, in addition to meeting the fully phased-in NMOG+NO X FTP standards, must also meet all other FTP and (as described below) SFTP standards required by the primary compliance program. These include the CO and formaldehyde FTP standards in Table IV-13, the 150,000 mile (15 year) useful life requirement, exhaust emissions testing with the new test fuel for gasoline- and ethanol-fueled vehicles discussed in Section IV.D, and the NMOG+NO X and CO SFTP standards in Table IV-16. The specific proposed standards are those for the bins in these tables closest to the fully phased-in NMOG+NO X standards: Bin 170 for Class 2b and Bin 230 for Class 3. (The PM and evaporative emissions standards phase in on separate schedules under both alternatives, as discussed in Sections IV.B.2.d and IV.C.)

Second, we are proposing to make an ABT program available for the percent-of-sales alternative, structured like the one proposed for the primary option. This would involve certifying the vehicles in a manufacturer's HDV fleet to the bin standards in Table IV-13, and demonstrating compliance with the fleet average standards for the primary program in each model year, including through the use of ABT credits as in the primary program. We are proposing to use the fleet average calculation method for purposes of ABT because, as explained above, we have determined that making this demonstration is equivalent to demonstrating compliance with the percent-of-sales requirement, and we see no value in complicating the program with another set of calculations.

However, we are proposing one difference between the primary and alternative options with respect to ABT provisions. Unlike in the primary option, manufacturers would not have to certify all vehicles into bins in order to take advantage of the ABT provisions under the percent-of-sales alternative. Rather they could choose to certify any “phase-out” vehicles (that is, those not counting toward the percent-of-sales phase-in) to the pre-Tier 3 NMHC and NO X standards, provided these vehicles do not have family emission limits (FELs) above those standards. These non-Tier 3 vehicles would not be subject to the Tier 3 standards or other vehicle-specific elements of the Tier 3 compliance program. For the purposes of the fleet average ABT calculation, the NMOG+NO X levels for these non-Tier 3 vehicles would be set equal to the sum of the NMOG and NO X standards for the highest bins: 395 mg/mi for Class 2b and 630 mg/mi for Class 3, because these standards are numerically equal to the pre-Tier 3 NMHC and NO X standards.

d. Phase-In of PM Standards

Consistent with the light-duty Tier 3 proposal discussed in Section IV.A, we are proposing to phase in the PM standards for HDVs as an increasing percentage of a manufacturer's production of chassis-certified HDVs (combined Class 2b and 3) per year. The reasons discussed in Section IV.A for this phase-in schedule in the light-duty sector also apply to the heavy-duty sector. In addition to concerns regarding the availability and required upgrades of test facilities used for both light-duty and heavy-duty vehicle testing, manufacturers have expressed uncertainty about PM emissions with new engine and emissions control technologies entering the market as a result of new GHG standards. Therefore we are proposing the same phase-in schedule as proposed for the light-duty sector in model years 2018-2019-2020-2021: 20-40-70-100 percent, respectively. This would apply to HDVs certified under either NMOG+NO X phase-in alternative. The California Air Resources Board is phasing in the LEV III PM standards for HDVs on the same schedule, except that LEVIII would also involve a 10 percent PM phase-in in the 2017 model year, and we ask for comment on our doing so as well, in the context of the voluntary opt-in discussed in Section IV.B.2.b. The voluntary NMOG+ NO X and PM standards may be pursued separately, with no requirement that they be met on the same vehicles.

For manufacturers choosing the declining fleet average NMOG+NO X compliance path, the PM phase-in requirement for HDVs would be completely independent of the NMOG+NO X phase-in. As a result, vehicles certified to any of the bin standards for NMOG and NO X need not necessarily meet Tier 3 PM standards before the 2021 model year. Instead, the current 0.02 g/mi PM standard would apply for those vehicles not yet phased into the Tier 3 PM standards. We are proposing that manufacturers choosing the percent-of-sales phase-in alternative for NMOG+NO X would be required to meet the PM phase-in requirements with only those vehicles certified to the Tier 3 NMOG+NO X standard, except in the 2018 and earlier model years when the standards, including the PM standards, would be voluntary, and in the 2021 model year when the 100 percent PM phase-in requirement exceeds the 87-88 percent NMOG+NO X phase-in requirement.

Consistent with the approach we are proposing for the light-duty sector, we would consider any vehicle under either compliance path that is not certified to Tier 3 standards for PM, NMOG, and NO X (as well as the other, concomitant Tier 3 standards and requirements such as extended useful life), an “Interim Tier 3” vehicle, a term that also applies to vehicles certified in one of the interim bins, as discussed above.

Note that compliance with Tier 3 evaporative emissions requirements would follow a separate phase-in schedule as described in Section IV.C, such that a vehicle in an exhaust emissions family that the manufacturer has phased into the new useful life and test fuel requirements, may be in an evaporative emissions family that has not yet phased these in for evaporative emissions testing.

i. Optional PM Phase-In

The proposed percent-of-sales phase-in schedule for the PM standard, described above, would allow manufacturers with multiple vehicle models to determine and plan the phase-in of those models based on anticipated volumes of each vehicle model. However, manufacturers certifying only a few vehicle models may not be able to take advantage of this schedule. This is because, in order to satisfy the phase-in schedule percentages, they may have to over-comply with the required percentages earlier than would a manufacturer with many vehicle models available for the phase-in.

For instance, a manufacturer with only two models that each equally accounted for 50 percent of its sales would be required to introduce (at least) one of the models in MY 2018 to meet the phase-in requirement of 20 percent in the first year. At the 50 percent level, this model would then also meet the requirements for MY 2019 (40 percent). To meet the MY 2020 requirement of 70 percent of sales, however, the manufacturer would need to introduce the second Tier 3 vehicle that year. Thus the manufacturer would have introduced 100 percent of its Tier 3 models one year earlier compared to a manufacturer that was able to delay the final 30 percent of its fleet until MY 2021 by distributing its redesigned models over the entire phase-in period.

To provide for more equal application of this benefit among all manufacturers in the early years of the program, we are proposing an optional “indexed” phase-in schedule that could be used by a manufacturer to meet its phase-in requirements. A manufacturer that exceeded the phase-in requirements in any given year would be allowed to, in effect, offset some of the phase-in requirements in a later model year. The optional phase-in schedule would be acceptable if it passes a mathematical test. The mathematical test is designed to provide manufacturers a benefit from certifying to the standards at higher volumes than obligated to under the normal phase-in schedule, while ensuring that significant numbers of vehicles are meeting the new Tier 3 requirements during each year of the optional phase-in schedule. In this approach, manufacturers would weight the earlier years by multiplying their percent phase-in by the number of years prior to MY 2022 (i.e., the second year of the 100 percent phase-in requirement).

The proposed mathematical equation for applying an optional phase-in is as follows:

(4 × APP2018) + (3 × APP2019) + (2 × APP2020) + (1 × APP2021) ≥ 440,

where APP is the anticipated phase-in percentage for the referenced model year. The sum of the calculation would need to be greater than or equal to 440, which is the result when the optional phase-in equation is applied to the primary percent phase-in schedule (4 × 20% + 3 × 40% + 2 × 70% + 1 × 100% = 440). EPA requests comment on this proposed optional phase-in mechanism.

e. NMOG+NO X and NMOG vs. NMHC

The reasons for setting combined NMOG+NO X standards outlined in Section IV.A.1.a for the light-duty sector apply to HDVs certified in the non-interim Tier 3 bins as well. In fact, the combined standard is especially appropriate in the heavy-duty sector with comparable sales of diesel and gasoline-fueled vehicles, because it avoids the need to set “lowest common denominator” standards for NMOG (likely based on feasible gasoline vehicle technologies) and NO X (likely based on feasible diesel vehicle technologies). These considerations also apply to the form of the SFTP standards, discussed below.

The current HDV standards that control emissions of volatile organic compounds (VOCs), adopted in a 2001 final rule, [272] are in the form of NMHC. This is consistent with HD engine standards adopted in the same final rule, but contrasts with Tier 2 LDV/LDT standards to control VOCs that are in the form of NMOG. We believe it is appropriate to transition HDVs to NMOG-based standards, and further to combined NMOG+NO X standards, consistent with the light-duty Tier 3 proposal and light- and medium-duty LEV III program. Further, the introduction of oxygenated test fuels requires an NMOG calculation to properly control VOC emissions not properly accounted for in an NMHC calculation. This would improve consistency with the LEV III program and help to facilitate a single nationwide vehicle fleet. We do not believe that this change would add significant cost to the program as manufacturers are already capable of and experienced in making NMOG determinations at their test facilities.

3. Supplemental FTP Standards for HDVs

Unlike passenger cars and light trucks, HDVs are not currently subject to SFTP standards. SFTP standards are intended to ensure vehicles have robust emissions control over a wide range of real-world driving patterns not well-covered by the FTP drive cycle. Even though HDVs are not typically driven in the same way as passenger cars and LDTs, especially as they frequently carry or tow heavy loads, we believe some substantial portion of real world heavy-duty pickup and van driving is not well-represented on the FTP cycle.

The goal in setting the SFTP standards levels is not to force manufacturers to add expensive new control hardware for off-FTP cycle conditions, but rather to ensure a robust overall control program that precludes high off-FTP cycle emissions by having vehicle designers consider them in their choice of compliance strategies. High off-FTP cycle emissions, even if encountered relatively infrequently in real-world driving, could create a substantial inadequacy in the Tier 3 program, which aims to achieve very low overall emissions in use. The SFTP provisions would also help make the HDV program more consistent with the HD engine program, which for several years has included “not-to-exceed” provisions to control off-cycle emissions. Therefore, in addition to the SFTP provisions, we are further limiting enrichment on spark ignition engines in all areas of operation unless absolutely necessary.

a. SFTP NMOG+NO X, PM and CO Standards

The proposed SFTP standards levels are provided in Table IV-16. These are consistent with those in the LEV III program.

Table IV-16—Proposed SFTP Standards for HDVs Back to Top
Vehicles in FTP bins NMOG+NO X (mg/mi) PM (mg/mi) CO (g/mi)
aThese standards apply for vehicles optionally tested using emissions from only the highway portion of the US06 cycle.
Class 2b with horsepower (hp)/GVWR ≤ 0.024 hp/lb a      
FTP Bins 200, 250, 340 550 7 22.0
FTP Bins 150, 170 350 7 12.0
Class 2b      
FTP Bins 200, 250, 340 800 10 22.0
FTP Bins 150, 170 450 10 12.0
Class 3      
FTP Bins 270, 400, 570 550 7 6.0
FTP Bins 200, 230 350 7 4.0

We are proposing that Tier 3 SFTP implementation for HDVs be linked directly to the Tier 3 FTP phase-in and bins for these vehicles. That is, an HDV certified to any of the Tier 3 FTP bin standards must meet the SFTP standards for that bin as well. However, because the FTP PM standard would phase in on a separate schedule, we propose to require that SFTP PM compliance be linked to the same schedule. That is, an HDV certified to the Tier 3 FTP PM standard must meet the applicable SFTP PM standard as well. This approach recognizes the complementary nature of FTP and SFTP provisions and helps to ensure that Tier 3 emissions controls are robust in real world driving. There are no proposed SFTP requirements for the interim Tier 3 bins in each class (Class 2b Bins 340 and 395 and Class 3 Bins 570 and 630), because these are essentially carry-over bins from the previous standards to aid the transition to Tier 3, and therefore are not intended to prompt vehicle redesigns to new standards. These implementation provisions are consistent with the approach taken in the LEV III program, except that California would allow FTP and SFTP phase-in requirements to be met on different vehicles, and would apply more of the Tier 3 requirements for SFTP and extended useful life to vehicles in the interim bins. We request comment on the proposed standards, and on whether or not EPA should adopt any LEV III provisions that differ from what we are proposing, such as the application of PM SFTP standards to vehicles that are in the interim bins and that also are certified to the Tier 3 p.m. FTP standards.

To help ensure a robust SFTP program that achieves good control over a wide range of real world conditions, the current Tier 2 light-duty program adopted a weighted-composite cycle, and we are proposing to retain this approach for light-duty Tier 3 testing, as discussed in Section IV.A.1.c. Under this composite cycle, NMOG+NO X emissions are calculated from results of testing over three cycles: the US06, the FTP, and the SC03, weighting these results by 0.28, 0.35, and 0.37, respectively. We considered applying the same composite cycle for all HDV SFTP testing. However, based on data provided by industry stakeholders, we decided that the full US06 cycle, combined with the ALVW loaded test condition, would not be sufficiently representative of real-world driving for two groups of HDVs: those with low power-to-weight ratios and Class 3 vehicles.

As part of their investigation of potential LEV III SFTP standards for MDVs, California Air Resources Board staff determined that it is not uncommon for vehicles above 8,500 lbs GVWR with low power-to-weight ratio, which are largely in Class 2b, to have to work extremely hard to keep up with the accelerations required in the initial and final portions of the full US06 cycle, even proving physically unable to do so in some cases, and raising the concern that these vehicles would not be able to run a valid emissions test. [273] Although our SFTP provisions allow a test to continue when a vehicle is incapable of attaining the vehicle speed demanded by the drive trace, we believe routine occurrence of such an event for a group of vehicles would not be consistent with a well-designed test regime. We would expect results from such tests to exhibit significant test-to-test variability, making it difficult to draw reliable conclusions from them. Furthermore, in real-world driving, we would expect that most drivers who regularly demand and do not receive adequate response would modify either their driving behavior or their vehicle purchase decisions.

Based on manufacturer-supplied data, the California Air Resources Board staff established a power-to-weight (GVWR) ratio of 0.024 horsepower (hp)/lb as an approximate threshold in their efforts to characterize this issue. The vast majority of Class 2b vehicles are above this threshold today. Those below it tend to be used in applications where towing is not done extensively and the need for cargo space is more important than payload weight. Furthermore, it is possible that this group of vehicles will grow as purchasers adjust to sustained high fuel prices and when EPA's GHG standards and NHTSA's new fuel consumption standards take effect.

In consideration of this matter, we are proposing that, in SFTP testing of Class 2b vehicles at or below 0.024 hp/lb, manufacturers may at their option replace the full US06 component of the composite SFTP emissions with the test results from only the second of the three emissions sampling bags in the US06 test, generally referred to as the “highway” portion of the US06, subject to correspondingly lower SFTP standards levels discussed above. (These vehicles would still be driven during the test in the same way as the higher power-to-weight Class 2b vehicles (over the full US06 cycle) just using best effort (maximum power) if the vehicle cannot maintain the driving schedule.) The large majority of Class 2b vehicles, with power-to-weight above 0.024 hp/lb, would be required to measure and use emissions over the full US06 cycle in the composite SFTP. We believe that this approach would provide a robust but repeatable and reliable test for the full range of Class 2b vehicles, as the highway portion of the US06 retains broad coverage of vehicle speed/acceleration combinations measured in real-world driving.

For Class 3 vehicles, which can weigh as much as 14,000 lbs GVWR, we are also concerned that the full US06 cycle would not provide a representative drive cycle for SFTP testing. These vehicles are much larger than the light-duty vehicles that formed the basis for development of the US06 cycle, and loading them to ALVW for the SFTP test yields a very heavy test vehicle, not likely to be safely driven in the real world in the way typified by this aggressive cycle. We believe that the LA-92 (or “Unified”) driving cycle developed by CARB is more representative of Class 3 truck driving patterns and would produce more robust results for use in SFTP evaluations. Therefore we are proposing that the LA-92 cycle be used in place of the US06 component of the composite SFTP for Class 3 HDVs. The set of composite SFTP cycles we are proposing is fully consistent with the MDV LEV III program.

Although we consider the highway portion of the US06 cycle appropriate for low power-to-weight vehicles, we also believe that the corresponding NMOG+NO X standards should be set at lower levels than for vehicles with emissions measured over the full US06 test. Our goal is to provide roughly equivalent stringency and avoid creating an ease-of-compliance incentive to produce vehicles in one group or the other. We have reviewed the MDV SFTP standards set by the California Air Resources Board staff and consider them appropriate in achieving this goal. These proposed standards are included in Table IV-16.

HDVs do not have SC03 emissions requirements under the current HDV standards. Manufacturers of HDVs have indicated that they expect the SC03 emissions to be consistently lower than either the US06 or the FTP emissions levels, and therefore the added SC03 testing burden may be unnecessary. We are therefore proposing that HDV manufacturers have the option to substitute the FTP emissions levels for the SC03 emissions results for purposes of compliance. However, we would retain the ability to determine the composite emissions using SC03 test results in confirmatory or in-use testing.

b. Enrichment Limitation for Spark-Ignition Engines

To prevent emissions from excessive enrichment in areas not fully encountered in the SFTP cycles, we are proposing limitations in the frequency and magnitude of enrichment episodes for spark-ignition HDVs. These limitations would be identical to those for light-duty vehicles discussed in detail in Section IV.A.4.c.

4. HDV Emissions Averaging, Banking, and Trading

This section describes our proposed approach for emissions credits related to exhaust emissions. See Section V.C for similar provisions that apply for evaporative emissions. We are proposing to continue the current practice of allowing manufacturers to satisfy standards through the averaging of emissions, as well as through the banking of emissions credits for later use and the trading of credits with others. There are a number of facets of this proposed Tier 3 ABT program for HDVs that would be different from the current program. First, instead of separate NMHC and NO X credits, manufacturers would earn combined NMOG+NO X credits, consistent with the form of the standards. Second, we are proposing to allow manufacturers to accrue a deficit in their credit balance. Deficits incurred in a model year may be carried forward for up to 3 model years, but must be made up with surplus credits after that to avoid noncompliance and possible penalties. Manufacturers would have to use any new credits to offset any shortfall before those credits can be traded or banked for additional model years. We are proposing that credits must be used within 5 years after they are earned, or otherwise be forfeited. The proposed 5/3-year credit/deficit life provisions are consistent with our proposed light-duty Tier 3 approach, the California LEV III program for MDVs, and EPA programs for controlling GHG emissions from light- and heavy-duty vehicles.

Third, as part of our proposal to require chassis certification of complete diesel HDVs, we are proposing to allow diesel HDVs to participate in this ABT program without restriction. Currently, they are not allowed to earn or use ABT credits. We are not proposing to restrict or adjust credit exchange between diesel and gasoline-fueled HDVs, consistent with our shift to combined NMOG+NO X standards that helps to ensure comparable stringency for these two engine types, and consistent also with the LEV III MDV program.

We are proposing that credits earned by a Tier 3 HDV may be used to demonstrate compliance with NMOG+NO X standards for any other Tier 3 HDV, regardless of size and without adjustment. This effectively allows manufacturers to plan a comprehensive HDV compliance strategy for their entire Class 2b and Class 3 product offering, by balancing credits so as to demonstrate compliance with the standards for both classes. HDV manufacturers are currently certifying their vehicles to existing standards without the use of NO X or NMHC credits, and the levels we are proposing for Tier 3 standards are not based on any assumption of credit transfers into Tier 3. As a result, we are not proposing provisions for converting pre-Tier 3 credits, should any exist at the time, into Tier 3 credits, including for use in the interim bins.

In the past we have set caps, called family emission limit (FEL) caps, on how high emissions can be for vehicles that use credits, regardless of how many credits might be available. Under our proposed bin structure, we believe that exhaust emission FEL caps are no longer relevant for Tier 3 HDVs, as every vehicle must meet whatever standards apply in the bin chosen for the vehicle by the manufacturer. (The bin standard becomes the effective FEL.) Indeed, because credits and deficits are calculated based on the difference between a manufacturer's fleet average emissions and the fleet average standards for a given model year, credits are not calculated for individual vehicle families at all. Under this proposed approach, the standards for NMOG and NO X in the highest available bin serve the purpose of the FEL caps in previous programs.

We are proposing no averaging program for the HDV SFTP program, because we believe that the bin structure and FTP-centered NMOG+NO X ABT program provide adequate flexibility for smooth program implementation, especially in light of our aim to have the FTP standards be the primary technology forcers. A separate ABT program for SFTP compliance would add substantial complexity with little benefit, and, by making it possible to demonstrate robust SFTP control on a vehicle that lacks commensurate FTP control, could prove at odds with the primary goal of the supplemental test for HDVs. However, we note that California's LEV III program does provide some flexibility in this matter, on a vehicle-for-vehicle basis rather than through use of emissions credits, and for this reason we request comment on the need for and considerations surrounding our granting similar flexibility for HDVsin Tier 3.

5. Feasibility of HDV Standards

The feasibility assessment, discussed in more detail in Chapter 1 of the draft RIA, recognizes that the proposed Tier 3 program is composed of several new requirements for Class 2b and 3 heavy-duty vehicles, which include primarily large gasoline and diesel pick-up trucks and vans with diverse application-specific designs. These proposed new exhaust emissions requirements include stringent NMOG+NO X and PM standards for the FTP and the newly proposed SFTP, that would as a whole require new emissions control strategies and hardware in order to achieve the proposed standards. The type of new hardware that would be required will vary depending on the specific application and emissions challenges. Additionally, gasoline and diesel vehicles would require different emissions control strategies and hardware. The level of stringency for the proposed SFTP NMOG+NO X standards would generally only require additional precise control of the engine parameters not necessitated in the past because of the lack of SFTP requirements. Similarly, the new PM standards on both the FTP and SFTP cycles would require more precise control of engine operation on gasoline vehicles while diesels already equipped with diesel particulate filters would require minimal changes. The new PM standards may also require that manufacturers consider the durability of their engines to the 150,000 miles useful life requirement with respect to engine wear resulting in increased oil consumption and potentially higher PM emissions.

In order to assess the technical feasibility of NMOG+NO X national fleet average FTP standards of 178 mg/mi for Class 2b vehicles and 247 mg/mi for Class 3 vehicles, we conducted an analysis of certification data for the HDVs certified in the 2010 and 2011 MYs. This analysis provided a baseline for the current HDV fleet emissions performance, as well as the emissions performance specific to the Class 2b and 3 vehicles. The emissions performance of each heavy-duty vehicle class specific to gasoline and diesel is shown in Table IV-17 below. It is important to note that the emissions results are only the 4,000 mile test point results and do not incorporate any deterioration which manufacturers must account for when certifying to a full useful life standard. Designs limiting the deterioration of emission control hardware are critical to meeting the emission standards at the proposed useful life of the Tier 3 program. Deterioration factors to adjust the values to the proposed Tier 3 useful life standard of 150,000 miles were not available however deterioration factors to adjust to 120,000 miles useful life are discussed in the RIA Chapter 1.

The analysis also reflects the importance of the NMOG+NO X standard approach where diesels and gasoline MDVs can balance their combined NMOG and NO X levels. Diesel vehicles in the analysis produce very low NMHC emissions (NMOG is not reported for diesels) but higher NO X emissions, while gasoline vehicles have opposite performance. The combined standard allows manufacturers to determine the proper balance of the unique emissions challenges of a diesel or gasoline vehicle.

Table IV-17—2010/11 Certification Test Results at 4,000 Miles Back to Top
NMHC NMOG NO X CO NMOG+NO X
Gasoline Class 2b 0.050 0.052 0.041 1.648 0.092
Class 3 0.080 0.083 0.073 2.373 0.156
NMHC+NO X            
Diesel Class 2b 0.037 0.138 0.195 0.174
Class 3 0.019 0.249 0.158 0.268
Combined Class 2b 0.043 0.026 0.089 0.922 0.133    
Combined Class 3 0.050 0.041 0.161 1.265 0.212    

Manufacturers typically certify their vehicles at emissions levels well below the numerical standards. This difference is referred to as “compliance margin” and is a result of manufacturers' efforts to address all the sources of variability that could occur during the certification or in-use testing processes and during in-use operation. These sources of variability include: Test-to-test variability, test location, build variation and manufacturing tolerances, vehicle operation (for example: Driving habits, ambient temperature, etc.), and the deleterious effects of sulfur and other oil and fuel contaminants. To meet the proposed NMOG+NO X standard of 178 mg/mi for Class 2b and 247 mg/mi for Class 3 vehicles and establish a compliance margin for these sources of variability, manufacturers will need to reduce their emission levels considerably from the levels indicated in this data set, particularly diesel vehicles.

However, as discussed above, these emission results do not include the expected emissions deterioration which would be determined by manufacturers during development and certification testing. Therefore, manufacturers would need to further reduce emissions levels in anticipation of the unavoidable emissions deterioration that will occur during the useful life of the vehicle. Further, deterioration is a function of several factors, but it is predominantly due to emissions control hardware thermal exposure (high temperatures), which is typically a significant issue on vehicles used for performing work like Class 2b and 3 vehicles.

We also expect that the 2011 heavy-duty GHG rule will present new challenges to manufacturers' emissions performance goals as vehicles begin to use new engines designed to meet the new GHG requirements. [274] Some of these new technologies may result in emissions challenges that are specific to certain operating conditions. For example, downsized gasoline engines will likely have improved FTP exhaust emissions but have increased challenge with the high-load SFTP requirements. Diesel-fueled vehicles may need to carefully balance engine controls which reduce GHG emissions but can increase criteria emissions (NO X).

With regard to the ability of the heavy-duty fleet to meet the proposed PM standards for the FTP and the SFTP, we based our conclusions on some testing of current HDGVs and the PM performance of the existing light-duty fleet with similar engines. Testing of two HDGVs with the highest sales volume (Ford F250 and Chevrolet Silverado 2500), albeit not aged to full useful life, confirmed that they have similar PM emissions levels as the light-duty counterparts and therefore also meet the proposed standards for both the Class 2b and Class 3 configurations. Data from light-duty gasoline vehicles with similar or common engines with their heavy-duty “sister” vehicle models demonstrates that these vehicles are currently meeting the proposed Tier 3 FTP PM standards at the Tier 2 useful life mileage of 120,000 miles. Heavy-duty diesel vehicles all are equipped with DPFs and have no challenges meeting the FTP or SFTP PM standards being proposed for Tier 3.

The SFTP test data from the same two heavy-duty vehicles described above indicates that gasoline vehicles can achieve the proposed standards for SFTP NMOG+NO X and PM. Since heavy-duty vehicles are not currently required to comply with any of the SFTP requirements, manufacturers have not focused on improving the emissions performance specifically over the SFTP cycles (US06 and SC03). Therefore, although the limited testing results had a high degree of variability, several tests met the proposed PM standards for the high power-to-weight Class 2b vehicles. Consistent with light-duty, vehicles that are demonstrating high PM on the US06 would need to control enrichment and oil consumption from engine wear. Manufacturers have confirmed that they have been implementing product changes to reduce oil consumption to address both customer satisfaction issues and to reduce cost of vehicle ownership.

Given the technologies likely to be applied to meet the proposed HDV exhaust emissions standards, discussed below, we consider the lead time available before the standards take effect under all of the proposed alternatives to be sufficient. HDV manufacturers are already adopting some of the complying technologies, especially for their light-duty vehicles, and these can readily be adapted for heavy-duty applications. In addition, manufacturers have already begun developing these technologies for HDVs, including diesels, in response to California's recently adopted LEV III MDV standards which begin to take effect in the 2015 model year. Finally, as described above in Sections IV.B.2, IV.B.3, and IV.B.4, our proposed program incorporates a number of phase-in and alternative compliance provisions that would ease the transition to final standards without disrupting HD pickup and van product redesign cycles. Among these is an alternative phase-in that starts mandatory standards in model year 2019. We invite comment on our conclusions relating to the feasibility of the proposed program in the lead time we are proposing.

We are not proposing relaxed standards for in-use testing of Tier 3 HDVs because we do not believe additional flexibility provisions are needed to successfully implement the new emission control technologies in the proposed timeframe. However, we note that the LEV III program provides such standards for PM, and also for NMOG+NO X in the lower-emissions MDV bins (those at or below Bin 250 and Bin 400, for Class 2b and Class 3 vehicles, respectively), and we are taking comment on the need to do so in Tier 3 as well.

We also note that the need for NMOG+NO X in-use testing standards is further mitigated by our proposed structuring of the NMOG+NO X standards as a declining fleet average with deficit and credit banking provisions. These provisions provide substantial flexibility to manufacturers in introducing any new NMOG or NO X control technologies for which long-term durability is not yet proven. Manufacturers can place any vehicles for which they have in-use performance concerns in a higher bin, and this is facilitated by the fact that, unlike LEV III, our Tier 3 proposal does not target sales volumes for any individual bins. Comments supporting relaxed in-use NMOG+NO X standards should therefore address why, in the absence of these standards, the proposed declining fleet average standard is not feasible in one or more model years.

Commenters on this issue are asked to also address the applicable model years for any such in-use testing standards. The LEV III MDV program has four different applicability periods based on a combination of specific model years listed in the regulations (up to 2020) and a set number of model years (two or five) after a test group is first certified. Comments are requested on whether it might be preferable to adopt a simpler approach in Tier 3, such as making in-use testing standards available in the model years in which standards are phasing in, that is, through model year 2021.

i. Technologies Likely To Be Applied

The technologies expected to be applied to vehicles to meet the lower proposed standards levels would address the emissions control system's ability to control emissions during cold start. Current vehicle emissions control systems depend on the time it takes for the catalyst to light-off, which is typically defined as the catalyst reaching a temperature of 250 °C. While the specific emissions challenge is somewhat different for gasoline engines than for diesel engines, achieving the necessary temperatures in the catalysts is a common challenge. In order to improve catalyst light-off, the manufacturers would likely add technologies that provide heat from combustion more readily to the catalyst or improve the catalyst efficiency at lower temperatures. These technologies could include calibration changes, thermal management, close-coupled catalysts, catalyst PGM loading, and possibly secondary air injection. In some cases, where the catalyst light-off response and efficiency are not enough to address the cold start emissions, hydrocarbon adsorbers may be applied to trap hydrocarbons until such time that the catalyst is lit-off. Note that with the exception of hydrocarbon adsorbers each of these technologies addresses both NMOG and NO X performance. Key potential technologies are described in greater detail below.

  • Engine Control Calibration Changes—These include changes to retard spark and/or adjust air/fuel mixtures such that more combustion heat is created during the cold start on gasoline engines. Diesel engines may use unique injection timing strategies or other available engine control parameters. Engine calibration changes can affect NMOG, NO X and PM emissions.
  • Thermal Management—This technology includes all design attributes meant to conduct the combustion heat into the catalyst with minimal cooling on both gasoline and diesel engines. This includes insulating the exhaust piping between the engine and the catalyst, reducing the wetted area of the exhaust path and/or reducing the thermal mass of the exhaust system. Close-coupling of catalysts (packaging the catalysts as close to the head of the engine as possible to mitigate the cooling effects of longer exhaust piping) can also be effective, but is more difficult to employ than in light-duty applications because of durability concerns with highly loaded operation and the potential increase in fuel consumption to protect the catalyst from high temperatures.
  • Catalyst PGM Loading—Additional Platinum Group Metal (PGM) loading in the catalyst provides a greater number of sites to catalyze emissions and addresses NMOG, NO X and PM emissions.
  • Selective Catalytic Reduction Optimization—Diesel applications would need to continue to refine this NO X emissions control strategy through improved hardware design and implementation in vehicle applications. Additional engineering enhancements in the control of the SCR system and related processes would also help reduce emissions levels.

6. Other HDV Provisions

a. HDV Useful Life

Currently the HDV regulatory useful life, the period of use or time during which emissions standards apply, is 120,000 miles or 11 years, whichever occurs first (40 CFR 86.1805-4). For Tier 3 vehicle criteria emissions we are proposing to extend the useful life to 150,000 miles or 15 years, whichever occurs first. This change would better reflect the improvements in vehicle durability and longevity that have occurred in the several years since the 120,000 mile useful life was established, and would maintain consistency with the LEV III MDV program and with our Tier 3 program for large LDTs, for which the same useful life period has been proposed. California's LEV III staff paper included a discussion of the feasibility of this longer useful life based on experience with it in the PZEV element of the ZEV mandate. [275]

We are proposing that the new useful life requirement apply to Tier 3 HDVs in all bins except those designated as interim bins, consistent with the purpose of the interim bins to provide for limited carry-over of pre-Tier 3 vehicle designs during the phase-in period. Although the percentage application in each year will therefore depend on each manufacturer's fleet binning strategy, the declining NMOG+ NO X fleet average standard would ensure a robust phase-in of the new useful life requirement over the 2018-2022 model years, such that it is expected to be about 50 percent in 2018, and necessarily reaches 100 percent by 2022 when the interim bins are no longer available. For those manufacturers choosing to certify to the voluntary standards, the new useful life will apply even earlier, in 2016 or 2017. For manufacturers choosing the alternative percent-of-sales NMOG+ NO X alternative, we are proposing that the new useful life requirement apply to all HDVs counted toward the phase-in requirement, resulting in a generally equivalent useful life phase-in rate to that of the primary approach. See Section IV.D.4.b for further discussion of useful life with regard to GHG standards. We are also proposing that manufacturers may optionally retain the 120,000 mile/11 year useful life for PM on interim Tier 3 vehicles that are not phased in to the Tier 3 p.m. standards.

b. Heavy-Duty Alternative Fuel Vehicles

As in the proposed light-duty program, we are proposing that manufacturers demonstrate heavy-duty flex fuel vehicle (FFV) and dual-fuel vehicle compliance with both the FTP and the SFTP emissions standards when operating on both the conventional petroleum-derived fuel and the alternative fuel. Dedicated alternative fuel vehicles would demonstrate compliance with both the FTP and SFTP emission standards while operating on the alternative fuel. For all of these vehicles, this includes the requirement to meet FTP emissions standards when conducting fuel consumption and GHG emissions testing, and also to meet the FTP and highway test requirements at high altitudes (see Sections IV.B.6.e and f). Because FFVs can operate on various combinations of their conventional and alternative fuel, the emissions requirements apply to operation at any mix of the fuels achievable in the fuel tank with commercially available fuels, including for compliance at high altitudes, even though the required demonstration of compliance is limited to the conventional and alternative fuels designated for certification testing.

c. Optional Certification for Vehicles Above 14,000 lbs GVWR

The HD greenhouse gas (GHG) standards include a provision for optional certification of complete gasoline-fueled HDVs above 14,000 lbs GVWR to g/mi GHG standards on the chassis test. [276] Because that rule does not change the requirements for certification to criteria pollutant standards, manufacturers choosing this option would have to certify the vehicle for GHGs, but use installed engines certified to g/hp-hr standards for all other emissions. We believe it may provide benefits for both the environment and the manufacturers to allow consistent certification of these vehicles on a chassis test for all emissions, treating any vehicles so certified in the same way as Class 3 vehicles, including applicable standards, inclusion into fleet average calculations, test fuel, useful life, and the application of Tier 3 evaporative emissions requirements.

