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Proposed Rule

Federal Implementation Plans To Reduce Interstate Transport of Fine Particulate Matter and Ozone

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Information about this document as published in the Federal Register.

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AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Proposed rule.

SUMMARY:

EPA is proposing to limit the interstate transport of emissions of nitrogen oxides (NOX) and sulfur dioxide (SO2). In this action, EPA is proposing to both identify and limit emissions within 32 states in the eastern United States that affect the ability of downwind states to attain and maintain compliance with the 1997 and 2006 fine particulate matter (PM2.5) national ambient air quality standards (NAAQS) and the 1997 ozone NAAQS. EPA is proposing to limit these emissions through Federal Implementation Plans (FIPs) that regulate electric generating units (EGUs) in the 32 states. This action will substantially reduce the impact of transported emissions on downwind states. In conjunction with other federal and state actions, it helps assure that all but a handful of areas in the eastern part of the country will be in compliance with the current ozone and PM2.5 NAAQS by 2014 or earlier. To the extent the proposed FIPs do not fully address all significant transport, EPA is committed to assuring that any additional reductions needed are addressed quickly. EPA takes comments on ways this proposal could achieve additional NOX reductions and additional actions including other rulemakings that EPA could undertake to achieve any additional reductions needed.

DATES:

Comments. Comments must be received on or before October 1, 2010.

Public Hearing: Three public hearings will be held before the end of the comment period. The dates, times and locations will be announced separately. Please refer to SUPPLEMENTARY INFORMATION for additional information on the comment period and the public hearings.

ADDRESSES:

Submit your comments, identified by Docket ID No. EPA-HQ-OAR-2009-0491 by one of the following methods:

  • http://www.regulations.gov. Follow the online instructions for submitting comments. Attention Docket ID No. EPA-HQ-OAR-2009-0491.
  • E-mail: a-and-r-docket@epa.gov. Attention Docket ID No. EPA-HQ-OAR-2009-0491.
  • Fax: (202) 566-9744. Attention Docket ID No. EPA-HQ-OAR-2009-0491.
  • Mail: EPA Docket Center, EPA West (Air Docket), Attention Docket ID No. EPA-HQ-OAR-2009-0491, U.S. Environmental Protection Agency, Mailcode: 2822T, 1200 Pennsylvania Avenue, NW., Washington, DC 20460. Please include 2 copies. 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 Street, NW., Washington, DC 20503.
  • Hand Delivery: U.S. Environmental Protection Agency, EPA West (Air Docket), 1301 Constitution Avenue, Northwest, Room 3334, Washington, DC 20004, Attention Docket ID No. EPA-HQ-OAR-2009-0491. 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-2009-0491. EPA's policy is that all comments received will be included in the public docket without change and may be made available online at http://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 http://www.regulations.gov or e-mail. The http://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 e-mail comment directly to EPA without going through http://www.regulations.gov, your e-mail 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, avoid 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.

Docket. All documents in the docket are listed in the http://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 http://www.regulations.gov or in hard copy at the Air and Radiation Docket and Information Center, EPA/DC, EPA West Building, 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.

Start Further Info

FOR FURTHER INFORMATION CONTACT:

Mr. Tim Smith, Air Quality Policy Division, Office of Air Quality Planning and Standards (C539-04), Environmental Protection Agency, Research Triangle Park, NC 27711; telephone number: (919) 541-4718; fax number: (919) 541-0824; e-mail address: smith.tim@epa.gov. For legal questions, please contact Ms. Sonja Rodman, U.S. EPA, Office of General Counsel, Mail Code 2344A, 1200 Pennsylvania Avenue, NW., Washington, DC 20460, telephone (202) 564-4079; e-mail address rodman.sonja@epa.gov.

End Further Info End Preamble Start Supplemental Information

SUPPLEMENTARY INFORMATION:

I. Preamble Glossary of Terms and Abbreviations

The following are abbreviations of terms used in the preamble.

ARP Acid Rain Program

BART Best Available Retrofit Technology

BACT Best Available Control Technology

CAA or Act Clean Air Act

CAIR Clean Air Interstate Rule

CBI Confidential Business Information

CFR Code of Federal Regulations

EGU Electric Generating Unit

FERC Federal Energy Regulatory Commission

FGD Flue Gas Desulfurization

FIP Federal Implementation Plan

FR  Federal Register

EPA U.S. Environmental Protection Agency

GHG Greenhouse Gas

Hg Mercury

IPM Integrated Planning Model

lb/mmbtu Pounds Per Million British Thermal Unit

μg/m3 Micrograms Per Cubic Meter Start Printed Page 45211

NAAQS National Ambient Air Quality Standards

NOX Nitrogen Oxides

NSPS New Source Performance Standard

OTAG Ozone Transport Assessment Group

PUC Public Utility Commission

SNCR Selective Non-catalytic Reduction

SCR Selective Catalytic Reduction

SIP State Implementation Plan

PM2.5 Fine Particulate Matter, Less Than 2.5 Micrometers

PM10 Fine and Coarse Particulate Matter, Less Than 10 Micrometers

PM Particulate Matter

RIA Regulatory Impact Analysis

SO2 Sulfur Dioxide

SOX Sulfur Oxides, Including Sulfur Dioxide (SO2) and Sulfur Trioxide (SO3)

TIP Tribal Implementation Plan tpy Tons Per Year

TSD Technical Support Document

II. General Information

A. Does this action apply to me?

This rule affects EGUs, and regulates the following groups:

Industry groupNAICS a
Utilities (electric, natural gas, other systems)2211, 2212, 2213
a North American Industry Classification System.

This table is not intended to be exhaustive, but rather provides a guide for readers regarding entities likely to be regulated by this action. This table lists the types of entities that EPA is aware of that could potentially be regulated. Other types of entities not listed in the table could also be regulated. To determine whether your facility would be regulated by the proposed rule, you should carefully examine the applicability criteria in proposed §§ 97.404, 97.504, 97,604, and 97.704.

B. Where can I get a copy of this document and other related information?

In addition to being available in the docket, an electronic copy of this proposal will also be available on the World Wide Web. Following signature by the EPA Administrator, a copy of this action will be posted on the transport rule Web site http://www.epa.gov/​airtransport.

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

1. Submitting CBI. Do not submit this information to EPA through http://www.regulations.gov or e-mail. 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. Send or deliver information identified as CBI only to the following address: Roberto Morales, OAQPS Document Control Officer (C404-02), U.S. EPA, Research Triangle Park, NC 27711, Attention Docket ID No. EPA-HQ-OAR-2009-0491.

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.

D. How can I find information about the public hearings?

The EPA will hold three public hearings on this proposal. The dates, times and locations of the pubic hearings will be announced separately. Oral testimony will be limited to 5 minutes per commenter. The EPA encourages commenters to provide written versions of their oral testimonies either electronically or in paper copy. Verbatim transcripts and written statements will be included in the rulemaking docket. If you would like to present oral testimony at one of the hearings, please notify Ms. Pamela S. Long, Air Quality Policy Division (C504-03), U.S. EPA, Research Triangle Park, NC 27711, telephone number (919) 541-0641; e-mail: long.pam@epa.gov. Persons interested in presenting oral testimony should notify Ms. Long at least 2 days in advance of the public hearings. For updates and additional information on the public hearings, please check EPA's website for this rulemaking, http://www.epa.gov/​airtransport. The public hearings will provide interested parties the opportunity to present data, views, or arguments concerning the proposed rule. The EPA officials may ask clarifying questions during the oral presentations, but will not respond to the presentations or comments at that time. Written statements and supporting information submitted during the comment period will be considered with the same weight as any oral comments and supporting information presented at the public hearings.

E. How is this Preamble Organized?

I. Preamble Glossary of Terms and Abbreviations

II. General Information

A. Does this action apply to me?

B. Where can I get a copy of this document and other related information?

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

D. How can I find information about the hearings?

E. How is the preamble organized?

III. Summary of Proposed Rule and Background

A. Summary of Proposed Rule

B. Background

1. What is the source of EPA's authority for this action?

2. What air quality problems does this proposal address?

3. Which NAAQS does this proposal address?

4. EPA Transport Rulemaking History

C. What are the goals of this proposed rule?

1. Primary Goals

2. Key Guiding Principles

D. Why does this proposed rule focus on the eastern half of the United States?

E. Anticipated Rules Affecting Power Sector

IV. Defining “Significant Contribution” and “Interference With Maintenance”

A. Background

1. Approach Used in NOX SIP Call and CAIR

2. Judicial Opinions

3. Overview of Proposed Approach

B. Overview of Approach To Identify Contributing Upwind States

1. Background

2. Approach for Proposed Rule

C. Air Quality Modeling Approach and Results

1. What air quality modeling platform did EPA use?

2. How did EPA project future nonattainment and maintenance for annual PM2.5, 24-Hour PM2.5, and 8-hour ozone?

3. How did EPA assess interstate contributions to nonattainment and maintenance?Start Printed Page 45212

4. What are the estimated interstate contributions to annual PM2.5, 24-hour PM2.5, and 8-hour ozone nonattainment and maintenance?

D. Proposed Methodology To Quantify Emissions That Significantly Contribute or Interfere With Maintenance

1. Explanation of Proposed Approach To Quantify Significant Contribution

2. Application

3. Discussion of Control Costs for Sources Other Than EGUs

E. State Emissions Budgets

1. Defining SO2 and Annual NOX State Emissions Budgets for EGUs

2. Defining Ozone Season NOX State Emissions Budgets for EGUs

F. Emissions Reductions Requirements Including Variability

1. Variability

2. State Budgets With Variability Limits

3. Summary of Emissions Reductions Across All Covered States

G. How the Proposed Approach Is Consistent With Judicial Opinions Interpreting Section 110(a)(2)(D)(i)(I) of the Clean Air Act

H. Alternative Approaches Evaluated But Not Proposed

V. Proposed Emissions Control Requirements

A. Pollutants Included in This Proposal

B. Source Categories

1. Propose To Control Power Sector Emissions

2. Other Source Categories Are Not Included

C. Timing of Proposed Emissions Reductions Requirements

1. Date for Prohibiting Emissions That Significantly Contribute or Interfere With Maintenance of the PM2.5 NAAQS

2. Date for Prohibiting Emissions That Significantly Contribute or Interfere With Maintenance of the 1997 Ozone NAAQS

3. Reductions Required by 2012 To Ensure That Significant Contribution and Interference With Maintenance Are Eliminated as Expeditiously as Practicable

4. How Compliance Deadlines Address the Court's Concern About Timing

5. EPA Will Consider Additional Reductions in Pollution Transport To Assist in Meeting Any Revised or New NAAQS

D. Implementing Emission Reduction Requirements

1. Approach Taken in NOX SIP Call and CAIR

2. Judicial Opinions

3. Remedy Options Overview

4. State Budgets/Limited Trading Proposed Remedy

5. State Budgets/Intrastate Trading Remedy Option

6. Direct Control Remedy Option

E. Projected Costs and Emissions for Each Remedy Option

1. State Budgets/Limited Trading

2. State Budgets/Intrastate Trading

3. Direct Control

4. State-Level Emissions Projections

F. Transition From the CAIR Cap-and-Trade Programs to Proposed Programs

1. Sunsetting of CAIR, CAIR SIPs, and CAIR FIPs

2. Change in States Covered

3. Applicability, CAIR Opt-Ins and NOX SIP Call Units

4. Early Reduction Provisions

5. Source Monitoring and Reporting

G. Interactions With Existing Title IV Program and NOX SIP Call

1. Title IV Interactions

2. NOX SIP Call Interactions

VI. Stakeholder Outreach

VII. State Implementation Plan Submissions

A. Section 110(a)(2)(D)(i) SIPs for the 1997 Ozone and PM2.5 NAAQS

B. Section 110(a)(2)(D)(i) SIPs for the 2006 PM2.5 NAAQS

C. Transport Rule SIPs

VIII. Permitting

A. Title V Permitting

B. New Source Review

IX. What benefits are projected for the proposed rule?

A. The Impacts on PM2.5 and Ozone of the Proposed SO2 and NOX Strategy

B. Human Health Benefit Analysis

C. Quantified and Monetized Visibility Benefits

D. Benefits of Reducing GHG Emission

E. Total Monetized Benefits

F. How do the benefits compare to the costs of this proposed rule?

G. What are the unquantified and unmonetized benefits of the transport rule emissions reductions?

1. What are the benefits of reduced deposition of sulfur and nitrogen to aquatic, forest, and coastal ecosystems?

2. Ozone Vegetation Effects

3. Other Health or Welfare Disbenefits of the Transport Rule That Have Not Been Quantified

X. Economic Impacts

XI. Incorporating End-Use Energy Efficiency Into the Proposed Transport Rule

A. Background

1. What is end-use energy efficiency?

2. How does energy efficiency contribute to cost-effective reductions of air emissions from EGUs?

3. How does the proposed rule support greater investment in energy efficiency?

4. How EPA and states have previously integrated energy efficiency into air regulatory programs?

B. Incorporating End-Use Energy Efficiency Into the Transport Rule

1. Options That Could Be Used To Incorporate Energy Efficiency Into Allowance Based Programs

2. Why EPA did not propose these options?

XII. Statutory and Executive Order Reviews

A. Executive Order 12866: Regulatory Planning and Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act (RFA)

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 and Safety Risks

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

I. National Technology Transfer Advancement Act

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

1. Consideration of Environmental Justice Issues in the Rule Development Process

2. Potential Environmental and Public Health Impacts to Vulnerable Populations

3. Meaningful Public Participation

4. Determination

III. Summary of Proposed Rule and Background

A. Summary of Proposed Rule

CAA section 110(a)(2)(D)(i)(I) requires states to prohibit emissions that contribute significantly to nonattainment in, or interfere with maintenance by, any other state with respect to any primary or secondary NAAQS. In this notice, EPA proposes to find that emissions of SO2 and NOX in 32 eastern states contribute significantly to nonattainment or interfere with maintenance in one or more downwind states with respect to one or more of three air quality standards—the annual average PM2.5 NAAQS promulgated in 1997, the 24-hour average PM2.5 NAAQS promulgated in 2006, and the ozone NAAQS promulgated in 1997.[1] These emissions are transported downwind either as SO2 and NOX or, after transformation in the atmosphere, as fine particles or ozone. This notice identifies emission reduction responsibilities of upwind states, and also proposes enforceable FIPs to achieve the required emissions reductions in each state through cost-effective and flexible requirements for power plants. Each state will have the option of replacing these Federal rules with state rules to achieve the required amount of emissions reductions from sources selected by the state.

With respect to the annual average PM2.5 NAAQS, this proposal finds that 24 eastern states have SO2 and NOX emission reduction responsibilities, and quantifies each state's full emission reduction responsibility under section 110(a)(2)(D)(i)(I). With respect to the 24-hour average PM2.5 NAAQS, this proposal finds that 25 eastern states have emission reduction responsibilities. The proposed reductions will at least partly eliminate, and subject to further analysis may fully eliminate, these states’ significant contribution and interference with maintenance for purposes of the 24-hour average PM2.5 standard. In all, emissions reductions related to interstate transport Start Printed Page 45213of fine particles would be required in 28 states.

With respect to the 1997 ozone NAAQS, this proposal requires emissions reductions in 26 states. For 16 of these states, we propose that the required reductions represent their full significant contribution and interference with maintenance for the ozone NAAQS. For an additional 10 states, the required NOX reductions are needed for these states to make measurable progress towards eliminating their significant contribution and interference with maintenance. EPA has begun to conduct additional information gathering and analysis to determine the extent to which further reductions from these states may be needed to fully eliminate significant contribution and interference with maintenance with the 1997 ozone NAAQS.

This proposed rule would achieve substantial near-term emissions reductions from the power sector. EPA projects that with the proposed rule, EGU SO2 emissions would be 5.0 million tons lower, annual NOX emissions would be 700,000 tons lower, and ozone season NOX emissions would be 100,000 tons lower in 2012, compared to baseline 2012 projections in the proposed covered states. Further, EGU SO2 emissions would be 4.6 million tons lower, annual NOX emissions would be 700,000 tons lower, and ozone season NOX emissions would be 100,000 tons lower in 2014, compared to baseline 2014 projections (which will have dropped from 2012 due to other federal and state requirements, thereby lowering the 2014 baseline). See Table III.A-2 for projected EGU emissions with the proposed rule compared to baseline, and Table III.A-3 for projected EGU emissions with the proposed rule compared to 2005 actual emissions. The reductions obtained through the Transport Rule FIPs will help all but a very few areas in the eastern part of the country come into attainment with the 1997 PM2.5 and ozone standards and take major strides toward helping states address nonattainment with the 2006 24-hour average PM2.5 standard. See Table III.A-1 for proposed list of covered states.

EPA is committed to fulfilling its responsibility to ensure that downwind states receive the relief from upwind emissions guaranteed under CAA section 110(a)(2)(D) For the 24-hour PM2.5 standard, EPA's air quality modeling shows that in the areas with continuing non-attainment or maintenance problems, the remaining exceedances occur almost entirely in the winter months. The relative importance of particle species such as sulfate and nitrate, is quite different between summer and winter. EPA is moving ahead before the final rule is published to determine the extent to which this wintertime problem is caused by emissions transported from upwind states. Further study of the 24-hour PM2.5 results could lead to a number of possible outcomes; EPA cannot judge the relative likelihood of these outcomes at this time. To the extent possible, EPA plans to finalize this rule with a full determination of, and remedy for, significant contribution and interference with maintenance for the 24-hour PM2.5 standard. To that end, EPA is expeditiously proceeding with examination of the residual wintertime problem. (See full discussion in section IV.D.)

In the case of ozone, EPA must determine whether further NOX reductions are warranted in certain upwind states that affect two or three areas with relatively persistent ozone air quality problems. To support a full significant contribution determination for these states, EPA is expeditiously conducting further analysis of NOX control costs, emissions reductions, air quality impacts, and the nature of the residual air quality issues. EPA's current information indicates that considering NOX reductions beyond the cost per ton levels proposed in this rule will require analysis of reductions from source categories other than EGUs, as well as from EGUs. EPA believes that developing supplemental information to consider NOX sources beyond EGUs would substantially delay publication of a final rule beyond the anticipated publication of spring 2011. EPA does not believe that this effort should delay the reductions and large health benefits associated with this proposed rule. Thus, EPA intends to proceed with additional rulemaking to address fully the residual significant contribution to nonattainment and interference with maintenance with the ozone standard as quickly as possible. (See full discussion in section IV.D.)

This proposed rule is the first of several EPA rules to be issued over the next 2 years that will yield substantial health and environmental benefits for the public through regulation of power plants. Fossil-fuel-fired power plants contribute a large and substantial fraction of the emissions of several key air pollutants, and the agency has statutory or judicial obligations to make several regulatory determinations on power plant emissions. The Administrator in January established improved air quality as an Agency priority and announced plans to promote a cleaner and more efficient power sector and have strong but achievable reduction goals for SO2, NOX, mercury, and other air toxics.”

In addition to this rule, other anticipated actions include a section 112(d) rule for electric utilities to be proposed by March 2011, potential rules to address pollution transport under revised NAAQS, revisions to new source performance standards for coal and oil-fired utility electric generating units, and best available retrofit technology (BART) and regional haze program requirements to protect visibility. These actions, and their relationship to this rule, are discussed further in section III.E.

Ongoing reviews of the ozone and PM2.5 NAAQS could result in revised NAAQS. To address any new NAAQS, EPA would propose interstate transport determinations in future notices. Such proposals could require greater emissions reductions from states covered by this proposal and/or require reductions from states not covered by this proposal. In addition, while this action proposes to require reductions from the power sector only, it is possible that reductions from other source categories could be needed to address interstate transport requirements related to any new NAAQS.

With this proposal, EPA is also responding to the remand of the CAIR by the Court in 2008. CAIR, promulgated May 12, 2005 (70 FR 25162) requires 28 states and the District of Columbia to adopt and submit revisions to their State Implementation Plans (SIPs) to eliminate SO2 and NOX emissions that contribute significantly to downwind nonattainment of the PM2.5 and ozone NAAQS promulgated in July 1997. The CAIR FIPs, promulgated April 26, 2006 (71 FR 25328), regulate EGUs in the covered states and achieve the emissions reductions requirements established by CAIR until states have approved SIPs to achieve the reductions. In July 2008, the DC Circuit Court found CAIR and the CAIR FIPs unlawful. North Carolina v. EPA, 531 F.3d 896 (DC Cir. 2008). The Court's original decision vacated CAIR. Id. at 929-30. However, the Court subsequently remanded CAIR to EPA without vacatur because it found that “allowing CAIR to remain in effect until it is replaced by a rule consistent with our opinion would at least temporarily preserve the environmental values covered by CAIR.” North Carolina v. EPA, 550 F.3d 1176, 1178 (DC Cir. 2008). The CAIR requirements are correctly in place and the CAIR's regional control programs are operating Start Printed Page 45214while EPA develops replacement rules in response to the remand.

As described more fully in the remainder of this preamble, the approaches used in this proposed rule to measure and address each state's significant contribution to downwind nonattainment and interference with maintenance are guided by and consistent with the Court's opinion in North Carolina v. EPA and address the flaws in CAIR identified by the Court therein. Among other things, the proposal relies on detailed, bottom-up scientific and technical analyses, introduces a state-specific methodology for identifying significant contribution to nonattainment and interference with maintenance, and proposes remedy options to ensure that all necessary reductions are achieved in the covered states.

In this action, EPA proposes to both identify and address emissions within states in the eastern United States that significantly contribute to nonattainment or interfere with maintenance by other downwind states. As discussed in sections III and VII in this preamble and described in greater detail in two separate Federal Register notices published on April 25, 2005 (70 FR 21147) and June 9, 2010 (75 FR 32673), EPA has determined, or proposed to determine, that the 32 states covered by this proposal either have not submitted SIPs adequate to meet the requirements of 110(a)(2)(D)(i)(I) with respect to the 1997 and 2006 PM2.5 NAAQS and the 1997 ozone NAAQS, or that the SIP provisions currently in place are not adequate to meet those requirements.