We request comment on the value of, and any issues concerning, our providing such an option to manufacturers of both gasoline and diesel-fueled HDVs above 14,000 lbs GVWR, including the applicability of the existing chassis test cycles for these larger trucks. Comment is also requested on whether manufacturers of such vehicles that are certified to a Final Tier 3 bin should be allowed to exclude them from the fleet average NMOG+NO X calculation, as a means of encouraging the production of such low-emissions vehicles by not penalizing them for having emissions somewhat above the Class 3 fleet average. Finally, we also request comment on whether any such option for diesel-fueled HDVs should extend to GHG emissions as well.

d. Existing Provision To Waive HDV PM Testing

EPA's existing program includes a provision for manufacturers to waive measurement of PM emissions in non-diesel heavy-duty vehicle emissions testing. We are proposing to eliminate this provision. We believe that the PM standards we are proposing for these vehicles are of sufficient stringency that routine waiver of testing would not be appropriate. The California Air Resources Board LEV III program reflects this view. We do not expect this change to be onerous for manufacturers, as the number of heavy-duty vehicle families is not large. Even so, we request comment on alternative approaches, such as that being proposed for light-duty vehicles, involving measuring PM on a subset of families each year. We request comment on any other potential situations in which waiver of PM measurement may be appropriate. Note that we are proposing to waive the PM emissions measurement requirement for small manufacturers, for reasons explained in Section IV.E.

e. Meeting HDV Standards in Fuel Consumption and GHG Emissions Testing

As with the proposed light-duty Tier 3 program, we are proposing that HDVs must meet the FTP bin standards when tested over both the city and highway test cycles. We do not believe this adds a very significant test burden as vehicle emissions are already required to be measured when these tests are run for GHG and fuel consumption determinations. Nor do we believe that this proposed requirement is design forcing. Rather, we are proposing this requirement to ensure that test vehicle calibrations are not set by manufacturers to minimize fuel consumption and GHG emissions, at the expense of high criteria pollutant emissions. Considering the additional work involved in measuring PM emissions and the reduced likelihood of high PM emissions on the highway test, we are not proposing that PM emissions testing be included in this requirement, but we ask for comment on whether we should instead include them, but waive the requirement to measure them in manufacturers' certification testing, to ensure that any unforeseen PM control technology challenges in highway driving conditions are addressed in the future.

f. HDV Altitude Requirements

As in the past, we intend that HDV Tier 3 standards result in emissions controls that are effective over a full range of operating altitudes. We do not anticipate that the proposed FTP bin standards would require the use of special hardware to achieve compliance at altitude. We also do not believe that adjustment to the FTP standards is appropriate for HDV testing at altitude, as we expect that manufacturers would be able to meet these standards with adequate compliance margin to cover this test condition. As in the proposed light-duty program, and for the same reasons, we are not proposing to require that HDVs comply with SFTP standards at altitude.

C. Evaporative Emissions Standards and Onboard Diagnostic System Requirements

Gasoline vapor emissions from vehicle fuel systems, which are a mixture of hydrocarbon compounds, occur when a vehicle is in operation, when it is parked, and when it is being refueled. These evaporative emissions from gasoline-powered vehicles which occur on a daily basis are primarily functions of temperature, fuel vapor pressure, and activity. EPA first instituted evaporative emissions standards in the early 1970s to address hydrocarbon emissions when vehicles are parked after being driven. These are commonly referred to as hot soak and diurnal emissions. Over the subsequent years the test procedures have been modified and improved, the standards have been revised to be more stringent, and we have addressed emissions which arose from new fuel system designs by establishing new requirements such as running loss emission standards and test procedure provisions to address resting losses (e.g., permeation). Onboard refueling vapor recovery (ORVR) requirements for control of refueling emissions first began to phase-in for light-duty vehicles (LDVs) and light-duty trucks (LDTs) in the 1998 MY. These were later expanded to cover medium-duty passenger vehicles (MDPVs) and some heavy-duty gasoline vehicles (HDGVs). Even though evaporative and refueling emission control systems have been in place for most of these vehicles for many years, evaporative emissions still contribute 30-40 percent of the on-road mobile source hydrocarbon inventory. These fuel vapor emissions are ozone and PM precursors, and also contain air toxics such as benzene. Even though there are mature evaporative emission control programs in place, further hydrocarbon emission reductions are needed and can be achieved from highway motor vehicles. Vehicles demonstrating near zero fuel vapor emissions have been certified by CARB and a limited number are in-use in California and other states. Furthermore, test programs conducted by the Coordinating Research Council and EPA show that attention is needed to insure better in-use performance of current evaporative control systems. Cost effective hydrocarbon emission reductions can be achieved through new vehicle standards and improved focus on in-use performance.

This section discusses the proposed vehicle-related evaporative emission standards and related provisions for LDVs, LDTs, MDPVs, and HDGVs. As discussed below, we are proposing more stringent standards that would apply for the 2- and 3-day evaporative emissions tests, a new canister bleed test and emission standard, a new certification test fuel specification, [277] and a new fuel/evaporative system leak test procedure and emission standard. We are also proposing refueling emission controls for a portion of HDGVs over 10,000 lbs gross vehicle weight rating (GVWR). This section also describes proposed phase-in flexibilities, credit and allowance programs, and seeks comment on several other issues related to evaporative emissions control.

The proposed evaporative emissions program has six basic elements: (1) The Tier 3 evaporative emission phase-in program (MY 2018-2022+), (2) the early allowance/credit program (MY 2015-2016), (3) the transitional program (MY 2017), (4) requirements for HDGVs including ORVR, (5) a leak emission standard and test procedures, and (6) other miscellaneous proposed changes and areas for comment.

In this proposed rule, the vehicle classifications, LDVs, LDTs, MDPVs, and HDGVs, would remain unchanged from Tier 2. For purposes of this discussion of the proposed Tier 3 evaporative emissions program, the vehicle standards can be further placed in four categories: (1) “Zero evaporative emission” PZEV vehicles certified by CARB as part of the ZEV program, (2) vehicles certified by CARB to meet LEV III evaporative emission program requirements on CARB certification fuel (7 RVP E10), (3) vehicles meeting the proposed Tier 3 evaporative emissions program requirements using the proposed certification test fuel (9 RVP E15), and (4) transitional vehicles meeting current EPA evaporative requirements on Tier 2 certification fuel (9 RVP E0). 278 279 For ease of reference these four categories may be referred to as PZEV evap, LEV III evap, Tier 3 evap, and Tier 2 evap in this section. [280]

1. Tier 3 Evaporative Emission Standards

a. Proposed Standards

This proposal for evaporative emissions builds on previous EPA requirements as well as CARB's recent LEV III rule which starts phasing in with the 2018 MY. This proposal facilitates a national program for vehicle evaporative emissions control. We believe the proposed program is appropriate since it would require new evaporative emissions control technology in new vehicles while also achieving improved in-use system performance.

This section describes proposed requirements for LDVs, LDTs, MDPVs, and HDGVs. The proposal includes more stringent emission standards for hot soak plus diurnal emissions (2- and 3-day tests), plus a new canister bleed standard and testing requirement for measuring emissions from the fuel tank and the evaporative canister. The proposal also introduces a limited corporate averaging program for demonstrating compliance with the hot soak plus diurnal standards. We are proposing a phase-in of the Tier 3 evaporative emission standards that would begin with the 2017 MY, with incentives for manufacturers to introduce Tier 3 compliant vehicles earlier or in greater numbers than required. The proposal includes revised provisions for demonstrating compliance with the evaporative emission standards at high altitude. See Section IV.C.3 for additional provisions for the HDGV category.

i. Hot Soak Plus Diurnal Standards

Previous hot soak and diurnal emission controls have dramatically reduced vehicle evaporative emissions over the past thirty plus years. However, some emissions remain and control technology is available to capture these emissions in a cost effective manner. Toward that end, EPA is proposing more stringent hot soak plus diurnal evaporative emission standards for the Tier 3 program. The standards apply to both the 2-day and 3-day evaporative emission test requirements.

The standards are designed to bring into the broader motor vehicle fleet the “zero evap” technology used by the manufacturers in their partial zero emission vehicles (PZEVs). Manufacturers developed this “zero evap” technology as part of their response to meeting the requirements of the CARB Zero Emission Vehicle (ZEV) program. This program, which is in effect in 11 other states, allows manufacturers to meet their ZEV mandate percentages (totally or in-part) by the use of vehicles which among other characteristics have very low fuel vapor emissions.

The standard levels presented in Table IV-18 are designed primarily to accommodate what is often referred to as new vehicle background hydrocarbon emissions. These emissions arise from the off-gassing of volatile hydrocarbons from plastics, rubbers, and other polymers found in new vehicles (e.g., new tires, interiors, seats, fuel system components, paints, and adhesives). In the field these emissions decrease over time as the vehicle ages, but this cannot necessarily be replicated in the time that manufacturers normally allocate for vehicle certification. In the past manufacturers have employed techniques such as vehicle baking (discussed below) to accelerate the rate of this off-gassing, and until recently it has not been a major consideration for certification.

In the past EPA has set relatively uniform (but not identical) evaporative emission standards for LDVs and LDTs and somewhat higher values for HDGVs. The proposed hot soak plus diurnal emission standards presented in Table IV-18 are somewhat higher as vehicles get larger in weight and physical size. This is because in general the vehicles have higher levels of non-fuel background emissions as they get larger. As mentioned above, the standards, which are approximately a 50 percent reduction from the existing hot soak plus diurnal standards, are intended primarily to accommodate non-fuel background emissions. Thus, the technology focus for the proposed Tier 3 evaporative emission standards is for vehicles to have essentially zero fuel vapor emissions.

As described in more detail in Section IV.C.2 below, EPA is proposing a program that would allow manufacturers to demonstrate compliance with the proposed hot soak plus diurnal evaporative emission standards using averaging concepts. Under the proposal, manufacturers may comply by averaging within each of the four vehicle categories but for the reasons discussed below, may not rely on averaging across categories. The technical approaches to meeting the proposed standards are discussed in Section IV.C.2. EPA is not proposing any changes to the existing light-duty running loss or refueling emission standards with the Tier 3 proposal, with the exception of the certification test fuel requirement.

Table IV-18—Proposed Evaporative Emission Standards (g/test) a b c Back to Top
Vehicle category Highest hot soak +diurnal level (over both 2-day and 3-day diurnal tests)
aThe standards are in grams of hydrocarbons as measured by flame ionization detector during the diurnal and hot soak emission tests in the enclosure known as the sealed housing for evaporative determination (SHED).
bNote that the proposed standards are the same for both tests; current standards are slightly different for the 2- and 3-day tests.
cVehicle categories are the same as in EPA's Tier 2 final rule; see 65 FR 6698, February 10, 2000.
LDV, LDT1 0.300
LDT2 0.400
LDT3, LDT4, MDPV 0.500
HDGVs 0.600

ii. Canister Bleed Emission Standard

In addition to more stringent hot soak plus diurnal standards, EPA is proposing a new canister bleed emission test and standard as part of the Tier 3 program. The proposed bleed test procedure is described in Section IV.C.4.a., below. The purpose of the new test and standard is to ensure that near-zero fuel vapor emissions are being emitted by vehicles from the fuel tank through the evaporative emission canister. Under this proposal, manufacturers would be required to measure diurnal emissions over the 2-day diurnal test procedure from just the fuel tank and the evaporative emission canister and comply with a 0.020 g/test standard for all LDVs, LDTs, and MDPVs and 0.030 g/test for HDGVs. The feasibility of this standard is discussed in Section IV.C.2.g.ii below. EPA is proposing not to apply the averaging program to this new bleed test standard as compliance is relatively straightforward and low in cost. Therefore, each evaporative/refueling emission family certified by manufacturers would need to demonstrate compliance with their respective standard. As discussed below, the canister bleed standard would not apply at high altitude. The canister bleed test and standard drives canister design elements such as total gasoline working capacity, internal architecture, and the type of carbon used. Since the performance of the canister is also evaluated in the hot soak plus diurnal evaporative emissions sealed housing for evaporative determination (SHED) test we are proposing that the canister bleed emission standard not be included in the In-Use Verification Program but it must be met in use. We would not expect to have canister bleed specific family criteria for certification but the test would have to be completed and the standard met for each evaporative/refueling family including potentially twice if there were two canisters used. A deterioration factor would not be required, but as mentioned above, the standard would have to be met in-use and could be evaluated in EPA confirmatory testing.

iii. Early and Transitional Hot Soak Plus Diurnal Standard

As part of its LEV III program, CARB has included an alternative set of evaporative emission standards, referred to as Option 1 standards. These are shown in Table IV-19.

Table IV-19—CARB Option 1 Evaporative Emission Standards Back to Top
Vehicle category Highest hot soak + diurnal level (over both 2- and 3-day diurnal tests) (g/test) Running Loss (g/mile)
Vehicle SHED Rig SHED
Passenger Car 0.350 0.0 0.05
LDT ≤ 6,000 lbs GVWR 0.500 0.0 0.05
All other vehicles > 6,000 lbs GVWR 0.750 0.0 0.05

The Option 1 standards include evaporative emission standards (hot soak plus diurnal) that are slightly higher numerically than our proposed standards. Vehicles certified under this option may not use averaging in the CARB LEV III program because they basically represent the same evaporative emission standards as exist for PZEVs under CARBs ZEV program wherein averaging is not permitted. Option 1 also includes an additional test of the vehicle fuel system (rig test) that from an engineering perspective is practically more difficult to conduct than the bleed test discussed above and is intended to force manufacturers to demonstrate at certification that their stand alone (not in chassis) fuel/vapor control system designs have no (≤54 mg) fuel vapor emissions. EPA is not proposing that Option 1 be part of the long term Tier 3 evaporative emission program. While we see the merit of the rig test as an engineering design and development tool for the manufacturers, by its very nature, the rig SHED standard is not implementable as an enforceable standard. We believe that the hot soak plus diurnal SHED test and the canister bleed test will accomplish the same objective of keeping fuel vapor emissions to a minimum.

EPA believes most manufacturers will prefer to certify to the averaging based standards proposed by EPA (similar in stringency and program construct to CARB Option 2). However, because some manufacturers may have vehicle models meeting the CARB Option 1 standards and emission requirements now or in the near future, EPA is proposing that compliance with the CARB Option 1 standards would be an acceptable interim alternative to compliance with the proposed Tier 3 evaporative emission standards if the model is certified by CARB before the 2017 MY. EPA proposes that these vehicles could then be certified using carryover provisions through the 2019 MY. [281] As noted in the following sections, vehicles certified under this provision would count toward the phase-in percentage requirements and could earn allowances as discussed below, but the vehicles would not be eligible to earn or use credits for the evaporative emissions averaging program. Carryover vehicles would have to meet EPA leak emission standard to be counted toward the sales percentage requirements for 2018 and later model years.

b. Useful Life

Trends indicate that vehicle lifetimes are increasing. It is important that emission control systems be designed to meet requirements while vehicles are in use. As discussed in Section IV.A and IV.B of this proposal, along with the new emission standards, we are proposing a longer useful life of 150,000 miles/15 years, whichever comes first, for LDTs up to 6,000 lbs GVWR but over 3,750 lbs loaded vehicle weight (LVW) (LDT2s), all LDTs over 6,000 lbs GVWR (LDT3/4), MDPVs, and HDGVs between 8,501 and 14,000 lbs GVWR. The proposed longer useful life would also apply to certifications to the Tier 3 evaporative emission requirements. For an evaporative/refueling family certified to 150,000 miles/15 year useful life for evaporative emissions this useful life would also apply to the refueling, leak, and high altitude standards, where applicable when a family certifies to the Tier 3 evaporative emission requirements. All of these standards impact the fuel and vapor control systems and it is technologically consistent to require the same useful life for these standards because they all rely on the mechanical integrity, durability, and operational performance of the same components in the evaporative emissions control system.

Due to limitations in the CAA, for LDVs and for LDTs up to 6,000 lbs GVWR and at or below 3,750 lbs LVW (LDT1s), we are keeping the current useful life of 120,000 miles/10 years unless, as described in Section IV.A, a manufacturer elects alternative exhaust emission requirements that are associated with 150,000 mile/15 year useful life for these vehicles. For manufacturers that select those optional standards, the useful life of 150,000 miles/15 years would apply for all Tier3 evaporative emission standards including the hot soak plus diurnal emission standards, the refueling emission standard, and the leak standard because of the design and operating relationships between the engine, the fuel system, the evaporative control system and their various components.

During the early and transitional program periods and until the final year of the allowed phase-in period for the Tier 3 evaporative emission program (MY 2015-2022) the differences between the proposed exhaust and evaporative emission phase-in programs presents the possibility that in some cases a manufacturer could certify a model to the Tier 3 exhaust requirements but not necessarily to the Tier 3 evaporative emission requirements. [282] In those situations, we are proposing that a family could have a 150,000 miles/15 years useful life for exhaust emissions but maintain the current useful life for all of the evaporative and refueling emission standards. We also propose that during the phase-in period, if a family is certified to the Tier 3 evaporative emission requirements but not yet certified for Tier 3 exhaust emission requirements, then the useful life could be 150,000 miles/15 years for evaporative and refueling emissions standards but the current useful life for exhaust emissions, However, by the 2022 MY EPA proposes that the useful life for all of these requirements would be 150,000 miles/15 years for LDT2/3/4s, MDPVs, and HDGVs since by that model year all vehicles must be certified using Tier 3 certification fuel and test procedures and meet Tier 3 evaporative emission standards. [283]

OBD regulations call for the systems to operate effectively over the useful life of the vehicle. We are not proposing to change that requirement, but rather to clarify that during the early and transition years of the phase-in (MY 2015-2022), all of the OBD monitoring requirements have the same useful life as that for the exhaust emission standard except for the evaporative system leak monitoring requirement which has the same as that required for the evaporative and refueling emission standards control systems.

2. Evaporative Emissions Program Structure and Implementation Flexibilities

a. Percentage Phase-In Requirements

The proposed Tier 3 evaporative emission standards would be phased in over a period of six model years (MYs), including a transitional year in 2017. For MY 2017, except as discussed below, the requirement would apply to 40 percent of a manufacturer's combined sales of LDVs, LDT1s, and LDT2s. To be consistent with the start date for new exhaust standards affecting these vehicles, the phase-in requirements would not include vehicles over 6,000 lbs GVWR until the 2018 MY. For the 2018-2019 MYs, the requirement would apply to 60 percent of a manufacturer's sales of all LDVs, LDTs, MDPVs, and HDGVs. This would increase to 80 percent for MYs 2020 and 2021 and by MY 2022 it would apply to 100 percent of sales in these four categories. Beginning in MY 2018 any vehicle included in the percentage projection, except vehicles that had earned allowances would have to meet the leak emission standard.

Our proposal for MY 2017 has two options and we are seeking comment on a third option. The first, which we are calling the “percentage” option, would require that 40 percent of a manufacturer' s LDVs, LDT1s, and LDT2s sold outside of California and the states that have adopted the CARB ZEV or LEV III programs must meet the Tier 3 evaporative emission requirements on average. The second which we are calling the “PZEV zero evap only” option, would require a manufacturer to sell all of the LDVs, LDT1s, and LDT2s certified with CARB as meeting the PZEV evaporative emission requirements (zero evap) in MY 2017 throughout all of the U.S. and not to offer for sale any non-PZEV zero evap version of those vehicles in any state whose vehicles are covered by the Tier 3 evaporative emission standards. Thus, this would apply to sales in any state except for California and states that have adopted the CARB ZEV or LEV III programs under section 177 of the Clean Air Act. Under this second option, no tracking of sales or end of year compliance calculation would be required. Some manufacturers may find this option attractive, as they have more limited product offerings and find tracking of production and sales more difficult.

The basic goal of the 2017 MY program is to provide evaporative emission reductions benefits in the other states which are similar to those expected in California and the states which adopted LEV III under section 177 of the Clean Air Act. Due to model phase-out and phase-in issues related to current and future products, some manufacturers have indicated that increasing production of Tier 3 evaporative emission compliant vehicles for the 2017 MY to meet the 40 percent value discussed above could be difficult and costly. To address this issue, we are asking for comment on a third option: decreasing this value from 40 percent to 20 percent but requiring that these same vehicles also meet the leak emission standard in the 2017 MY. This approach has the potential to address the transition issue and EPA believes that the leak standard will provide evaporative emission reduction benefits equal to or greater than the Tier 3 evaporative emission standards. Thus, under this approach, the manufacturers' product transition concerns could be addressed and the overall evaporative emission reductions would still be achieved for 2017 MY vehicles. As discussed below, beginning in the 2018 MY, a Tier 3 compliant vehicle must also meet the leak emission standard. This option would be effective only in the 2017 MY. EPA asks for comment on whether this option should require the leak emission standard to apply to the same 20 percent of vehicles that are complying with the Tier 3 evaporative emission requirements, or whether this option should allow manufacturers the flexibility to meet some or all of the 20 percent leak emission standard requirement with vehicles not yet compliant with the Tier 3 evaporative requirements.

At the time of certification, manufacturers would identify which families would be included in their Tier 3 evaporative emission percentage calculations (this could be families above or below the individual Tier 3 evaporative emission standards for the given class of vehicles as well as vehicles meeting CARB's Option 1 standards) and could also include earned allowances as discussed below. They would use projected sales information for these families plus allowances as desired and available, to show how they expect to meet the phase-in percentages for the model year of interest. At the end of the model year they would be expected to show that the percentages were met and if not they would either use additional allowances or bring more vehicle families into the calculation.

Requiring a showing at the time of certification based on projected sales requires due diligence by the manufacturers and EPA, but the Tier 3 evaporative emissions program allows for fleet averaging, so a validation or “truing up” of these sales projections is necessary for determining compliance with the requirements of the standard. This is discussed in Sections IV.C.2.c.and d. As discussed further below, validated sales information would also be used for earning early allowances and to show compliance with the alternative phase-in schedule approach.

For these purposes, vehicles included in the phase-in percentage could be: (1) Families which certified to CARB LEV III requirements in MYs 2015 and 2016 (CARB Option 1), (2) families certified to meet Tier 3 evaporative emission requirements, and (3) vehicles from the early allowance program. However, beginning in the 2017 MY, any new evaporative/refueling emission family certifications would have to meet the proposed EPA Tier 3 certification requirements for both test procedure and certification test fuel for the evaporative and refueling emission standards. The leak emission standard would apply in the 2018 MY. Furthermore, assuming other regulatory provisions related to carryover of emissions data are met, 2015-2016 MY CARB evaporative emissions certifications could be carried over until the end of the 2019 MY and included as compliant vehicles within the program if they met the leak emission standard.

The phase-in percentages for MYs 2017 through 2022 reflect a percentage phase-in concept applied successfully by EPA in previous rules involving evaporative and refueling emissions control. The proposed phase-in provides an appropriate balance between the needed emission reductions and time for the manufacturers to make an orderly transition to the new technology on such a broad scale. The higher initial percentage here is appropriate because the expected evaporative emission control technology is already being used to varying degrees by 16 manufacturers on over 50 vehicle models today and is projected to gain even deeper penetration by 2017 due to the partial zero emission vehicles (PZEV) option within the CARB ZEV program.

As a flexibility, we are proposing to allow manufacturers to demonstrate compliance with the phase-in percentage requirements of the evaporative emissions program by using a manufacturer-determined alternative phase-in percentage scheme. Under this approach, before the 2018 MY, manufacturers would have to present a plan to EPA which demonstrates that the sum of the product of a weighting factor and the percentages of their U.S. vehicle sales for each model year from 2018 through 2022 is greater than or equal to 1040. The 1040 value is equal to the sum of the product of the weighting factors and the percentage requirements for MYs 2018 through 2022, calculated in the following manner: [(5)(2018MY %)+4(2019MY %)+3(2020MY %)+2(2021MY %)+(1)(2022MY %)]. This would allow manufacturers to use a phase-in more consistent with product plans which may call for a lower percentage in the early years or to benefit from producing and selling more than the minimum percentage of compliant vehicles early. This flexibility could also be helpful in the event that a manufacturer elects to put some vehicles on a different phase-in schedule for meeting Tier 3 exhaust and evaporative emission standards. As explained further below, any allowances earned could be counted toward compliance with the 1040 value. Within this proposed flexibility EPA asks for comment in three areas. First, we seek comment on the need for and value of this alternative phase-in percentage flexibility option. Second, we did not include the 2017 MY in this flexibility because we believe that the PZEV zero evap nationwide option, the use of any earned allowances, and the ability to have a deficit in a given year are sufficient. However, we ask for comment on including the 2017 MY “percentage” option in this flexibility (both the 40 and 20 percent approaches discussed above). If after comment the 40 percent option from the 2017 MY is included in the final rule, the sum of the percentages would include an additional 240= (6)(40) for a total; of 1280; the equation above would add a term of (6)(2017MY %). Similarly, we ask for comment on whether the 20 percent option from the 2017 MY should be included in the alternative phase-in approach. If it is included in the final rule, the sum of the percentages would include an additional 120= (6)(20) for a total; of 1160; the equation above would add a term of (6)(2017MY %).

b. Early Allowance Program

We are proposing incentives for early introduction of vehicles compliant with the Tier 3 evaporative emission regulations. Manufacturers could take advantage of these incentives prior to MY 2018 by selling vehicles that meet the Tier 3 evaporative emission regulations earlier than required or in greater numbers than required.

As described below, manufacturers could earn “allowances” for selling any vehicle certified to the proposed Tier 3 evaporative emission regulations earlier than required. The vehicles could be LDVs, LDTs, MDPVs, or HDGVs. Specifically these include the following: (1) For MYs 2015 and 2016, any LDVs and LDTs meeting the Tier 3 evaporative emission regulations and sold outside of California and the states that have adopted CARB's ZEV or LEV III programs, (2) for MYs 2015-2017, any MDPV or HDGV meeting the Tier 3 evaporative emission regulations early and sold in any state, (3) for MY 2017, any LDT3/4 meeting the Tier 3 evaporative emission regulations and sold outside of California and the states that have adopted CARB's LEV III or ZEV programs, and (4) for MYs 2015-2017, any HDGV between 10,001 and 14,000 lbs GVWR meeting the refueling emissions regulations and sold outside of California and the states that have adopted CARB's LEV III or ZEV programs.

In order to demonstrate compliance with the proposed Tier 3 evaporative emission regulations, the vehicles could be certified to either the proposed Tier 3 evaporative emission standards or CARB's PZEV zero evaporative emission and useful life requirements. Vehicles generating allowances would have to meet the proposed evaporative emission standards (CARB Option 1 or EPA Tier 3), the high altitude evaporative emission standard, the canister bleed standard as well as the refueling emission standards. Manufacturers would earn one allowance for each qualifying vehicle sold. Manufacturers can use these allowances in MY 2017 through 2022 to help demonstrate compliance with the phase-in percentage requirements and fleet average evaporative emission standards for those years.

Allowances would be used in the compliance determination in the following manner. Vehicles qualifying for allowances could be used in the fleet average evaporative emission standard calculation for any year during the phase-in. This would apply to the primary phase-in and alternative phase-in programs. Allowance vehicles would be entered into the compliance calculation with an emission value equivalent to the evaporative emission standard for their vehicle category from Table IV-18 even if it was certified to CARB Option 1 standards (Table IV-19). For the percent phase-in requirement in either the primary or alternative phase-in schemes, allowance vehicles would count for one vehicle for each allowance used within their vehicle category. For the primary scheme this would be counted as one vehicle, but for the alternative phase-in option the value would be multiplied by the weighting factor (5 for 2018, 4 for 2019, 3 for 2020, etc). Within the alternative phase-in scheme the manufacturer would be limited to using these early allowances for no more than 10 percentage points of the phase-in requirements in any given model year (e.g., MYs 2018-2022). EPA believes this limitation is appropriate. Early introduction of “zero evap” technology should be encouraged, but not necessarily at the expense of its widespread use across the various vehicle categories as the phase-in progresses. The proposed allowances are designed primarily to facilitate manufacturer transition during the program phase-in. As such, we propose that they could not be traded between manufacturers and unused allowances would expire after the 2022 MY.

An example here may be helpful in demonstrating how the proposed concept would work. Take a hypothetical manufacturer who earned 10,000 allowances in 2015 and 2016 and sells 100,000 units per year. In 2018, the manufacturer would have a phase-in requirement of 60 percent or 60,000 vehicles. For the primary phase-in option the manufacturer could use part or all of its allowances in 2018. For the alternative phase-in scheme the proposed regulations would limit the use of allowances to 10 percentage points at the 60 percent. Without a multiplier this would require the use of all 10,000 allowances in 2018, but with the proposed multiplier only 2,000 allowances would be needed to reach the 10 percentage point maximum. Using a similar calculus, the manufacturer could use another 10 percentage points in 2019, but it would require 2,500 allowances since the multiplier is 4. The number of allowances to reach 10 percentage points would increase each year as the multiplier decreased.

For the MY 2017, manufacturers choosing EPA's proposed “percentage” option (see Section IV.C.2.a) could earn allowances for sales of LDT3s, LDT4s, MDPVs, and HDGVs that meet the proposed Tier 3 evaporative emission standards and other related requirements assuming their LDV, LDT1/2 sales meet the 40 percent requirement. Similarly, manufacturers choosing EPA's proposed “PZEV zero evap only” option could earn allowances in MY 2017 for LDT3/4s, MDPVs, and HDGVs that meet the CARB Option 1 evaporative emission standards and related requirements. For both the “percentage” and “PZEV zero evap only” options for the 2017 model year, to avoid double counting, the allowances would be earned only for those vehicles sold outside of California and the states that have adopted CARB's LEV III/ZEV program requirements. Vehicles earning allowances could either be vehicles certified to the Tier 3 evaporative emission standards or vehicles certified using carryover data from the CARB PZEV zero evaporative emission requirements from the 2015 or 2016 MYs. Since credits and allowances serve primarily the same purpose and allowing for splits of allowances/credits greatly complicates program implementation, we are proposing that manufacturers could only earn allowances in MYs 2015-2017 for any qualifying LDT3s, LDT4s, MDPVs, and HDGVs since these vehicles are not covered by the proposed Tier 3 standards until the 2018 MY. EPA asks for comment on whether this opportunity to earn allowances coupled with the aforementioned restriction on their use is the appropriate balance.

c. Evaporative Emissions ABT

Throughout EPA's programs for mobile source emission controls, we have often included emission averaging programs for exhaust emissions. An emission averaging program is an important factor we take into consideration in setting emission standards under the Clean Air Act. An emission averaging program can reduce the cost and improve the technological feasibility of achieving standards, helping to ensure the standards achieve the greatest achievable reductions, considering cost and other relevant factors, in a time frame that is earlier than might otherwise be possible. Manufacturers gain flexibility in product planning and the opportunity for a more cost-effective introduction of product lines meeting a new standard. Emission averaging programs also create an incentive for the early introduction of new technology, which allows certain emission families to act as leaders for new technology. This can help provide valuable information to manufacturers on the technology before they apply the technology throughout their product line.

These programs generally involve averaging and banking, and sometimes trading (ABT). Averaging allows a manufacturer to certify one or more families at emission levels above the applicable emission standards as long as the increased emissions are offset by one or more families certified below the applicable standards. These are referred to as family emission limits (FELs). The over-complying families generate credits that are used by the under-complying families. Compliance is determined on a total mass emissions basis to account for differences in production volume, and on other factors as necessary. The average of all emissions for a particular manufacturer's production within category must be at or below the level of the applicable emission standards. Banking allows a manufacturer to generate emission credits and bank them for future use in its own averaging program in later years. Trading allows a manufacturer to sell credits or obtain credits from another manufacturer.

EPA is proposing an emissions ABT program for the Tier 3 hot soak plus diurnal evaporative emissions standards. This would be the EPA's first averaging program for evaporative emissions from light-duty or heavy-duty vehicles. It would not apply to the high altitude standard, the canister bleed standard or the leak emission standard because it is the low altitude “zero evap” hot soak plus diurnal standard which will drive the fundamental technology used to comply with all of these requirements. EPA is proposing to include trading of emission credits between manufacturers, but in past similar programs there have been very few trades. Incorporating trading within the program adds a significant degree of complexity, so we are seeking comment on the need for and value of including trading.

The evaporative emissions ABT program would start with the 2017 MY for the percentage option. The programs would continue for the 2018 MY and beyond and would not sunset, as does the allowance program. Vehicles generating averaging/banking credits in the 2017 MY or later would not be permitted to also generate allowances as this would be double counting.

A key element of an averaging program is the identification of the averaging sets. This sets the criteria for which emission families can be averaged for purposes of compliance as well as credit and deficit determinations. We are proposing four averaging sets and the applicable emission standard for each of the averaging sets as shown in Table IV-18. Except as noted in section d below, credit exchanges between averaging sets would not be permitted. Participation in averaging is voluntary since a manufacturer could elect to certify each family within the averaging set to its individual limit as if there was no averaging program.