As described in section IV in this preamble, EPA is proposing a state-specific methodology to identify specific reductions that states in the eastern United States must make to satisfy the CAA section 110(a)(2)(D)(i)(I) prohibition on emissions that significantly contribute to nonattainment or interfere with maintenance in a downwind state. The proposed methodology uses state-specific inputs and focuses on the emissions reductions available in each individual state to address the Court's concern that the approach used in CAIR (which identified a single level of emissions achievable by the application of highly cost effective controls in the region) was insufficiently state specific. The proposed methodology uses air quality analysis to determine whether a state's contribution to downwind air quality problems is above specific thresholds. If a state's contribution does not exceed those thresholds, its contribution is found to be insignificant and it is no longer considered in the analysis. If a state's contribution exceeds those thresholds, EPA takes a second step that uses a multi-factor analysis that takes into account both air quality and cost considerations to identify the portion of a state's contribution that is significant or that interferes with maintenance. Section 110(a)(2)(D) requires states to eliminate the emissions that constitute this “significant contribution” and “interference with maintenance.”

This proposed methodology for determining upwind state emission reduction responsibility is designed to be applicable to current and potential future ozone and PM2.5 NAAQS. It is based on cost and air quality considerations that are common to any NAAQS, but also calls for evaluation of facts specific to a particular NAAQS. As a result, application of the methodology to a revised, more stringent NAAQS might lead to a determination that greater reductions in transported pollution from upwind states are reasonable than for a current, less stringent NAAQS.

To facilitate implementation of the requirement that significant contribution and interference with maintenance be eliminated, EPA developed state emissions budgets. By tying these budgets directly to EPA's quantification of each individual state's significant contribution and interference with maintenance, EPA directly linked the budgets to the mandate in section 110(a)(2)(D)(i)(I), and thus addressed the Court's concerns about the development of budgets for the CAIR. EPA also addressed these concerns by completely eschewing any consideration or reliance on Fuel Adjustment Factors and the existing allocation of Title IV allowances.

These new emissions budgets are based on the Agency's state-by-state analysis of each upwind state's significant contribution to nonattainment and interference with maintenance downwind. A state's emissions budget is the quantity of emissions that would remain after elimination of the part of significant contribution and interference with maintenance that EPA has identified in an average year (i.e., before accounting for the inherent variability in power system operations).[2] EPA proposes SO2 and NOX budgets for each state covered for the 24-hour and/or annual average PM2.5 NAAQS. EPA proposes an ozone season [3] NOX budget for each state covered for the ozone NAAQS.

EPA recognizes that baseline emissions from a state can be affected by changing weather patterns, demand growth, or disruptions in electricity supply from other units. As a result, emissions could vary from year to year in a state where covered sources have installed all controls and taken all measures necessary to eliminate the state's significant contribution and interference with maintenance. As described in detail in section IV of this preamble, EPA proposes to account for the inherent variability in power system operations through “assurance provisions” based on state variability limits which extend above the state emissions budgets. See section V for a detailed discussion of the assurance provisions. The small amount of variability allowed takes into account the inherent variability in baseline emissions. Section IV in this preamble describes the proposed approach to significant contribution and interference with maintenance and the state emissions budgets and variability limits in detail.

EPA is also proposing FIPs to immediately implement the emission reduction requirements identified and quantified by EPA in this action. For some covered states, these FIPs will completely satisfy the emissions reductions requirements of 110(a)(2)(D)(i)(I) with respect to the 1997 and 2006 PM2.5 NAAQS and the 1997 ozone NAAQS. The exception is for the 10 eastern states for which EPA has not completely quantified the total significant contribution or interference with maintenance with respect to the 1997 ozone NAAQS and the 15 states for which EPA has not completely quantified total significant contribution or interference with maintenance with respect to the 2006 PM2.5 NAAQS in which case the FIPs would achieve measurable progress towards implementing that requirement.

The emissions reductions requirements (i.e., the “remedy”) that EPA is proposing to include in the FIPs responds to the Court's concerns that EPA had not shown that the CAIR reduction requirements would get all Start Printed Page 45215necessary reductions “in the state” as required by section 110(a)(2)(D)(i)(I). The proposed FIPs include assurance provisions specifically designed to ensure that no state's emissions are allowed to exceed that specific state's budget plus the variability limit.

The proposed FIPs would regulate EGUs in the 32 covered states. EPA is proposing to regulate these sources through a program that uses state-specific budgets and allows intrastate and limited interstate trading. EPA is also taking comment on two alternative regulatory options. All options would achieve the emissions reductions necessary to address the emissions transport requirements in section 110(a)(2)(D)(i)(I) of the CAA.

The option EPA is proposing for the FIPs (“State Budgets/Limited Trading”) would use state-specific emissions budgets and allow for intrastate and limited interstate trading. This approach would assure environmental results while providing some limited flexibility to covered sources. The approach would also facilitate the transition from CAIR to the Transport Rule for implementing agencies and covered sources.

The first alternative remedy option for which EPA requests comment would use state-specific emissions budgets and allow intrastate trading, but prohibit interstate trading. The second alternative remedy option, for which EPA also requests comment, would use state-specific budgets and emissions rate limits. See section V for further discussion of the remedy options.

The proposed remedy option and the first alternative, both of which are cap-and-trade approaches, would use new allowance allocations developed on a different basis from CAIR. Allowance allocations, like the state budgets described previously, would be developed based on the methodology used by EPA to quantify each state's significant contribution and interference with maintenance. See section IV for the proposed state budget approach and section V for proposed allowance allocation approaches.

In this action, EPA proposes to require reductions in SO2 and NOX emissions in the following 25 jurisdictions that contribute significantly to nonattainment in, or interfere with maintenance by, a downwind area with respect to the 24-hour PM2.5 NAAQS promulgated in September 2006: Alabama, Connecticut, Delaware, District of Columbia, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin.

EPA proposes to require reductions in SO2 and NOX emissions in the following 24 jurisdictions that contribute significantly to nonattainment in, or interfere with maintenance by, a downwind area with respect to the annual PM2.5 NAAQS promulgated in July 1997: Alabama, Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia, and Wisconsin.

EPA also proposes to require reductions in ozone season NOX emissions in the following 26 jurisdictions that contribute significantly to nonattainment in, or interfere with maintenance by, a downwind area with respect to the 1997 ozone NAAQS promulgated in July 1997: Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Florida, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Michigan, Mississippi, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, and West Virginia.

As discussed previously, EPA also is proposing FIPs to directly regulate EGU SO2 and/or NOX emissions in the 32 covered states. The proposed FIPs would require the 28 jurisdictions covered for purposes of the 24-hour and/or annual PM2.5 NAAQS to reduce SO2 and NOX emissions by specified amounts. The proposed FIPs would require the 26 states covered for purposes of the ozone NAAQS to reduce ozone season NOX emissions by specified amounts.

In response to the Court's opinion in North Carolina v. EPA, EPA has coordinated the compliance deadlines for upwind states to eliminate emissions that significantly contribute to or interfere with maintenance in downwind areas with the NAAQS attainment deadlines that apply to the downwind nonattainment and maintenance areas. EPA proposes to require that all significant contribution to nonattainment and interference with maintenance identified in this action with respect to the PM2.5 NAAQS be eliminated by 2014 and proposes an initial phase of reductions starting in 2012 (covering 2012 and 2013) to ensure that the reductions are made as expeditiously as practicable and that no backsliding from current emissions levels occurs when the requirements of the CAIR are eliminated. Sources will be required to comply by January 1, 2012 and January 1, 2014 for the first and second phases, respectively. With respect to the 1997 ozone NAAQS, EPA proposes to require an initial phase of NOX reductions starting in 2012 to ensure that reductions are made as expeditiously as practicable. Sources will be required to comply by May 1, 2012 and May 1, 2014 for the first and second phases, respectively. EPA has determined, that for many states, these reductions will be sufficient to eliminate their significant contribution with respect to the 1997 ozone NAAQS. EPA intends to issue a subsequent proposal that would require all significant contribution and interference with maintenance be eliminated by a future date for the 1997 ozone NAAQS. See Table III.A-1 for proposed lists of covered state.

Table III.A-1—Lists of Covered States for PM2.5 and 8-Hour Ozone NAAQS

StateCovered for 24-hour and/or annual PM2.5Covered for 8-hour ozone
Required to reduce SO2 and NOXRequired to reduce ozone Season NOX
AlabamaXX
ArkansasX
ConnecticutXX
DelawareXX
District of ColumbiaXX
FloridaXX
Start Printed Page 45216
GeorgiaXX
IllinoisXX
IndianaXX
IowaX
KansasXX
KentuckyXX
LouisianaXX
MarylandXX
MassachusettsX
MichiganXX
MinnesotaX
MississippiX
MissouriX
NebraskaX
New JerseyXX
New YorkXX
North CarolinaXX
OhioXX
OklahomaX
PennsylvaniaXX
South CarolinaXX
TennesseeXX
TexasX
VirginiaXX
West VirginiaXX
WisconsinX
Totals2826

As discussed previously, EPA is proposing new SO2 and/or NOX emissions budgets for each covered state. The budgets are based on the EPA's state-by-state analysis of each upwind state's significant contribution to nonattainment and interference with maintenance downwind, before accounting for the inherent variability in power system operations.

As discussed in detail in section IV, the proposed approach to significant contribution to nonattainment and interference with maintenance would group the 28 states covered for the 24-hour and/or annual PM2.5 NAAQS in two tiers reflecting the stringency of SO2 reductions required to eliminate that state's significant contribution to nonattainment and interference with maintenance. There would be a stringent SO2 tier comprising 15 states (“group 1”) and a moderate SO2 tier comprising 13 states (“group 2”), with uniform stringency within each tier.[4] For these same 28 states, there would be one annual NOX tier with uniform stringency of NOX reductions across all 28 states. Similarly, for the 26 states covered for the ozone NAAQS there would be one ozone season NOX tier with uniform stringency across all 26 states.

The proposed stringent SO2 tier (“group 1”) would include Georgia, Illinois, Indiana, Iowa, Kentucky, Michigan, Missouri, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin. The proposed moderate SO2 tier (“group 2”) would include Alabama, Connecticut, Delaware, District of Columbia, Florida, Kansas, Louisiana, Maryland, Massachusetts, Minnesota, Nebraska, New Jersey, and South Carolina.

As discussed previously, EPA proposes to require an initial phase of reductions starting in 2012 (covering 2012 and 2013) requiring SO2 and NOX reductions in the 28 states covered for 24-hour and/or annual PM2.5 NAAQS. A second phase of reductions would be due in 2014, covering 2014 and thereafter. As described later, for certain states the 2014 reduction requirements would be more stringent, and for certain states would remain at the same level as the 2012 requirements.