An evaporative emission ABT includes two very distinct steps. The first is the determination of the credit/deficit status of each family relative to its applicable standard from Table IV-18. The second is the role of ABT in the overall compliance demonstration which will be discussed in Section IV.C.2.d which follows.

A manufacturer choosing to participate in the evaporative emissions ABT program would certify each emission family to an FEL. The FEL selected by the manufacturer becomes the emission standard for that emission family. As noted below, emission credits (or deficits) are based on the difference between the emission standard that applies (by vehicle category) and the FEL. The vehicles would have to meet the FEL for all emission testing.

We are proposing that the FELs selected by the manufacturer would have to be selected at 0.025 g/test increments above or below the applicable Tier 3 evaporative emission standards for each vehicle category. FELs could not be set any higher than 0.500 g/test for LDVs, 0.650 g/test for LDT1s and LDT2s, 0.900 g/test for LDT3s and LDT4s, 1.000 g/test for MDPVs, 1.4 g/test for HDGVs at or below 14,000 lbs GVWR, and 1.9 g/test for those above 14,000 lbs GVWR, respectively. These FEL caps are the 3-day hot soak plus diurnal emission standards currently applicable under EPA's regulations. The vehicle groupings for defining these FEL caps differ somewhat from the groupings that apply for the standards; we request comment on the need to reconcile these different groupings.

Evaporative emission credits under the proposed Tier 3 hot soak plus diurnal standards would be calculated differently in the 2017 model year and the 2018 and later model years. For 2017 calculations would be based on sales in the U.S. excluding California and the section 177 states which have adopted the LEV III/ZEV programs. For 2018 and later model years it would be based on all 50 states. Calculations would use the following equation: Credits = (fleet average standard − fleet average FEL) × “U.S. sales”. The “fleet average standard” term here is the applicable Tier 3 hot soak plus diurnal standard for the vehicle category from Table IV-18. The sales number used in the 2018 and later MY calculation would be the number of vehicles of the evaporative emission families in that category sold in the U.S. which are subject to the Tier 3 evaporative emission standards. [284] Emission credits banked under the proposed evaporative emission ABT program would have a five year credit life and would not be discounted. This means the credits would maintain their full value through the fifth model year after the model year in which they are generated. At the beginning of the sixth model year after they are generated, the credits would expire and could not be used by the manufacturer. We are proposing to limit credit life so there is a reasonable overlap between credit generating and credit using vehicles. As mentioned above, for purposes of the compliance calculation, allowance vehicles would have an FEL equivalent to the EPA emission standard (Table IV-18) for their respective vehicle category.

We request comment on all aspects of the ABT program. In particular, we request comment on the structure of the proposed evaporative emission ABT program and how the various provisions may affect manufacturers' ability to utilize ABT to achieve the desired evaporative emission-reductions in the most efficient and economical way. We also ask for comment on basing ABT calculations on nationwide sales in 2018 and later model years, even if there is a separate calculation for California and the section 177 states.

d. Compliance Demonstration

Demonstration of compliance with the evaporative emissions standards would be done after the end of each model year. There are two steps. In the first step, manufacturers would have to show compliance with the phase-in percentages whether they used the primary phase-in scheme or an alternative phase-in scheme. It is sales from these families together with their respective FELs which would be used to make the demonstration of compliance with the emission standard on average within each vehicle averaging set. Compliant vehicles types for these purposes would be the same as described in Section IV.C.2.a above for projected sales. If the required sales percentages are not met by direct sales or allowances, non-Tier 3 vehicles would have to be identified to make up the shortfall. In the second step, using the family emission limits, manufacturers would calculate the sales-weighted average emission levels within each of the four vehicle categories using U.S. sales. [285] Manufacturers would be allowed to use credits only within a defined averaging set. The averaging sets are: (1) LDVs and LDT1s, (2) LDT2s, (3) LDT3s, LDT4s, and MDPVs, and (4) HDGVs. These sales-weighted calculated values would have to be at or below the emission standard for that vehicle category as proposed in Table IV-18, unless credits from ABT are used. If the difference between the standard and the sales-weighted average FEL is a positive value this could be a banked credit available for future use. If the difference between the standard and the sales-weighted average FEL is a negative value this would be a credit deficit. Credit deficits would be allowed to be carried forward. However, manufacturers would be required to make up the deficit within the next three model years with credits from vehicles in the same averaging set except as described below. As discussed above, manufacturers would be required to identify and include in the calculations vehicle families from each and any covered category (see Table IV-18) whose total annual nationwide sales in the given model year equals or exceeds the prescribed percentages. If the inclusion of non-Tier 3 vehicles results in an exceedance of the hot soak plus diurnal emission standard for that category of vehicles, the credit deficit would have to be made up in a subsequent model year.

Allowances could also be used to demonstrate compliance with the percentage phase-in requirements and the vehicle category average emission standard. For purposes of the percentage phase-in requirements vehicles which have earned allowances are counted as compliant in the percentage calculation. For purposes of the calculations for compliance with the emission standard, allowance vehicles enters into the evaporative emissions ABT calculation as having an emission rate equivalent to the standard for that category of vehicle. Thus, allowance vehicles would help in demonstrating compliance with the percentage phase-in requirement (up to ten percentage points per model year) and would help in reducing deficits since their calculation value would be equivalent to the level of the standard. EPA asks for comment on whether allowances should be permitted to be used across vehicle categories during the transition years.

As was discussed above, during the 2017-2019 model years EPA is allowing manufacturers to meet the percentage phase-in requirements using carryover certification data from vehicles certified to CARBs Option 1 standards in the 2015 or 2016 model years. These vehicles may have CARB Option 1 certification values slightly higher than those proposed for EPA's Tier 3 program for the given vehicle and vehicle category. Since the emission standard values in Tables IV-18 and IV-19 are very similar for any given vehicle category, for purposes of simplification during the phase in, EPA proposes that any CARB Option 1 vehicles used in the 2017-2019 MY emission standard compliance determination be entered into the calculation with the emission level equivalent to the Tier 3 vehicle category in which the vehicle model would otherwise fit. Furthermore, we are proposing not allowing manufacturers to generate emission credits for families certified with EPA based on carryover CARB PZEV evaporative emissions data using CARB Option 1 as in Table IV-19. We are proposing not to include these vehicles in the ABT program since the programs are not directly comparable, and the structure of the current CARB ZEV program, which is the genesis of most PZEV offerings, allows for a different number of PZEV sales as a function of manufacturer size.

As mentioned above, we are proposing to limit use of credits only within a defined averaging set. Cost effective technology is available to meet the proposed hot soak plus diurnal emission standards on average within each of the vehicle categories in the averaging sets, especially since the proposed standards are designed to accommodate nonfuel hydrocarbon background emissions. Thus, further flexibility is not needed. Moreover, we are proposing to constrain averaging to within these sets because of equity issues for the manufacturers. We are concerned that the four or five manufacturers with a wide variety of product offerings in most or all of these categories would have a competitive advantage over the majority of manufacturers which have more limited product lines. This effect could be even more pronounced if the number of evaporative families was considered, since larger more diverse manufacturers have more models and thus more evaporative families. EPA asks for comment on issues related to averaging sets.

Manufacturer use of credits from different averaging sets to demonstrate compliance would be permitted in limited cases. As noted above, if a manufacturer has a credit deficit at the end of a model year in a given averaging set, they would have to use credits from the same averaging set during the next three years to make up the deficit. However, if a deficit still exists at the end of the third year, we propose that the manufacturer could use credits from a different averaging set to cover the remaining deficit with the following limitations. Manufacturers would be able to use credits from the LDV and LDT1 averaging set to address remaining deficits in the LDT2 averaging set, and vice versa. We also are proposing that manufacturers be permitted to use credits from the LDT3, LDT4, and MDPV averaging set to address remaining deficits in the HDGV averaging set, and vice versa. No other use of credit exchanges across different averaging sets would be allowed. These restrictions are being proposed because of equity concerns caused by the different nature and size of various manufacturer product lines.

During the program phase in there will be a declining percentage of vehicles not yet covered by the proposed Tier 3 evaporative emission requirements and thus covered by the current EPA requirements in 40 CFR 86.1811-09 and 86.008-10. These vehicles would need to be certified to current EPA requirements or seek EPA certificates based on LEV II or LEVIII emission data, subject to the certification fuel requirements discussed below.

For both the percentage phase-in and sales-weighted average calculation steps above, we are proposing to base the calculation on nationwide sales (excluding California and the section 177 states in the 2017 MY) and annual nationwide sales beginning in the 2018 MY. We believe this approach is consistent with the manufacturers' plans for 50-state vehicles. A program design which would enable a nationwide program has been an important premise of this proposal. Furthermore, this is simpler for the manufacturers and for EPA since it relieves the need to project future model year sales or track past model year sales at a disaggregated level. We recognize that decisions by manufacturers on a national fleet versus a bifurcated approach such as exists today (California and section 177-states separate from the rest of U.S. sales) have not yet been made. [286] The CARB LEV III and EPA phase-in requirements are identical beginning in 2018, so EPA sees little need for concern that a nationwide-based accounting approach could lead to disproportionate state by state impacts or the encouragement of practices which would lead to any particular state or area not receiving the anticipated emission reductions with this nationwide approach to the calculation. However, for evaporative emissions for the 2017 MY we are proposing that percentage phase-in and sales be done on a disaggregated level (i.e., California and section 177 states and the remainder of the country) since at the present time the anti-backsliding provisions of the LEV III evaporative emissions program stays in place through the 2017 MY. This is being done differently for the calculations for the early allowance program because these “zero evap” vehicles are already counted in the pre-existing ARB program.

As was discussed above, manufacturers not meeting the percentage phase-in requirements would need to include non-Tier 3 vehicles in the count and include their emissions in the overall calculation of compliance with the hot soak plus diurnal standard and resolve shortfalls in compliance with the emission standard with future reductions, earned allowances, or credits. Resolving this sales percentage shortfall problem becomes a bit more complicated for the 2017 MY 20 percent option upon which EPA is seeking comment, because it would require that 20 percent of vehicles meet the proposed Tier 3 evaporative emission requirements and that 20 percent meet the proposed leak emission standard. These may or may not be the same vehicles, (e.g., non-Tier 3 vehicles could end up in the end of year calculation and we are seeking comment on whether to allow the two 20 percent requirements to be allowed to be met on different vehicles). As a means to resolve this potential problem, EPA asks comment on a provision which would require that any shortfall of either of the 20 percent values (Tier 3 evaporative or leak emission standard) for the 2017 MY be covered by future sales of vehicles meeting the Tier 3 evaporative emission requirements in excess of the evaporative emission percentage sales requirement for that MY or some combination of MYs. For example, if a manufacturer were 5 percentage points short in the 2017 MY, then it would have to accelerate sales of vehicles meeting Tier 3 evaporative emission requirements in the 2018-2021 MYs to cover the 5 percentage points (e.g., 65 percent in 2018 instead of 60 percent or 63 percent in 2018 MY and 62 percent in the 2019 MY, etc.).

e. Small Volume Manufacturers

As another flexibility, we are proposing that small volume manufacturers, those with average annual nationwide sales of 5,000 units or less, be permitted to delay meeting the proposed Tier 3 evaporative emission standards, including the requirement to use EPA certification test fuel, until the 2022 MY (see Section IV.E.5 below for a discussion of our proposed 5,000 vehicle threshold). This would include the hot soak plus diurnal standards, the canister bleed emission standard, and the leak emission standard. In the interim, these vehicles would have to meet the current evaporative and refueling emission standards. The initial determination of whether a manufacturer is under the 5,000 unit threshold would be based on the three year average of actual nationwide sales for MYs 2012-2014. This allowance would not be affected if a qualifying manufacturer's nationwide sales later exceeded that value before 2022. Similarly, new market entrants (not in the market in the 2012 MY) with projected sales of less than 5,000 units could be covered by the small volume manufacturer provisions. However, in this case if actual running average nationwide sales exceeded 5,000 units per year in any three consecutive model years they would have to meet the Tier 3 evaporative requirements in the third model year thereafter. For example, if a new market entrant in 2015 projected nationwide production of 4,000 units per year and the average of actual values in 2015-2017 exceeded 5,000 units per year they would have to meet Tier 3 evaporative requirements by the 2020 MY.

f. High-Altitude Requirements

We adopted the most recent vehicle evaporative emission standards in 2007. [287] These newest standards apply only to testing under low-altitude conditions. [288] In that rule, we decided to continue to apply the previous “Tier 2” standards for testing under high-altitude conditions. This was necessary to achieve an equivalent level of overall stringency for high-altitude testing. This was intended to account for the various effects of altitude and lower atmospheric pressure on vapor generation rates, canister loading and purging dynamics, and other aspects of controlling evaporative emissions due primarily to lower air and vapor concentrations in air. While it is important for vehicles to have effective emission controls at high altitudes, we do not want the high-altitude standards and test procedures to dictate the fundamental design of the Tier 3 evaporative emission control systems since the high altitude vehicle population is only about five percent of the national total. Therefore, we believe it is appropriate to address this goal by applying the current EPA 2-day low altitude evaporative emission standards and requirements for high-altitude testing. The vehicle categories for the high altitude standards in this proposed rule are the same as for the low altitude standards. The proposed standards are presented below in Table IV-20. This would both reduce emissions at high altitude and again create a requirement to confirm that emission controls function effectively at high altitude without forcing manufacturers to apply altitude-specific technologies. Furthermore, the leak emission standard proposed in Section IV.C.5.b below would apply equally at low and high altitude testing.

Table IV-20 Proposed High-Altitude Evaporative Emission Standards Back to Top
Vehicle category Highest hot soak +diurnal level (over both 2-day and 3-day tests) (g/test)
[g/test]
LDV, LDT1 0.65
LDT2 0.85
LDT3, LDT4 1.15
MDPV 1.25
HDGVs ≤ 14,000 lbs GVWR 1.75
HDGVs > 14,000 lbs GVWR 2.3

A few additional points should be noted about our proposed Tier 3 high altitude evaporative emissions control program. First, by proposing to apply the current low altitude evaporative emission standards and requirements by category for high-altitude, we are proposing not to include the canister bleed test and emission standard. These vehicles would have to meet the canister bleed emission standard at low altitude and any adjustment to meet the standard at high altitude to account for canister adsorption and desorption effects of higher altitudes would result in fundamentally the same technology and increase the testing burden, but not necessarily lead to more emissions control. Therefore, we believe the low-altitude canister bleed test is sufficient for achieving the proposed level of emission control for operation in both low-altitude and high-altitude conditions. Second, for vehicles certified with FELs above or below the applicable standard for testing at low altitude, we propose that the same differential apply to the FELs for high-altitude. For example, if an LDV was certified with an FEL of 0.400 g instead of the 0.300 g standard, the high-altitude FEL would be 0.75 g (0.65g + 0.10g). This high-altitude FEL would not be used for any emission-credit calculations, but it would be used as the emission standard for compliance purposes. Third, gasoline RVP for certification test fuel would be set at 7.8 RVP with 15 percent ethanol, as specified in Section IV.D. Finally, we are proposing a minor adjustment to the high altitude test procedures. Today, the 2- and 3-day test procedures apply equally at low and high altitude. We are proposing to keep that requirement but to allow for an adjustment of 5 °F in the temperatures related to the running loss test within the 3-day test cycle. Thus, the applicable fuel and ambient temperatures at § 86.134-96 (f) and (g) would 90 ± 5 °F instead of 95 ± 5 °F for high altitude testing. EPA believes this is appropriate given the differences in atmospheric conditions at low versus high altitude and will still result in equivalent control of running loss emissions at higher altitudes. We request comment on the alternative approach of keeping test temperatures the same, but omitting the 3-day test cycle for testing at high altitude. This would effectively establish the 2-day test cycle as a sufficient means of demonstrating that emission control systems continue to operate properly at high altitude.

As mentioned above, emission data from vehicles meeting the current CARB zero evap and useful life requirements could be used to qualify that vehicle to meet the Tier 3 evaporative emission regulations for the 2017-2019 MYs. To qualify for a federal certificate, the vehicle would also have to meet the Tier 3 high altitude evaporative emission requirements. While CARB requires vehicles to meet EPA high altitude requirements, we ask for comment on the need for and value of an interim option which would permit manufacturers to gain such certification by an engineering demonstration that the vehicle would comply at any altitude rather than by performing additional testing.

g. Technological Feasibility

The basic technology for controlling evaporative emissions was first introduced in the 1970s. Manufacturers routed fuel tank and carburetor vapors to a canister filled with activated carbon, where vapors were stored until engine operation allowed for purge air to be drawn through the canister to extract the vapors for delivery to the engine intake. Over the past 30 years, evaporative emission standards have changed several times, most notably in the mid-1990s when enhanced evaporative controls were required to address 2- and 3-day diurnal emissions and running losses. Refueling emission controls were added with phase-in beginning in the 1998 MY. Almost universally manufacturers elected to integrate evaporative and refueling emission control systems. In the mid-2000s more stringent evaporative emission standards with E10 durability gasoline led to the development and adoption of technology to identify and eliminate permeation of fuel through fuel tanks, fuel lines, and other fuel-system components.

i. Hot Soak Plus Diurnal

The current baseline technology for LDVs, LDTs, and MDPVs is a properly designed and assembled fuel/evaporative system for controlling emissions over the 2- and 3-day test sequences to meet the current standard of 0.650 grams/test. This involves activated carbon canisters which capture gasoline vapors, with engine calibrations designed to maximize canister purge over the test sequence. Fuel systems generally include widespread use of various grades of permeation-resistant materials.

The anticipated control technologies to comply with the proposed hot soak plus diurnal evaporative emission standards include an improved carbon canister designs to even better capture vapor emissions from the canister, air intake designs to prevent the escape of unburned fuel from the engine's crankcase, various upgrades to further limit potential micro-sized leaks, and further steps to reduce permeation rates. Applying these new or improved technologies will allow manufacturers to meet the proposed 300 mg standard for LDVs/LDT1s. The proposed evaporative emission standards are slightly higher for larger vehicles to account for potentially higher background emissions and in some cases larger surface area components, but the baseline and anticipated control technologies follow a very similar path. These baseline and control technologies are described further in the rest of this section.

Current evaporative canisters use high working-capacity activated carbon, usually with multiple compartments, to optimize vapor loading and purging behavior. These canisters sometimes employ carbons of different working capacities within each chamber. Testing indicates that the total canister adsorption capacity in grams of gasoline vapor is generally dictated by the requirements of the refueling emission test and standard rather than the evaporative emission test (either the 2- or 3-day sequence).

Manufacturers have identified the engine's intake system as another source of evaporative emissions. These result from crankcase vapors and from unburned fuel from injectors, or sometimes from an injection event that occurred shortly before engine shutdown. We estimate a typical emission rate of about 40 mg associated with each engine shutdown event; however, since the actual emission rates depend on timing of individual injection events and cylinder position at shutdown, baseline emission rates can vary significantly. These vapors must follow a contorted path before reaching the ambient air, which would generally cause these emissions to show up during the first day of the diurnal test rather than the hot soak test. One way to prevent these emissions is to add activated carbon to the air intake downstream of the air filter, typically in the form of reticulated foam coated with activated carbon. This device would have only a few grams of working capacity and would be designed to purge easily to ensure that the vapor storage is available at engine shutdown. This carbon insert would almost completely eliminate any vapor emissions from the air intake system.

Manufacturers wanting to avoid adding any specialized emission control component to control evaporative emissions from the air intake could pursue alternative approaches. First, it is possible to allow the engine to continue rotating for 2-3 revolutions after engine shutdown to sweep any hydrocarbon vapors from the intake system into or through the cylinder. These vapors could be burned in the cylinder, oxidized at the catalyst, or stored until the engine starts again. This may still allow for a small amount of residual vapor release, but this should be a very small quantity. Vehicle owners would be unlikely to notice this amount of engine operation after shutdown. Second, to the extent that manufacturers use direct injection, there should be no fuel vapor coming from the intake system. Any unburned fuel coming from the injectors would be preserved in the cylinder or released to the exhaust system and the catalyst. A small amount of crankcase vapor might remain, but this would likely not be enough to justify adding carbon to the intake system.

Fuel tanks are designed to limit permeation emissions. Fuel tanks are typically made of high-density polyethylene with an embedded barrier layer of ethyl vinyl alcohol (EvOH) representing about 1.8 percent of the average wall thickness. The EvOH layer is effective for reducing permeation emissions. Recent developments in production processes have led to improved barrier coverage around the ends of the tank where the molded plastic is pinch-welded to form a closed vessel. We are expecting manufacturers to increase the EvOH barrier thickness to about 3 percent of the average wall thickness to provide a more uniform barrier layer, to provide better protection with ethanol-based fuels, and to improve permeation resistance generally. These changes are expected to decrease emission rates over the diurnal test from about 40 mg per day to 15 mg per day from the fuel tank assembly or less.

Fuel lines are also already designed for low permeation rates. The biggest portion of fuel and vapor lines are made of metal, but that may still leave several feet of nonmetal fuel line. There may be development of new materials to further reduce permeation rates, but it is more likely that manufacturers will adjust the mix of existing types of plastic fuel lines to achieve the desired performance at the lowest possible price.

The bigger area of expected development with respect to fuel lines is to re-engineer fuel systems to further reduce the number of connections between fuel-system components and other fuel-line segments. Today these systems may involve more than the optimum number of connections and segments due to assembly and production considerations or other factors. Designing the fuel system more carefully to minimize connection points will limit possible paths for fuel vapors to escape. This would reduce emission rates and it should also improve system durability by eliminating potential failure points. A broader approach to addressing this source of emissions is to integrate designs and to move fuel-system components inside the fuel tank, which eliminates the concern for vapor emissions and permeation from those components and connections.

A remaining area of potential evaporative emissions is the connection between the fill neck and the fuel tank. Manufacturers can reduce emissions by perhaps 10 mg per day by making this connection permeation-resistant. The challenge is to design a low-cost solution that is easily assembled and works for the demanding performance needs related to stiffness/flexibility. The best approach is likely either to use mating parts made from low-permeation materials, or to use conventional materials but cover this joint with material that acts as a barrier layer.

Purge rates are currently designed to flow relatively large volumes of outside air through the canister when the purge solenoid is activated. This involves using available manifold vacuum to create purge flow, with limits in place to avoid drawing too much unmetered fuel vapor from the canister. Tightening the evaporative emission standard would lead manufacturers to address remaining emission sources from micro-size leak points, permeation, and diffusion, as noted above. Since the amount of additional vapor being captured by the carbon canister is small and the test procedure is not changing, we do not expect the change in standards to drive changes in purge strategy, rates, or canister capacity. Nonetheless, vehicle system and engine changes to improve fuel economy could impact future purge strategies. Thus, as part of this approach, manufacturers may incorporate designs to reduce vapor volume/mass directed to the canister and thus potentially reduce the purge air volume requirements. In addition, canister designs can be optimized to increase the effectiveness of a given volume of purge air. This could involve selecting different combinations of carbon characteristics and canister architecture types and by adding features to add heat (or preserve heat) in the canister during a purge event. It is also possible that fuel economy strategies which impact purge volume may lead some manufacturers to add vacuum pumps to supplement engine-based purge on some vehicle models in the future.

It is worth noting that there may be some models where manufacturers incorporate hardware or another control technique that may not be widely used across by all manufacturers or across all models. This is especially true for this set of proposed emission control requirements since we are considering such a wide array of basic vehicle and engine designs. Also, future vehicle/engine systems such as hybrids may have more unique challenges in areas such as the diurnal fuel tank vapor load sent to the activated carbon canister and subsequent purging of those vapors. In response to this challenge, manufacturers may employ techniques to reduce fuel tank vapor generation and/or to enhance purge efficiency. Hardware such as a vapor blocking valve or other techniques to enhance purge efficiency from the canister through heating may be employed to a limited degree.

The technologies discussed above are in use to varying degrees on many of the CARB PZEV zero evap vehicles mentioned above. Taken together, we believe these technologies provide manufacturers with effective tools for reducing emissions sufficiently to meet the proposed evaporative emission standards.

ii. Canister Bleed Emission Standard

More stringent evaporative emission standards have led to more careful measurements, which led manufacturers to discover that 80 mg or more of fuel vapor would diffuse from the canister vent as a result of the normal redistribution of vapors within the activated carbon while the vehicle is at rest. The emission rate depends on the tank volume, its fill quantity, and the size and architecture of the canister and the characteristics of the carbon itself. While the biggest effect of this vapor distribution is a uniform concentration within the canister, it can also cause vapors to escape through the canister vent even without continued canister loading that would result from fuel tank heating. These are referred to as canister bleed emissions. These emissions occur to some degree during the 2- and 3-day evaporative emissions test, but a separate standard is needed if the goal of near zero fuel vapor emissions is to be achieved.

The design to address this concern is a supplemental “scrubber” canister (or canister compartment) with a very low working capacity carbon. Adding 100 or 200 ml of this type of carbon near the canister vent provides a margin of “reserve capacity” to capture diffusion losses from the canister. Since this extra carbon has low working capacity and it purges readily, it is typically cleared of hydrocarbon vapors and ready to perform its function after any amount of engine operation or even with natural back purge which occurs when the fuel in the tank cools. This scrubber element is expected to eliminate all but 5-10 mg of emissions from the evaporative canister over the measurement procedure.

iii. Leak Emission Standard

Vapor leaks in the vehicle fuel/evaporative system can arise from micro-cracks or other flaws in various fuel/evaporative system component structures or welds, problems with component installations, and more generally from connections between components and fuel lines and vapor lines. Because these emissions from these areas would occur in the 2-3 day evaporative emissions test if the problems were present, manufacturers have taken steps to address these potential problem areas as part of their overall evaporative emissions control strategy. Since the 2- and 3-day hot soak plus diurnal standards are proposed to become more stringent and leak emissions occur during the evaporative emissions test, we expect manufacturers to take the measures described above in Section IV.C.2.g.i. These include reducing connections, improving the quality of fuel and vapor line connections, use of improved component materials and revised installation practices. Manufacturers could also review their OBD leak warranty data and related information from OBD queries to help inform their strategies. One of the key reasons for proposing a leak emission standard is to promote the continuing development of designs, part production techniques, and assembly practices which will yield less in-use emissions deterioration and improved in-use emissions performance. EPA believes this focus on in-use durability is important because a vehicle with even a small leak, e.g., the size of the 0.020-0.040 inch orifice diameter monitored by OBD systems would likely emit above the proposed hot soak plus diurnal evaporative emission standard in use.

3. Heavy-Duty Gasoline Vehicle (HDGV) Requirements

a. Overview of the Proposal for HDGVs

As presented above, EPA is proposing to include HDGVs within the Tier 3 evaporative emissions program. The proposed hot soak plus diurnal and canister bleed test emission standards that would apply to these HDGVs are as presented in Table IV-18 and the high altitude standard is presented in Table IV-20. These vehicles would be included in the averaging calculation beginning in the 2018 MY and would be eligible for creating and using allowances and credits as discussed above. Furthermore, for the reasons discussed below, EPA is proposing that HDGVs equal to or less than 14,000 lbs GVWR be required to meet the refueling emission standard by the 2018 MY.

b. Background on the HDGV Sector

HDGVs are generally gasoline-powered vehicles with either a GVWR of greater than 8,500 lbs, or a vehicle curb weight of more than 6,000 lbs, or a basic vehicle frontal area in excess of 45 square feet. [289] HDGVs are predominantly but not exclusively commercial vehicles, mostly trucks and other work type vehicles built on truck chassis. EPA often discusses HDGVs in three basic categories for regulatory purposes according to their GVWR class. These include Class 2b (8,501-10,000 lbs GVWR), Class 3 (10,001-14,000 lbs GVWR), and Class 4 and above (over 14,000 lbs GVWR). These are further sub-categorized into complete and incomplete vehicles. [290] Class 2b HDGVs are mostly produced by the manufacturers as complete vehicles and are very similar to lower GVWR LDTs of the same basic model sold by the manufacturers. Class 3 HDGVs are also built from LDT chassis with fuel system designs that are similar to their Class 2b and LDT counterparts, but these are on some occasions sent to secondary manufacturers as incomplete vehicles to attach a load carrying device or container. EPA estimates that more than 95 percent of Class 2b/3 vehicles are complete when they leave the original equipment manufacturer (OEM). Class 4 and above HDGVs are built on a more traditional heavy-truck chassis and in most cases leave the OEM as an incomplete vehicle. For Class 2b/3 vehicles, it is common to certify the vehicle for emissions purposes (exhaust, evaporative, etc) as a full chassis, while for Class 4 and above the vehicle is certified as a chassis for evaporative emissions while the engine is dynamometer certified for exhaust emissions.

For LDVs and LDTs, the current EPA evaporative and refueling emission test procedures are the same for all vehicle categories and the emission standards are of a similar but not always identical stringency, within the subclasses. However, this is not true for HDGVs. For HDGVs, the level of the evaporative emission standards and the test procedures vary by category and the refueling emission control requirements are also different. There are several reasons for these differences, including variations in the size, design, and other properties of the basic fuel system, the dimensions of the vehicles, and the potential for actions of secondary manufacturers to impact the fuel system. There are many fuel system similarities between Class 2b/3 HDGVs and heavy LDTs, but fewer similarities between heavy LDTs and HDGVs in Class 4 and above.

Over the past 15 to 20 years, there have been several notable changes in HDGV products and market that have influenced the application of evaporative and refueling emission control requirements and may impact potential new or revised requirements going forward. Most noteworthy among these are the increased use of diesel engines across all weight classes and the emergence of better defined market segments for primary OEMs and secondary manufacturers.

The increased use of diesel engines has reduced overall HDGV sales and brought about a consolidation of manufacturer HDGV product offerings. For Class 2b/3 HDGVs, these are now all derived from LDT chassis and have the same basic fuel system and engine characteristics. This has led EPA to extend the light-duty evaporative and refueling test procedures and emission standards to the Class 2b/3 HDGVs, when applicable. In a rule promulgated in 2000, EPA required manufacturers to certify these HDGVs using light-duty test procedures. Also, in this same rule, EPA extended the vehicle refueling emission standards to complete Class 2b vehicles. These actions were technically appropriate because of the similarities between the LDT and Class 2b HDGVs and fuel systems and the large fraction of complete Class 2b HDGVs produced by the vehicle manufacturers. Today, fuel systems for Class 3 HDGVs are comparable those for Class 2b HDGVs, so it is reasonable and technically feasible to extend the Class 2b refueling emission requirements to Class 3 HDGVs.

Class 4 and heavier HDGVs still play a small but important role in the traditional truck and heavy-duty vehicle markets. These vehicles are sometimes distinctly different from Class 2b/3 vehicles in terms of testing, chassis designs, and fuel system characteristics; secondary manufacturers also play a larger role in the overall completion of the vehicle. For these vehicles, the engines are certified for emissions on an engine dynamometer while the evaporative emissions are certified separately on the vehicle chassis. Furthermore, these vehicles are larger dimensionally (which often means longer fuel and vapor lines) and have larger volume fuel tanks (sometimes two), which may be mounted on the underbody or side-rail. It is common for a secondary manufacturer to complete the vehicle by adding the cargo container or other working equipment box or package (e.g., small cargo truck or tow truck) and in some cases to reconfigure components. While the extrapolation of refueling emission control technology is conceptually straightforward, in some cases there may be unique technical issues related to implementing refueling emission controls for these heavier HDGVs relative to Class 2b/3 HDGVs and LDTs.

Based on these considerations, EPA is proposing that the refueling emission standards in § 86.1816-05 to apply to Class 3 HDGVs as well. This is appropriate because the fuel and evaporative control systems on these vehicles are very similar to those on their slightly lighter-weight Class 2b counterparts, and in some cases Class 3 HDGVs are already designed to meet this proposed requirement. EPA is proposing that this requirement be met beginning in the 2018 MY. EPA is also proposing that manufacturers be permitted to comply as early as the 2015 MY to earn on a one-to-one basis allowances which could be used to phase-in the Class 3 refueling emission control requirement or as an allowance under the Tier 3 evaporative emission program. EPA believes this is appropriate since the expected daily average reduction in vehicle refueling emissions for this class of vehicles is large relative to the reduction in evaporative emissions expected under Tier 3. Any certifications, including those done early, must use EPA Tier 3 test procedures and certification test fuels.

c. Other Potential Program Elements for HDGVs

EPA is seeking comments on several other programmatic elements related to the Tier 3 evaporative and refueling emission control proposal.

First, even if we do not revise the current evaporative emission standards for these vehicles and they are not required to control refueling emissions, we are seeking comment on requiring manufacturers to certify their evaporative emissions using Tier 3 certification test fuel. Tier 3 certification test fuel would provide equivalent or better emissions control as compared to current certification test fuel in terms of the fuel quality impact on emission control system designs to meet the existing evaporative emission standards and would provide equivalent or better in-use performance. Requiring this new certification test fuel has the potential to add efficiency to the certification process since manufacturers could certify one system for EPA and CARB for each evaporative family. Since incomplete vehicles and those over 14,000 lbs GVWR often do not use the same test vehicle/engine for evaporative and exhaust emission testing, we seek comment on whether a requirement for vehicle evaporative and/or refueling emission certification on Tier 3 test fuel would technically necessitate engine exhaust emission certification on Tier 3 test fuel.

Second, as mentioned in Section IV. B., EPA is also seeking comment on requiring the use of Tier 3 certification test fuel for HDGVs which are engine-dynamometer certified, not chassis-certified, for exhaust emissions. This would potentially include all engine families certified for use in HDGVs above 8,500 lbs. GVWR. We are seeking comment on this change because we believe it may be the best and most representative technical approach for the future in the context of the engine/emission control system/fuel system design and performance and fuel quality. Overall, we believe this change to the certification test fuel for HDGVs would provide equivalent or better emissions control for the regulated pollutants as compared to current certification test fuel, in terms of the impact of fuel quality on emission control system designs and in-use performance, and may also simplify manufacturers' testing operations by providing for a single test fuel. We are also seeking comment on putting this requirement in place in the 2020-2022 MY time frame. Consistent with the approach proposed in Section IV.D.4 for light- and heavy-duty vehicles, we are committed to the principle of ensuring that any change in test fuel for heavy-duty engines would not affect the stringency of either the fuel consumption or GHG emissions standards. As part of the separate rulemaking discussed in Section IV.D.4, we would expect to establish the appropriate test procedure adjustment for HD engine fuel consumption standards and to determine the need for any test procedure adjustment for GHG emissions standards based on the change in certification test fuels.

Third, to simplify the evaporative emission regulations for HDGVs and to bring them more in line with the current structure of the product offerings in this sector, we are proposing to permit evaporative emissions certification by engineering analysis for vehicles above 14,000 lbs GVWR (instead of above 26,000 lbs GVWR as is permitted in the current regulations). These HDGVs would remain subject to the emission standards when tested using the specified procedures. This is the same cut point allowed by CARB and would allow for one certification method. Furthermore, for HDGVs over 14,000 lbs GVWR, we request comment on taking an additional step to rely even further on design parameters and engineering analysis. Under this approach, manufacturers would need to demonstrate that the design of their purge strategy, canister capacity, and overall control system would control emissions to the same degree as similar (or comparable) Class 2b or Class 3 vehicles that meet emission standards when tested over the established measurement procedures. The standard would be a performance standard in that the manufacturer could use any design that met the criteria of controlling emissions to the same degree that occurs in vehicles that meet the emissions standard. However, unlike the proposed approach, compliance with the standard would be based solely on an engineering review of the design. Compliance would not be determined by measuring performance on the emissions test. This would take into account the limitations in managing any significant degree of testing with these over-size vehicles. In particular, we request comment on the enforceability of taking the approach of a design standard.

Fourth, we are proposing a revised description of evaporative emission families that does not reference sealing methods for carburetors or air cleaners as this technology is now obsolete for heavy-duty gasoline engines.

Fifth, we also seek comment on the implications on these evaporative emission standards were we to require the certification test fuel to be 10 psi RVP E10 as discussed below in Section IV.D.1.

Sixth, we are proposing to clarify how evaporative emission standards affect engine manufacturers and proposing more descriptive provisions related to certifying vehicles above 26,000 lbs GVWR using engineering analysis. These improved descriptive provisions would apply to vehicles above 14,000 GVWR lbs if the proposed change in GVWR cut point for engineering analysis certification is finalized.

Finally, EPA is asking for comment on several other provisions related to the heavier HDGVs (over 14,000 lbs GVWR). First, if we do not include these heavier HDGVs in the Tier 3 final rule requirements, we are asking comment on whether manufacturers should be able to voluntarily certify any HDGVs not covered by the rule to the same requirements as being proposed for Class 2b/3 HDGVs, and through this action earn allowances and credits for use within the Tier 3 program as discussed above for other vehicles. This would include both evaporative and refueling emissions standards. Second, EPA also asks comment on whether there should be a provision to permit HDGVs over 14,000 lbs GVWR to be grouped with those between 10,001 and 14,000 lbs GVWR for purposes of complying with evaporative and refueling emission control standards and related provisions. In these cases, we would expect these HDGVs to meet all the requirements applicable to the group in which they are being included (e.g., useful life, OBD, etc.).

4. Test Procedures and Certification Test Fuel

a. Review and Update of Testing Requirements

EPA adopted the current test requirements for controlling evaporative emissions in 1993. [291] Those changes included: (1) Diurnal testing based on heating and cooling the ambient air in the SHED [292] instead of forcing fuel temperatures through a specified temperature excursion; (2) repeated 24-hour diurnal measurements to capture both permeation and diurnal emissions; (3) high-temperature hot soak testing; (4) high-temperature running-loss measurements with a separate standard, including controlled fuel temperatures according to a fuel-temperature profile developed for the vehicle; and (5) canister preconditioning to ensure that vehicles could effectively create canister capacity to prepare for several days of non-driving.

These test procedures are generally referred to as “enhanced evap” testing. EPA adopted these “enhanced evap” test procedures in coordination with CARB. The test requirements include two separate test sequences to demonstrate the effectiveness of evaporative emission controls. The “two-diurnal sequence” involves canister loading to two-gram breakthrough, followed by driving for the exhaust test (about 31 minutes), a hot soak test, and two days of cycled ambient temperatures. The “three-day sequence” involves canister loading with 50 percent more vapor than needed to reach breakthrough, followed by driving for the exhaust test, driving for the running loss test (about 97 minutes total), a high-temperature hot-soak test, and three days of cycled ambient temperature.

The 2-day sequence was intended primarily to insure a purge strategy which would create enough canister capacity to capture two days of diurnal emissions after limited driving. The two-day measurement period was effective for requiring control of permeation and other fugitive emissions. The 3-day sequence was intended to establish a design benchmark for achieving adequate canister storage capacity to allow for several days of parking on hot summer days, in addition to requiring vehicle designs that prevent emissions during high-temperature driving and shutdown conditions.

After adopting these evaporative test procedures, we set new standards for refueling emissions control which called for onboard refueling vapor recovery (ORVR). [293] Manufacturers have typically designed their ORVR systems to be integrated with their evaporative controls, using a single canister and purge strategy to manage all fuel vapors vented from the fuel tank. Due to the magnitude of the refueling emission load and the manner in which the load rates affect activated carbon capture efficiency, it has become clear that ORVR testing with these integrated systems serves as the benchmark for achieving adequate canister storage capacity.

In the nearly 20 years since adopting these test procedures, manufacturers have made great strides in developing designs and technologies to manage canister loading and purging and to reduce permeation emissions. Except as discussed below, we are not proposing to change the test procedures for demonstrating compliance with the proposed Tier 3 emission standards.

As described above, we are proposing to adopt a new standard based on measured values over a “canister bleed test,” which is intended to measure only fuel vapors which diffuse from the evaporative canister. CARB developed this procedure as a means of setting a standard that would not be affected by nonfuel background emissions. This procedure is a variation of the established two-day test sequence. The canister is preconditioned by purging and loading to breakthrough, then attached to an appropriate test vehicle for driving over the duty cycle for the exhaust test. The canister is then attached to a fuel tank for measurement. After a stabilization period, the tank and canister undergo two days of temperature cycling. Canister emissions are measured using a flame ionization detector (FID), either using a conventional SHED approach or by collecting emissions in a bag and measuring the mass. Rather than repeating CARB's regulations, we are proposing to incorporate those regulations by reference into the CFR. This will avoid the possibility of complications related to minor differences that may occur with separate test procedures.

CARB also adopted a fuel system “rig test” as an optional approach to demonstrate control of evaporative emissions without the effects of the nonfuel hydrocarbon emissions that are seen in testing the whole vehicle in the SHED. We generally expect manufacturers to comply with the proposed EPA requirements which include the canister bleed test and emission standard instead of CARB Option 1 which includes the rig test and emission standard. However, since we are proposing to accept CARB Option 1 certifications for the 2017 through 2019 model years, we are also proposing to incorporate by reference CARB's rig test into the CFR to accommodate those manufacturers that do in fact rely on this approach.

Also, as discussed further below, we are proposing to adopt a new leak test procedure which would be used to measure leak rates for the proposed leak emission standard. The leak test standard test procedure is contained in the proposed regulatory text. Further detail can be found in the draft Regulatory Impact Analysis (Appendix to Chapter 1).

Manufacturers have raised a pair of related concerns regarding the current test procedures. First, hybrid vehicles and new engine designs for meeting fuel economy standards and CO 2 emission standards increase the challenge of maintaining an adequate purge volume to prepare vehicles for the diurnal test. For hybrid vehicles this is related to the amount of time the engine is running. For other technologies this is related to the trend toward decreasing available vacuum in the intake manifold, which is the principal means of drawing purge air through the canister. Second, preconditioning the canister by loading to breakthrough serves as a disincentive for some control strategies that might otherwise be effective at reducing emissions, such as designs involving greater canister capacity or better containment of fuel vapors inside the fuel tank. In addition, we have learned from studying in-use emissions and in- use driving behaviors and usage patterns that it is not uncommon for vehicles to go for an extended period with little or no opportunity to purge the canister.

We request comment on an optional adjustment to the test procedure intended to address these three concerns. In this alternative, for designs involving pressurized tanks, manufacturers would determine an alternative vapor load to precondition the canister before the exhaust test. If, for example, a fuel system is designed to stay sealed up to 1 psi and to vent vapors to the canister if rising temperatures trigger a pressure-relief valve, the manufacturer could quantify the actual vapor load to the canister during three consecutive days of cycling through diurnal test temperatures. This three-day vapor load would be the amount of fuel vapor used to precondition the canister (loaded at the established rate of 15 grams per hour). This canister loading may also involve butane instead of fuel vapor, but we would likely require a greater mass of butane to account for the fact that it is easier to remove the butane from the activated carbon in the canister. This approach would be flexible to accommodate any design target for pressurizing fuel tanks. Canister preconditioning for the ORVR test (for integrated and nonintegrated systems) would remain unchanged.

b. Test Fuel

EPA is proposing to change the certification test fuel specifications as described in Section IV.D. Here we discuss some implications for evaporative and refueling emissions testing. We are proposing to revise the certification test fuel specification (including durability fuel) in conjunction with the proposed Tier 3 standards, principally to include ethanol and reduce sulfur such that the test fuel better aligns with the current and projected in-use fuel. Any Tier 3 evaporative emission certification would have to use Tier 3 certification test fuel and test procedures. This could be done as early as the 2015 MY and would be required for all vehicle models by the 2020 MY. We are further proposing to apply the new test fuel at the same time to ORVR testing. Therefore, beginning in the 2017 MY if manufacturers do any new testing to demonstrate compliance with the proposed Tier 3 evaporative emission standards, they would need to submit test data to demonstrate compliance with the refueling emission standards using the new certification test fuel as well as the leak (when applicable), refueling, canister bleed, and high altitude testing requirements and emission standards. We are also proposing that any family that is not yet captured within the Tier 3 phase-in percentage may remain on current certification fuel or, as discussed below, California certification test fuel and test procedures through the 2019 MY. By the 2020 MY all evaporative and refueling emission certifications would have to be on EPA test procedures and certification fuels. It is useful to clarify that any confirmatory or in-use testing for these families would be done on the fuel on which they were originally certified. However, by the 2020 MY all vehicles must be certified with Tier 3 certification test fuel and that test fuel would have to be used in confirmatory and in-use testing.

Finally, we are proposing that any vehicle certified to the refueling spit back standard separately (mostly incomplete HDGVs) may continue to do so using current certification fuel until the 2022 MY even if it's evaporative and/or refueling emissions are certified on Tier 3 certification fuel. This is reasonable since the fill quality of the vehicle and eliminating spit back are not necessarily related to the ethanol or sulfur content of the gasoline.

There are two main fuel properties that influence evaporative emissions: Ethanol content and vapor pressure. Current requirements specify an emission test fuel with no ethanol for emissions testing; however, the current regulation specifies that manufacturers must perform service accumulation (durability) using fuel with, at a minimum, the highest concentration of ethanol permissible under federal law for in-use gasoline and that is commercially available in at least one state. In this case, this provision has the effect of insuring that manufacturers would design their fuel systems to account for the effect of ethanol on permeation emissions. Even without ethanol in the test fuel, the extended operation with gasoline-ethanol blends for service accumulation would effectively force the manufacturers to design systems which effectively control emissions from the blended fuel. By regulation manufacturers must use a 10 percent ethanol fuel in current evaporative emissions durability work. As a result, adding ethanol to the test fuel for Tier 3 evaporative and refueling emission testing should pose no new or greater challenge for manufacturers. A second issue related to adding ethanol to the certification test fuel relates to the emission measurement in the SHED. Emissions are detected by flame ionization detectors (FID), which are less responsive to ethanol than gasoline. This effect causes under-reporting from the ethanol portion of the fuel vapor. Fuel-related emissions from the vehicle may be slightly more weighted toward ethanol than gasoline, depending on how the different fuel constituents permeate through various fuel-system materials, how they evaporate from the bulk fuel in the tank at varying temperatures, and how they adsorb onto and desorb from the activated carbon in the canister. We are proposing to address this issue by the use of a prescribed scaling factor. Under this approach manufacturers would simply multiply their SHED measurement results by a fixed value to adjust upward for the difference in the FID response to ethanol. Data available to EPA suggest that a scaling value of approximately 1.1 would be appropriate for E15. [294] This means that the value measured in the SHED would be multiplied by 1.10 to account for a difference in the FID response. This was determined using data which indicates that from a near worst case perspective the term within the bracket { } below equals 1.1.

M HC adj= [(P B V n / T)-(.000297)(ppm Cfid)*{1 + ((1−r a) (r eth))/ 1 + ((r eth)(r a))}]

This adjustment would apply to hot soak plus diurnal, refueling, canister bleed, and spitback emission standards testing. For higher ethanol blends (such as E85), the regulation already specifies measurement and calculation procedures to adjust for this effect. We are not proposing any changes to these procedures.

c. Vehicle Preconditioning for Nonfuel Hydrocarbon Emissions for the Tier 3 Evaporative Emission Standards

The proposed Tier 3 hot soak plus diurnal, leak, and canister bleed emission standards taken together are expected to bring about the widespread use of technology which effectively eliminates fuel vapor emissions. The canister bleed and leak emission standards are not influenced by non fuel hydrocarbon emissions from the vehicle. Nonfuel hydrocarbon emissions from the vehicle are measured as part of SHED emission testing, and are indistinguishable for fuel hydrocarbons when a FID is used to measure the concentration. The level of these nonfuel hydrocarbon emissions vary by vehicle and component design and material. These emissions arise from paint, adhesives, plastics, fuel/vapor lines, tires, and other rubber or polymer components and are generally greater with larger size vehicles. These nonfuel hydrocarbon emissions are usually highest with newly manufactured vehicles and decrease relatively quickly over time.

Currently, manufacturers often conduct some preconditioning to reduce or eliminate the effects of these nonfuel hydrocarbon emissions on evaporative emissions measurements in the SHED. In the past, this practice has not been addressed through regulatory provisions. However, given the stringent level of the proposed Tier 3 hot soak plus diurnal evaporative emission standards, and that nonfuel hydrocarbon emissions are expected to be a significant portion of the hydrocarbon emissions measured in the SHED, EPA believes that some sort of preconditioning before certification testing is appropriate and that a regulatory provision addressing this practice may be warranted. Providing some recognition of and allowance for this practice would help to create the proper balance between necessary and proper preconditioning to address high nonfuel hydrocarbon emissions and excessive preconditioning which could undermine the intent of the proposed hot soak plus diurnal emission standard (∼ 50 mg or less of fuel evaporative emissions). EPA believes the goal of evaporative emissions preconditioning should be to get nonfuel hydrocarbon emissions to what we call vehicle background levels. A working definition of vehicle background level might be the level which would occur naturally twelve months after production. A provision in the regulations which addresses preconditioning reduces ambiguity for the manufacturers and could reduce or eliminate any uncertainty in the true meaning of certification test results.

Manufacturer activity with regard to preconditioning often involves two practices. First, manufacturers in some cases “bake” their test vehicles at temperatures of 50 °C or higher for periods of up to ten or more days to accelerate the off-gassing of these nonfuel hydrocarbon emissions before testing is conducted. While this practice is common, there is no standardized method or protocol for this preconditioning prior to new vehicle certification testing. For example, some manufacturers bake for a set period of time in a climate chamber while others bake in the climate chamber and periodically measure nonfuel background in a SHED until an acceptable or stable level of nonfuel hydrocarbon emissions is achieved. Second, manufacturers often remove, modify, or clean certain components which are the largest source of nonfuel hydrocarbon emissions. Preconditioning could also include measures to eliminate minor fuel drips, spills, or other fuel remnants which occur as a result of vehicle preparation for testing.

We are not proposing to specify standardized preconditioning practices or protocols with regard to addressing nonfuel hydrocarbon emissions before evaporative emission certification testing. However, we are proposing general provisions in four areas. First, we would specify in the regulations that preconditioning for the purpose of addressing nonfuel hydrocarbon emissions is permitted. Second, we would specify that any preconditioning is voluntary. Third, we would specify that if preconditioning is conducted, the details must be specified to EPA before certification testing, (i.e., at the time of the pre-certification planning meeting). The goal of this preconditioning should be to get nonfuel hydrocarbon emissions to what we would term vehicle background levels as discussed above. The specifics to be discussed with EPA could include details on vehicle baking practices such the temperature and time duration in the climate chamber and practices conducted as an alternative or complement to vehicle baking such as installing used tires (drive and spare) on certification vehicles, and allowing the windshield washer tank to be filled only with water. In seeking to understand this issue, we ask for comment on which components are the largest sources of these nonfuel hydrocarbons and of these which are practical to modify or remove for the evaporative emissions test.

Fourth, as part of these considerations we would specifically propose that no preconditioning be permitted for testing of any vehicle aged more than twelve months from its date of manufacture. The only exception we would consider is the use of an aged spare tire in lieu of the spare tire on the test vehicle. For these vehicles, nonfuel hydrocarbon emissions would presumably be reduced to a stable level due to natural off gassing which begins after the vehicle is manufactured. Emissions from any replacement parts or other vehicle maintenance would presumably be encompassed within the margin below the standard created by this natural off-gassing. EPA asks comment on how to address testing of vehicles with relatively new drive tires and whether used drive tires should be allowed in these circumstances. Data available to EPA indicates that the background emission rate stabilizes to about two-thirds of the level of the standard after about twelve months. These levels are adequately below the proposed Tier 3 evaporative emission standards so that nonfuel background would not unduly influence test pass/fail outcomes and are within the range of values EPA expects to be accommodated within the proposed evaporative emission standard. This proposed restriction for vehicles older than 12 months would include certification, confirmatory and in-use testing for any vehicle certified to the proposed Tier 3 evaporative emission standards. We request manufacturer data related to the change in nonfuel hydrocarbon emission rates over time and on the best method to consider these emissions as part of preconditioning before evaporative emission testing.

d. Reciprocity With CARB

Over the past 15 years EPA's “enhanced evap” test procedures have been based on testing with 9 pound per square inch (psi) RVP gasoline with test temperatures representing a summer day with peak temperatures of about 96 °F. CARB adopted the same basic procedures, but specified that testing should occur with 7 psi RVP gasoline at temperatures of up to 105 °F. EPA and CARB agreed that certification could be based on testing with either EPA or CARB conditions and that these provided equivalent stringency for purposes of evaporative control system design. However, the provision allowing for this equivalence of test data preserved EPA's ability to also test with either EPA or CARB temperature conditions. CARB always specified EPA test conditions for refueling as they were deemed worst case. CARB recently moved to change their certification test fuel to a 7 RVP gasoline with 10 percent ethanol and as discussed in Section IV.D, we are now proposing to change the Federal certification test fuel specification to a 9 RVP gasoline with 15 percent ethanol.

During the development of this proposal we carefully considered the practice of CARB/EPA reciprocity with regard to certification test fuels, hot soak plus diurnal test procedures, and emission test results when it comes to evaporative emissions certification. With this notice we are proposing a revised approach to the CARB/EPA reciprocity with regard to evaporative and refueling emissions. A uniform national certification test fuel is important to the design of fuel/evaporative systems which will operate effectively across the U.S. Consistent with our desire to have a national program with vehicles designed for E15 as discussed in Section IV.D, and consistent with our treatment of exhaust emission standards, we are proposing a 9 RVP test fuel with 15 percent ethanol for all evaporative (hot soak plus diurnal, canister bleed, and leak emission standards) and refueling emissions testing. Thus, after the evaporative emissions fuel phase-in discussed above (ending after the 2019 MY), EPA will no longer accept test data on CARB test fuel and diurnal test temperatures. However, CARB has agreed to accept emission test data on EPA test fuel and temperature conditions for certification such that a uniform national program could still exist. This approach applies to all evaporative and refueling emission standards.

Generally, any vehicle family counted in the Tier 3 evaporative emission standards phase-in must be certified on Tier 3 certification test fuel using EPA test procedures. However, EPA recognizes that the California and federal evaporative emission standard programs would be starting from different bases and that the transition provisions are different in some ways. For example, the proposed EPA program starts in the 2017 MY but after that has the same basic program construct as CARB in 2018. However, prior to the 2017 MY, CARB has a ZEV program provision which will continue to bring zero evap technology into the fleet before 2017. To capitalize on this technology and to facilitate transition, we are proposing that any CARB evaporative emission test data from MYs 2015 and 2016 certifications could be used in federal certification for those evaporative/refueling families through the 2019 MY. Assuming these vehicle families meet Tier 3 evaporative emission standards and they are sold nationwide they could be included in the percentage phase-in calculations as Tier 3 vehicles. A good example of these would be vehicles meeting CARB Option 1 standards discussed above. If the vehicles do not meet the Tier 3 evaporative emission requirements manufacturers could potentially sell them nationwide, but they would not be included as compliant vehicles in the percentage phase-in calculation. EPA proposes a similar provision for a manufacturer which elects to use the CARB test procedures and test fuels to meet the refueling emission standard. That is, if a manufacturer uses evaporative emission test data from 2015 or 2016 model year CARB certifications to meet the Federal requirements in 2017-2019 model years, it may also use CARB refueling emission test data from model year 2015 and 2016 certifications for federal certification for the refueling requirements for those evaporative/refueling families through the 2019 MY. Any in-use testing on vehicle families certified on this data would be conducted using the CARB temperature conditions and test fuel and the CARB ethanol SHED adjustment value of 1.08 for 10 percent ethanol. However, by the 2020 MY all vehicles would have to be certified using EPA certification test fuel and test procedures. In the interim, the equivalency and acceptance by EPA of certification on California test fuels is dependent on our proposed 9 psi RVP level for the certification test fuel. Were we to require the more stringent level of 10 psi RVP more typical of E10 as discussed in section IV.D.1, testing using California test fuels and conditions would no longer be equivalent.

e. Evaporative and Refueling Emission Standards for Various Fuels

The evaporative and refueling emission standards today apply in different ways to different fuels. In the case of gasoline, all the standards apply and testing is required for certifying all vehicles. Evaporative emission standards do not apply for diesel-fueled vehicles; the refueling standards apply to diesel-fueled vehicles, but manufacturers can get EPA approval to omit testing for certification. For other fuels, there is a mix of standards applying or not applying, and if standards apply, testing is either required or not required. The statutory provisions in this regard are straightforward: Clean Air Act section 202(k) specifies that gasoline-fueled vehicles must be certified to evaporative emission standards, and section 202(a)(6) specifies that all motor vehicles be certified to refueling emission standards. This raises two questions. First, we request comment on using this rulemaking as the proper context for applying the refueling standards to vehicles powered by every kind of fuel. Where standards do not apply today (natural gas, fuel cells, electric, etc.), we would expect to waive test requirements for certification, so this would not be any substantial burden. Dedicated ethanol-fueled vehicles would face a new requirement, but we are not aware that there are any such vehicles today.

Second, we have the discretion to apply evaporative emission standards to vehicles powered by fuels other than gasoline. The standards expressly do not apply for diesel fuel. By omission, the standards do not apply for dedicated ethanol-fueled vehicles, fuel-cell vehicles, and electric vehicles. The standards apply for natural gas and liquefied petroleum gas even though these are sealed systems with no emission control systems for controlling evaporative emissions. We request comment on adjusting the regulations such that evaporative emission standards apply only to volatile liquid fuels, which is the approach we have taken for nonroad applications (see, for example, 40 CFR 1060.801). Under this approach, diesel fuel would continue to be excluded from standards because it is nonvolatile. This approach would also exclude natural gas and liquefied petroleum gas because they are not liquid fuels at atmospheric pressure.

5. Improvements to In-Use Performance of Fuel Vapor Control Systems

a. Background on Data Related to In-Use Performance

As part of the Compliance Assistance Program (CAP 2000) in-use verification program (IUVP) [295] the manufacturers began testing the evaporative emissions performance of small samples of in-use vehicles owned and used by the public. These regulations can be found at 40 CFR 86 1845-01, and 1845-04. In 2000, EPA extended this requirement to cover chassis-certified HDVs, which for these purposes are basically all HDGVs up to 14,000 lbs GVWR. [296] The in-use testing for evaporative emissions started in 2004 for 2001 MY LDVs, LDTs, and MDPVs and in 2008 for 2007 MY chassis certified HDGVs. Current IUVP data for evaporative emissions covers about 1800 vehicle tests. This data shows that when evaluated in the laboratory using certification test procedures, the vast majority (over 95 percent) of the vehicles pass the evaporative emission standards to which they were certified. While this information is indicative of good in-use performance, it has limitations. First, the test results are for small sample sizes. For the approximately 150 million LDVs, LDTs, MDPVs, and chassis-certified HDGVs produced between 2001 (the start of the IUVP program) and 2010 (latest available data), only about 0.001 percent of vehicles were tested. Second, the IUVP regulations place limits on the age/mileage for vehicle testing. Each model year is tested in two “batches,” nominally at the one and four year age points. One year old vehicles must have at least 10,000 miles and four year old vehicles must have at least 50,000 miles with at least one within the higher mileage group having an odometer reading of at least 75 percent of useful life (90,000 miles for most Tier 2 vehicles). The useful life period for LDVs and LDT1s/LDT2s is 10 years/120,000 miles, for LDT3s/LDT4s/MDPVs and complete HDGVs it is 11 years/120,000 miles. Thus, few firm conclusions can be drawn about full useful life emissions performance.

Recent evaporative emission testing conducted by EPA and others evaluated in-use LDVs and LDTs certified to meet the enhanced evaporative emission standards implemented for 1996 and later model years [297] as well as Tier 2 standards implemented for 2004 and later model year vehicles. Three Coordinating Research Council (CRC) programs (E-77-2/2b/2c), tested evaporative emission levels of vehicles with varying amounts of ethanol and levels of RVP in the gasoline test fuel. [298] These programs were unique in that a subset of the vehicle SHED tests were of vehicles with implanted leaks at the nominal minimal level of detection for OBD systems (0.020 inch) in three different locations in the fuel/evaporative control system. These tests showed hydrocarbon emission rates 2-10 times greater than for the same vehicles tested in the SHED without the leaks and showed an order of magnitude of difference depending on where the leak was introduced.

Furthermore, the CRC E-77-2 evaporative emissions test programs which looked at permeation in aged vehicles meeting EPA's enhanced evaporative emission control standards, introduced a new Static Test Procedure which pressurized the vapor space and activated the fuel pump during different portions of the SHED test, while the vent from the vehicle canister was routed to a trap canister outside of the SHED. By pressurizing the vapor space it was possible to determine if there was a vapor leak in the system by looking for a slope change in the vapor concentration in the SHED over time relative to permeation alone. Similarly, by activating the fuel pump it was possible to determine if there was a liquid leak in the system by looking for a slope change in the vapor concentration in the SHED over time relative to permeation alone. Out of the 15 randomly recruited vehicles in the program, seven of them displayed vapor and/or liquid leaks on one or more fuel ethanol/RVP combination (4 of these 7 were Tier 2 vehicles). A closer look at the data indicates that over the course of the study, which covered a two to four year period depending on the vehicle, the magnitude of the leaks increased with time.

These studies taken together were of concern to EPA with regard to the in-use performance of evaporative emission control systems because they indicated that leaks could be a large portion of the evaporative emissions inventory if they occurred in even a relatively small fraction of the in-use fleet. The key missing piece of information was how often the leaks of 0.020 inches or larger occur in the fleet.

To help us better understand this concern, EPA partnered with the Colorado Department of Public Health and Environment (CDPHE) and with CRC as an advisor for a pilot field study in Denver in the summer of 2008 to assess the frequency of high evaporative emissions vehicles in the fleet. The project identified high evaporative emission emitters through an innovative screening tool known as a remote sensing device (RSD). The vehicles were identified at the entrance to the Inspection and Maintenance (I/M) station as high evaporative emission emitters. The operators of these vehicles were asked to participate in further evaluation using a Portable Sealed Housing for Evaporative Determination (PSHED) in addition to a modified California method test procedure to locate the source of the high emissions indicated by the PSHED level. [299] The CDPHE continued to collect the same type of data in different locations in the Denver area for the next two summers.

Of the 5,830 vehicles which came through the Ken Caryl I/M station in 2009, 601 were identified as potentially high evaporative emitters using the RSD tool. [300] Of these, 84 vehicle owners agreed to be included in the PSHED evaluation that summer. Furthermore, 110 additional vehicles were recruited which were potentially low to marginally high evaporative emitters. [301] The study was structured to recruit higher evaporative emitting vehicles more heavily than lower emitting vehicles. Afterwards the percentages were adjusted to represent the actual mix in the fleet of light duty vehicles. Thus, it was determined that 10 percent of the fleet had evaporative emissions which exceeded a cut point reflecting an in-use evaporative emission rate of about 1 gram of total HC over 15 minutes (see Table 5-9 in the 2012 DeFries report referenced above). This value is approximately the emission rate that would be expected from a leak of 0.020 inches which is the detection standard for OBD II systems. [302]

An examination of the test data reveals two additional significant points. First, the data indicates a trend for greater frequency of leaks in older vehicles. This is not unexpected given the manner in which factors such as vibration, fuel quality, weather elements, corrosion, maintenance, and other operating conditions affect the durability of system components, fittings, and connections over time. Second, there were relatively few newer model year vehicles in the population surveyed. This is expected and almost unavoidable since the Colorado I/M program generally exempts vehicles which are four years old or newer. While it is reasonable to expect there to be a lower prevalence of leaks in newer vehicles, the lack of data for newer vehicles does not necessarily indicate that no problems exist in newer model year vehicles or that problems will not occur in the future with Tier 3 vehicles.

Since many of the vehicles in the sample group met OBD requirements for evaporative system leak monitoring, it was deemed useful to examine whether the OBD system identified the leak. As mentioned above, approximately 10 percent of the vehicles in the “adjusted fleet” had vapor leaks which were of the magnitude expected from a 0.020 inch or larger leak. Over the three years of study, there were a total of 180 SHED tests (either PSHED or laboratory SHED) on vehicles with OBD data collected in the I/M program. Of these 180 vehicles, 171 had the evaporative OBD monitors ready. Of these, 171 vehicles, 20 were found to have emission rates of 1 g/15 min in the PSHED (the emission rate linked to a 0.020” leak). Of these 20 vehicles only 3 came into the I/M test with an OBD diagnostic trouble code (DTC) set indicating an evaporative system problem. 303 304 A closer look, including field inspection comments, of the 20 vehicles shows that half were not expected to diagnose the problem because it was outside of the OBD system design capabilities. Of the vehicles which potentially should have set an evaporative DTC, at least 50 percent and perhaps as much as 70 percent of codes were not set on high evap emissions vehicles. The lack of codes being set for these vehicles may reflect OBD performance issues or allowances (known as enable criteria) in the OBD regulations regarding when the OBD evaporative emission leak monitoring system is not required to operate or situations when the monitor is otherwise not ready for what may be allowable reasons such as an allowable deficiency.

To better understand this issue EPA has examined evaporative emission system DTC and monitor ready information from I/M programs from Texas and California. [305] Since the data was gathered by the states under different protocols and time periods, the content of the data sets are not identical. To provide some degree of uniformity in our analysis, we examined the data for five MY (2000-2004) but within each state we only looked at calendar years of data beginning after the initial state I/M exemption period (2-4 calendar years depending on the state) had passed. Thus the analysis focused on I/M OBD information for calendar years 2004-2010. Examined together, the data generally indicates the following:

  • Depending on age, 0.3-2.5 percent of vehicles with evaporative monitors ready came into the I/M stations with evaporative related MIL or DTCs set.
  • The percent of vehicles with evaporative emission related MILs set increased by a factor of 2-4 over about 5 years.
  • Evaporative emission monitors were not ready for 3-16 percent of vehicles when arriving at the I/M station.
  • The percent of vehicles with monitors ready at the I/M station generally decreased by 3 to 7 percentage points over about 5-6 years; decrease was less for model year vehicles less than five years old.
  • While it varies by age, 60-80 percent of evaporative system DTCs are leak related.

There is no question of the value of OBD leak monitoring for evaporative systems, especially when owners complete needed repairs. Undoubtedly these percentages and thus in-use leak values would be higher without OBD evaporative system leak monitoring. However, this data suggests that EPA OBD regulations in place for 2000-2004 MY vehicles would not alone be sufficient to address concerns regarding the emission effects of vapor leaks from the fuel and evaporative control systems. [306]

In summary, information gathered from evaporative emissions testing conducted in the IUVP program indicates that relatively low mileage/newer vehicles perform well when evaluated under laboratory conditions. However, data gathered from in-use testing conducted by EPA, Colorado, and others indicates that as vehicles age some vehicles have a propensity to develop leaks in the fuel/evaporative system and that these leaks increase in size as the vehicles age. Beyond this, a review of OBD evaporative system leak monitor data from the I/M programs of two states revealed four important trends: (1) even when the OBD system identifies leaks owners do not always respond by getting the needed repair completed, (2) the fraction of vehicles with leaks identified by OBD increases as vehicles age, (3) vehicles sometimes are operating in conditions in which the OBD leak monitor is not ready to identify a potential problem, and (4) evaporative system leaks are the dominant DTC for vehicles with monitors ready and evaporative system DTC set.