For the 15 states in the stringent SO2 tier (“group 1”), the 2014 phase would substantially increase the SO2 reduction requirements (i.e., these states would have smaller SO2 emissions budgets starting in 2014), reflecting the greater reductions needed to eliminate the portion of significant contribution and interference with maintenance that EPA has identified in this proposal from these states with respect to the 24-hour PM2.5 NAAQS. For the 13 states in the moderate SO2 tier (“group 2”), the 2014 SO2 emissions budgets would remain the same as the 2012 SO2 budgets for these states.

The 2014 annual NOX emissions budgets for all 28 states covered for the 24-hour and/or annual PM2.5 NAAQS would remain the same as the 2012 annual NOX budgets.

With respect to the ozone NAAQS, EPA is proposing a single phase of reductions which begins in 2012. Thus, the rule does not call for any adjustment to be made to the 2012 ozone season NOX budgets for the 26 states covered for the ozone NAAQS. EPA intends to issue a subsequent proposal that would, among other things, address whether an additional phase of NOX reductions is necessary to address all significant Start Printed Page 45217contribution and interference with maintenance with respect to the 1997 ozone NAAQS. While this proposal assures downwind states that they will receive relief from upwind reductions that will help them achieve the NAAQS, EPA is committed to fulfilling its obligation to assure the downwind states that they receive the full relief they are entitled to under section 110(a)(2)(D). The Agency intends to quickly address any remaining significant contribution to nonattainment and interference with maintenance in a subsequent action that will also address a new more stringent ozone standard that is expected to be established by EPA later in 2010.

Tables III.A-2 and III.A-3 show projected Transport Rule emissions reductions for EGUs in all states that EPA proposes to cover.

Table III.A-2—Projected SO2 and NOX EGU Emissions in Covered States With the Transport Rule 5 Compared to Base Case 6 Without Transport Rule or CAIR

[Million tons]

2012 Base case emissions2012 Transport rule emissions2012 Emissions reductions2014 Base case emissions2014 Transport rule emissions2014 Emissions reductions
SO28.43.45.07.22.64.6
Annual NOX2.01.30.72.01.30.7
Ozone Season NOX0.70.60.10.70.60.1

Table III.A-3—Projected SO2 and NOX EGU Emissions in Covered States With the Transport Rule Compared to 2005 Actual Emissions

[Million tons]

2005 Actual emissions2012 Transport rule emissions2012 Emissions reductions from 20052014 Transport rule emissions2014 Emissions reductions from 2005
SO28.93.45.52.66.3
Annual NOX2.71.31.41.31.4
Ozone Season NOX0.90.60.30.60.3

In addition to the emissions reductions shown previously, EPA projects other substantial benefits, as described in section IX in this preamble. Air quality modeling was used to quantify the improvements in PM2.5 and ozone concentrations that are expected to result from the emissions reductions in 2014. The results of this modeling were used to calculate the average reduction in annual average PM2.5, 24-hour average PM2.5, and 8-hour ozone concentrations for monitoring sites in the eastern U.S. that are projected to be nonattainment in the 2014 base case. For annual PM2.5 and 24-hour PM2.5, the average reductions are 2.4 micrograms per cubic meter (μg/m3) and 4.3 μg/m3, respectively. The average reduction in 8-hour ozone at monitoring sites projected to be nonattainment in the 2014 base case is 0.3 parts per billion (ppb). The reductions in annual PM2.5, 24-hour PM2.5, and ozone concentrations for individual nonattainment and/or maintenance sites are provided in section IX.

Table III.A-4 compares projected EGU emissions with the Transport Rule to projected EGU emissions with CAIR.

Table III.A-4—Simple Comparison of SO2 and NOX Emissions From Electric Generating Units in States in the CAIR or Transport Rule Regions * for Each Rule

200520122014
ActualTransport ruleCAIR **Transport ruleCAIR **
SO2 (Million Tons)9.54.15.13.34.6
NOX (Million Tons)Annual Ozone Season2.9 1.01.6 0.71.7 0.81.6 0.71.7 0.8
* Emissions totals include states covered by either the Transport Rule or CAIR. For PM2.5 (SO2 and annual NOX), the following 30 states are included: AL, CT, DE, DC, FL, GA, IL, IN, IA, KS, KY, LA, MD, MA, MI, MN, MS, MO, NE, NJ, NY, NC, OH, PA, SC, TN, TX, VA, WV, WI. For ozone (ozone-season NOX), the following 30 states are included: AL, AR, CT, DE, DC, FL, GA, IL, IN, IA, KS, KY, LA, MD, MA, MI, MS, MO, NJ, NY, NC, OH, OK, PA, SC, TN, TX, VA, WV, WI.
** CAIR SO2 totals are interpolations from emissions analysis originally done for 2010 and 2015. CAIR NOX totals are as originally projected for 2010. This CAIR modeling represents a scenario that differed somewhat from the final CAIR (the modeling did not include a regionwide ozone season NOX cap and included PM2.5 requirements for the state of Arkansas).
Start Printed Page 45218

In addition to discussion of EPA's proposed regulatory approach (discussed in sections IV and V), this preamble also covers the stakeholder outreach EPA conducted (section VI), SIP submissions (section VII), permitting (section VIII), projected benefits of the proposed rule (section IX), economic impacts (section X), end-use energy efficiency (section XI), and statutory and executive order reviews (section XII).

Table III.A-5 shows the results of the cost and benefits analysis for the proposed and alternate remedies. Further discussion of these results is contained in preamble section XII-A and in the Regulatory Impacts Analysis. A listing of health and welfare effects is provided in RIA Table 1-6. Estimates here are subject to uncertainties discussed further in the body of the document. The social costs are the loss of household utility as measured in Hicksian equivalent variation. The capital costs spent for pollution controls installed for CAIR were not included in the annual social costs since the Transport Rule did not lead to their installation. Those CAIR-related capital investments are roughly estimated to have an annual social cost less than $1.15 to $ 1.29 billion (under the two discount rates.)

Most of the estimated PM-related benefits in this rule accrue to populations exposed to higher levels of PM2.5. Of these estimated PM-related mortalities avoided, about 80 percent occur among populations initially exposed to annual mean PM2.5 level of 10 μg/m3 and about 97 percent occur among those initially exposed to annual mean PM2.5 level of 7.5 μg/m3. These are the lowest air quality levels considered in the Laden et al. (2006) and Pope et al. (2002) studies, respectively. This fact is important, because as we estimate PM-related mortality among populations exposed to levels of PM2.5 that are successively lower, our confidence in the results diminishes. However, our analysis shows that the great majority of the impacts occur at higher exposures.

Table III.A-5—Summary of Annual Benefits, Costs, and Net Benefits of Versions of the Proposed Remedy Option in 2014 a

[Billions of 2006$]

DescriptionPreferred remedy—State budgets/ limited tradingDirect controlIntrastate trading
Social costs:
3% discount rate$2.03$2.68$2.49.
7% discount rate$2.23$2.91$2.70.
Health-related benefits: b, c
3% discount rate$118 to $288 + B$117 to $286 + B$113 to $276 + B.
7% discount rate$108 to $260 + B$108 to $262 + B$104 to $252 + B.
Net benefits (benefits-costs):
3% discount rate$116 to $286$115 to $283$110 to $273.
7% discount rate$105 to $258$105 to $259$101 to $249.
Notes: (a) All estimates are rounded to three significant digits and represent annualized benefits and costs anticipated for the year 2014. For notational purposes, unquantified benefits are indicated with a “B” to represent the sum of additional monetary benefits and disbenefits. Data limitations prevented us from quantifying these endpoints, and as such, these benefits are inherently more uncertain than those benefits that we were able to quantify. (b) The reduction in premature mortalities account for over 90 percent of total monetized benefits. Benefit estimates are national. Valuation assumes discounting over the SAB-recommended 20-year segmented lag structure described in Chapter 5. Results reflect 3 percent and 7 percent discount rates consistent with EPA and OMB guidelines for preparing economic analyses (U.S. EPA, 2000; OMB, 2003). The estimate of social benefits also includes CO2-related benefits calculated using the social cost of carbon, discussed further in Chapter 5. Benefits are shown as a range from Pope et al. (2002) to Laden et al. (2006). Monetized benefits do not include unquantified benefits, such as other health effects, reduced sulfur deposition or visibility. These models assume that all fine particles, regardless of their chemical composition, are equally potent in causing premature mortality because there is no clear scientific evidence that would support the development of differential effects estimates by particle type. (c) Not all possible benefits or disbenefits are quantified and monetized in this analysis. B is the sum of all unquantified benefits and disbenefits. Potential benefit categories that have not been quantified and monetized are listed in RIA Table 1-4.

B. Background

1. What is the source of EPA's authority for this action?

The statutory authority for this action is provided by the CAA, as amended (42 U.S.C. 7401 et seq.). Relevant portions of the CAA include, but are not necessarily limited to, sections 110(a)(2)(D), 110(c)(1), and 301(a)(1).

Section 110(a)(2)(D) of the CAA, often referred to as the “good neighbor” provision of the Act, requires states to prohibit certain emissions because of their impact on air quality in downwind states. Specifically, it requires all states, within 3 years of promulgation of a new or revised NAAQS, to submit SIPs that:

(D) Contain adequate provisions—

(i) Prohibiting, consistent with the provisions of this subchapter, any source or other type of emissions activity within the State from emitting any air pollutant in amounts which will—

(I) Contribute significantly to nonattainment in, or interfere with maintenance by, any other State with respect to any such national primary or secondary ambient air quality standard, or

(II) Interfere with measures required to be included in the applicable implementation plan for any other State under part C of this subchapter to prevent significant deterioration of air quality or to protect visibility.

(ii) Insuring compliance with the applicable requirements of sections 7426 and 7415 of this title (relating to interstate and international pollution abatement). 42 U.S.C. 7410(a)(2)(D).

This proposal addresses the requirement in section 110(a)(2)(D)(i)(I) regarding the prohibition of emissions within a state that significantly contribute to nonattainment or interfere with maintenance of the NAAQS in any other state. As discussed in greater detail later, EPA has previously issued two rules interpreting and clarifying the requirements of section 110(a)(2)(D)(i)(I). The NOX SIP Call, promulgated in 1998, was largely upheld by the U.S. Court of Appeals for the DC Circuit in Michigan v. EPA, 213 F.3d 663 (DC Cir. 2000). The CAIR, promulgated in 2005, was remanded by the DC Circuit in North Carolina v. EPA, 531 F.3d 896 (DC Cir. 2008), modified on reh'g, 550 F.3d. 1176 (DC Cir. 2008). These decisions provide additional guidance regarding the requirements of section 110(a)(2)(D)(i)(I) and are discussed later in this section.

Section 301(a)(1) of the CAA gives the Administrator of EPA general authority to “prescribe such regulations as are necessary to carry out [her] functions under this chapter.” 42 U.S.C. 7601(a)(1). Pursuant to this section, EPA has authority to clarify the applicability of CAA requirements. In this action, Start Printed Page 45219EPA is clarifying the applicability of section 110(a)(2)(D)(i)(I) by proposing to identify SO2 and NOX emissions that each affected state must prohibit pursuant to that section with respect to the PM2.5 NAAQS promulgated in 1997 and 2006 and the 8-hour ozone NAAQS promulgated in 1997. The improvements in air quality that would result from the reductions in upwind state emissions that EPA is proposing to require would assist downwind states affected by transported pollution in developing, pursuant to section 110 of the CAA, their SIPs to provide for expeditious attainment and maintenance of the NAAQS.

Section 110(a) of the CAA assigns to each state both the primary responsibility for attaining and maintaining the NAAQS within such state, 42 U.S.C. 7410(a)(1), and the primary responsibility for prohibiting emissions activity within the state which will significantly contribute to nonattainment or interfere with maintenance in a downwind area. 42 U.S.C. 7410(a)(2)(D)(i)(I). States fulfill these CAA obligations through the SIP process described in section 110(a) of the Act.

Section 110(c)(1) of the Act, however, requires EPA to act when a state has not been able to or has not fulfilled its obligation to submit a SIP that meets the requirements of the Act. Specifically, section 110(c)(1) provides that: The Administrator shall promulgate a Federal implementation plan at any time within 2 years after the Administrator—

(A) Finds that a State has failed to make a required submission or finds that the plan or plan revision submitted by the State does not satisfy the minimum criteria established under subsection (k)(1)(A) of this section, or

(B) Disapproves a State implementation plan submission in whole or part, unless the State corrects the deficiency, and the Administrator approves the plan or plan revision, before the Administrator promulgates such Federal implementation plan.

42 U.S.C. 7410(c)(1). Section 110(k)(1)(A), in turn, calls for the Administrator to establish criteria for determining whether SIP submissions are complete. 42 U.S.C. 7410(k)(1)(A).

As discussed in greater detail in section VII, for all states covered by the FIPs proposed in this action, EPA either has taken, has proposed to take, or believes it may need to take one of the following actions with respect to the 1997 ozone NAAQS, the 1997 PM2.5 NAAQS and/or the 2006 PM2.5 NAAQS: (1) Find that the state has failed to make a SIP submission required by section 110(a)(2)(D)(i)(I) or section 110(k)(5) of the Act; (2) find that such a SIP submission is incomplete; or (3) disapprove such a SIP submission. Once EPA has taken one of the these actions, pursuant to section 110(c)(1), it has authority to promulgate a FIP directly implementing the requirements of section 110(a)(2)(D)(i)(I), provided the state has not submitted and EPA has not approved a SIP submission that corrects the SIP deficiency prior to promulgation of the FIP.

2. What air quality problems does this proposal address?

a. Fine Particles

Fine particles are associated with a number of serious health effects including premature mortality, aggravation of respiratory and cardiovascular disease (as indicated by increased hospital admissions, emergency room visits, health-related absences from school or work, and restricted activity days), lung disease, decreased lung function, asthma attacks, and certain cardiovascular problems. See EPA, Air Quality Criteria for Particulate Matter (EPA/600/P-99/002bF, October 2004) at 9.2.2.3. See also integrated science assessment for the PM NAAQS review, December 2009, http://cfpub.epa.gov/​ncea/​cfm/​recordisplay.cfm?​deid=​216546. Individuals particularly sensitive to fine particle exposure include older adults, people with heart and lung disease, and children. This rule, and the NAAQS to which it is related, consider the effects of fine particles on vulnerable populations (see further discussion in section XII.G and section XII.J of this notice). More detailed information on health effects of fine particles can be found on EPA's Web site at: http://epa.gov/​pm/​standards.html.

In addition to effects on public health, fine particles are linked to a number of public welfare effects. First, PM2.5 are the major cause of reduced visibility (haze) in parts of the United States, including many of our national parks and wilderness areas. For more information about visibility, visit EPA's Web site at http://www.epagov/​visibility. Second, particles can be carried over long distances by wind and then settle on ground or water. The effects of this settling include: Making lakes and streams acidic; changing the nutrient balance in coastal waters and large river basins; depleting the nutrients in soil; damaging sensitive forests and farm crops; and affecting the diversity of ecosystems. More information about these effects is available at EPA's Web site at http://www.epa.gov/​acidrain/​effects/​index.html. Finally, particle pollution can stain and damage stone and other materials, including culturally important objects such as statues and monuments.

In 1997, EPA revised the NAAQS for PM to add new annual average and 24-hour standards for fine particles, using PM2.5 as the indicator (62 FR 38652). These revisions established an annual standard of 15 μg/m3 and a 24-hour standard of 65 μg/m3. During 2006, EPA revised the air quality standards for PM2.5. The 2006 standards decreased the level of the 24-hour fine particle standard from 65 μg/m3 to 35 μg/m3, and retained the annual fine particle standard at 15 μg/m3.

In the preamble to the final rule for CAIR in May 2005, EPA discussed ambient monitoring for 2001-2003, the most recent 3-year period available at the time. These results showed widespread exceedances of the 15 μg/m3 annual PM2.5 standard in the eastern United States, with additional exceedances in parts of California and one county in Montana. At that time, 82 counties in the U.S. had at least one monitor that violated the 1997 annual PM2.5 standard.

The PM2.5 ambient air quality monitoring for the 2006-2008 period (most recent available) shows significant improvements. Nonetheless, areas which continue to violate the 15 μg/m3 annual PM2.5 standard are located across a significant portion of the eastern half of the United States, in parts of California and one county in Arizona. Based on these nationwide data, 23 counties have at least one monitor that violates the annual PM2.5 standard.

The PM2.5 ambient air quality monitoring for this same 2006-2008 time period shows that areas violating the 2006 24-hour PM2.5 standard of 35 μg/m3 (i.e., the revised 2006 standard for 24-hour PM2.5) are located across much of the eastern half of the United States, in parts of California, and in some counties in several other western states—Alaska, Washington, Oregon, Utah, and Arizona. Based on these nationwide data, 52 counties have at least one monitor that violates the 24-hour PM2.5 standard.

EPA believes that a great deal of the improvement in PM2.5 annual and 24-hour concentrations in the eastern U.S. can be attributed to EGU SO2 reductions achieved due to the CAIR. While the CAIR requirements related to SO2 did not begin until 2010, many actions were taken by EGU owners and operators in anticipation of those requirements. Emissions of SO2 from EGUs covered by the CAIR that were also in the acid rain Start Printed Page 45220program (under CAA Title IV) tracking system decreased from 10.2 million tons in 2005 to 7.6 million tons in 2008. Almost all of these emissions reductions were achieved in the areas of the eastern United States covered by the CAIR. See http://www.epa.gov/​airmarkt/​progress/​ARP_​4.html. EPA believes that there would be substantially more nonattainment counties for both the annual and 24-hour standards if the CAIR were not in effect.

As required by the CAA, and in response to litigation over the 2006 standards, EPA is currently conducting a review of the 2006 PM2.5 standards. Information and documents related to this review are available at: http://epa.gov/​ttn/​naaqs/​standards/​pm/​s_​pm_​index.html. EPA expects to complete this review and to publish any revised standards that may result from the review by October 2011. EPA is planning to propose the revised standards by February 2011.

b. Ozone

Short-term (1- to 3-hour) and prolonged (6- to 8-hour) exposures to ambient ozone have been linked to a number of adverse health effects. At sufficient concentrations, short-term exposure to ozone can irritate the respiratory system, causing coughing, throat irritation, and chest pain. Ozone can reduce lung function and make it more difficult to breathe deeply. Breathing may become more rapid and shallow than normal, thereby limiting a person's normal activity. Ozone also can aggravate asthma, leading to more asthma attacks that may require a doctor's attention and the use of additional medication. Increased hospital admissions and emergency room visits for respiratory problems have been associated with ambient ozone exposures. Longer-term ozone exposure can inflame and damage the lining of the lungs, which may lead to permanent changes in lung tissue and irreversible reductions in lung function. A lower quality of life may result if the inflammation occurs repeatedly over a long time period (such as months, years, or a lifetime). There is also recent epidemiological evidence indicating that there is a correlation between short-term ozone exposure and premature mortality.

People who are particularly susceptible to the effects of ozone include people with respiratory diseases, such as asthma. Those who are exposed to higher levels of ozone include adults and children who are active outdoors. This rule, and the NAAQS which it is related to, consider the effects of ozone on vulnerable populations (see further discussion in section XII.G and section XII.J of this notice).

In addition to causing adverse health effects, ozone affects vegetation and ecosystems, leading to reductions in agricultural crop and commercial forest yields; reduced growth and survivability of tree seedlings; and increased plant susceptibility to disease, pests, and other environmental stresses (e.g., harsh weather). In long-lived species, these effects may become evident only after several years or even decades and have the potential for long-term adverse impacts on forest ecosystems. Ozone damage to the foliage of trees and other plants can also decrease the aesthetic value of ornamental species used in residential landscaping, as well as the natural beauty of our national parks and recreation areas. More detailed information on effects of ozone can be found at the following EPA Web site: http://www.epa.gov/​ttn/​naaqs/​standards/​ozone/​s_​o3_​index.html.

In 1997, at the same time we revised the PM2.5 standards, EPA issued its final action to revise the NAAQS for ozone (62 FR 38856) to establish new 8-hour standards. In this action published on July 18, 1997, we promulgated identical revised primary and secondary ozone standards that specified an 8-hour ozone standard of 0.08 parts per million (ppm). Specifically, the standards require that the 3-year average of the fourth highest 24-hour maximum 8-hour average ozone concentration may not exceed 0.08 ppm. In general, the 8-hour standards are more protective of public health and the environment and more stringent than the pre-existing 1-hour ozone standards.

At the time EPA published the CAIR and the CAIR FIP rulemakings, wide geographic areas, including most of the nation's major population centers, experienced ozone levels that violated the 1997 NAAQS of 8-hour ozone 0.08 ppm (effectively 0.084 ppm as a result of rounding). These areas included much of the eastern part of the United States and large areas of California. The EPA published the 8-hour ozone attainment and nonattainment designations in the Federal Register on April 30, 2004 (69 FR 23858). These designations, based on ozone season monitoring data for the 2001-2003 time period, resulted in 112 areas designated as nonattainment. As of December 2009, significant emissions reductions have allowed 58 of the original 112 nonattainment areas to be re-designated to attainment. In addition, a number of areas still designated as nonattainment ozone monitoring data for 2006-2008 (most recent data available) show levels below the standard. EPA believes a number of factors contributed to NOX emissions reductions subsequent to the 2001-2003 time period. First, EGU emissions were substantially reduced as EGUs in the eastern U.S. came into compliance with the NOX SIP Call. A series of progress reports discussing the effect of the NOX SIP Call reductions can be found on EPA's Web site at: http://www.epa.gov/​airmarkets/​progress/​progress-reports.html. Additional information on emissions and air quality trends are available in EPA's 2007 and 2008 air quality trends reports, which are available at: http://www.epa.gov/​airtrends/​.