The propensity for leaks in the vehicle fleet has the potential to reduce the benefits of the Tier 3 evaporative emission standards substantially. If on any given day, as few as five percent of Tier 3 vehicles had a leak(s) of 0.020 inches or greater this would cause in-use emissions equivalent to all of the projected emission reductions from the proposed Tier 3 evaporative emission standards on that day. [307] Thus, EPA is proposing three measures to address this issue: (1) An emission standard focused on reducing fuel/evaporative system vapor leaks over the vehicle useful life, (2) an upgrade to OBD emissions monitoring requirements to improve their role in identifying problems and improving in-use emissions performance, and (3) additions to the IUVP program focused on testing a broader sample of fuel/evaporative system leaks in IUVP than is done for evaporative emission standards alone.

b. Proposed Leak Emission Standard

The evaporative emission standards in this proposal will help to promote widespread use of improved technology and materials which will reduce evaporative emissions in-use. The proposed new requirement for a leak emission standard and procedure will help to ensure the durability of Tier 3 evaporative emission control systems nationwide.

Based on the information described above concerning evaporative emissions in-use, we believe a leak emission standard is necessary to meet our goal that vehicles meeting Tier 3 evaporative emission requirements not have fuel/evaporative system vapor leaks. Toward that end, we are proposing a leak emission standard that would have to be met both at new vehicle certification and in use. The leak emission standard would apply beginning in the 2018 MY to any vehicle certified to the Tier 3 evaporative emission standards or a CARB carryover vehicle counted toward the sales percentage phase-in requirements, including LDVs, LDTs, MDPVs, and complete HDGVs up to 14,000 lbs GVWR. The emission standard would be applicable for the same useful life period as for the evaporative emission standards that apply to the vehicle. The standard would apply to vehicles using volatile fuel (e.g., gasoline, FFV, and methanol fuel vehicles, but not diesel or CNG vehicles).

To be compatible with CARB OBD requirements being met by most manufacturers and the OBD requirements included in this notice, we are proposing that the leak emission standard be expressed in the form of a cumulative equivalent orifice diameter. We are proposing a value of 0.02 inches. [308] The standard basically requires that the cumulative equivalent diameter of any orifices or “leaks” in the system not exceed 0.02 inches. This is consistent with California OBD requirements (and those being proposed in this rule as well) that the OBD system be capable of identifying leaks in the fuel/evaporative system of a cumulative equivalent diameter of 0.020 inches EPA believes an emission standard at this level is feasible since earlier testing programs identified vehicles with essentially no leaks and it is essentially equivalent to that required for CARB OBD evaporative system leak monitoring. As discussed in the technological feasibility section above, the actions manufacturers will have to take to meet the proposed Tier 3 evaporative emission standards are expected to do more to address potential leak points and thus in a broader sense to improve in-use durability for evaporative control systems compared to vehicles meeting earlier or current evaporative emission standards.

The proposed leak emission standard would provide added assurance that as the manufacturers design for “zero evap” standards they also design the systems to avoid leaks over the full useful life. We are proposing a leak emission standard of 0.02 inches which with rounding is a bit less stringent than the 0.020 inch OBD fuel/evaporative system leak monitoring requirement. EPA believes this level of precision is sufficient to accomplish the air quality objective and yet provides some compliance margin between the emission standard and the monitor requirement which is reflected through multipliers for the exhaust emission standards monitored through OBD. EPA asks for comment and rationale on setting the standard at 0.02 inches equivalent diameter or the more stringent 0.020 inch equivalent diameter specified for OBD evaporative system leak monitoring. If finalized as proposed, the emission standard would be specified to one significant digit (e.g., 0.02 inches) but would have to be measured and reported to at least two significant digits.

The proposed leak emission standard would apply at the time of certification as well as during confirmatory and in-use verification program testing. We do not expect that new vehicles being certified would have a leak problem, and since a vehicle with a leak would likely fail the evaporative emissions SHED test, there is little value in mandating a leak test at certification. Thus, EPA proposes to allow manufacturers to attest to compliance with the leak emission standard at certification.

To implement the proposed leak emission standard within the current regulatory structure a few minor changes are needed. First, current EPA regulations such as those at § 86.098-24, specify criteria for evaporative/refueling emission families. EPA believes this basic structure is appropriate for the leak emission standard, with the additional criteria that vehicles in the same evaporative/refueling family must use the same basic approach to OBD leak detection. Significantly different volume fuel tanks would likely also be a family determinant, but we believe this is already covered by the evaporative/refueling family criteria. Second, since the leak emission standard is a pass/fail requirement and not an emission rate, there is no requirement for the application of a deterioration factor. Third, EPA proposes to require that the manufacturers recommend one or more leak entry test points for each family. This point should be outside of the gas cap/fillpipe area, since our experience indicates that testing could always be done through that point of entry to the fuel/evaporative system.

EPA asks for comment on the timing, form and level of the proposed emission standard. EPA believes that linking the timing of the proposed leak emission standard to the implementation of proposed Tier 3 evaporative emission standards in 2018 provides adequate lead time and is consistent with the technical rationale supporting the feasibility of the Tier 3 evaporative emission standard.

c. Proposed Leak Emission Standard Test Procedure

In order to implement a new leak emission standard, a leak test procedure is required. The fundamental concepts underlying fuel/evaporative system leak test are not new to the manufacturers. There is already a simple leak check in40 CFR 86.608-98(a)(xii)(A) and in the past at least three states included a fuel/evaporative system pressure leak test in I/M programs. More importantly, all LDVs, LDTs, MDPVs and HDGVs manufactured today have the onboard capability to run a pressure or vacuum leak based check on the vehicle's evaporative emission system as part of OBD evaporative system leak monitoring. These systems employ either positive or negative pressure leak detection pumps or operate based on natural vacuum for negative pressure leak detection. EPA is proposing a test based on a similar concept of placing the system under a slight positive pressure (but from an external source), measuring the flow needed to maintain that pressure in the fuel/evaporative control system, and converting that flow rate to an equivalent orifice diameter. With regards to the test procedure we will first discuss where the leak test could occur in the FTP test sequence. We will then discuss how the test is proposed to be conducted.

First with regard to when the test would be conducted within the current FTP sequence we are proposing that it be inserted immediately following the first two preconditioning steps within the FTP sequence (see Figure B96-10 in 40 CFR 86.130-96). Thus, the vehicle preconditioning steps for the leak test would be: (1) fill the vehicle fuel tank to 40 percent of capacity using the appropriate certification test fuel and then (2) let the vehicle soak for a minimum of a six hour period at a temperature in the range of 68-86 °F. EPA proposes that the test be conducted with 9 RVP E15 test fuel for both certification and IUVP. This is the same preconditioning that is called for today in 40 CFR part 86 subpart B for exhaust, evaporative, and refueling emissions testing. After preconditioning is complete, the leak test would be conducted and the test sequence could then proceed as prescribed in subpart B or testing terminated if the purpose was only to conduct leak testing. EPA believes this modest level of preconditioning is sufficient to create standard conditions which enable repeatable and reliable measurement results. Preconditioning could not include any prescreening for leaks nor would any tightening of fittings or connections be permitted.

After preconditioning is complete, manufacturers would then run the leak test. Each complete test would involve running the test procedure at one entry point in the system. Presumably this would be either near the back of the fuel system (perhaps near the gas cap) or near the front of the fuel system on the pressure side of the locations near where the system is sealed (perhaps at the canister vent). If the fuel/evaporative system has an imbedded evaporative system test port then that point could be used. Alternatively, manufacturers could also develop a test rig such as a “fill pipe extension” which would screw into the fill pipe opening using cap threads at one end and on the other end have threads to screw the fill pipe vehicle cap in place. Within this extension there would be an access port for the leak test equipment to be attached. Thus, the full system could be tested without any direct intrusion or the need for a separate gas cap assessment. The manufacturer would have to specify the test point at the time of the pre-certification meeting. If the manufacturer selected an entry point which required the fuel cap to be removed, then the cap would have to undergo a separate test as is now done in many I/M stations. [309] In this case, tests from both points combined must pass the proposed emission standard.

The procedure would be conducted as follows:

  • Calibrate the testing apparatus and otherwise verify testing apparatus is ready and able to complete the procedure
  • Seal fuel system so as to pressure test entire system (purge valve, cap, etc.)
  • Attach test apparatus to vehicle's fuel system at selected test point
  • Pressurize fuel system with nitrogen or another inert gas to at least 2.4 kilopascals (kPa)
  • Allow flow and pressure to stabilize in accordance with specification provided in the proposed regulatory text
  • Calculate effective leak orifice diameter from measured output flow rate and temperature and pressure data or use apparatus with built in computer providing an equivalent digital readout. Calculate to the nearest 0.01 inch.
  • Calculated effective orifice diameter must be less than or equal to the standard
  • If leak test is conducted at the fuel cap then manufacturer must also show evidence that the vehicle's fuel cap is performing properly. [310]
  • EPA is seeking comment on requiring two separate test points one near the evaporative canister and the other near the fuel cap. Furthermore, we are specifically proposing that in some cases two separate test points in the locations mentioned above would be required. This would especially be important if the fuel cap/fill neck area is isolated from the rest of the fuel/evaporative system as a result of the 40 percent fill or if dual tanks are not otherwise connected through vapor lines. Of course, dual tank, dual canister systems would have to be evaluated as separate systems. Tests could be void if the test apparatus fails, becomes disconnected, fails to maintain a stable flow rate or pressure, or the test was stopped before completion due to safety considerations or some other relevant vehicle issue.

The test procedure presented above is based on current fuel system designs. In the future, it is reasonable to expect changes in designs of the fuel systems such that the procedure above may need adjustment. EPA would, of course, monitor these fuel system changes and modify the test procedure provisions as needed. Furthermore, current EPA regulations (see § 1065.10(c)) contain provisions which provide the opportunity for manufacturers to seek approval for special or alternate test procedures if from a practical perspective their systems cannot be evaluated under EPA requirements or they have an approach deemed equivalent or better. EPA would make such provisions for the leak emission standard testing requirement. Any such special or alternative procedures would have to be reported under § 86.004-21(b)(9). [311]

d. Proposed Onboard Diagnostic (OBD) System Regulation Changes

EPA has its own OBD regulations which are similar but not identical to CARB's. EPA first adopted OBD requirements for 1994 and later model year LDVs and LDTs. While EPA has extended its requirements from LDVs and LDTs to larger and heavier vehicles, [312] EPA's last broad upgrade to its basic OBD regulation was in the 2005 timeframe. Since that time, CARB has adopted and the manufacturers have implemented a number of provisions to enhance the effectiveness of their OBD programs. These provisions include new requirements for OBD evaporative system leak detection as well as provisions to help insure that systems are built and operate as designed over their full useful life, give reliable results (find and signal only true deficiencies), and operate frequently during in use operation. It is permitted in current EPA regulations and common practice for the industry to certify their OBD systems with CARB and for EPA to accept CARB OBD certifications as satisfying EPA requirements. EPA is proposing to continue that practice but to upgrade our regulations to be consistent with the latest CARB regulations.

EPA has reviewed the current CARB regulatory requirements related to OBD (see California Code of Regulations (CCR) § 1968.2 dated May 18, 2010) and, as discussed below we are proposing to adopt most of these provisions with the Tier 3 program. We are proposing this for two basic reasons. First, this is consistent with the goal of a national program and one vehicle technology for all 50 states. Second, implementation of these requirements is now demonstrated technology and compliance with these requirements is common within the industry today. Thus, the added burden is minimal. Furthermore, OBD has the advantage of running frequently on in-use vehicles to identify potential exhaust and evaporative system performance problems, so adopting these provisions would create the opportunity for OBD to serve a more prominent role in ensuring the proposed Tier 3 emission standards are met in-use.

There is an important link between OBD provisions related to evaporative emission control system leak monitoring and the proposed leak test emission standard. They each provide an important incentive to design fuel/evaporative systems with fewer propensities to develop leaks in use but each addresses the issue from a different perspective. The distinction is that the proposed leak emission standards prohibits leaks of greater than 0.02 inches cumulative equivalent diameter, while the proposed OBD evaporative system leak monitoring provision would require that the OBD system find leaks larger than 0.020 inches cumulative equivalent orifice diameter and notify the owner, but with no inherent obligation to repair the problem. Thus adopting a 0.020 inch cumulative equivalent orifice diameter would align these two programs and, as will be discussed below, creates the potential for an optional leak detection test procedure for in-use testing.

To be more specific, we are proposing to update our OBD regulations to be consistent with current California OBD requirements add two new requirements and retain three minor exceptions. These changes would be fully effective in the 2017MY, but EPA asks comment on whether the requirement should be linked to be effective with certification to any of the Tier 3 emission standards (either exhaust or evaporative) or phased in for the 2017 model year for LDVs and LLDTs and the 2018 MY for the HLDTs, MDPVs, and HDGVs up to 14,000 lbs GVWR. [313] EPA would continue to accept certifications with CARB OBD requirements as satisfying EPA OBD requirements. We are proposing to incorporate by reference section 1968.2 of the California Code of Regulations as discussed below. This would include paragraphs (c) through (j) in their entirety. These paragraphs are entitled: (c) Definitions, (d) General requirements, (e) Monitoring requirements for gasoline/spark ignited engines, (f) Monitoring requirements for diesel/compression ignition engines, (g) Standardization requirements, (h) Monitoring system demonstration requirements for certification, (i) Certification documentation, (j) Production vehicle evaluation testing. The substance of many of these provisions is already contained in current EPA OBD requirements for LDVs, LDTs, MDPVs, and complete HDGVs less than 14,000 lbs GVWR. [314]

The most noteworthy changes we are proposing are summarized below. The CCR below is the California Code of Regulations cite for each pertinent provision.

  • EPA proposes to add a 0.020 inches leak detection monitoring threshold upstream of the purge valve for all 4 vehicle categories LDV, LDT, MDPV, and complete HDGVs up to 14,000 lbs GVWR except for those with fuel tanks larger than 25 gallons capacity (see CCR 1968.2(e)). OBD leak monitoring systems would have to identify, store, and if required signal any leak(s) equal to or greater than 0.020 inches cumulative equivalent diameter. This would thus include diagnostic trouble codes (DTC) P0440, P0442, P0446, P0455, P0456, and P0457.
  • EPA proposes to incorporate by reference the full array of rate based monitoring requirements (see CCR1968.2 (d)). Meeting the rate based monitoring requirements will help to insure that, even with enable criteria, the exhaust and evaporative system monitors run frequently enough that on average a problem would be identified and signaled to the owner in operation within two weeks. This will help to improve the fraction of time monitors are ready to find a potential problem.
  • EPA proposes to incorporate by reference provisions regarding monitoring system demonstration requirements for certification. We are proposing to incorporate by reference CARB provisions in this area and to accept submissions to CARB for purposes of compliance demonstration (see CCR 1968.2(h)). Adopting current CARB monitoring system demonstration requirements assures that monitoring systems operate as designed when installed on certification vehicles.

We also propose that this certification include a requirement for manufacturers to demonstrate the ability of the OBD leak monitoring system to detect a 0.020 inch leak. Current CARB protocols do not require that manufacturers demonstrate that the certification vehicle can find a vapor leak in the fuel/evaporative system. We are proposing to add a requirement that manufacturers must demonstrate for certification that the OBD system can find and report the implanted leak would help to ensure the OBD system's capability to function as designed and for the OBD-based leak based evaporative system leak to be used as an optional test procedure for in-use testing for the proposed leak emission standard. We are proposing that this be added for the same vehicles now required for monitoring system demonstration requirements for certification under CARB OBD regulations. Since the CARB regulation requires only a relative few vehicle models each year per manufacturer, we propose that manufacturers be given the option to either test the remainder for an implanted leak in the fuel/evaporative system or certify by attestation that each of their remaining families meets the requirement based on development and other information.

  • EPA proposes to incorporate by reference the CARB production vehicle evaluation data program. This program requires manufacturers to demonstrate that the OBD system functions as designed and certified when installed on production vehicles. (see CCR 1968.2(j))
  • For the OBD evaporative system leak monitoring requirement, EPA proposes a scan readable function (a new PID in Service $01 of SAE J1979) which could be used to indicate or ascertain the distance traveled since the OBD leak monitoring diagnostic was last completed successfully and if the system passed or failed (identified any leak above 0.020 inches) during that monitoring event (unless it is otherwise already required in other OBD system modes). Updating this PID this would be based on SAE J1979 mode 6 ($06) test results: “Request On-board Monitoring Test Results for Specific Monitored Systems.” With this proposed requirement, the PID distance would be initialized to maximum range of NV RAM initialization (such as battery disconnect or controller reprogramming) and code clear. As a result, in the event that a vehicle had a memory clear event in the past, but has not had sufficient operation for the evaporative system to be evaluated, the scan readable mileage function would indicate that the system had not completed a full leak detection of the evaporative control system within the last 750 miles (1200km). OBD systems already maintain information for active, pending, historic and permanent codes. This would be a modest upgrade to this requirement which would enable the use of the OBD-based evaporative system leak monitor with the IUVP program as discussed below. See CCR 1968.2 (g) for information related to code storage. EPA seeks comment on alternative equivalent approaches (e.g., a scan readable mileage stamp or flag traceable to mileage indicating when the full OBD leak monitoring protocol was last completed successfully and the result (p/f)) which accomplish the same objective and whether this capability should be optional for the 2017 MY since this requirement is designed to enable the use of OBD in leak emission standard testing and that standard is proposed to begin in the 2018 MY.
  • The minor exceptions which are contained in EPA's current OBD regulations are proposed to be continued. Compliance with 13 CCR 1968.2(d)(1.4), pertaining to tampering protection is not required. Also, the deficiency provisions of 13 CCR 1968.2(k) would not be adopted. In addition, demonstration of compliance with 13 CCR 1968.2(e)(15.2.1)(C), to the extent it applies to the verification of proper alignment between the camshaft and crankshaft, would apply only to vehicles equipped with variable valve timing. For all model years, the deficiency provisions of paragraph (i) of the current regulations apply only to alternative fuel vehicle/engine manufacturers selecting this paragraph for demonstrating compliance.

If adopted, these proposed changes, taken together would improve the performance, reliability, general utility, and effectiveness of OBD systems for Tier 3 exhaust and evaporative emission controls. Furthermore, if adopted, these changes create the opportunity for OBD evaporative system leak monitoring systems to serve a more prominent role in ensuring compliance with the leak emission standard. EPA believes that they could be implemented for minimal cost since most manufacturers are meeting them today and will have to for LEV III vehicles. However, EPA requests comment on applying the proposed new OBD requirements to small business vehicle manufacturers and independent commercial importers.

As discussed below, the proposed OBD requirements would apply to small entities and independent commercial importers (ICI) in the 2022 MY. Small alternative fuel converters would still be able to meet the OBD requirements using the provisions of 40 CFR part 85 subpart F. Finally, it should be noted that as CARB updates its OBD regulations in the future EPA would consider these changes and propose to adopt them or incorporate them by reference, if appropriate. In fact, CARB is currently proposing some changes to its OBD program in response to the LEV III program exhaust emission standards. [315] We request comment on incorporating these changes into this rule or other rules in the future. We also would generally expect to continue the current practice allowed by EPA regulations which is for EPA to accept CARB OBD certifications as satisfying EPA requirements provided that they include at least all of the requirements covered by the EPA regulations.

e. In-Use Verification Program (IUVP) Requirements for the Leak Emission Standard

i. Introduction

We believe it is important to identify leaks since vehicles with leaks would be expected to have daily emission rates above the proposed Tier 3 evaporative emissions standards and the Colorado data suggests a propensity for the diameter of vehicle leak orifice to get larger over time and thus to have even higher emissions. This is also important because evaporative leak emissions occur virtually every day whether the vehicle is driven or not. Thus identifying potential leak problems will be important to capturing the emission benefits of the proposed evaporative emission requirements.

Toward that end, EPA is proposing to include assessment of compliance with the leak emission standard within the IUVP program. We considered expanding the evaporative emission testing portion of the IUVP program as a means to assess leaks, but we decided to focus on the leak emission standard because it is less burdensome and is cost effective for accomplishing the objective. EPA believes adding a leak test requirement does not create an unreasonable burden. The draft test procedure described above is simple to run, inexpensive to conduct in terms of equipment and labor, and can be completed relatively quickly compared to an evaporative emissions test. However, we are retaining the evaporative emissions testing requirements currently in IUVP to monitor broader evaporative control system effectiveness (e.g., purge, canister control efficiency, permeation).

ii. IUVP Test Requirements

We are proposing that the leak emission test be conducted for each and every vehicle assessed in IUVP for exhaust emissions under 40 CFR 86.1845.04. This would begin for 2018 MY certifications for vehicle families meeting the proposed new leak emission standard. This would include the low and high mileage tests for any exhaust vehicle evaluated for exhaust emissions plus a requirement that there be at least one representative of each evaporative/refueling/leak family evaluated at each year point. We are proposing this approach to implementing IUVP for the leak emission standard in lieu of creating a new set of requirements which would require yet another set of vehicles to be procured for testing. We are not proposing to include the leak test with any evaporative emissions test in IUVP, since a leak would be evident in the results of the evaporative emissions test.

The current IUVP regulations at § 86.1845-04, Table S04-07, call for test sample sizes on a sliding scale based on annual vehicle sales by test group. This can vary from zero for very small sales test groups to six vehicles for test groups with sales exceeding 250,000. There are more exhaust emission test groups than there are evaporative/refueling/leak test families and exhaust emission test groups may cover one or more of the same evaporative/refueling/leak families, so we would expect to receive multiple leak emission test results for most evaporative/refueling/leak families. This will expand the amount of IUVP data we receive in this important area and improve our ability to assess the overall leak performance for a given evaporative/refueling/leak family and the fleet as a whole.

As discussed above, EPA believes that the fuel and evaporative control system leaks are heavily influenced by age as well as design and other factors. EPA would consider extending the age point for leak emission testing for IUVP beyond the four year point to better assess this effect. However, in the past, manufacturers have expressed concern about the implications of testing older vehicles and about finding vehicles still within their warranty and recall liability periods. EPA asks comment on the viability of extending leak emission IUVP testing beyond the nominal four year point (e.g., six to eight years). We recognize that there are cost and vehicle procurement issues, but the Colorado data strongly suggests a relationship between vehicle age and the propensity for the development of leaks.

iii. Assessment of IUVP Leak Emission Standard Test Results

The current regulations contain provisions addressing follow-on testing requirements for exhaust emissions for vehicles which fail to meet various performance thresholds within IUVP (see 40 CFR 86.1846-01). As mentioned above, we expect that it will be common to get more than one leak emission test result over the course of each model year's mileage testing point for each evaporative/refueling/leak family as a result of the requirement to assess leaks with each exhaust IUVP test. However, the proposed leak emission standard is basically pass/fail at 0.02 inches and it is difficult to establish a threshold criteria for a pass/fail standard such as has been done for exhaust emissions where there is a multiplier applied to the level of the individual exhaust emission standard.

Given the importance of the leak emission standard in assuring in-use evaporative emissions control, we are proposing a set of criteria for assessing leak emission standard results from IUVP. These criteria can be summarized as follows for each low and high mileage test point for each model year tested:

  • lf 50 percent or more of all vehicles evaluated in an evaporative/refueling/leak emission family for any given model year pass the leak emission standard, testing is complete. This applies to cumulative testing for that family throughout the model year for that mileage group. This is consistent with the exhaust emission requirements for IUVP and EPA believes it is reasonable since vehicles are tested in the “as received” condition from consumers.
  • If only one representative of the evaporative/refueling/leak family is tested in a mileage group for that model year's vehicles and it passes the leak emission standard testing is complete. If that vehicle does not pass the leak emission standard a manufacturer may test an additional vehicle to achieve the 50 percent rate.
  • If an evaporative/refueling/leak emission family fails to achieve the 50 percent rate, it is presumed that the family will enter into In-Use Confirmatory Testing Program (IUCP).

Before IUCP begins, the manufacturer may ask for engineering analysis discussions with EPA to evaluate and understand the technical reasons for the testing outcomes and the implications for the broader fleet. Technical information for these discussions could include but would not be limited to detailed system design, calibration, and operating information, technical explanations as to why the individual vehicles tested failed the leak emission standard, and comparisons to other similar families from the same manufacturer. Relevant information from the manufacturer such as data or other information on owner complaints, technical service bulletins, service campaigns, special policy warranty programs, warranty repair data, state I/M data, and data available from other manufacturer specific programs or initiatives could help inform understanding of implications for the broader fleet. As part of this process a manufacturer could elect to provide evaporative emissions SHED test data on the individual vehicle(s) that did not pass the leak emission standard during IUVP. With an adequate technical basis, the outcome of this engineering analysis discussion could result in an EPA decision not to require IUCP testing.

We would propose to operate within the basic structure of the IUCP program in the current regulations. Prior to commencing IUCP testing the manufacturer, after consultation with EPA submits a written plan describing the details of the vehicle procurement, maintenance, and testing procedures. This plan could include inclusion of a hot soak plus diurnal SHED test to supplement leak emission test results. We propose that EPA must approve this plan before testing begins. As prescribed now in the IUCP regulations for exhaust, if five vehicles were tested and all passed the leak emission standard then testing would be complete. If all five vehicles did not pass, then five more would be tested. More vehicles could be tested at the manufacturer's discretion but all testing would have to be completed within the time period specified in the regulations today. EPA and the manufacturer would then enter into discussions regarding interpretation, technical understanding, and compliance/enforcement implications of the test results, if any.

iv. Proposed Optional Test Procedure Approach for IUVP/IUCP

Assuming implementation of the OBD regulation changes proposed in Section IV.C.5.d, above, EPA is proposing an optional approach to a portion of the leak emission test procedure discussed in Section IV.C.5.c. This optional testing approach would be included in the proposed IUVP/IUCP testing program for the leak emission standard, but would not be used for certification testing for the leak emission standard. It would be considered an approach which could be used by the manufacturers to assess compliance with the leak emission standard. EPA could also use this procedure for conducting assessments and asks for comment on using this procedure for compliance purposes with a 0.02 inch cumulative equivalent diameter orifice standard.

Under this optional approach manufacturers would be able to rely upon the operation of their OBD evaporative system leak detection hardware and operating protocols in lieu of running the stand alone in-use leak test to check for the presence of a 0.02 inch leak in the fuel/evaporative system. This approach relies on the leak emission standard equivalent orifice diameter being established at the same level as proposed for OBD (0.020 inches). Thus, the IUVP/IUCP protocol would be modified and simplified to expedite completion of testing and reduce costs.

Quite simply, if a vehicle is brought in for IUVP or IUCP testing and a scan tool query of the onboard computer indicates that the vehicle had successfully completed a full OBD-based evaporative system leak monitoring check within the last 750 miles and no evaporative system leak problems for any diameter above 0.020 inches was indicated (diagnostic trouble codes P0440, P0442, P0446, P0455, P0456, and P0457), the vehicle would be been deemed to have met and passed the leak emission standard test requirement. However, if the system had not successfully completed a full OBD-based evaporative system leak check within 750 miles with no problem indicated then the manufacturer would have the option to run its OBD-based evaporative system leak check in the laboratory after prescribed preconditioning. This OBD-based approach is sometimes used in auto manufacturer dealerships and repair facilities to diagnose and fix evaporative system leaks found by the OBD system. If the vehicle completes the full OBD-based leak test in the laboratory then the vehicle's pass/fail results for the 0.02 inch cumulative equivalent diameter orifice would be based on the OBD test result. This optional protocol could apply to every leak emission standard test after certification unless not approved by EPA for IUCP under 40 CFR 1846.01(i). Replicate tests would not be required or allowed but void tests could be repeated.

Furthermore, EPA proposes to allow the manufacturer to run the stand alone EPA leak test in several situations. First, manufacturers could conduct the stand alone test to confirm that a problem identified by the OBD-based evaporative system monitoring leak check was a leak and not a problem with the OBD leak monitor itself. Second, a manufacturer could run the stand alone EPA leak test to confirm that the leak value identified by the OBD system was truly above the level of the proposed leak emission standard. Third, it could be used for vehicles which had not successfully completed a full OBD-based evaporative system leak monitoring check within the last 750 miles. Fourth, it could be used to confirm that a DTC set within the last 750 miles actually indicated the presence of a leak(s) greater than the proposed standard. However, if a manufacturer elected to use only OBD-based evaporative system leak based monitoring in its IUVP testing; these results would be the basis for decisions regarding IUCP. As is required in the current IUVP regulations, all test data whether OBD based or based on EPA's stand alone test procedure would have to be reported to EPA.

There could be some advantages to this option since it employs a pressure/vacuum approach manufacturers understand and creates positive/negative pressures manufacturers have accommodated within their fuel/evaporative system. One potential downside is that under current designs vehicle engines would have to be operating to create the pressure or vacuum and because the engine is operating this would require the OBD-based leak test to be stand alone after the preconditioning sequence is complete. This would be more challenging for natural vacuum leak detection systems unless extended driving was involved to create the fuel system heat needed for a natural vacuum event or this was done through a climate chamber or SHED based diurnal heat build.

Allowing for this approach raises at least two implementation questions. The first is related to the value of conducting the OBD-based test for a vehicle with an active or pending leak DTC already set in the computer and/or an MIL indicated. In this case, EPA would permit the manufacturer to run the OBD-based leak test and/or the stand alone EPA leak test or concede that the vehicle would not pass the leak emission standard and count the result. Second is the question of gas caps. This is among the most common codes found in OBD records and is often related to operator error such as not tightening the gas cap properly. Codes of this nature have no value in this leak emission assessment, so a manufacturer would be permitted to correct the problem before testing and clear this OBD code before testing or run the stand alone EPA leak test.

6. Other Initiatives

This proposal includes consideration of several amendments or clarifications to existing requirements related to evaporative emissions. As part of this process, the following provisions warrant adjustment, clarification, or correction:

  • Even though the evaporative emission standards in 40 CFR part 86 apply to the same engines and vehicles that must meet exhaust emission standards, we require a separate certificate for complying with evaporative and refueling emission standards. An important related point to note is that the evaporative and refueling emission standards always apply to the vehicle, while the exhaust emission standards may apply to either the engine or the vehicle. Since we plan to apply evaporative/refueling/leak emission standards and the recently adopted greenhouse gas standards to vehicle manufacturers, we believe it would be advantageous to have the regulations related to their certification requirements written together as much as possible to reduce burden and increase efficiency. We are therefore proposing to move the emission standards and certification requirements from 40 CFR part 86 to the new 40 CFR part 1037, which was originally used for greenhouse gas standards for heavy-duty highway vehicles. This is not intended to change the requirements that apply to these vehicles, except as noted in this section. We propose to make the provisions in part 1037 effective with model year 2014.
  • As described in Section VI.C.3, we are proposing to allow for certifying vehicles above 14,000 lbs GVWR based on an engineering analysis instead of new testing (as is currently allowed for vehicles at or above 26,000 lbs GVWR). We are also proposing to clarify the provisions describing how the certification process plays out for these vehicles.
  • Section 86.1810-01 contains specifications addressing whether diesel fuel vehicles can be waived from demonstrating compliance with the refueling emission standard through testing. In the current regulation the potential for a waiver from testing depends on the diesel fuel having an RVP equal to or less than 1 psi and the fuel tank having a temperature which does not exceed 130 °F. We have examined this provision and are proposing to withdraw the fuel temperature limit specification. Short of fuel spillage in the SHED, EPA sees no likelihood that a diesel fueled vehicle with RVP less than 1 psi could fail the refueling emission standard even at fuel tank temperatures above 130 °F. This is due to the inherently low vapor pressure of diesel at these temperatures and the likelihood that vapor shrinkage conditions will occur in the fuel tank during refueling since the dispensed fuel will be cooler than the tank fuel.
  • When adopting the most recent evaporative emission change we did not carry through the changes to the regulatory text applying evaporative emission standards for methanol-fueled compression-ignition engines. The proposed regulations correct this oversight.
  • We are proposing provisions to address which standards apply when an auxiliary (nonroad) engine is installed in a motor vehicle, which is currently not directly addressed in the highway regulation. The proposed approach would require testing complete vehicles with any auxiliary engines (and the corresponding fuel-system components). Incomplete vehicles would be tested without the auxiliary engines, but any such engines and the corresponding fuel-system components would need to meet the standards that apply under our nonroad program as specified in 40 CFR part 1060.
  • We are proposing to remove the option for secondary vehicle manufacturers to use a larger fuel tank capacity than is specified by the certifying manufacturer without re-certifying the vehicle. Secondary vehicle manufacturers needing a greater fuel tank capacity would need to either work with the certifying manufacturer to include the larger tank, or go through the effort to re-certify the vehicle itself. Our understanding is that this provision has not been used and would be better handled as part of certification rather than managing a separate process. We are proposing corresponding changes to the emission control information label.
  • Since we adopted evaporative emission standards for gaseous-fuel vehicles, we have developed new approaches for design-based certification (see, for example, 40 CFR 1060.240). We request comment on changing the requirements related to certifying gaseous-fuel vehicles to design-based certification. This would allow for a simpler assessment for certifying these vehicles without changing the standards that apply.
  • With regard to OBD, we note also that under § 86.1806-01(b)(4) OBD systems must have the ability to detect absence of purge air flow from a complete evaporative emission control system. This is clearly important because the proper operation of an integrated evaporative/refueling emission control system depends on purge. Similarly, evaporative/refueling system operation depends on the presence, proper adsorption/desorption performance, and sustained working capacity of the activated carbon canister. It is thus curious to observe that the current OBD provisions do not directly address the activated carbon canister in any way. The absence of the canister would likely be noted as a gross leak and/or a problem with purge. Nonetheless, we are seeking comment on a provision which would require the OBD system to sense for evidence of ongoing adsorption and desorption of hydrocarbon vapors. These could both be sensed by changes in canister carbon bed temperature or perhaps for the presence of vapor in the fuel going to the intake manifold after a cold start or refueling event. In some cases, EPA believes these parameters could be monitored by hardware and sensors now on most vehicles and thus this might be primarily an OBD software change. Similarly, we are seeking comment on whether the operation of a vacuum pump or similar device used to assist or supplement vehicle engine vacuum purge or any device otherwise used to enhance or control purge flows, rates, or schedules should be required to be monitored as part of OBD.
  • With future technology, we anticipate a trend toward the implementation of fuel tanks with higher operating pressures and in some cases fuel tanks which are sealed to the atmosphere during normal operation. Data available to EPA indicates that a leak in such a system will result in substantial emissions relative to very low pressure systems which employ running loss control strategies and an activated carbon canister as part of the methodology to control vapor emissions. [316] Based on this concern, we are seeking comment on the feasibility and cost of requiring the OBD leak detection monitoring system to detect and signal the presence of a smaller diameter orifice than proposed for non-pressurized systems (∼ 0.010 inch) upstream of the purge valve for all 4 vehicle categories LDV, LDT, MDPV, and complete HDGVs up to 14,000 lbs GVWR. This would apply to any vehicle with a designed in-use operating pressure in excess of 0.36 psi (10 inches water). As a means to prevent a sealed fuel tank from venting leaks directly to atmosphere, we ask for comment on an added requirement that the fuel vapor vent valve be set to the open position at key off (and vent to the canister) if the OBD system detected a leak and triggered an MIL related to any leak greater than a pre-established threshold. The vent open at key off concept for pressurized fuel systems would not be intended to disenable the OBD system from conducting its normal evaporative system check during operation. Furthermore, as discussed above, we are proposing a 0.020″ leak detection threshold for all systems. However, we are asking for comment on setting the threshold in the 0.010″-0.015″ range for pressurized systems. In the context of this request for comment, we ask for input regarding the feasibility of the smaller threshold, the effects of the vent valve open requirement on ORVR, and the repairability of leaks of less than 0.020″.