Second, mobile source emissions standards for onroad gasoline and vehicle emissions standards began to reduce mobile source emissions as the fleet began turning over vehicles to meet tightened NOX emissions standards. Continued improvement in ozone is expected with continued reductions in mobile source emissions.

On March 12, 2008, EPA published a revision to the 8-hour ozone standard, lowering the level from 0.08 ppm to 0.075 ppm. On September 16, 2009, EPA announced it would reconsider these 2008 ozone standards. The purpose of the reconsideration is to ensure that the ozone standards are clearly grounded in science, protect public health with an adequate margin of safety, and are sufficient to protect the environment. EPA proposed revisions to the standards on January 19, 2010 (75 FR 2938) and will issue final standards soon. Information on the 2008 revisions to the ozone standard, and on all subsequent activity based on the reconsideration, is available at: http://www.epa.gov/​air/​ozonepollution/​actions.html#sep09s.

3. Which NAAQS does this proposal address?

This proposed action addresses the requirements of CAA section 110(a)(2)(D)(i)(I) as they relate to:

(1) The 1997 annual PM2.5 standards,

(2) The 2006 daily PM2.5 standards, and

(3) The 1997 ozone standards

The original CAIR and CAIR FIP rules, which pre-dated the 2006 standards, addressed the 1997 ozone and PM2.5 standards only. The 1997 8-hour ozone standard is 0.08 ppm. The 1997 PM2.5 standards promulgated in 1997 established a 15 μg/3 standard for 24-hour PM2.5 and a 65 μg/m3 standard for annual PM2.5. In 2006, the 24-hour PM2.5 standard was lowered to 35 μg/m3 and the 15 μg/m3 annual PM2.5 standard was left unchanged. Start Printed Page 45221

For this proposal, EPA fully addresses the requirements of CAA section 110(a)(2)(D)(i)(I) for the annual PM2.5 standard of 15 μg/m3. For the 24-hour standard of 35 μg/m3 and for the 1997 8-hour ozone standard of 0.08 ppm, EPA fully addresses the CAA section 110(a)(2)(D)(i)(I) requirements for some states, but for the remaining states EPA will address whether further requirements are needed.

This action does not address the CAA section 110(a)(2)(D)(i)(I) requirements for the revised ozone standards promulgated in 2008. These standards are currently under reconsideration. We are, however, actively conducting the technical analyses and other work needed to address interstate transport for the reconsidered ozone standard as soon as possible. We intend to issue as soon as possible a proposal to address the transport requirements with respect to the reconsidered standard.

4. EPA Transport Rulemaking History

a. CAA Provisions

For almost 40 years, Congress has focused major efforts on curbing ground-level ozone. In 1970, Congress amended the CAA to require, in Title I, that EPA issue and periodically review and, if necessary, revise NAAQS for ubiquitous air pollutants (sections 108 and 109). Congress required the states to submit SIPs to attain and maintain those NAAQS, and Congress included, in section 110, a list of minimum requirements that SIPs must meet. Congress anticipated that areas would attain the NAAQS by 1975.

In 1977, Congress amended the CAA by providing, among other things, additional time for areas that were not attaining the ozone NAAQS to do so, as well as by imposing specific SIP requirements for those nonattainment areas. These provisions first required the designation of areas as attainment, nonattainment, or unclassifiable, under section 107; and then required that SIPs for ozone nonattainment areas include the additional provisions set out in part D of Title I, as well as demonstrations of attainment of the ozone NAAQS by either 1982 or 1987 (section 172).

In addition, the 1977 Amendments included two provisions focused on interstate transport of air pollutants: the predecessor to current section 110(a)(2)(D), which requires SIPs for all areas to constrain emissions with certain adverse downwind effects; and section 126, which, in general, authorizes a downwind state to petition EPA to impose limits directly on upwind sources found to adversely affect that state. Section 110(a)(2)(D)(i)(I), which is key to the present action, is described in more detail later.

In 1990, Congress amended the CAA to better address, among other things, continued nonattainment of the 1-hour ozone NAAQS, the requirements that would apply if EPA revised the 1-hour standard, and transport of air pollutants across state boundaries (Pub. L. 101-549, Nov. 15, 1990, 104 Stat. 2399, 42 U.S.C. 7401-7671q).

As amended in 1990, the CAA further requires EPA to designate areas as attainment, nonattainment, and unclassifiable under a revised NAAQS (section 107(d)(1); section 6103, Pub. L. 105-178). The CAA authorizes EPA to classify areas that are designated nonattainment under the new NAAQS and to establish for those areas attainment dates that are as expeditious as practicable, but not to exceed 10 years from the date of designation (section 172(a)).

All areas are required to submit SIPs within certain timeframes (section 110(a)(1)), and those SIPs must include specified provisions, under section 110(a)(2). In addition, SIPs for nonattainment areas are generally required to include additional specified control requirements, as well as controls providing for attainment of any revised NAAQS and periodic reductions providing “reasonable further progress” in the interim (section 172(c)). If states do not submit SIPs in a timely or approvable manner, EPA has the authority to make findings of failure to submit or impose FIPs on specific sources in the state that contribute to downwind nonattainment and interference with maintenance. Significant contribution and interference with maintenance are discussed in detail in section IV later.

The 1990 Amendments reflect general awareness by Congress that ozone is a regional, and not merely a local, problem. Ozone and its precursors may be transported long distances across state lines, thereby exacerbating ozone problems downwind. Ozone transport is recognized as a major reason for the persistence of the ozone problem, notwithstanding the imposition of numerous controls, both Federal and State, across the country.

The CAA further addresses interstate transport of pollution in section 126, which Congress revised slightly in 1990. Subsection (b) of that provision authorizes each state (or political subdivision) to petition EPA for a finding designed to protect that entity from upwind sources of air pollutants.[7]

In addition, the 1990 Amendments added section 184, which delineates a multi-state ozone transport region (OTR) in the Northeast, requires specific additional controls for all areas (not only nonattainment areas) in that region, and establishes the Ozone Transport Commission (OTC) for the purpose of recommending to EPA regionwide controls affecting all areas in that region. At the same time, Congress added section 176A, which authorized the formation of transport regions for other pollutants and in other parts of the country.

In September 1994, the Northeast OTC states signed a Memorandum of Understanding (MOU) committing to reduce NOX emissions throughout the region. In 1999 through 2002, most of the OTC states achieved substantial NOX reductions through an ozone season cap and trade program for NOX called the OTC NOX Budget Program, which EPA administered, and through NOX emissions rate limits from certain coal plants under Title IV.

Separate from activity in the OTC, EPA and the Environmental Council of the States (ECOS) formed the OTAG in 1995. This workgroup brought together interested states and other stakeholders, including industry and environmental groups. Its primary objective was to assess the ozone transport problem and develop a strategy for reducing ozone pollution throughout the eastern half of the United States.

Notwithstanding significant efforts, the states generally were not able to meet the November 15, 1994 statutory deadline for the attainment demonstration and rate of progress (ROP) SIP submissions required under section 182(c). The major reason for this failure was that at that time, states with downwind nonattainment areas were not able to address transport from upwind areas. As a result, EPA recognized that development of the necessary technical information, as well as the control measures necessary to achieve the large level of reductions likely to be required, had been particularly difficult for the states affected by ozone transport.

Accordingly, as an administrative remedial matter, EPA established new timeframes for the required SIP submittals. To allow time for states to incorporate the results of the OTAG Start Printed Page 45222modeling into their local plans, EPA extended the submittal date to April 1998.[8] The OTAG's air quality modeling and recommendations formed the basis for what became the NOX SIP Call rulemaking and included the most comprehensive analyses of ozone transport ever conducted. The EPA participated extensively in the OTAG process that generated much useful technical and modeling information on regional ozone transport.

OTAG was established to address transport issues associated with meeting the 1-hour standard. The EPA did not promulgate the 8-hour standard until shortly after OTAG concluded; thus, OTAG did not recommend strategies to address the 8-hour NAAQS. However, because EPA had proposed an 8-hour standard, OTAG did examine the impacts of different strategies on 8-hour average ozone predictions. They found that ozone transport caused problems for downwind areas under either the 1-hour or 8-hour standard.

EPA's Transport SIP Call Regulatory Efforts. Shortly after OTAG began its work, EPA indicated that it intended to issue a SIP call to require states to implement the reductions necessary to address the ozone transport problem. On January 10, 1997 (62 FR 1420), EPA published a notice of intent and indicated that before taking final action, EPA would carefully consider the technical work and any recommendations of OTAG. The EPA published the NPR for the NOX SIP Call by notice dated November 7, 1997 (62 FR 60319). The NPR proposed to make a finding of significant contribution due to transported NOX emissions to nonattainment or maintenance problems downwind and to assign NOX emissions budgets for 23 jurisdictions. In light of OTAG's work and additional information, EPA was able to assess ozone transport as it relates to the 8-hour NAAQS and to set forth requirements as necessary to address the 8-hour standard in the rulemaking. The regional reductions of NOX that would have been achieved through this SIP call for the 1-hour NAAQS were key components for meeting the new 8-hour ozone standard in a cost-effective manner. Therefore, EPA believed that the OTAG recommendations for how to address ozone transport were valid for both NAAQS.

The EPA published a supplemental notice of proposed rulemaking (SNPR) dated May 11, 1998 (63 FR 25902), which proposed a model NOX budget trading program and state reporting requirements and provided the air quality analyses of the proposed statewide NOX emissions budgets.

Revision of the Ozone NAAQS. On July 18, 1997 (62 FR 38856), EPA issued its final action to revise the NAAQS for ozone. The EPA's decision to revise the standard was based on the Agency's review of the available scientific evidence linking exposures to ambient ozone to adverse health and welfare effects at levels allowed by the pre-existing 1-hour ozone standards. The 1-hour primary standard was replaced by an 8-hour standard at a level of 0.08 ppm, with a form based on the 3-year average of the annual fourth-highest daily maximum 8-hour average ozone concentration measured at each monitor within an area. The new primary standard provided increased protection to the public, especially children and other at-risk populations, against a wide range of ozone-induced health effects.

The pre-existing 1-hour secondary ozone standard was replaced by an 8-hour standard identical to the new primary standard. The new secondary standard provided increased protection to the public welfare against ozone-induced effects on vegetation.

Section 126 Petitions. In a separate rulemaking, EPA proposed action on petitions submitted by 8 northeastern states [9] under section 126 of the CAA. Each petition specifically requested that EPA make a finding that NOX emissions from certain major stationary sources significantly contributed to ozone nonattainment problems in the petitioning state. Both the NOX SIP Call and the section 126 petitions were designed to address ozone transport through reductions in upwind NOX emissions. However, the EPA's response to the section 126 petitions differed from EPA's action in the NOX SIP Call rulemaking in several ways. In the NOX SIP Call, EPA was determining that certain states were or would be significantly contributing to nonattainment or maintenance problems in downwind states. The EPA required the upwind states to submit SIP provisions to reduce the amounts of each state's NOX emissions that significantly contributed to downwind air quality problems. The states had the discretion to select the mix of control measures to achieve the necessary reductions. By contrast, under section 126, if findings of significant contribution were made for any sources identified in the petitions, EPA would have determined the necessary emissions limits to address the amount of significant contribution and would have directly regulated the sources. A section 126 remedy would have applied only to sources in states named in the petitions.

b. NOX SIP Call

Based on the findings of OTAG, EPA proposed a rulemaking known as the NOX SIP Call in 1997 and finalized it in 1998. (See “Finding of Significant Contribution and Rulemaking for Certain States in the Ozone Transport Assessment Group Region for Purposes of Reducing Regional Transport of Ozone; Rule,” (63 FR 57356).) This rule concluded that NOX emissions in 22 states and the District of Columbia contribute to ozone nonattainment in other states, and the rule required affected states to amend their SIPs and limit NOX emissions. EPA set an ozone season NOX budget for each affected state, essentially a cap on ozone season (summertime) NOX emissions in the state. Sources in the affected states were given the option to participate in a regional cap and trade program. The first control period was scheduled for the 2003 ozone season.

In response to litigation over EPA's final NOX SIP Call rule, the Court issued two decisions concerning the NOX SIP Call and its technical amendments.[10] The Court decisions, discussed later, generally upheld the NOX SIP Call and technical amendments, including EPA's interpretation of the definition of ”contribute significantly” under CAA section 110(a)(2)(D). The litigation over the NOX SIP Call coincided with the litigation over the 8-hour NAAQS. Because of the uncertainty caused by the litigation on the 8-hour NAAQS, EPA stayed the portion of the NOX SIP Call based on the 8-hour NAAQS (65 FR 56245, September 18, 2000). Therefore, for the most part, the Court did not address NOX SIP Call requirements under the 8-hour ozone NAAQS.

(1) What was the NOX SIP Call?

The NOX SIP Call was EPA's principal effort to reduce interstate transport of precursors for both the 1-hour ozone NAAQS and the 8-hour ozone NAAQS. The EPA's rulemaking was based on its consideration of OTAG's recommendations, as well as information resulting from EPA's additional work, and extensive public input generated through notice-and-comment rulemaking. The EPA believed Start Printed Page 45223that requiring NOX emissions reductions across the region in amounts achievable by uniform controls was a reasonable, cost-effective step to take to mitigate ozone nonattainment in downwind states for both the 1-hour and 8-hour standards.

It was also EPA's goal to ensure that sufficient regional reductions were achieved to mitigate ozone transport in the eastern half of the United States and thus, in conjunction with local controls, enable nonattainment areas to attain and maintain the ozone NAAQS.

This NOX SIP Call required those jurisdictions that EPA determined significantly contribute to 1-hour and 8-hour ozone nonattainment problems in downwind states to revise their SIPs to include NOX control measures to mitigate the significant ozone transport during summer months known as the “ozone season” (May-September). The EPA determined emissions reductions requirements for the covered states and source categories (see section IV.A for a description of the approach EPA used to determine emissions reductions requirements). The affected states were required to submit SIPs providing the specified amounts of emissions reductions. By eliminating these amounts of NOX emissions, the control measures would assure that the remaining NOX emissions would meet the level identified in the rule as the state's NOX emissions budget and would not “significantly contribute to nonattainment, or interfere with maintenance by,” a downwind state, under section 110(a)(2)(D)(i)(I).

The SIP requirements permitted each state to determine what measures to adopt to prohibit the significant amounts and hence meet the necessary emissions budget. Consistent with OTAG's recommendations to achieve decreased NOX emissions primarily from large stationary sources in a trading program, EPA encouraged states to consider electric utility and large boiler controls under a cap and trade program as a cost-effective strategy. The EPA also recognized that promotion of energy efficiency could contribute to a cost-effective strategy. See section V.D.1 for a discussion on the approach taken to implement the emissions reductions requirements in the NOX SIP Call.

(2) Legal Challenges to the NOX SIP Call

Several petitioners challenged the NOX SIP Call in the United States Court of Appeals for the District of Columbia Circuit (DC Circuit). In Michigan v. EPA, 213 F.3d 663 (DC Cir., 2000), cert. denied, 532 U.S. 904 (2001), the Court upheld the rule in most respects. Of greatest relevance here, the Court upheld the essential features of EPA's approach to identifying and eliminating states” NOX emissions that significantly contribute to downwind nonattainment. It upheld key aspects of EPA's air quality modeling and its use of cost-effectiveness criteria in defining states” “significant contribution.” See id. at 673-79. In addition, it accepted EPA's use of a uniform control requirement (i.e., requiring all covered jurisdictions, regardless of amount of contribution, to reduce NOX emissions by an amount achievable with highly cost effective controls). See id. at 679-80. The Court, however, agreed with petitioners that certain specific applications of EPA's approach were flawed. It thus vacated the rule with respect to Wisconsin, Missouri, and Georgia, and held that EPA had failed to provide adequate notice on two specific issues (a change in the definition of EGU and a change in control level assumed for specific sources). See id. at 681-85, 692-94. The Court also subsequently delayed the implementation date to May 31, 2004. Michigan v. EPA, 2000 WL 1341477 (DC Cir. 2000).

The decision resolved only issues involving the 1-hour ozone NAAQS and did not resolve any issues involving the 8-hour NAAQS, which provided another basis for the rule. See id. at 670-71. EPA ultimately stayed the 8-hour basis of the NOX SIP Call. See 65 FR 56245. In addition, in a subsequent case that reviewed separate EPA rulemakings making technical corrections to the NOX SIP Call, the DC Circuit remanded the case for a better explanation of EPA's methodology for computing the growth component in the EGU heat input calculation. See Appalachian Power Co. v. EPA, 251 F.3d 1026 (DC Cir. 2001). More recently, the Court also rejected a challenge to a subsequent EPA rule withdrawing EPA's findings of significant contribution for Georgia for the 1-hour ozone standard. See North Carolina v. EPA, 587 F.3d 422 (DC Cir. 2009).

(3) How the NOX Budget Trading Program (NBP) Worked

The NBP was a market-based cap and trade program created to reduce the regional transport of emissions of NOX from power plants and other large combustion sources that contribute to ozone nonattainment in the eastern United States. Over six ozone seasons (2003-2008), the NBP significantly lowered NOX emissions from affected sources, contributing to improvements in regional air quality across the Midwest, Northeast, and Mid-Atlantic. The cap level was intended to protect public health and the environment and to sustain that protection into the future regardless of growth in the affected sector. Ozone season NOX emissions decreased from levels in baseline years in all states participating in the NBP. (All NBP states transitioned to the CAIR NOX ozone season program in 2009 except Rhode Island.) Allowance trading was generally active from the start of the program in 2003. Prices and trading were down in 2008, primarily due to uncertainty. Compliance remained virtually 100 percent throughout the program's 6 years. Many nonattainment areas in the East saw substantial improvements in air quality concentrations that brought them in line with ozone NAAQS. The NBP, together with other Federal, State, and local programs, contributed to NOX reductions that have led to improvements in ozone and PM2.5, saving 580-1,800 lives annually in 2008.[11] Changes in ozone and nitrate concentrations due to the NBP have also contributed to improvements in ecosystems in the East.

EPA stopped administering the NBP at the conclusion of 2008 control period activities. States still have the emissions reductions requirement and could use the CAIR NOX ozone season trading program to achieve this.

See section V.D.4.e. for a discussion of the results of the NOX Budget Trading Program.

(4) Clean Air Interstate Rule

Following promulgation of the new NAAQS in 1997, the CAA required all states, regardless of whether they have attainment air quality in all areas, to submit SIPs containing provisions specified under section 110(a)(2). In addition, states are required to submit SIPs for nonattainment areas which are generally required to include additional emissions controls providing for attainment of the NAAQS.

As described previously, section 110(a)(2)(D)(i)(I) provides a tool for addressing the problem of transported pollution that significantly contributes to downwind nonattainment and maintenance problems. Under section 110(a)(2)(D), a SIP must contain adequate provisions prohibiting sources in the state from emitting air pollutants in amounts that would contribute significantly to nonattainment or interfere with maintenance in one or more downwind states. Section 110(k)(5) authorizes EPA to find that a SIP is substantially inadequate to meet any CAA requirement. If EPA makes such a finding, it is to require the state Start Printed Page 45224to submit, within a specified period, a SIP revision to correct the inadequacy (“SIP call”). In 1998, EPA used this authority to issue the NOX SIP Call, discussed previously, to require states to revise their SIPs to include measures to reduce NOX emissions that were significantly contributing to ozone nonattainment problems in downwind states.

Sulfur dioxide and NOX are not the only emissions that contribute to interstate transport and PM2.5 nonattainment. However, EPA stated in the CAIR that it believed that, given current knowledge, it was not appropriate to specify emissions reductions requirements for direct PM2.5 emissions or organic precursors (e.g., volatile organic compounds (VOCs) or ammonia (NH3)). Similarly, for 8-hour ozone, EPA continued to rely on the conclusion of the OTAG that analysis of interstate transport control opportunities should have focused on NOX, rather than VOCs. [12]

(5) What is the CAIR?

The CAA contains a number of requirements to address nonattainment of the PM2.5 and the 8-hour ozone NAAQS, including requirements that states address interstate transport that significantly contributes to such nonattainment. [13] Based on air quality modeling, ambient air quality data analyses, and cost analyses, EPA found that emissions in certain upwind states resulted in amounts of transported PM2.5, ozone, and their emissions precursors that significantly contributed to nonattainment in downwind states.

In the CAIR, promulgated on May 12, 2005 (70 FR 25162), EPA required SIP revisions in 28 states and the District of Columbia, within 18 months after publication of the notice of final rulemaking, to ensure that certain emissions of SO2 and/or NOX—important precursors of PM2.5 (NOX and SO2) and ozone (NOX)—were prohibited. Achieving the emissions reductions identified, EPA concluded, would address the states' requirements under section 110(a)(2)(D)(i)(I) of the CAA and would help PM2.5 and ozone nonattainment areas in the eastern half of the United States attain the standards. Moreover, EPA concluded that such attainment would be achieved in a more certain, equitable, and cost-effective manner than if each nonattainment area attempted to implement local emissions reductions alone, and would also assist the covered states and their neighbors in making progress toward their visibility goals.

The CAIR built on EPA's efforts in the NOX SIP Call to address interstate pollution transport for ozone, and was EPA's first attempt to address interstate pollution transport for PM2.5. It required significant reductions in emissions of SO2 and NOX, which contribute to fine particle concentrations. In addition, NOX emissions contribute to ozone problems. EGUs were found to be a major source of the SO2 and NOX emissions which contributed to fine particle concentrations and ozone problems downwind.

CAIR was designed to provide significant air quality attainment, health, and environmental improvements across the eastern U.S. in a highly cost-effective manner by reducing SO2 and NOX emissions from EGUs that contribute to the PM2.5 and 8-hour ozone problems described in the rule. CAIR's emissions reductions requirements were based on controls that EPA had determined to be highly cost-effective for EGUs under optional cap and trade programs. However, states had the flexibility to choose the measures to adopt to achieve the specified emissions reductions. EPA required the emissions reductions to be implemented in two phases, with the first phase in 2009 and 2010 (for NOX and SO2, respectively), and the second phase for both pollutants in 2015. These requirements are described in more detail in section V.D.1.