D. Emissions Test Fuel

1. Proposed Changes to Gasoline Emissions Test Fuel

In-use gasoline has changed considerably since EPA's fuel specifications for emissions testing of light- and heavy-duty gasoline vehicles were first set and last revised. Gasoline sulfur and benzene have been reduced and, perhaps most importantly, gasoline containing 10 percent ethanol by volume (E10) has replaced clear gasoline (E0) across the country. This has had second-order effects on other gasoline properties. In-use fuel is projected to continue to change with the implementation of the RFS2 program (e.g., the expansion of the number of retailers that offer E15) as well as today's proposed Tier 3 gasoline sulfur program. As a result, we are proposing to update our federal emission test fuel specifications not only to better match today's in-use fuel but also to be forward looking with respect to future ethanol and sulfur content. [317] The revised test fuel specifications would apply for exhaust emissions testing, fuel economy/greenhouse gas testing, and emissions testing for non-exhaust emissions (evaporative, refueling, and leak detection testing). The proposed gasoline specifications, found at § 1065.710, would apply to emissions testing of light-duty cars and trucks as well as heavy-duty gasoline vehicles certified on the chassis test, those subject to the proposed Tier 3 standards. [318]

We are not proposing changes to the exhaust or evaporative durability fuel requirements outlined in the provisions of § 86.113-04(a)(3), except to remove the minimum sulfur content (15 ppm) currently specified at § 86.113-04(a)(3)(i). Those provisions require that “Unless otherwise approved by the Administrator, unleaded gasoline representative of commercial gasoline that will be generally available through retail outlets must be used in service accumulation.” We would expect that manufacturers would use service accumulation fuels which are generally representative of the national average in-use fuels (or worst case for durability) during the model year which is being certified, including, for example, the ethanol content (for exhaust emissions), sulfur level, and fuel additive package. For exhaust emission bench aging durability programs as allowed under the provisions of § 86.1823-08(d) and (e), the bench aging program should be designed using good engineering judgment to account for the effects of in-use fuels on exhaust emissions, including the effects of future in-use fuels on catalytic converters, oxygen sensors, fuel injectors, and other emission-related components.

For evaporative emissions, durability fuel requirements are the same as for exhaust emissions (as outlined above), plus an additional requirement in the provisions of § 86.1824-08(f), that the service accumulation fuel “contains ethanol in, at least, the highest concentration permissible in gasoline under federal law and that is commercially available in any state in the United States. Unless otherwise approved by the Administrator, the manufacturer must determine the appropriate ethanol concentration by selecting the highest legal concentration commercially available during the calendar year before the one in which the manufacturer begins its mileage accumulation.” Thus, as E15 in-use fuel becomes progressively more available, we would expect that E15 service accumulation fuel would be used for whole vehicle evaporative durability programs. Similarly, evaporative bench aging durability programs allowed under the provisions of § 86.1824-08(d) and (e), should be designed using good engineering judgment to account for the durability effects of in-use fuels on evaporative emissions, bleed emissions, and leakage emissions.

Where possible, we are proposing changes consistent with the CARB's planned LEV III gasoline test fuel specifications. [319] Below is an overview of some of the key changes. A summary of the proposed test fuel specifications is provided in Table IV-21. For more information on how we arrived at the proposed test fuel property ranges and ASTM test methods, refer to Chapter 3 of the draft RIA.

  • Ethanol—adding a 15 volume percent ethanol specification to be forward-looking with respect to the maximum gasoline ethanol concentration Tier 3 vehicles could expect to encounter. EPA recently issued a waiver under section 211(f)(4) of the CAA permitting E15 to be introduced into commerce for use in MY2001 and newer light-duty motor vehicles. [320] While E15 is only commercially available at a limited number of fuel retailers, EPA believes it could become a major gasoline blend over the next 10-15 years given instability in crude oil pricing and growing RFS2 renewable fuel requirements. The use of E15 as the emission test fuel will help ensure that all future vehicles are capable of meeting Tier 3 emission standards while operating on E15.
  • Octane—lowering gasoline octane to around 87 (R+M)/2 to be representative of in-use fuel, i.e., regular-grade gasoline. Manufacturers could continue to use high-octane gasoline for testing of premium-required [321] vehicles and engines as well as for testing unrelated to exhaust emissions. Historically, the high octane rating of test fuel has not had any real emissions implications. However, as manufacturers begin introducing new advanced vehicle technologies (e.g., turbocharged downsized), this may no longer be the case. For those vehicles where operation on high-octane gasoline is required by the manufacturer, we would allow the manufacturer to test on a fuel with a minimum octane rating of 91 (R+M)/2 (in lieu of the proposed 87 (R+M)/2 general test fuel). According to the proposed regulations found at § 1065.710(d), vehicles or engines are considered to require premium fuel if they are designed specifically for operation on high-octane fuel and the manufacturer requires the use of premium gasoline as part of their warranty as indicated in the owner's manual. Cases where premium gasoline is not required but is recommended to improve performance would not qualify as a vehicle or engine that requires the use of premium fuel. For qualifying vehicles and engines, all emission tests must use the specified high-octane fuel. For vehicles and engines certified on high-octane gasoline, all EPA confirmatory and in-use testing would also be conducted on high-octane gasoline. All other test fuel specifications would be the same as those proposed in Table IV-21. We seek comment on the need for limiting the maximum octane of gasoline used in the certification of premium-required engines and vehicles.
  • Distillation Temperatures—adjusting gasoline distillation temperatures to better reflect today's in-use gasoline/E10. This includes minor T10, T90 and FBP adjustments based on AAM in-use fuel surveys and refinery batch test data, with additional adjustments to reflect future E15 performance (significantly lower T50 range). We seek comment on the appropriateness of the proposed distillation temperatures including the proposed 170-190 °F T50 range for an E15 fuel. For more information on how we arrived at the proposed distillation temperatures in Table IV-21, refer to Chapter 3 of the draft RIA.
  • Sulfur—lowering the sulfur content of test fuel to 8-11 ppm to be consistent with our proposed Tier 3 gasoline sulfur standards. The proposed 10-ppm annual average sulfur standard is expected to result in two-thirds less sulfur nationwide so it is appropriate to lower the gasoline test fuel specification in concert.
  • Benzene—setting a benzene test fuel specification of 0.6-0.8 volume percent to represent in-use fuel under our new MSAT2 regulations. [322] The MSAT2 standards, which took effect January 1, 2011, limit the gasoline pool to 0.62 volume percent benzene on average. Beginning July 1, 2012, no refinery may produce gasoline above 1.3 volume percent benzene on average.
  • Total Aromatics—lowering the aromatics content of test fuel to better match today's in-use gasoline/E10 and accommodate E15. According to AAM fuel surveys, the average aromatics content in gasoline has dropped 16 percent over the past decade due to ethanol blending. [323] Additional ethanol blending to produce E15 is expected to result in even greater aromatics reductions. Accordingly, we believe the proposed 19.5-24.5 volume percent test fuel specification is appropriate.
  • Distribution of Aromatics—in addition to total aromatics and benzene, we are proposing regulations that would require a distribution of aromatics (i.e., a certain amount of C7, C8, C9, and C10+ hydrocarbons) to ensure that test fuel is more representative of in-use gasoline. Heavier aromatics in gasoline are believed to contribute to vehicle PM emissions, so it is important that vehicles are designed to meet the proposed Tier 3 emission standards on fuel with a distribution of aromatic compounds representative of in-use gasoline. We also seek comment on the need for a multi-substituted alkyl aromatics (MSAA) specification, as has been proposed by CARB. For more information on our proposed aromatics specifications, refer to Chapter 3 of the draft RIA.
  • Olefins—adjusting the olefins specification to better match today's in-use gasoline/E10 according to AAM fuel surveys. Not only is the proposed 4.5-11.5 mass percent range (approximately 4-6 volume percent) more representative of in-use fuel, the narrower test fuel range would result in more consistent vehicle test results.
  • Other Specifications—adding distillation residue, total content of oxygenates other than ethanol, copper corrosion, solvent-washed gum, and oxidation stability specifications to better control other performance properties of test fuel. These proposed specifications are consistent with ASTM's D4814 gasoline specifications and CARB's LEV III test fuel requirements.
  • Updates to Gasoline Test Methods—updating some of the gasoline test methods currently specified in § 86.113 with more appropriate, easier to use, or more precise test methods for ethanol-blended gasoline. Key changes include replacement of ASTM D323 with ASTM D5191 for measuring vapor pressure; replacement of ASTM D1319 with ASTM D5769 for measuring aromatics and benzene; and replacement of ASTM D1266 with three alternative ASTM test methods (D2622, D5453 or D7039) for measuring sulfur. We request comment on the use of three different test methods for the measurement of sulfur content.
  • Consolidation of Test Fuels—consolidation of all gasoline exhaust and evaporative emission test fuels into a single general test fuel. This would be used for all on-highway vehicle testing with the exception of cold CO vehicle testing (which would use higher volatility test fuel) and high-altitude testing (which would be permitted to use lower volatility fuel). As discussed above, commercial gasoline would continue to be used for service accumulation (durability fuel). This is consistent with CARB's LEV III approach and should help limit the total number of test fuels that automakers need to manage.
Table IV-21—Proposed Gasoline Emissions Test Fuel Back to Top
Property Unit Specification ASTM reference procedure
General testing Low-temperature testing High altitude testing
Antiknock Index (R+M)/2 87.0—88.4 87.0 Minimum D2699-11 and D2700-11.
Sensitivity (R-M) 7.5 Minimum  
Dry Vapor Pressure Equivalent (DVPE) kPa (psi) 60.0-63.4 (8.7-9.2) 77.2-81.4 (11.2-11.8) 52.4-55.2 (7.6-8.0) D5191-10b.
Distillation          
10% evaporated °C (°F) 49-60 (120-140) 43-54 (110-130) 49-60 (120-140) D86-10a.
50% evaporated °C (°F) 77-88 (170-190)  
90% evaporated °C (°F) 154-166 (310-330)  
Evaporated final boiling point °C (°F) 193-216 (380-420)  
Residue Milliliter 2.0 Maximum  
Total Aromatic Hydrocarbons vol. % 19.5-24.5 D5769-10.
C6 Aromatics (benzene) vol. % 0.6-0.8  
C7 Aromatics (toluene) vol. % 4.4-5.5  
C8 Aromatics vol. % 5.5-6.9  
C9 Aromatics vol. % 5.0-6.2  
C10+ Aromatics vol. % 4.0-5.0  
Olefins mass % 4.5-11.5 D6550-10.
Ethanol vol. % 14.6-15.0 D5599-00 (Reapproved 2010).
Total Content of Oxygenates Other than Ethanol vol. % 0.1 Maximum  
Sulfur mg/kg 8.0-11.0 D2622-10, D5453-09 or D7039-07.
Lead g/liter 0.0026 Maximum D3237-06.
Phosphorus g/liter 0.0013 Maximum D3231-11.
Copper Corrosion No. 1 Maximum D130-10.
Solvent-Washed Gum Content mg/100 ml 3.0 Maximum D381-09.
Oxidation Stability Minute 1,000 Minimum D525-05.

EPA seeks comment on the appropriateness of the proposed forward-looking E15 test fuel for light- and heavy-duty gasoline vehicles. While we believe we have discretion under the statute to transition from E0 to E15 test fuel, we acknowledge that vehicle manufacturers will need to calibrate their vehicles to meet the proposed Tier 3 standards on fuel containing 15 percent ethanol by volume. Our analysis of the proposed Tier 3 standards (emission control technology, feasibility, cost, etc.) assumes the use of the proposed E15 test fuel. We anticipate that vehicle electronic control systems will be fully capable of adjusting to maintain emission performance when operating on E10 (or any remaining E0), but if E15 were not to enter the gasoline pool in significant quantities, it may be more appropriate to require that vehicles be calibrated for and tested on E10.

We are seeking comment on various alternative approaches, e.g., starting with E10 as the test fuel and transitioning to E15 as the market further transitions to E15 in use. This could include a market review in 2014 or 2015 followed by regulatory action to implement the change from E10 to E15 test fuel, if warranted. Or, it could include the establishment of a “trigger point” (e.g., 30 percent of gasoline is E15) in the Tier 3 final rule to prompt an automatic move to E15 after a certain period of time, e.g., two or three years. Or, we could simply set a future date (e.g., 2020) with sufficient time for transitioning to E15 test fuel. These transition approaches would give vehicle manufacturers additional lead time to prepare for higher ethanol concentrations in test fuel. We seek comment on the various transition approaches, their timing, and the appropriate specifications for an E10 test fuel to be used in the interim.

While the volatility (i.e., RVP) of CARB's E10 test fuel is 7.0 psi to be representative of in-use gasoline in California during summer months, conventional E10 in the rest of the country is currently around 10 psi. Thus, should we finalize E10 instead of E15, in the absence of any standard to reduce the in-use RVP of E10 to 9.0 psi or lower, we would also have to consider raising the RVP of certification test fuel to 10 psi to reflect the RVP level of the current in-use fuel. Were we to raise the volatility to 10 psi RVP, EPA believes that the proposed evaporative emission standards would be feasible, but this would increase the stringency of the proposed evaporative emission standards (see Section IV.C). Changing certification test fuel to 10 psi RVP would increase vapor generation rates during the refueling test by about 10 percent and during the hot soak, diurnal, canister bleed, and running loss tests by as much as 25 percent in total. To the extent that the refueling test dictates the size of the canister, the increased vapor generation would necessitate increases in the volume of activated carbon used in the vehicle's onboard canister by about 10 percent. Perhaps more importantly, manufacturer's vehicle purge strategies and technologies would likely have to be modified to removing the larger vapor loads from the canister during vehicle operation. Some vehicles have adequate engine vacuum available to provide the increased purge, while others may require new or innovative approaches to increase purge volume or canister purge efficiency as discussed in the evaporative emissions technology discussion. While we have not performed a detailed analysis, EPA estimates that on average the evaporative standard compliance costs could be about $10-15 per vehicle higher at 10 psi RVP compared to 9 psi RVP for canister and purge upgrades. With respect to lead time, EPA's current proposal calls for either 40 percent of light-duty vehicles to meet the Tier 3 evaporative emission standards in 2017 MY (percentage option) or for a manufacturer to sell only zero evap PZEVs nationwide (PZEV only option). This basic approach for 2017 could still be feasible depending on the resolution of the test procedure issues and proposed flexibilities in phase-in schemes.

Raising the certification test fuel to 10 psi RVP would also impact the equivalency of CARB and EPA refueling and hot soak plus diurnal evaporative emission test procedures. These potential impacts would have to be addressed to maintain CARB/EPA evaporative emissions test reciprocity. Furthermore, there may be test procedure options for minimizing the burden of changing certification test fuel RVP while maintaining the needed in-use control.

EPA does not believe that a 10 psi certification test fuel would impact the feasibility or cost of the proposed leak emission standard or the proposed change in the OBD evaporative system leak detection requirements, since these are based on orifice diameter. Nor, do we believe that it would have any negative impact on permeation emissions or exhaust emissions.

As mentioned above, EPA issued a waiver allowing E15 to be introduced into commerce for use in MY 2001 and newer light-duty motor vehicles. On July 25, 2011, EPA finalized regulations to mitigate the potential for misfueling of vehicles, engines, and equipment not covered by the E15 waiver, i.e., MY 2000 and older light-duty motor vehicles, all heavy-duty gasoline vehicles and engines, motorcycles, and all gasoline-powered nonroad products (which includes boats). [324] Two of the required mitigation measures are a label for fuel pumps that dispense E15 to alert consumers to the appropriate and lawful use of the fuel and a prohibition on the use of E15 by consumers in vehicles not covered by the waiver, excluding flexible fuel vehicles (FFVs). If, as discussed in this proposed rule, any class of new heavy-duty gasoline vehicles or engines begin testing on E15 for certification, EPA would not need to issue a waiver under section 211(f)(4) to allow introduction of E15 into commerce for use in these vehicles certified on E15 test fuel. However, EPA acknowledges that changes to the gasoline pump label and prohibitions finalized in the E15 Misfueling Mitigation Measures Rule would have to be made before E15 could lawfully be sold for use in these heavy-duty vehicles. This would be addressed in a future action.

As discussed above in Sections IV.A.7.c (tailpipe emission testing) and IV.C.4.b (evaporative emission testing), we are proposing to require certification of all Tier 3 light-duty and chassis-certified heavy-duty gasoline vehicles on E15 test fuel. As described in those sections, we are proposing that EPA still accept testing for certification on CARB's E10 test fuel during the phase-in periods for the respective proposed Tier 3 vehicle tailpipe and evaporative emissions standards and, if certified on CARB's E10 test fuel, that EPA would not perform or require in-use exhaust or evaporative testing on E15 test fuel.

As mentioned earlier, we plan to continue to allow manufacturers to test vehicles on premium-grade gasoline should the vehicles require it. Since we cannot predict all future changes in gasoline vehicle technologies and in-use fuels, we are proposing to allow vehicle manufacturers to specify an alternative test fuel under certain situations. Under this proposal, if manufacturers were to design vehicles that required operation on a higher octane, higher ethanol content gasoline (e.g., dedicated E30 vehicles or FFVs optimized to run on E30 or higher ethanol blends), under 40 CFR 1065.701(c), they could petition the Administrator for approval of a higher octane, higher ethanol content test fuel if they could demonstrate that such a fuel would be used by the operator and would be readily available nationwide, vehicles would not operate appropriately on other available fuels, and such a fuel would result in equivalent emissions performance. For vehicles certified on high-octane, high-ethanol gasoline, all EPA confirmatory and in-use testing would also be conducted on high-octane, high-ethanol gasoline. This could help manufacturers who wish to raise compression ratios to improve vehicle efficiency as a step toward complying with the 2017 and later light-duty greenhouse gas and CAFE standards. This in turn could help provide a market incentive to increase ethanol use beyond E10 and enhance the environmental performance of ethanol as a transportation fuel by using it to enable more fuel efficient engines. We seek comment on the appropriateness of the alternative test fuel provisions at § 1065.701(c) and the need to specify more precisely the makeup of such a fuel (ethanol content, as well as other fuel parameters) in the regulations at this time. We are also seeking comment on whether there are other aspects of today's proposed standards that might need to be modified to provide an incentive for, or remove obstacles to, the development of highly efficient vehicles optimized for use on higher level ethanol blends.

2. Proposed Flexible Fuel Vehicle Test Fuel

While the Agency has for some time had testing requirements for flexible fuel vehicles (FFVs) on E85 fuel blends, EPA currently has no regulatory specifications for the test fuel itself. Historically, our laboratory practice has been to blend indolene (E0) with neat ethanol and normal butane to produce an FFV test fuel with 83 volume percent ethanol and an RVP from 6.0 to 6.5 psi. However, the lack of E85 test fuel specifications has caused confusion and inconsistency among FFV manufacturers in carrying out their certification requirements.

Similar to the previous discussion regarding gasoline test fuels, we believe it is important that the fuel used to test FFVs reflect the composition of actual in-use E85. This may become increasingly important if E85 usage in FFVs increases to help satisfy the growing RFS2 renewable fuel requirements.

The term “E85” has historically been used to describe an ethanol blend with a maximum ethanol content of 83 volume percent and specified minimum ethanol content for use in FFVs. In the recently updated ASTM International specification, the minimum ethanol concentration was reduced from 68 to 51 volume percent. [325] As part of the updated specification, ASTM retired the name E85 because it has caused confusion regarding the necessary variability in the ethanol content of the blend depending upon seasonal climactic conditions. The official name in the new ASTM specification is “ethanol fuel blends for flexible-fuel automotive spark-ignition engines.” For the sake of brevity, we shall refer to this fuel as E51-83.

Consistent with our current policy regarding the formulation of FFV test fuel, we believe that the ethanol content should be at or near the maximum ethanol level on which the vehicles were designed to operate to ensure that the testing reflects the full range of in-use formulations and emissions performance. To provide adequate flexibility for test fuel manufacturers, we are proposing that the ethanol content must be from 80 to 83 volume percent. Rather than specify ranges for the other fuel parameters as we have done for gasoline test fuel in Table IV-21, we are proposing that the FFV test fuel would be defined based on the results from blending the proposed E15 standard gasoline test fuel with ethanol. We propose that denatured fuel ethanol (DFE) that meets the proposed specifications would be used to increase the ethanol content to 80 to 83 volume percent. [326]

It is important to ensure that the volatility of FFV test fuel meets minimum volatility specifications to provide adequate startability and for safety reasons. The ASTM minimum RVP specification that conforms to the specified temperature at which FFV emission testing takes place (68 to 86 °F) is 5.5 psi. EPA conducted discussions with vehicle and test fuel manufacturers to arrive at the current guidance that the RVP of the finished test fuel should be between 6.0 and 6.5 psi. We propose to formalize the current guidance in the regulatory requirements for FFV test fuel. We propose that commercial grade normal butane could be added to trim the RVP of the finished test fuel to meet the proposed specifications. [327] A 6.0 to 6.5 range in RVP has historically provided test fuel manufacturers adequate flexibility in formulating test fuels. Limiting the amount of butane that is added to formulate FFV test fuels is important because if excessive volumes of butane were used it could inappropriately reduce the stringency of emissions testing.

As an alternative to the use of DFE to manufacture FFV test fuel, we propose that neat (undenatured) fuel grade ethanol could be used. We also propose that as an alternative to using a finished E15 standard gasoline test fuel in the manufacture of FFV test fuel that the gasoline blendstock used to produce a compliant E15 test fuel could be used to manufacture the FFV test fuel. This would allow ethanol to be blended only once to produce FFV test fuel. The test fuel manufacturer would be required to test a sample of the subject gasoline blendstock after the addition of ethanol to produce a finished standard E15 gasoline test fuel and demonstrate that the blend meets all of the proposed requirements for standard gasoline test fuel described in Section IV.D.1.

We propose that the above FFV emissions test fuel specifications would become applicable on the same schedule as the proposed E15 standard gasoline test fuel specifications become applicable for light- and heavy-duty gasoline vehicles (described below in Section IV.D.3). We believe that the proposed requirements would ensure that FFV test fuel reflects the composition of in-use ethanol fuel blends for flexible-fuel automotive spark-ignition engines while minimizing the burden on the industry with respect to test fuel formulation and the number of test fuel blend components that must be stored.

Under the Tier 2 program, FFVs utilize a test fuel containing 10 percent ethanol with an RVP of approximately 10 psi for evaporative emission testing. The proposed E15 certification fuel for non-FFVs is a 9 psi E15 fuel. We seek comment on whether the new E15 evaporative emissions test fuel for FFVs should continue to have an RVP of 10 psi to maintain the level of performance established under the Tier 2 program.

3. Proposed Implementation Schedule

As described earlier in Section IV.C, we are proposing Tier 3 exhaust and evaporative emission standards with today's notice. The proposed changes in the specifications for test fuel would apply to vehicles certified to these new standards. We are proposing to transition to the new test fuel during the first few years that the Tier 3 standards are phasing in. As described in Sections IV.A and IV.B, testing with the new fuel would start with light-duty vehicles certified to Tier 3 bin standards at or below Bin 70, and heavy-duty vehicles certified to Tier 3 bin standards at or below Bin 250 (for Class 2b) and Bin 300 (for Class 3). Starting with model years 2020 for light-duty and 2022 for heavy-duty, we would require that all manufacturers use the new test fuel for all exhaust emission testing (with the exception of Small Volume Manufacturers and small businesses, which could delay using the new test fuel until model year 2022). Manufacturers would also need to comply with cold temperature CO and NMHC standards using the new test fuel for any models that use E15 test fuel for meeting the light-duty Tier 3 exhaust emission standards. These same tests would also provide the basis for meeting GHG requirements under 40 CFR part 86 and fuel economy requirements under 40 CFR part 600, as described in the following section.

We are proposing to require evaporative emission testing with the new test fuel for any models that are certified to the Tier 3 evaporative emission standards. To the extent that these models are different than those used for exhaust emission testing with the new test fuel, manufacturers would need to do additional testing to demonstrate compliance with all applicable standards. They may alternatively use the new test fuel earlier than the regulations specify to avoid additional testing. We further propose to require that manufacturers submit certification data based on the new test fuel to demonstrate compliance with refueling emission standards for any vehicles that are certified to the Tier 3 evaporative emission standards.

4. Potential Implications on CAFE Standards, GHG Standards, and Fuel Economy Labels

EPA and the National Highway Traffic Safety Administration (NHTSA) recently finalized a joint greenhouse gas (GHG) emissions and corporate average fuel economy (CAFE) standards for MY 2017-2025 light-duty vehicles, light-duty trucks, and medium-duty passenger vehicles. [328] These GHG and CAFE standards build upon the National Program that was first announced by the President in May 2009 and which allows manufacturers to build a single fleet of light vehicles that can satisfy all federal and state requirements for GHG emissions and fuel economy. The first round of standards by EPA and NHTSA under the National Program cover MY 2012-2016. [329]

The recently finalized MY 2017-2025 GHG and CAFE standards affect essentially the same vehicle classes over the same timeframe as this proposal for non-GHG emissions standards and gasoline fuel quality. Accordingly, EPA believes it is important for the two rulemakings to be coordinated so that manufacturers can develop future product development plans with a full understanding of the major regulatory requirements they would be facing over the MY 2017-2025 time frame.

The Agency would like to highlight two important issues of overlap between these two rulemakings: Test fuel and useful life. As explained above, today's action proposes to update EPA's test fuel to better match in-use fuels, with the change in test fuel phased-in from MY 2017-2020 for light-duty exhaust emission compliance. The proposal involves several changes to the emissions test fuel specifications, including, notably, a 15 percent by volume ethanol content. The current emissions test fuel contains zero ethanol. Regarding useful life, we are proposing a longer useful life for some vehicles, as described in Section IV.A.7.b, from the current 120,000 miles to 150,000 miles.

a. Test Fuel

The proposed change in test fuel, if finalized, could have implications for both the CAFE and GHG emissions compliance programs, as well as the fuel economy labeling program. EPA is committed to the principle of ensuring that the proposed change in test fuel would not affect the stringency of either the CAFE or GHG emissions standards, and that the labeling calculations would be updated to reflect the change in test fuel.

While NHTSA establishes the fuel economy standards for the CAFE program, EPA is responsible for vehicle testing and calculation of fuel economy values used by manufacturer for compliance with the CAFE standards. Under the Energy Policy and Conservation Act (EPCA), limitations are placed on the test procedures used to measure fuel economy for passenger cars. For passenger automobiles, EPA has to use the same procedures used for model year 1975 automobiles, or procedures that give comparable results. [330] When EPA has made changes to the FTP or HFET, we have evaluated whether it is appropriate to provide for an adjustment to the measured fuel economy results, to comply with the EPCA requirement for passenger cars that the test procedures produce results comparable to the 1975 test procedures. These adjustments are typically referred to as a CAFE or fuel economy test procedure adjustment or adjustment factor.

Because ethanol has a lower energy content than gasoline, i.e., fewer British thermal units (Btus) or joules per gallon, [331] and fuel economy is defined in terms of miles per gallon of fuel, it is almost certain that the same vehicle tested on a test fuel with 15 percent ethanol content will yield a lower fuel economy value relative to the value if it were tested on the current test fuel with zero ethanol content. For CAFE purposes, the existing fuel economy equation for gasoline that has been in use for many years already contains an adjustment for the energy content of the test fuel to calculate fuel economy equivalent to what would have been determined using the 1975 baseline test fuel. [332] Therefore, it is not clear that any further action is necessary to account for the proposed change in certification test fuel. Within this equation, however, is a so-called “R-factor” to account for the fact that the change in fuel economy is not directly proportional to the change in energy content of the test fuel. Although an R-factor of 0.6 has been used since 1988, manufacturers have suggested that a higher value may be more appropriate. We discuss this issue in a memo to the docket. [333] This is a technical issue with the fuel economy equation that has been raised in the context of the proposed certification test fuel change, but technically it is distinct from the proposed change in test fuel. EPA will continue to investigate this issue and if necessary address it as part of a future action.

EPA is also committed to retaining equivalent stringency for GHG emissions compliance associated with the proposed test fuel change. The proposed changes in test fuel properties in this rule do not have any appreciable impact on carbon dioxide grams per mile levels. This is supported by data from the EPAct study, which show that the change in the test fuel have both positive and negative impacts that offset each other and that there is no net impact on carbon dioxide grams per mile levels. This is discussed in a memo to the docket. [334] We seek comment on the impact of this proposal on CO 2 emissions. Should action to adjust the compliance calculation for the light-duty GHG standards become warranted, we would include such changes as a part of a future action.

EPA expects that there may be a potential impact on manufacturer's fuel economy and greenhouse gas testing burden during the Tier 3 phase-in years. Currently, for example, manufacturers carry over a considerable amount of previous model year data in support of their Fuel Economy Labeling and CAFE/Greenhouse Gas programs. We are proposing that Tier 3 compliant vehicles would be required to test on E15 test fuel, and thus, manufacturers would normally not be allowed to carry over previous model year data from vehicles tested on E0 test fuel. EPA anticipates that such carryover requests could be handled during the Tier 3 phase-in years with modifications to EPA's current policy for the use of analytically derived data (see EPA's fuel economy, CO 2, and carbon-related exhaust emissions testing regulations at 40 CFR 600.006-08(e) and EPA guidance letter CD-12-03 (February 27, 2012) and CCD-04-06, (March 11, 2004 [335] )). EPA requests comments on whether there is a need for further reductions in fuel economy/greenhouse gas testing burden beyond that allowed by the above EPA guidance letters. Any comments supporting the need to reduce fuel economy/greenhouse gas testing burden (beyond that allowed by EPA's policy for the use of analytically derived data) should describe one or more specific methods of reducing such testing burden.

Finally, EPA will need to update the fuel economy labeling calculations in 40 CFR Part 600 to reflect the proposed E15 test fuel. The current methodology, which took effect with the 2008 model year, contains equations that, when applied to test results using current fuel (zero alcohol), adjust for an average national impact of ethanol in fuel on fuel economy. These equations would need to be revised such that the adjustment remains consistent with the actual national use of ethanol in fuel.

b. Useful Life for GHG Standards

As stated above, EPA is committed to retaining equivalent stringency for GHG emissions compliance beginning in MY 2017. In contrast to the proposed Tier 3 test fuel, for which we are uncertain as to the effects on GHG emissions, we believe that certifying a vehicle to a longer useful life for any emission constituent would have only a beneficial effect on emissions. To address potential concerns about changes in the stringency of the GHG standards resulting from a longer useful life, we are not proposing to require a longer useful life for GHG emission standards. As this approach may result in additional testing burden, we are proposing that manufacturers could optionally certify GHG emissions to a 150,000 mile, 15 year useful life.

5. Consideration of Nonroad, Motorcycle, and Heavy-Duty Engine Emissions Test Fuel

As described earlier in Section IV.D.1., we are proposing new specifications for the gasoline emissions test fuel used for testing highway vehicles subject to the proposed Tier 3 standards. In developing today's proposal, EPA also considered proposing the change in test fuel specifications for other categories of engines, vehicles, equipment, and fuel system components that use gasoline. This would include a wide range of applications, including small nonroad engines used in lawn and garden applications, recreational vehicles such as ATVs and snowmobiles, recreational marine applications, on-highway motorcycles, and larger heavy-duty gasoline engines. While engines in some of these categories employ advanced technologies similar to light-duty vehicles and trucks, the vast majority of these engines employ much simpler designs, with many of the engines being carbureted with no electronic controls. Because of lower level of technology, emissions from these engines are potentially much more sensitive to changes in fuel quality.

EPA is not proposing to apply the new emissions test fuel specifications to these other categories of engines, vehicles, equipment, and fuel system components. In discussing the potential change in test fuel specifications with the large number of businesses potentially impacted by such a change, many companies supported such a change. However, a number of manufacturers raised concerns about the level of ethanol in the new fuel, the cost of recertifying emission families on the new fuel, the impact on nationwide product offerings, and the cost impact of complying with the existing standards on the new test fuel. EPA believes it is important that the emissions test fuel for these other categories reflect real-world fuel qualities but has elected to defer moving forward now pending additional analysis of the impacts of changing the test fuel specifications for the wide range of engines, vehicles, equipment and fuel system components that could be impacted. These impacts include the impact on the emissions standards, as well as the other issues raised by the manufacturers. EPA plans to explore such a change in a separate future action. EPA requests comment on the implications of changing the test fuel for these other categories and whether a different test fuel would be more appropriate for these other categories.

6. Consideration of CNG and LPG Emissions Test Fuel

There are currently no sulfur specifications for the test fuel used for certifying natural gas vehicles. There is also no sulfur specification in § 86.113 for the test fuel used for certifying liquefied petroleum gas (LPG) vehicles. The corresponding LPG test fuel for heavy-duty highway engines and for nonroad engines in § 1065.720 includes an 80 ppm maximum sulfur specification.

We request comment on the appropriateness of changing § 86.113 to reference 40 CFR part 1065 for both natural gas and LPG test fuels. We further request comment on amending these specifications to better reflect in-use fuel characteristics, and in particular on the appropriateness of aligning the sulfur specifications with those that apply for gasoline test fuel. Changing the sulfur specifications would depend on establishing that the new specification is consistent with the range of properties expected from in-use fuels.

E. Small-Business Provisions

As in previous vehicle rulemakings, our justification for including provisions specific to small businesses is that these entities generally have a greater degree of difficulty in complying with the standards compared to other entities.

In developing the proposed Tier 3 vehicle program, we evaluated the environmental need as well as the technical and financial ability of manufacturers and others to meet the standards as expeditiously as possible. We believe it is feasible and necessary for the vast majority of the program to be implemented in the established time frame to achieve the air quality benefits as soon as possible. Based on information available from small manufacturers and others, we believe that entities classified as small generally face unique circumstances with regard to compliance with environmental programs, compared to larger entities. Thus, as discussed below, we are proposing several flexibility provisions for small businesses in the vehicle industry to reduce the burden that this program could have on them. These proposed provisions are based on the recommendations of the Small Business Advocacy Review (SBAR) Panel described in Section XIII.C of today's proposal and include a few additional provisions.

Small entities generally lack the resources that are available to larger companies to carry out necessary research and development and to raise capital for investing in a new regulatory program. Small entities are also likely to have more difficulty in competing for any needed engineering and construction resources and lower production volume over which to spread their compliance costs. Small entities also tend to have limited product lines, which limits their ability to take advantage of the phase-in and ABT flexibility provisions in the proposal. As such, we are proposing regulatory flexibility provisions that would provide additional lead time and reduced testing burden for small entities in meeting the proposed Tier 3 standards. This proposed approach would allow the overall program to begin as early as possible; achieving the air quality benefits of the program as soon as possible, while helping to ensure that small entities have adequate time to make any necessary modifications to their product lines. We believe that small business regulatory flexibilities could provide these entities with additional help and/or time to take advantage of technological developments by other parties and to accumulate capital internally or to secure capital financing from lenders, and could spread out the availability of any needed engineering resources. We believe these provisions will also reduce their overall compliance burden and allow them to more easily transition to the new standards in a way that matches their business practices.

The provisions described below would be available to all small businesses subject to the Tier 3 emission standards. The types of companies subject to the Tier 3 emission standards include vehicle manufacturers, and two additional categories of businesses that are generally referred to as independent commercial importers (ICIs) and alternative fuel vehicle converters. As discussed below, the proposed set of flexibilities would also be available to manufacturers in these three business categories that sell less than 5,000 vehicles per year that are subject to the Tier 3 emission standards.

1. Lead Time for Exhaust and Evaporative Emission Standards

As noted above, small businesses have limited resources available for developing new designs to comply with new emission standards. In addition, it is often necessary for these businesses to rely on vendor companies for technology. Moreover, percentage phase-in requirements and declining fleet average standards pose a dilemma for a small manufacturer that has a limited product line (e.g., the manufacturer certifies vehicles in only one or two test groups). Thus, similar to the flexibility provisions implemented in previous vehicle rules, the Panel recommended that EPA allow small businesses the following flexibility option for meeting the proposed Tier 3 emissions standards.

EPA is proposing that small businesses (and small volume manufacturers, as discussed below) be given additional lead time to comply with the proposed Tier 3 exhaust and evaporative emission standards. Specifically, we propose to allow small manufacturers to postpone compliance with the standards and other Tier 3 requirements, including use of the proposed new certification test fuel, until model year 2022. For model year 2022 and later, small manufacturers would be subject to the same Tier 3 exhaust and evaporative requirements as other manufacturers, including moving to the declining FTP fleet average NMOG+NO X curve and complying with the fully phased-in standard of 30 mg/mi, as well as certifying on E15 test fuel. (This approach is similar to that in the Tier 2 rule where EPA allowed small manufacturers to wait until the end of the phase-in to comply with the Tier 2 standards.) As described earlier in this section, the proposed Tier 3 rule has several different phase-in schedules; with the final dates varying from model year 2021 for the new light-duty exhaust PM standards to model year 2025 for the new light-duty exhaust gaseous pollutant standards. Requiring all small businesses to comply with the full slate of Tier 3 requirements in model year 2022 should provide sufficient lead time for manufacturers to plan for and implement the technology changes needed to comply with the Tier 3 standards.

During the SBAR Panel process, one small entity representative (SER) recommended that EPA adopt relaxed exhaust standards for small manufacturers. The SER noted that the exhaust emission averaging program being proposed by EPA would allow large manufacturers that have many engine families to certify their small, niche products at emission levels numerically higher than the standards. Small manufacturers that typically do not have more than one or two emission families generally cannot use averaging to the same extent because of their limited product offerings. The SER was concerned that the high-performance vehicles produced by large manufacturers which they compete against would be able to certify at numerically higher levels at less cost than the SER would incur. The SER-recommended relaxed NMOG+NO X standards over the Federal Test Procedure (FTP) are 125 mg/mi in model year 2020 and 70 mg/mi in model year 2025. This is the same general approach that the CARB Board approved for small volume manufacturers in LEV III (a relaxed standard NMOG+NO X of 125 mg/mi followed by a fully phased-in standard of 70 mg/mi in model year 2025), except that the CARB program introduces the relaxed standard and the change in test fuel in model year 2022.

As described above, although we are proposing a delay in the Tier 3 requirements, EPA is not proposing to relax the fully phased-in standards for the small entities. We believe that these standards are technologically feasible and can be readily achieved with the additional lead time we are proposing as the technology would have already been demonstrated by other manufacturers, in some cases on the very same engines used by the small manufacturers. In addition, the compliance costs for many of these vehicles, even if higher on an absolute basis, may still be lower on a relative basis given the higher average cost of the vehicles. Furthermore, EPA is proposing to allow manufacturers to apply for hardship relief (discussed below) on a case-by-case basis. EPA requests comment on our proposed approach and whether there is an additional need for the final rule to allow small manufacturers to meet relaxed NMOG+NO X exhaust emission standards on the FTP over the long term, as suggested by the SER and as reflected in action by CARB.

In light of the CARB Board-approved implementation schedule for small manufacturers described above, we also request comment on an option that would not provide a permanent relaxed standard for small manufacturers, but would provide a temporary relaxed standard matching the California standard from model year 2022 through 2024. This option would apply to the Tier 3 exhaust emission standards starting in 2022, except that a relaxed NMOG+NO X standard of 125 mg/mi would apply in model years 2020-2024 for FTP testing. For model years 2025 and later, the standard would be the same as for all other manufacturers, or 30 mg/mi. Under this option, small manufacturers would have to take some action to reduce emissions in 2022 and could postpone meeting fully phased-in Tier 3 standards until 2025.

2. Assigned Deterioration Factors

Under EPA's regulations, manufacturers must demonstrate that their vehicles comply with the emission standards throughout the “useful life” period. This is generally done by testing vehicles at low-mileage and then applying a deterioration factor to these emission levels. The deterioration factors are determined by aging new emission control systems and then testing the aged systems again to determine how much deterioration in emissions has occurred. In order to reduce the testing burden in previous rulemaking, EPA has allowed small manufacturers to use deterioration factor values assigned by EPA instead of performing the extended testing. A manufacturer would apply the assigned deterioration factors to its low-mileage emission level to demonstrate whether it complied with the Tier 3 emission standards.

With today's proposal, EPA proposes that small businesses be allowed the option to use EPA-developed assigned deterioration factors in demonstrating compliance with the Tier 3 exhaust and evaporative emission standards. In the past, EPA has relied on deterioration factor data from large manufacturers to develop the assigned deterioration factors for small manufacturers. EPA would expect to follow a similar procedure to determine the assigned deterioration factors for the Tier 3 standards once large manufacturers start certifying their Tier 3 designs. Given that larger manufacturers would begin phasing in to the Tier 3 standards in model year 2017, EPA should have a significant set of emissions deterioration data upon which to base the assigned deterioration factors for small businesses within the first few years of the Tier 3 program. EPA recognizes that assigned deterioration factors need to be determined well in advance of model year 2022 in order to provide sufficient time for small businesses to decide whether or not to use the assigned deterioration factors for certification purposes.

3. Reduced Testing Burden

Under EPA's regulations, manufacturers must perform in-use testing on their vehicles and demonstrate their in-use vehicles comply with the emission standards. The current in-use testing regulations provide for reduced levels of testing for small manufacturers, including no testing in some cases. EPA is proposing to continue the reduced levels of testing for small businesses under the Tier 3 program. Under the reduced testing provisions, manufacturers that sell less than 5,000 units per year would not be required to do any testing under the in-use program. Manufacturers that sell between 5,001 and 15,000 units per year would be required to test two vehicles per test group, but only under the high-mileage conditions specified in the in-use program.

Under current regulations, manufacturers may waive testing for PM emissions for light-duty vehicles and trucks, except for diesel-fueled vehicles. Manufacturers are still subject to the standards and must make a statement of compliance with the PM standards. As described in Section IV.A, EPA is proposing new PM standards and will require manufacturers to test for PM emissions for all fuels. Because PM testing requires additional test equipment and facilities, the costs incurred for PM testing can be substantial, especially for a company selling small numbers of vehicles. Therefore, EPA is proposing to continue the waiver for PM testing in the Tier 3 timeframe for small businesses. Small businesses will not be required to measure PM emissions when they certify to the Tier 3 emission standards. In lieu of testing, small businesses will be required to make a statement of compliance with the Tier 3 p.m. standards. We would retain the ability to determine the PM emissions results in confirmatory or in-use testing.

As described in Section IV.C, EPA is proposing new OBD requirements for vehicles certifying to the Tier 3 standards. The proposed OBD requirements are the same as CARB's existing OBD requirements. The proposed OBD provisions require additional amounts of testing and information that can add significant cost for manufacturers if they are not already meeting the CARB OBD requirements. Small business vehicle manufacturers tend to comply with the CARB OBD requirements because they want to sell in the California market. On the other hand, alternative-fuel converters do not generally certify with CARB because of the significant cost burden of complying with the CARB OBD requirements. We are therefore proposing that small business alternative-fuel converters may continue to comply with EPA's existing OBD requirements (see 40 CFR 86.1806-05) when the Tier 3 standards become effective. However, the proposed upgraded OBD requirements would have to be met by small entities and ICI's by the 2022 MY.

Alternative-fueled vehicles, MDPVs, FFVs, and HDVs do not have SFTP emissions requirements under the current regulations. As described in Section IV.A, EPA is proposing to apply the Tier 3 SFTP standards to all vehicles, including alternative-fueled vehicles, MDPVs, FFVs, and HDVs. Because SFTP testing includes emission measurement over the SC03 test cycle, which requires additional test facilities beyond those needed to run the FTP, the costs incurred for SC03 testing can be substantial, especially for companies like alternative fuel converters that sell very low numbers of converted vehicles. We are proposing that for the categories of vehicles newly subject to the SFTP standards, including alternative-fueled vehicles, manufacturers have the option to substitute the FTP emissions levels for the SC03 emissions results for purposes of compliance when calculating the SFTP emissions. However, we would retain the ability to determine the composite emissions using SC03 test results in confirmatory or in-use testing. Because the vehicles being converted to an alternative fuel will likely have been tested for SFTP compliance, we expect the SFTP emissions should be similarly low, and therefore the added SC03 testing burden is unnecessary.

During the SBAR process, one SER requested that EPA eliminate some of the evaporative emission testing requirements for small businesses based on its belief that some of the tests may be duplicative. While EPA understands the reasons behind the SER's suggestion, we believe it may be premature to consider such an option in the Tier 3 rule given the potential impact of the CO 2 emission standards on engine and fuel system development. Currently, it is generally understood that the 2-day diurnal test drives the purge characteristics of evaporative control systems, while the refueling test, and to a lesser degree the 3-day test, drive the capacity requirement of evaporative canisters. Prospectively, due to expected changes in engine and fuel system designs in response to upcoming CO 2 emission standard requirements, this may not be the case. Therefore, EPA believes it is appropriate to retain all of the evaporative test procedures. It can be noted that under current regulations, EPA does allow manufacturers to waive 2-day diurnal testing for certification purposes (see 40 CFR 86.1829-01(b)(2)(iii)) and perform only the 2-day diurnal test as part of the in-use testing program (see 40 CFR 86.1845-04(c)(5)(ii)). These provisions would continue in the Tier 3 program. In general, EPA is open to changes that reduce test burden while maintaining the environmental effectiveness of its programs and could consider changes like those suggested by the SER in the future as the impacts of the future regulations on engine and vehicle design become clearer. Therefore, EPA requests comment on streamlining the current test procedures for small businesses in ways that would still maintain the overall effectiveness of the tests.

4. Hardship

EPA is proposing hardship provisions for small businesses subject to the Tier 3 exhaust and evaporative emission standards. Under the hardship provisions, small businesses would be allowed to apply for additional time to meet the 100 percent phase-in requirements for exhaust and evaporative emissions. All hardship requests would be subject to EPA review and approval. Appeals for such hardship relief would need to be made in writing and must be submitted well before the earliest date of potential noncompliance. The request would need to identify how much time is being requested. It must also include evidence that the noncompliance would occur despite the manufacturer's best efforts to comply, and must contain evidence that severe economic hardship would be faced by the company if the relief is not granted. The hardship provision should effectively provide the opportunity for small businesses to obtain more time to comply with the new Tier 3 standards. The existing hardship provisions limit the extra time that can be requested to 1 year, but we are proposing that such a limit is not needed as part of the Tier 3 hardship provisions.

5. Applicability of Flexibilities

Under EPA's Tier 2 regulations, EPA provides a number of flexibilities for small volume manufacturers (SVMs). The criteria for determining if a company is a “small volume manufacturer” is based on the annual production level of vehicles and is based on whether the company produces less than 15,000 vehicles per year. Unlike EPA's current small volume manufacturer criteria, the Small Business Administration (SBA) defines which manufacturers are small businesses based on the number of employees for vehicle manufacturers and annual revenues for ICIs and alternative fuel converters. For example, SBA defines a small business vehicle manufacturer as those who have less than 1,000 employees.

With today's notice, EPA proposes that all small businesses that are subject to the Tier 3 standards and that meet the SBA criteria be eligible for the flexibilities described above. Unless otherwise noted, the proposed flexibilities would be available to all small business vehicle manufacturers, ICIs, and alternative fuel converters subject to the Tier 3 standards. In addition, EPA is proposing that manufacturers subject to the Tier 3 standards which meet a specified sales-based criterion be eligible for the flexibilities described above. It is relatively easy for a manufacturer to project and ultimately determine sales. Determining the annual revenues or number of employees is less straightforward. In the recent rule setting the first light-duty vehicle and truck CO 2 emission standards, EPA adopted provisions for small manufacturers based on a sales cutoff of 5,000 vehicles per year as opposed to the 15,000 level noted earlier that is used in the Tier 2 program. EPA proposes that the small volume manufacturer definition be based on the 5,000 vehicle per year level for the Tier 3 program. For purposes of the Tier 3 rule, the 5,000 limit would be based on a running three-year average of the number of light-duty vehicles, light-duty trucks, medium-duty passenger vehicles, and complete heavy-duty trucks below 14,000 lbs GVWR. EPA believes the 5,000 unit cut-off for small volume manufacturers would include all of the vehicle manufacturers, ICIs, and alternative fuel converters that currently meet the applicable SBA definition as well as a few additional companies that have similar concerns to small businesses.

EPA requests comment on the issue of extending eligibility for the Tier 3 small volume manufacturer provisions to very small manufacturers that are owned by large manufacturers but are able to establish that they are operationally independent. EPA has established such a provision in the light-duty greenhouse gas (GHG) program. [336] EPA requests comment specifically on whether a manufacturer who meets the criteria for establishing operational independence under 86.1838-01(d) for eligibility for SVM provisions under the GHG program should be considered to be operationally independent and similarly eligible for SVM provisions under the Tier 3 program.

F. Compliance Provisions

1. Exhaust Emission Test Procedures

We are proposing technical amendments to 40 CFR part 1066 as part of the effort to migrate test requirements from 40 CFR part 86 for light-duty vehicles and measurement of criteria pollutants. The proposed procedures in part 1066 reference large portions of part 1065 to align test specifications that apply equally to engine-based and vehicle-based testing, such as CVS and analyzer specifications, calibrations, test fuels, calculations, and definitions of many terms. The proposed part 1066, as amended, also incorporates most of the detailed part 86 procedures.

Current testing requirements related to chassis dynamometers rely on a combination of regulatory provisions, EPA guidance documents, and extensive learning from industry experience that has led to a good understanding of best practices for operating a vehicle in the laboratory to measure emissions. This proposal attempts to capture this range of material, integrating and organizing these specifications and procedures to include a complete set of provisions to ensure that emission measurements are accurate and repeatable. We request comment on the range of proposed requirements related to these chassis test procedures.

Proposed revisions to part 1066, and adjustments from part 86, include the following:

  • Clarification of regulatory requirements.
  • Correction of typographical errors.
  • Migration of mass-based emission calculations from part 86 to part 1066.
  • Introduction of a new NMOG calculation.
  • Revision of 40 CFR part 1066, subpart B, to increase the specificity with which part 1065 references are made as they pertain to testing equipment, test fluids, test gases, and calibration standards.
  • Addition of coastdown procedures for light-duty vehicles.
  • Reordering of the test sequence with respect to vehicle preparation and running a test.
  • Specifying part 1065 procedures for PM measurement, including certain deviations from part 1065 for chassis testing.
  • Insertion of detailed test specifications for vehicles certified under 40 CFR part 86, subpart S.

We are proposing the use of part 1065 for PM measurement with slight adjustments to the dilution air temperature, minimum dilution ratio, and background measurement requirements. By controlling the parameters that affect PM formation (dilution air temperature, dilution factor, sample residence time, filter face temperature, and filter face velocity), the proposed procedures include improvements that will reduce lab-to-lab and test-to-test variability.

We are proposing to eliminate separate sampling of Bag 2 of the FTP test cycle to allow for an increase in sampled PM mass. The proposed alternative approach is to sample Bags 1 and 2 of the FTP on a single filter, and sample Bags 2 and 3 of the FTP onto a second filter. This will generally involve simultaneous sampling of Phase 2 onto two separate filters. As an additional alternative, manufacturers may run cold and hot UDDSs without simultaneous sampling of the cold UDDS Phase 2, or to sample Bag 1, Bag 2, and Bag 3 on a single filter. Manufacturers choosing any of these options must still run a separate three-bag test for evaporative emission testing. We request comment on continuing to allow sampling under the traditional FTP methodology of a bag or filter per test phase (3 phases in total) instead of these proposed new methods. We also request comment on the appropriate transition to using the new sampling and calculation methods.

We are proposing to revise the chassis dynamometer specifications in part 1066 by removing the maximum roll diameter and by requiring speed and force measurements at a minimum frequency of 10 hertz (Hz). Some manufacturers may be interested in testing with nonstandard dynamometer configurations, such as new flat-track dynamometers or old twin-roll dynamometers. We may approve the use of these and other nonstandard dynamometer configurations as alternative procedures under 40 CFR 1065.10(c)(7).

Part 1066 relies extensively on calculations involving physical parameters to calculate emission rates and perform various calibrations and verifications. As reflected in the current version of part 1066, manufacturers have used a variety of units to perform these calculations. We would expect that dynamometers and other laboratory equipment are all capable of operating in SI units even if current practice in some laboratories is to use other units. Moving toward standardized units for calculations would allow us to more carefully and appropriately specify precision values for various measured and calculated parameters. This would also simplify calculations, facilitate review of results from different laboratories, and help with communications regarding any round-robin testing that might occur. Note that we are not contemplating converting emission standards to SI units. We request comment on completing the migration toward SI units in part 1066. In particular, we request comment on adding vehicle speed specifications in meters per second in addition to the current specification in miles per hour (or kilometers per hour for motorcycles). Specifying vehicle speeds to the nearest 0.01 m/s would allow for equivalent vehicle operation relative to current drive schedules. The cycle validation criteria would be based on a speed tolerance of ±1.0 m/s rather than ±2 mph (or rather than the proposed change to a ±2.0 mph tolerance). This is not a direct unit conversion, but is calculated based on the stated precision and rounding allowance to provide a comparable degree of variability in vehicle speeds.

We are proposing to phase in the requirements to use part 1066 test procedures for certifying all sizes of chassis-tested vehicles. For this phase-in approach, all aspects of part 1066 related to PM testing must be met at the start of MY 2017 for vehicles certifying to the PM standards. All other aspects of part 1066 must be met starting with the certification of all MY 2022 vehicles.

As described in Section IV.D, we are proposing new test fuel specifications for E15 gasoline test fuel in 40 CFR part 1065. The test fuels specified for natural gas and liquefied petroleum gas, while not used for very many engine families, are currently following different specifications under 40 CFR part 86 and part 1065. We request comment on further revising 40 CFR part 86 to refer to the test fuel specifications in part 1065 for natural gas and liquefied petroleum gas.

The proposal also includes various technical amendments to 40 CFR part 1065. The proposed technical amendments have no effect on the stringency of the regulations. These revisions include several minor changes to clarify regulatory requirements, align with chassis-testing procedures where appropriate, and correct typographical errors.

2. Reduced Test Burden

We are proposing to update the regulatory provisions that allow manufacturers to omit testing for certification, in-use testing, and selective enforcement audits in certain circumstances. Sections IV.A.3, IV.B.6, and IV.E.3 describe how this applies for demonstrating that vehicles meet the Tier 3 p.m. standards. We are also proposing to allow manufacturers to omit PM measurements for fuel economy and GHG emissions testing that goes beyond the testing needed for certifying vehicles to the Tier 3 standards. Requiring such measurement would add a significant burden with very limited additional assurance that vehicles adequately control PM. We are also proposing to allow manufacturers to ask us to omit PM and formaldehyde measurement for selective enforcement audits. If there is a concern that any type of vehicle would not meet the Tier 3 p.m. or formaldehyde standards, we would not approve a manufacturer's request to omit measurement of these emissions during a selective enforcement audit.

The regulations currently allow for waived formaldehyde testing for gasoline- and diesel-fueled vehicles. The Tier 3 NMOG+NO X emission standards are stringent enough that it is unlikely that vehicles would comply with the NMOG+NO X standards while exceeding the formaldehyde standards. We are therefore proposing to continue this waiver practice, such that manufacturers of Tier 3 vehicles do not need to submit formaldehyde data for certification.

We are also requesting comment on rearranging the default testing specification for certifying vehicles to evaporative emission standards, as described in Section IV.C. This would involve requiring manufacturers to perform testing with the two-day test sequence, while making the three-day test sequence optional.

3. Miscellaneous Provisions

The following additional certification and compliance provisions are included in the proposed rule:

  • The certification practice for assigned deterioration factors which are available for both small volume manufacturers and small volume test groups has matured significantly since it was first adopted. We are proposing to revise § 86.1826 to more carefully reflect the current practice. For example, the regulations specify that manufacturers with sales volumes between 300 and 15,000 units per year should propose their own deterioration factors based on engineering analysis of emission data from other families. We believe it is best for EPA to develop a set of assigned deterioration factors that can apply to all small volume manufacturers and small volume test groups.
  • The regulations in 40 CFR part 86 rely on rounding procedures specified in ASTM E29. This standard is revised periodically. The newer versions are not likely to change in a way that affects the regulation, but the updates make it difficult to maintain a coordinated reference to the current protocol. We are proposing to address this by specifying that the rounding protocol described in 40 CFR 1065.20(e) applies, unless specified otherwise. We are not proposing to change all the references in part 86; rather, we are proposing to define “round” in subparts A and S to have the meaning given in 40 CFR part 1065 so that all new regulatory text would rely on this new description. The rounding specifications in 40 CFR part 1065 are intended to be identical to those in the latest versions of ASTM E29 and NIST SP811. For example, this now includes procedures for nonstandard rounding, such as rounding to the nearest 25 units, or the nearest 0.05, where that is appropriate.
  • Independent Commercial Importers (ICIs) are companies that import specialized vehicles into the U.S. and are subject to EPA requirements specified in Part 85, Subpart P. The standards which apply to the vehicles imported depend, in part, on the model year of the vehicle being imported. Therefore, vehicles imported by ICIs in the future could be subject to the proposed Tier 3 standards and the proposed regulations reflect the application of the Tier 3 standards to ICIs. Because all existing ICIs are small-volume manufacturers, the Tier 3 standards would not apply until 2022 at the earliest. In addition, the certification practices for ICIs have matured significantly since they were first adopted. EPA is proposing two changes to update the regulations affecting ICIs. First, the proposed provisions would require ICIs to use electric dynamometers when running exhaust emission tests. Electric dynamometers have been required for many years for vehicle manufacturers and EPA believes it is time to require such test equipment for ICIs in the future. In cases where an ICI can demonstrate that they will incur a substantial increase in compliance costs, the proposed regulations include a provision that allows EPA to approve requests, on a case-by-case basis, to allow testing on other types of dynamometers until the ICI is able to comply with the proposed electric dynamometer requirements. Second, we are proposing to incorporate into regulation that ICIs be allowed to use a specific set of reduced testing requirements for up to 300 units each year that have been modified to a U.S.-certified configuration. This has been allowed for ICIs since 1999 and was approved under EPA's authority to establish equivalent alternate test procedures. [337] Instead of running a full set of emission tests, the reduced testing requirements would allow ICIs to run an FTP for exhaust emissions, a highway fuel economy test, and a shortened one-hour evaporative emission tests for hot-soak and diurnal emissions that applied prior to the current enhanced evaporative emission test procedures. We do not believe the proposed changes should have any significant cost impacts on ICIs. Most of the ICIs have electric dynamometers or can upgrade them for a relatively small cost. The reduced testing burden provisions keep the cost of testing low, compared to the cost of running a full set of emission tests that otherwise could be required.
  • We are proposing to adopt CARB's onboard diagnostic requirements for all light-duty vehicles, light-duty trucks, and heavy-duty vehicles, as described in Section IV.C.5.d. We currently allow for this as an option, but almost all manufacturers do this already to avoid certifying multiple systems. Now that we are adopting evaporative provisions that depend on California's regulatory specifications and we are making efforts to adopt a single, national regulatory program, we believe this is an appropriate step. This proposal includes heavy-duty vehicles above 14,000 lbs GVWR, though these vehicles would not need to meet the new requirements related to leak testing. These changes would apply starting in model year 2017 for vehicles subject to Tier 3 standards. The changes apply directly for heavy-duty vehicles above 14,000 lbs GVWR, since all those vehicles are already certified based on CARB's regulations. In the case of alternative fuel conversions, we are proposing to continue to apply the requirements of 40 CFR 86.1806-05.

4. Manufacturer In-Use Verification Testing (IUVP) Requirements

The fuel on which a vehicle will be operated in-use and tested is considered an integral part of the vehicle emission control system design. The Tier 2 program recognized that to achieve the desired emission reductions, vehicles must operate on the same fuel that the emission control system was originally designed to encounter in-use and during testing. In the Tier 2 program, we acknowledged that during the transition of the in-use fuel from sulfur levels of 300 ppm to the required 30 ppm average level, vehicles designed for 30 ppm could encounter in-use sulfur levels well above the level for which their emission control systems were designed. To address this issue, we allowed manufacturers, with agency approval, to perform specific preconditioning test procedures during the IUVP testing to ensure that potential exposure to high sulfur fuel in-use would not impact the emission test results. These procedures included specific drive cycles or maneuvers not regularly encountered during normal in-use operation that would result in removal of sulfur contamination from the emission control system.

Consistent with the Tier 2 program, EPA continues to recognize the importance of the fuel to the emission control system design, particularly on Tier 3 vehicles designed to meet the most stringent emission levels of the program (i.e., Bin 70 and cleaner). Under EPA's proposal, in-use fuel would transition from an average sulfur level of 30 ppm required by Tier 2 to a new average level of 10 ppm under Tier 3. The proposed sulfur requirements would be average standards. Thus, even after the transition to the 10 p.m. average sulfur level, vehicles might still encounter sulfur levels during in-use operation above 10 ppm and as high as the 95 ppm cap, which could adversely impact the emission control system. Tier 3 vehicles tested by manufacturers in IUVP that have been exposed to such sulfur levels could experience sulfur-related impacts, which in turn could cause the vehicle to temporarily exceed emission standards.

To address the potential emission impact on Tier 3 vehicles from exposure to higher sulfur levels, we are proposing some modifications to the IUVP testing process based in part on what was allowed under the Tier 2 program. Tier 3 vehicles tested in the IUVP would be tested initially without allowing any sulfur cleanout procedure, such as a US06 test run prior to the FTP or Highway Fuel Economy (HFET) tests. If a vehicle failed the NMOG+NO X standard for the FTP or HFET cycle during the initial round of testing, manufacturers would be allowed to perform a sulfur cleanout procedure before repeating the FTP or HFET. For the sulfur cleanout, manufacturers would be allowed to perform up to two US06 cycles. The measured US06 cycle and a preconditioning US06 cycle, if performed as part of the initial measured tests would serve as the cleanout procedure and therefore no additional US06 cycles would be allowed. Alternative sulfur cleanout procedures would require approval by EPA. Following the sulfur cleanout procedure, the manufacturer would prep and soak the vehicles and then repeat the FTP and HFET tests. If a manufacturer chose to perform the sulfur cleanout procedure, it would be required to submit evidence that the vehicle encountered high sulfur levels in the fuel just prior to emission testing. This would include an analysis of a fuel sample from the vehicle fuel system as received from in-use operation just prior to testing. If the fuel sample indicated that the vehicle was operating on fuel containing 15 ppm or higher sulfur levels in the recent past, only the emission results of the tests following the cleanout procedure would be used for purposes of determining emission compliance and whether to enter the in-use compliance program (IUCP).

The proposed rule includes the changes to the IUVP testing described above for light-duty vehicles and MDPVs. The changes to IUVP testing are not applicable to heavy-duty vehicles tested in the IUVP program. Also, as described in Section IV.D, we are proposing to incorporate leak testing into the IUVP test protocol. We are not proposing additional changes to the overall IUVP test program.

V. Proposed Fuel Program Back to Top

Under today's Tier 3 program, we are proposing reductions in gasoline sulfur levels nationwide. These standards would help prevent the significant impairment of the emission control systems expected to be used in Tier 3 technology, significantly improve the efficiency of emissions control systems currently in use, and continue prevention of the substantial adverse effects of sulfur levels on the performance of vehicle emissions control systems. Section V.A provides an overview of the fuel program and how we arrived at the proposed gasoline sulfur standards. Section V.B presents our assessment of the impacts the proposed fuel program would have on stationary source permitting and our conclusion that the proposed refinery lead time is adequate. Section V.C contains our proposed standards for denatured fuel ethanol. In Section V.D, we introduce and seek comment on possible options for regulating gasoline-ethanol blends intended for flexible fuel vehicles. Section V.E presents the proposed program flexibilities including the averaging, banking, and trading (ABT) program as well as small refiner and small volume refinery provisions. Section V.F lays out the compliance provisions for the proposed Tier 3 gasoline program. Finally, Section V.G presents our statutory authorities for lowering gasoline sulfur. As a result of these proposals, we have to amend certain existing provisions in the current Tier 2 requirements at 40 CFR part 80. We are not reopening Tier 2 and our proposed amendments should not be construed as a reopener.

A. Proposed Tier 3 Gasoline Sulfur Standards

1. Overview

a. History of Sulfur Control

Sulfur is naturally occurring in crude oil. Crude oil containing higher concentrations of sulfur (i.e., greater than 0.5 percent) is called “sour” and crude containing lower sulfur concentrations (e.g., West Texas Intermediate) is referred to as “sweet.” Regardless of the concentration, because sulfur is naturally occurring in crude oil, it is also naturally occurring in gasoline. As discussed in Section IV.A.6, sulfur impairs the performance of today's vehicle emission control technologies (i.e., precious metal catalytic converters), reducing the emission benefits of current and advanced vehicles. As explained below, in 2000 EPA took action to reduce gasoline sulfur levels under what is known as the Tier 2 Program [338] and is proposing to take further action under the proposed Tier 3 Program.

Tier 2 was a major, comprehensive program designed to reduce emissions from passenger cars, light trucks, and large passenger vehicles (including sport utility vehicles, minivans, vans, and pick-up trucks) and the sulfur content of gasoline. Under this program, automakers were required to manufacture low-emission vehicles when operated on low-sulfur gasoline, and refiners were required to produce low-sulfur gasoline nationwide.

Required reductions in gasoline sulfur began in 2004 with refinery and importer caps of 300 ppm and a corporate average cap of 120 ppm. For most refiners and importers, compliance with the final sulfur standards (30-ppm annual average and 80-ppm per gallon cap) was required beginning in 2006. Due to extensions provided for some refineries under the ultra-low sulfur diesel program, final compliance for all U.S. refineries was January 1, 2011. The Tier 2 gasoline sulfur program also had an ABT program that allowed companies to generate credits for implementing the required changes earlier than required and allowed ongoing flexibility to meet the 30-ppm average sulfur standard.

At full implementation, the Tier 2 program (treating vehicles and fuels as a system) required passenger vehicles to be over 77 percent cleaner and gasoline sulfur to be reduced by up to 90 percent from pre-program levels.

b. Need for Additional Gasoline Sulfur Control

We are proposing to lower today's gasoline sulfur standards under Clean Air Act section 211(c)(1). This is because emission products of gasoline with current levels of sulfur cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare and impair to a significant degree the emissions control device or systems on the vehicles subject to the proposed Tier 3 standards. For more on our legal authority to set gasoline sulfur standards, refer to Section V.G.

As explained in Section IV.A.6, robust data from many sources shows that gasoline sulfur at current levels (i.e., around 30 ppm on average) continues to degrade vehicle catalytic converter performance during normal operation. The most significant problem is for NO X. Today's proposed NMOG+NO X vehicle emission standards, an 80 percent reduction from current Tier 2 standards, would not be possible without the gasoline sulfur controls we are proposing today. Tier 3 vehicles must achieve essentially zero warmed-up NO X emissions to comply and maintain this performance for up to 150,000 miles. An increase in emissions of only a few milligrams per mile due to sulfur could make compliance impossible for some vehicles. The standards are projected to be especially challenging for larger SUVs and pick-up trucks.

Reducing gasoline sulfur would also help reduce emissions of pollutants that endanger public health and welfare from vehicles already on the road today. For the Tier 2 rule, we had data that showed benefits of reducing gasoline sulfur, but little to no data existed for sulfur levels below 30 ppm that we could use to project continued emission reductions. Since then, we have tested a wide range of Tier 2 vehicles to better understand the impact that even lower gasoline sulfur could have on emissions. Our test data showed significant NO X and VOC reductions when vehicles were tested on ultra-low sulfur gasoline. As explained in more detail in Section III.B, lowering average gasoline sulfur from 30 to 10 ppm would result in approximately 280,000 less tons of NO X and 40,000 less tons of VOC. The projected in-use emission benefits would occur almost immediately in 2017 when the Tier 3 gasoline sulfur standards take effect.

c. Summary of Proposed Tier 3 Fuel Program

Under today's Tier 3 fuel program, we are proposing that gasoline and any ethanol-gasoline blend contain no more than 10 ppm sulfur on an annual average basis beginning January 1, 2017. Similar to the Tier 2 gasoline program, the proposed Tier 3 program would apply to gasoline in the United States and the U.S. territories of Puerto Rico and the Virgin Islands, excluding California. The program, when finalized, would result in gasoline that contains an average of two-thirds less sulfur than it does today. We are proposing a three-year delay for small refiners and small volume refineries. Eligible small refining entities, described in more detail in Section V.E.2, would have until January 1, 2020 to comply with the new sulfur standards.

We are proposing an ABT program that would allow refiners to optimize their investment strategies to enable reduction in capital and compliance costs. Refiners and importers overcomplying with the 10-ppm standard beginning January 1, 2017 could generate standard credits that could be used internally, banked, or traded to other companies. We are also proposing an early credit program that would allow refiners and importers to spread out their investments over time to allow for an orderly transition. Starting January 1, 2014, refiners and importers taking steps to reduce gasoline sulfur below the current 30-ppm standard could generate early credits that could be used to postpone final investments for up to three years. For a more detailed discussion of the proposed ABT program, refer to Section V.E.1. As a result of the early credit program and notwithstanding the proposed delay offered to small refiners and small volume refineries, we anticipate considerable reductions in gasoline sulfur levels prior to 2017, with final refinery steps to get to 10 ppm occurring on or before January 1, 2020.

We are proposing to either maintain the current 80-ppm refinery gate per-gallon cap and 95-ppm downstream per-gallon cap or lower them to 50 and 65 ppm, respectively. We also evaluated and are seeking comment on the potential of lowering these caps to 20 ppm and 25 ppm, respectively. There are advantages and disadvantages associated with the various sulfur cap options (explained in more detail in Section V.A.3), but under all the proposed options, we believe that the stringency of the 10-ppm annual average standard would result in reduced gasoline sulfur levels nationwide.

A summary of the proposed Tier 3 gasoline sulfur standards is presented below in Table V-1. Domestic refiners and gasoline importers would be subject to both the 10-ppm annual average sulfur standard and the refinery gate per-gallon cap, when finalized. Gasoline in the distribution system (i.e., at terminals, retail stations, etc.) would be subject to the downstream per-gallon cap. For more information on how we arrived at the proposed sulfur standards, refer to Sections V.A.2 and V.A.3.

Table V-1—Proposed Tier 3 Gasoline Sulfur Standards Back to Top
Cap Option 1 Cap Option 2
Limit Effective Limit Effective
aEffective January 1, 2020 for eligible small refiners and small volume refineries.
Refinery annual average standard 10 ppm January 1, 2017a 10 ppm January 1, 2017.a
Refinery gate per-gallon cap 80 ppm Already 50 ppm January 1, 2020.
Downstream per-gallon cap 95 ppm Already 65 ppm March 1, 2020.

d. Refinery Feasibility

While evaluating the merits of a national gasoline sulfur program to reduce emissions and enable future vehicle technologies, we also considered the refining industry's ability to reduce sulfur to 10 ppm on average by January 1, 2017 and the associated costs (for more on fuel costs, refer to Section VII.A). Based on information gathered from numerous stakeholder meetings, discussions with vendor companies that provide the gasoline desulfurization technologies, as well as the results from our refinery-by-refinery modeling, we believe it is technologically feasible at a reasonable cost for refiners to meet the proposed sulfur standards in the lead time provided. A summary of our feasibility analysis is presented below. For more on our fuels feasibility assessment and refinery modeling, refer to Chapters 4 and 5 of the draft RIA.

Gasoline desulfurization technologies are well known and readily available. Many technologies were demonstrated under Tier 2 and have been further demonstrated by current fuel programs in California, Japan, and Europe. Under California's Phase 3 Reformulated Gasoline program (CaRFG3), gasoline sulfur is limited to 15 ppm on average with a 20-ppm per-gallon cap. [339] California reduced their per-gallon cap in phases from 60 ppm effective December 31, 2003, to 30 ppm effective December 31, 2005, to 20 ppm effective December 31, 2011. Actual in-use gasoline sulfur levels, however, have been largely constrained by the Predictive Model that California refiners are using to demonstrate compliance. As a result, gasoline sulfur levels are lower than the CaRFG3 limits. Based on the Predictive Model, California gasoline contained approximately 10 ppm sulfur on average in 2010 (9 ppm in the summer and 11 ppm in the winter).

Japan currently has a 10-ppm gasoline sulfur cap that took effect in January 2008. Europe also has a 10-ppm sulfur cap that has been adopted by the 30 Member States that comprise the European Union (EU) and the European Free Trade Association (EFTA) as well as Albania and Bosnia-Herzegovina. [340] Beijing, China also recently introduced a 10-ppm sulfur limit for gasoline. [341] We note, however, that many oil refineries outside of the United States operate differently from their U.S. counterparts. U.S. refiners have invested more heavily in fluidized catalytic cracker (FCC) units than the rest of the world in order to maximize gasoline production. Because the FCC unit is responsible for nearly all the sulfur that ends up in gasoline, many U.S. refineries face a bigger challenge in achieving 10-ppm gasoline sulfur levels. Nevertheless, these international fuel programs (along with California) provide evidence that advanced gasoline desulfurization technologies have been deployed and are readily available to comply with the proposed Tier 3 fuel program.

When considering the proposed Tier 3 sulfur standards, refineries can be grouped into three general categories based on their current post-Tier 2 refinery configurations: those without an FCC unit, those hydrotreating the gasoline stream coming from their FCC unit (i.e., postreating) [342] , and those hydrotreating their FCC feed (i.e., pretreating). Most refineries without FCC units would not need to do anything to meet the proposed Tier 3 sulfur standards. Refineries equipped with FCC units that invested in an FCC postreater under Tier 2 would likely just need to revamp (i.e., renovate) their existing unit for a modest cost. Refineries that only have an FCC pretreater would meet the Tier 3 sulfur standards by either revamping their existing pretreaters (perhaps also cutting the heavy portion of FCC naphtha into the diesel pool) or invest in a grassroots FCC postreater. Our refinery-by-refinery modeling suggests that 29 refineries would not need to make any capital changes, 66 would need to revamp their existing FCC postreaters, and 16 would need to add grassroots postreaters (we did not model any undercutting of heavy FCC naphtha into the distillate pool). [343] Refiners that need to install a new postreater would have to make the largest desulfurization investments under Tier 3, typical of many of the refinery investments made under Tier 2. For more on our estimated sulfur control costs, refer to Section VII.B.

We believe that the choice of technology for each refinery is fairly insensitive to capital cost assumptions. Revamping an existing FCC postreater will almost always be the preferred compliance path if it is available. The majority of refineries only have an existing FCC postreater, so revamping it will be the preferred choice, given the much higher capital costs associated with adding grassroots FCC pre or postreaters. The 16 refineries we project would add grassroots postreaters do not have existing postreaters that could be revamped. As a result, their choices are limited to revamping their existing pretreater or installing a grassroots postreater. We believe based on conversations with industry technology vendors and engineering firms that installing a grassroots postreater would be more likely for these refineries, because revamping their pretreater would still incur a significant capital cost and would reduce compliance flexibility. Thus, in the refinery-by-refinery analysis performed by EPA for this proposal, higher capital costs (either directly or thru a higher ROI) would be unlikely to alter the selection of pretreater versus postreater control technology. Higher capital costs would likely impact both technology options proportionally with no overall effect.

We have built in a number of flexibilities that will reduce the compliance burden for refiners. In particular, coupling the proposed 10-ppm annual average sulfur standard with refinery gate and downstream per-gallon caps should continue to allow for batch-to-batch variability, refinery upsets, and turnarounds while still maintaining the overall air quality benefits of the program. For more information on the applicable per-gallon sulfur caps, refer to Section V.A.3.

We are also proposing an ABT program that would allow refiners to spread out their investments over time and achieve compliance in the most cost-effective manner. If some refineries either comply with the 10-ppm standard earlier than required, or reduce sulfur partway toward 10 ppm early, this would allow other refineries to delay compliance for a finite period through the use of early credits. The ABT program would also allow for ongoing company averaging. This would allow some refineries to stay slightly above the standard at the expense of other refineries over complying, resulting in the most cost-effective mechanism for meeting the 10-ppm annual average standard. For more information on the proposed ABT program, refer to Section V.E.1. Finally, our Tier 3 gasoline sulfur program, when final, would allow three years of additional lead time for small refiners and small volume refineries (i.e., refineries processing less than or equal to 75,000 net barrels per day of crude oil). As a group, we believe that these refineries are disproportionally impacted when it comes to their cost of compliance and ability to rationalize investment costs in today's gasoline market. Giving these refineries additional lead time would allow them more time to invest in desulfurization technology, take advantage of advancements in technology, develop confidence in a Tier 3 credit market as a means of compliance, and avoid competition for capital, engineering, and construction resources with the larger refineries. For more on the proposed provisions for small refiners and small volume refineries, refer to Section V.E.2.

The proposed Tier 3 rulemaking should not adversely affect the supply of gasoline in the U.S. This judgment is based on a review of both gasoline and diesel fuel supply when the Tier 2 gasoline sulfur and ultra-low sulfur highway and nonroad diesel rules were phasing in between 2003 and 2011. At the end of this time period, the U.S. gasoline and diesel fuel markets were increasingly being supplied by U.S. refiners, instead of by imports, compared to the beginning of this time period. Most striking is that the more stringent ultra-low sulfur diesel fuel standards showed the largest shift as U.S. refiners not only began to supply more of the U.S. diesel fuel market, but became net exporters of diesel fuel. For more on our fuel supply assessment, refer to Section 5.3 of the draft RIA.

2. Proposed Annual Average Sulfur Standard

In the subsections that follow, we lay out our rationale for proposing a 10-ppm average standard, our assessment of how the proposed ABT program would help with compliance, and our conclusion that the proposed lead time is adequate. In the following section, we explain our rationale behind the proposed sulfur caps and seek comment on potential alternatives.

a. Appropriateness of Proposed 10-ppm Sulfur Standard

As explained in Section IV.A.6, sulfur in fuel oxidizes in the exhaust and coats the sites where chemical reactions can take place on the precious metal catalysts used in vehicles to reduce emissions of VOC, NO X, PM, CO, and toxics. Accordingly, any sulfur in gasoline causes vehicle emissions to increase. Sulfur can be burned off the catalyst during high-temperature, rich operation of the vehicle (i.e., aggressive driving conditions), but as long as there is any sulfur in the fuel, exhaust emissions will increase. Because any amount of sulfur in the fuel can have this effect, the lower the sulfur the better.

Refiners experience the same phenomenon with precious metal catalysts used in the reformer and isomerization units at their refineries. [344] To protect the precious metal catalysts in these units, refiners reduce the sulfur in the feed to these units to 1 ppm or below. Thus, it is technically possible for refiners to reduce their gasoline sulfur levels to virtually zero. While refiners did not have reason to reduce the sulfur in FCC gasoline until Tier 2 required such reductions, some refiners have achieved reductions in this stream at some of their refineries for other reasons such as (1) Protecting the FCC catalyst from the contaminants in the gas oil feed, (2) reducing stack emissions from the regenerator of the FCC unit, and most importantly (3) increasing gasoline yields from the FCC unit. For most refineries, FCC gasoline accounts for about one-third of gasoline and before Tier 2 was the source of over 95 percent of the sulfur in gasoline. Under Tier 2, most refiners significantly desulfurized FCC gasoline to around 70 to 80 ppm, yet FCC gasoline continues to contribute the majority of sulfur in gasoline today.

While further reducing sulfur in gasoline will continue to reduce vehicle emissions, our emissions analysis shows that a 10-ppm annual average is sufficient to enable vehicles to reach the proposed Tier 3 standards. Moreover, for the following reasons, reducing sulfur further below 10 ppm becomes increasingly difficult and costly. First, FCC naphtha is very rich in high-octane olefins. As the severity of desulfurization increases, more olefins are saturated, further sacrificing the octane value of this stream and further increasing hydrogen consumption. Making up for this lost octane represents a significant portion of the sulfur control costs. Second, as desulfurization severity increases, there is an increase in the amount of sulfur removed (in the form of hydrogen sulfide) which recombines with the olefins in the FCC naphtha, thus offsetting the principal desulfurization reactions. There are means to deal with the recombination reactions, but they result in even greater capital investments. Third, while FCC gasoline contributes the majority of sulfur to the finished gasoline, as the sulfur level drops below 10 ppm, the sulfur level of the various other gasoline streams within the refinery also become important. Any necessary treatment of these additional streams increases both capital and operating costs.

U.S. refineries are currently in different positions, both technically and financially. In general, they are configured to handle the different crude oils they process and turn it into a widely varying product slate to match available markets. Those processing heavier, sour crudes would have a more challenging time reducing gasoline sulfur under the proposed Tier 3 program. As explained earlier, refineries have different sulfur levels in their non- FCC streams based on their feedstocks and configurations. Those with higher sulfur levels in other refinery streams would have a more difficult time desulfurizing gasoline. Perhaps most important, U.S. refineries vary greatly in size (atmospheric crude capacities range from less than 5,000 to more than 500,000 barrels per day) and thus have different economies of scale for adding capital to their refineries. As such, it can be less costly per gallon for some larger refineries to get down to 10 ppm than for smaller refineries, as discussed in Chapter 5 of the draft RIA. As a result, under a 10-ppm average standard, the flexibility afforded by the ABT program helps those refineries with very high costs. They have the option of staying above 10 ppm if they can acquire credits from other refineries that were able to lower their sulfur level below 10 ppm. However, if the gasoline sulfur standard were to be 5 ppm, this would essentially end the ability of refiners to average sulfur reductions across their refineries. There simply would not be enough opportunity to generate credits below 5 ppm. As discussed in Chapter 5 of the draft RIA, to estimate the costs for a 10-ppm annual average standard where some refineries stay above 10 ppm, we also estimated the costs for refineries to get down to 5 ppm. To do so, we estimated that sulfur control costs would increase by at least 50 percent compared to the proposed 10-ppm standard, which is over two times more costly per ppm-gallon of gasoline sulfur reduced. This 5-ppm cost assessment is reasonable for those refineries that would likely generate credits under a 10-ppm average standard as these refineries are most likely in the best position for achieving such low sulfur levels. However, were we to actually assess the costs of a 5-ppm standard, at least some of these refineries would likely have additional costs for controlling the sulfur in other gasoline blendstocks, and we would likely apply a higher overdesign factor to account for industry-wide compliance at 5 ppm. More detailed refinery information may be needed for such an analysis but, for the more challenged refineries, a 5-ppm standard could potentially be cost prohibitive. A 5-ppm standard would also introduce further costs to address the contribution to gasoline sulfur from gasoline additives, transmix, ethanol denaturants, and contamination in the distribution system. Therefore, a 10-ppm annual average standard appears to be the point which properly balances feasibility with costs. Also, for these reasons, EPA believes that a viable ABT program is important to the success of the proposed Tier 3 fuels program (explained in more detail in Section V.A.2.b).

Finally, as discussed in Section IV.A.6, reducing sulfur below 10 ppm would further reduce vehicle emissions and allow the proposed Tier 3 vehicle standards to be achieved more easily. However, we believe that a 10-ppm average standard will be sufficient to allow vehicles to meet the proposed Tier 3 standards. The level of the Tier 3 standards was considered in light of a 10-ppm average sulfur level for gasoline. If we were to consider lowering sulfur further, we would then also have to consider reducing the vehicle standards further. Given the challenges associated with sulfur reductions below 10 ppm as discussed above, we do not believe this would be appropriate.

b. How Would the Proposed ABT Program Assist With Compliance?

As described more fully in Section V.E.1, we are proposing an ABT program that would reduce the average compliance burden for gasoline producers and importers. This program would permit the generation of credits by refineries that reduce their annual average sulfur level below 10 ppm, and transfer of these credits to other refineries to reduce or eliminate their need to make capital investments to meet the 10-ppm standard. The ABT program would thus provide refiners with multiple approaches to compliance, and each could choose the approach that minimizes their costs.

We modeled an ABT program to estimate how it would affect compliance. As described in more detail in Section VII.B.4, our modeling determined the lowest cost approach on a refinery-by-refinery basis under two scenarios: an idealized scenario in which every refinery has the opportunity to make credit transfers with every other refinery in the nation, and a more limited scenario in which credit transfers would only occur within companies that own more than one refinery. Today a significant fraction of Tier 2 sulfur credits are transferred within companies, but there is still a considerable amount of inter-company trading occurring. [345] Thus, assuming no trading between companies is a conservative assumption and the real impact is likely to be somewhere in between the two scenarios. Table V-2 describes how compliance would be affected under these two scenarios.

Table V-2—Impacts of Nationwide ABT Program on Compliance Back to Top
ABT with nationwide credit transfers ABT with intra-company credit transfers
Number of refineries that generate credits 46 18
Number of refineries that consume credits 25 8
Number of refineries that neither generate nor consume credits 40 85
Total modeled refineries 111 111

Based on our ABT modeling, we believe that a significant number of refineries would take advantage of the opportunity to generate or use credits, thus lowering their compliance burden under the proposed 10-ppm annual average standard. For a more complete discussion of our analysis of the proposed ABT program, refer to Chapter 5 of the draft RIA.

c. Adequacy of Proposed Refinery Lead Time

Given the complexity of gasoline refining, numerous planning and action steps would be required for refiners to complete the refinery changes needed to comply with the proposed Tier 3 sulfur standards. The steps required to implement these changes include: the completion of scoping studies, financing, process design for new or revamped refinery units or subunits, permitting, detailed engineering based upon the process design, field construction of the gasoline sulfur reduction facilities, and start-up and shakedown of the newly installed desulfurization equipment.

We conducted a thorough lead time analysis in which we sequenced the estimated time to complete scoping studies, process design, permitting, detailed engineering, field construction, and start-up and shakedown in advance of production based upon the methodology used in our recent gasoline and diesel rules.

For the proposed Tier 3 gasoline sulfur program, we estimated refinery lead times step-by-step for the construction of new grassroots FCC postreaters and the revamp of existing pre and postreaters. For each refinery project type, we estimated lead times for scoping studies, process design, permitting, detailed engineering, field construction, and start-up and shakedown. Estimated required lead times for scoping studies are six months. Process design ranged from six months for desulfurization equipment revamping to nine months for a grassroots postreater. It is during the process of performing their scoping studies and process design analysis that refiners would complete their permit applications.

Based on discussions with refiners, a review of the permitting experience for Tier 2 and our current analysis, we estimated that permitting for desulfurization equipment revamping and the construction of a grassroots postreater would take 9 months. However, we estimated the overall lead-times for Tier-3-related revamps to be considerably shorter, as described below. The estimates for permitting time are consistent with those of EPA's Office of Air Quality Planning and Standards (OAQPS) and our regional offices, both of which have engaged in extensive dialog with potentially affected parties. A discussion of the permitting implications of Tier 3 is contained in Section V.B of the preamble. Detailed engineering efforts were estimated to require six months for desulfurization equipment revamping and nine months for grassroots postreaters. Field construction was estimated to require six months for revamped pre-and postreaters and 12 months for grassroots postreaters. Start-up and shakedown processes were estimated to require six months for revamped FCC treaters and 9 months for grassroots postreaters. There is some degree of overlap among each of these steps as shown in Table V-3.

To allow refiners to complete all these different steps and comply with the 10 ppm average gasoline sulfur standard, assuming the Tier 3 proposal were to be finalized by the end of 2013, we would be providing three years of lead time. In addition to the three years of lead time, the proposed rulemaking also provides additional flexibility provided by the ABT program, small refinery delays, and hardship provisions. To support this timeline, we conducted several analyses of the expected refinery lead time requirements associated with the proposed Tier 3 standards and found that refinery operators would have more than adequate time to implement the required refinery charges. A justification for proposed timeline appears below.

Complying with Tier 3 is expected to involve some grassroots FCC postreaters, but mostly we believe that refiners will revamp existing FCC postreaters. Revamping of existing FCC postreaters can be accomplished in approximately 2 years, or less (See Table V-3). Grassroots FCC postreaters are expected to require on average about three-years to install and start-up (See Table V-3). In comparision to FCC pretreaters, hydrocrackers and distillate hydrotreaters, FCC postreaters are much less costly, low pressure units that take less time to scope out, require shorter lead times for ordering the equipment, and less time to install. Furthermore, the grassroots FCC postreaters to be installed for Tier 3 are expected to be in a moderate to light desulfurization service because the refineries they will be installed in will already be complying with Tier 2 using an FCC pretreater. FCC naphtha from a refinery with an FCC pretreater is expected to only contain about 100 ppm sulfur. To comply with Tier 3, refiners installing these grassroots FCC postreaters would only need to desulfurize the FCC naphtha down to 25 ppm (about a 75% reduction). In comparison, a single-stage FCC postreaters would have to desulfurize FCC naphtha from as high as 2400 ppm sulfur down to 25 ppm, a 99% sulfur reduction. The more moderate desulfurization service of the grassroots FCC postreaters needed to comply with Tier 3 would be expected to streamline the scoping and design work.

It is useful to compare the proposed lead time for Tier 3 to what was provided for Tier 2. In the case of the Tier 2 standard, we provided a three-year lead time along with an ABT program and other flexibilities to ease compliance. Refiners, though, commented that the three year timeline that we provided was not enough time. For the Tier 2 analysis, we assumed that refiners would solely install low-pressure FCC postreaters, which we believe could be scoped out, designed, installed and started up within a 3 year time period. However, many refiners complied with Tier 2 by installing high-pressure FCC pretreaters which require long lead times for the procurement of the required equipment. Furthermore, those refiners that did not install high-pressure FCC pretreaters instead installed grassroots FCC postreaters, many of which were designed for severe desulfurization service. An additional difference between Tier 3 and Tier 2 is that for Tier 3 we expect the installation of only 16 grassroots units, along with many revamps, but for Tier 2 virtually all refiners installed both grassroots FCC pretreaters and postreaters. The demands on the desulfurization vendors for scoping studies, and on the E & C industry for design and construction, and on the refiners to train their operations staff and start up the new units, was a lot greater for Tier 2 than what we would expect for Tier 3. The total estimated investment cost for Tier 2 versus Tier 3 also highlights the difference in investment demands.

The total investment for Tier-2 desulfurization processing units was estimated to be about $6.1 billion, while the total investment for Tier-3 desulfurization processing units is estimated to be about $2.1 billion. This simple comparison helps to illustrate that the proposed Tier 3 would be easier for refineries to obtain necessary permits, secure engineering and construction (E&C) resources, install new desulfurization equipment and make all necessary retrofits to meet the proposed sulfur standards.

We assessed the permitting situation in more detail working in conjunction with the Office of Air Quality, Planning and Standards (OAQPS). Since the permitting process has little impact on the overall cost of compliance with Tier 3, it is an issue primarily in terms of its potential impact on the time needed to complete the necessary refinery modifications. On a refinery-by-refinery basis, we provided OAQPS estimates of the additional heating demands for the new and revamped units per the desulfurization vendor submissions. OAQPS was able to project which refineries would likely trigger NO X, particulate matter and greenhouse gas emission permitting limits, which would likely lengthen the permitting process as refiners would need to offset the projected emission increases. As it turns out, only 2 of the 16 refineries which are projected to install grassroots units were projected to exceed particular permitting limits, and these solely did so based on the most conservative assumption that each would produce all the additional hydrogen on site using hydrogen plants (as opposed to using existing reforming capacity) and produce the electricity on site, to satisfy the needs of the new desulfurization equipment. When we provided a second heat demand estimate to OAQPS which assumes that refiners purchase their hydrogen and electricity from third parties, none of the refineries which we projected would install grassroots units was projected to have emission increases which would require offsets. Thus, many of the grassroots units that we project would be installed may end up with a streamlined permitting process. We seek comment on our estimates of the number of refineries that may trigger the need for new permits and the length of time necessary to obtain the various types of permits that may be required once the refiner applies for them.

The various flexibilities that the proposed Tier 3 rule provides to refiners provide refiners additional time for complying. These flexibilities include the ABT program, the small refiner delay provisions and the hardship provisions. The ABT program allows a refiner, either within its own company or by purchasing credits on the open market, to delay higher investment cost investments, such as the investments in grassroots FCC postreaters, which would provide additional lead time for installing these units. This would occur if refiners would reduce the sulfur levels of their gasoline through operational changes or revamps of their existing FCC pretreaters and postreaters when the ABT Program begins in 2014. Potentially every refinery with either an FCC pretreater or an FCC postreater may be capable of generating early credits. Furthermore, we project that 66 refineries would revamp their existing FCC postreaters to comply with Tier 3. Since revamps can be completed within two years or less, these refiners could potentially begin generating early credits during 2016, or before if refiners begin each of these revamps in early 2014. During the period between 2014 and 2017, these refineries which reduce their gasoline sulfur levels below that required by Tier 2 would generate credits. Refineries with higher cost capital investments, such as the grassroots FCC postreaters, could then delay making those investments through the purchase of credits. We estimate that sufficient credits could be genereated early to allow many of these refineries to delay compliance until as late as 2020. The quantitative early credit analysis that we conducted showed that if refiners with an existing pretreater or postreater would generate early credits by lowering their gasoline sulfur down to 20 ppm starting in 2014 and if revamps were started up in 2016, one year before the program start date, that almost 6 times more credits would be available to offset the early credit demand by the refiners installing grassroots postreater units, assuming that they start up those units in 2018. Even if all grassroots postreaters were assumed to not start up until 2020, there would be almost 4 times more early credits available to those refiners installing grassroots postreaters assuming that the same early credit generation scenario would occur.

Additional flexibility is also provided by the small refineries provisions which delays compliance by the refineries that refiner less than a net of 75,000 barrels of crude oil per day until 2020. Three of the 16 FCC postreater grassroots units that we project will be installed would be by small refineries. However, small refineries could also decide to comply early and generate credits starting as early as 2014.

As in previous fuel programs, we are proposing hardship provisions to accommodate a refiner's inability to comply with the proposed standard at the start of the Tier 3 program, and to deal with unforeseen circumstances that may occur at any point during the program. These provisions would be available to all refiners, small and non-small, though relief would be granted on a case-by-case basis following a showing of certain requirements; primarily that compliance through the use of credits was not feasible. We are proposing that any hardship waiver would not be a total waiver of compliance; rather, a hardship waiver would be short-term relief that would allow a refiner facing a hardship situation to, for example, receive additional time to comply. This hardship provision would allow a refiner to seek a delay in the case that there was insufficient time to comply.

Finally, we believe that in reality, less leadtime than shown in Table V-3 would actually be necessary. We held discussions with many refiners during 2011, and so they have been well aware of Tier 3 and are familiar with the likely requirements. During our subsequent discussions with technology vendors and engineering firms, they explained to us that many refiners have already initiated, and by now, likely completed their scoping studies. Thus, actual time needed for designing, installing and starting of new desulfurization equipment for Tier 3 times would be even less than what we projected because many refineries may have already completed required scoping studies in anticipation of the Tier-3 standards. Moreover, lead times for those refineries that have yet to start the scoping process can also be expected to decrease, since fewer refineries will be competing for the services of the desulfurization vendors. We request comment on the amount of lead time that we are providing refiners to scope, design, permit, construct and start-up a grassroots desulfurization unit, considering all the proposed flexibilities which allow refiners to stagger their capital investments and ease compliance.

As in prior rules, we also evaluated the capability of E&C industries to design and build gasoline hydrotreaters as well as performing routine maintenance. Two areas where it is important to consider the impact of the fuel proposed sulfur standards are: (1) Refiners' ability to procure design and construction services and (2) refiners' ability to obtain the capital necessary for the construction of new equipment required to meet the new gasoline quality specification. We evaluated the requirement for engineering design and construction personnel in a manner consistent with the Tier 2 analysis, particularly for three types of workers needed to implement the refinery changes: front-end designers, detailed designers, and construction workers. We developed estimates of the maximum number of each of these types of workers needed throughout the design and construction process and compared those figures to the number of personnel currently employed in these areas.

The number of job hours necessary to design and build individual pieces of refinery equipment and the job hours per piece of equipment were taken from Moncrief and Ragsdale. [346] Their paper summarizes analyses performed in support of a National Petroleum Council study of gasoline desulfurization, as well as other potential fuel quality changes. The design and construction factors for desulfurization equipment are summarized in Table V-4.

Table V-4—Design and Construction Factors Back to Top
aRevamped equipment estimated to require half as many hours per piece of equipment.
Gasoline Refiners:  
Number of New Pieces of Equipment per Refinery 60
Number of Revamped Pieces of Equipment per Refinery 15
Job Hours Per Piece of New Equipment: a  
Front End Design 300
Detailed Design 1,200
Direct and Indirect Construction 9,150

Refinery projects will differ in complexity and scope. Even if all refiners desired to complete their project by the same date, their projects would inevitably begin over a range of months. Thus, two projects scheduled to start up at exactly the same time are not likely to proceed through each step of the design and construction process at the same time. Second, the design and construction industries will likely provide refiners with economic incentives to avoid temporary peaks in the demand for personnel.

Applying the above factors, we projected the maximum number of personnel needed in any given month for each type of job. The results are shown in Table V-5. In addition to total personnel required, the percentage of the U.S. workforce in these areas is also shown, assuming that half of all projects occur in the Gulf Coast

Table V-5—Maximum Monthly Demand for Personnel Back to Top
Front-end design Detailed engineering Construction
aBased on current employment in the U.S. Gulf Coast assuming half of all projects occur in the Gulf Coast.
Tier 3 Gasoline Sulfur Program:      
Number of Workers 202 809 6,012
Percentage of Current Workforcea 11% 9% 4%

To meet the proposed Tier 3 sulfur standards, refiners are expected to invest $2.2 billion between 2014 and 2019 and utilize approximately 1,000 front-end design and engineering jobs and 6,000 construction jobs. The number of estimated jobs required is small relative to overall number available in the U.S. job market. As such, we believe that three years, plus the additional flexibilities provided, is adequate lead time for refineries to obtain necessary permits, secure E&C resources, install new desulfurization equipment, and make all necessary retrofits to meet the proposed sulfur standards. For an in depth assessment of stationary source implications, refer to Section V.B. For more on our E&C assessment, refer to Section 4.5 of the draft RIA.

3. Per-Gallon Sulfur Caps

In much of Europe and Japan, the gasoline sulfur level is capped at 10 ppm. We, however, are not considering a 10-ppm cap for the U.S. The U.S. gasoline distribution system poses contamination challenges that make it difficult to set and enforce such a tight downstream per-gallon sulfur standard. In Europe, Japan, and California, finished petroleum products are generally shipped short distances directly from the refinery to the terminal with limited susceptibility to contamination. The U.S. has the longest and most complex gasoline distribution system in the world, making it harder to control sulfur contamination than in other countries. Petroleum products are shipped long distances through multi-product pipelines. Further, gasoline goes through the same pipelines and terminals back-to-back with jet fuel (containing up to 3,000 ppm sulfur). Products are often in the custody of a number of separate companies before reaching the terminal. This system is very effective at delivering petroleum products t