In addition to promulgating findings of significant contribution to nonattainment, EPA assigned emissions reductions requirements for SO2 and/or NOX that each of the identified states must meet through SIP measures.

Section V.D.1 discusses the approach taken in CAIR using three model multi-state cap and trade programs for SO2 and NOX that EPA developed and that states could choose to adopt to meet the required emissions reductions in a flexible and cost-effective way.

The requirements in the CAIR were intended to address regional interstate transport of air pollution. EPA recognized, however, that additional local reductions might be necessary to bring some areas into attainment even after significantly contributing upwind emissions were eliminated. 70 FR 25165-66, May 12, 2005. In addition, states that shared an interstate nonattainment area were expected to work together in developing the nonattainment SIP for that area, reducing emissions that contributed to local-scale interstate transport problems.

CAIR FIPs. When EPA promulgated the final CAIR in May 2005, EPA also issued a national finding that states had failed to submit SIPs to address the requirements of CAA section 110(a)(2)(D)(i) with respect to the 1997 ozone and PM2.5 NAAQS. States were to have submitted 110(a)(2)(D)(i) SIPs for those standards by July 2000. This action triggered a 2-year clock for EPA to issue FIPs to address interstate transport. On March 15, 2006 the EPA promulgated FIPs to ensure that the emissions reductions required by the CAIR are achieved on schedule. The FIPs did not limit states” flexibility in meeting their CAIR requirements as all states remained free to submit SIPs at any time that, if approved by EPA, would replace the FIP for that state.

As the control strategy for the FIPs, EPA adopted the model cap and trade programs that it provided in the CAIR as a control option for states, with minor changes to account for federal, rather than state, implementation. The FIPs required power plants in affected states to participate in one or more of three separate emissions cap and trade programs that cover: (1) Annual SO2 emissions, (2) annual NOX emissions, and (3) ozone season NOX emissions. Emission cap and trade programs are a proven method for achieving highly cost-effective emissions reductions while providing regulated sources with flexibility in choosing compliance strategies.

The FIPs also provided states with an option to submit abbreviated SIPs to meet CAIR. Under this option, states could save the time and resources needed to develop the complete trading program SIP, while still being able to make key decisions, such as the methodology for allocating annual and/or ozone season NOX allowances.

New Jersey and Delaware. Separately, on March 15, 2006, EPA issued a final rule to include Delaware and New Jersey in the CAIR to control SO2 and NOX emissions because they contribute to PM2.5 nonattainment in other states. 71 FR 25288, April 28, 2006. These states were already included in the CAIR because their sources contributed to nonattainment of other states' 8-hour ozone air quality standard. The CAIR FIP established requirements for Delaware and New Jersey with respect to both ambient air quality standards.

(6) Legal Challenges to the CAIR

Petitions for review challenging various aspects of the CAIR were filed in the U.S. Court of Appeals for the DC Circuit. In North Carolina v. EPA, 531 Start Printed Page 45225F.3d 896, modified on reh'g 550 F.3d 1176 (D.C. Cir. 2008), the Court granted several of the petitions for review and remanded the rule to EPA for further proceedings. In its July 2008 opinion, North Carolina, 531 F.3d 896, the Court upheld several challenged aspects of EPA's approach, but also found fatal flaws in the rule—flaws it found significant enough to warrant vacatur of the CAIR and the associated FIPs in their entirety. In December 2008, however, the Court responded to petitions for rehearing and determined that “notwithstanding the relative flaws of CAIR, allowing the CAIR to remain in effect until it is replaced by a rule consistent with our opinion would at least temporarily preserve the environmental values covered by CAIR.” North Carolina, 550 F.3d at 1178. Accordingly, it decided to remand the rule without vacatur “so that EPA may remedy CAIR's flaws in accordance with [the Court's] July 11, 2008 opinion in this case.” Id.

Although the entire rule was remanded, important parts of EPA's rulemaking were upheld by the Court in its July 2008 ruling. The Court upheld key aspects of the air quality modeling portion of EPA's significant contribution analysis. It upheld EPA's decision to consider upwind states for inclusion in the CAIR only if those states contributed to projected nonattainment in 2010. See North Carolina, 531 F.3d at 913-914. The Court further upheld the contribution threshold used in the air quality modeling portion of the significant contribution analysis for PM2.5, EPA's use of whole states as the unit of measurement, and the first-phase NOX compliance deadline of 2009 See id. at 914-17, 923-27, 928-29.

The Court also found significant flaws in EPA's approach. The Court emphasized the importance of individual state contributions to downwind nonattainment areas and held that EPA had failed to adequately measure significant contribution from sources within an individual state to downwind nonattainment areas in other states. Id. at 907. Further, the Court noted that EPA had not provided adequate assurance that the trading programs established in the CAIR would achieve, or even make measurable progress towards achieving, the section 110(a)(2)(D)(i)(I) mandate to eliminate significant contribution. See North Carolina, 532 F.3d at 907-08. For these reasons, it concluded that EPA had not shown that the CAIR rule would achieve measurable progress towards satisfying the statutory mandate of section 110(a)(2)(D)(i)(I) and thus EPA lacked authority for its action. See id. at 908. Moreover, it emphasized that where the rule constitutes a complete 110(a)(2)(D)(i)(I) remedy, it must actually require the elimination of emissions that contribute significantly to nonattainment or interfere with maintenance downwind. See id.

The Court further rejected the state budgets for SO2 and NOX which were used to implement the CAIR trading programs, finding the budgets to be insufficiently related to the 110(a)(2)(D)(i)(I) mandate of eliminating significant contribution and interference with maintenance. See id. at 916-21. It also rejected EPA's effort to harmonize the CAIR SO2 trading program with the existing requirements of Title IV of the CAA, holding that section 110(a)(2)(D)(i)(I) did not give EPA authority to terminate or limit Title IV allowances. In addition, the Court found that EPA had failed to give meaning to the “interfere with maintenance” prong of section 110(a)(2)(D)(i)(I), that EPA had not demonstrated that the 2015 compliance deadline used in the CAIR was coordinated with the downwind state's deadlines for attaining the NAAQS, and that EPA had not adequately supported its determination that sources in Minnesota significantly contributed to nonattainment or interfered with maintenance in downwind states. See id. at 908-11, 911-13, and 926-28.

(7) How the Clean Air Interstate Rule Worked

Building on the emissions reductions under the NBP and Acid Rain Program (ARP), CAIR was designed to permanently lower emissions of SO2 and NOX in the eastern United States. As explained previously, although the DC Circuit remanded the rule to EPA, it did so without vacatur allowing the rule to remain in effect while EPA addresses the remand. Thus, CAIR is continuing to help states address ozone and PM2.5 nonattainment and improve visibility, reducing transported precursors of SO2 and NOX, through the implementation of three separate cap and trade compliance programs for annual NOX, ozone season NOX, and annual SO2 emissions from power plants.

See section V.D.4.e. for a discussion on CAIR implementation in 2009, the first year of the NOX annual and ozone season programs. The CAIR annual SO2 program began January 1, 2010. Quarterly emissions will be posted on EPA's web site (see http://camddataandmaps.epa.gov/​gdm/​) and an assessment of emissions reduction data will be available at the end of each compliance period.

C. What are the goals of this proposed rule?

In developing this proposed rule, EPA was guided by a number of goals and guiding principles, as discussed in this section of the preamble.

1. Primary Goals

a. Respond to the Court Remand of the CAIR

Most importantly, this proposal responds to the remand of the CAIR by the Court. As noted previously, the Court granted several petitions for review of the CAIR, finding fatal flaws with the rule; yet, it ultimately decided to remand the rule without vacatur to preserve the environmental benefits of the rule. North Carolina v. EPA, 531 F.3d 896, modified on reh'g, 550 F.3d 1176 (DC Cir. 2008).

The action EPA is proposing would respond to the July and December 2008 opinions of the DC Circuit and correct the flaws in the CAIR methodology that were identified by the Court. The action responds to the Court's concerns in numerous ways. The methodology used to measure each state's significant contribution emphasizes air quality considerations and uses state specific data and information. The methodology also gives independent meaning to the interfere with maintenance prong of section 110(a)(2)(D)(i)(I). The state budgets for SO2, annual NOX and ozone season NOX are directly linked to the measurement of each state's significant contribution and interference with maintenance. The compliance deadlines are coordinated with the attainment deadlines for the relevant NAAQS. And the proposed remedy includes assurance provisions to assure that all necessary reductions occur in each individual state.

The action would also propose FIPs which would replace the remanded CAIR FIPs. The proposed FIPs would apply to all states covered by the rule, including those for which EPA had previously approved SIPs under the remanded CAIR. If finalized as proposed, these FIPs would eliminate or, at a minimum, make measurable progress towards eliminating emissions of SO2 and NOX that significantly contribute to or interfere with maintenance of the 1997 and 2006 PM2.5 NAAQS and the 1997 ozone NAAQS in the eastern half of the United States.

b. Address Transport Requirements With Respect to the Existing PM2.5 Standards

This proposed rule is designed to address the requirements of section 110(a)(2)(D)(i)(I) of the CAA as they Start Printed Page 45226relate to the 1997 and 2006 PM2.5 standards for states in the eastern United States. The proposed rule would both identify the emissions from states in the eastern U.S. that significantly contribute to nonattainment and interfere with maintenance of the NAAQS in downwind states, and prohibit such emissions.

States are obligated to submit SIPs to EPA addressing the provisions of section 110(a)(2), including the transport provisions of section 110(a)(2)(D)(i)(I), within 3 years of the promulgation of a new or revised NAAQS. For the 1997 NAAQS, these SIPs were due in 2000. On April 25, 2005 (effective May 25, 2005) EPA issued findings that states had failed to submit SIPs to satisfy the requirements of section 110(a)(2)(D)(i) of the Act under the 1997 ozone and PM2.5 standards. 70 FR 21147, April 25, 2005. These findings started a 2-year clock for the promulgation of a FIP by EPA unless, prior to that time, each state makes a submission to meet the requirements of 110(a)(2)(D)(i) and EPA approves the submission. This 2-year period expired in May 2007. Because the Court found CAIR inadequate to satisfy the requirements of 110(a)(2)(D)(i)(I), neither EPA's FIP implementing the requirements of CAIR nor any states SIPs that relied on CAIR to satisfy the requirements of this section, are adequate to meet the requirements of section 110(a)(2)(D)(i)(I). EPA's obligation to issue a FIP has therefore not yet been met. The requirements of the FIPs proposed in this rule are designed to address this obligation.

Revisions to the 1997 PM2.5 standards were signed by the Administrator on September 21, 2006, and published in the Federal Register on October 17, 2006. 71 FR 61144. The revisions were effective December 18, 2006. EPA interprets the 3 year deadline for submission of 110(a)(2) SIPs to be 3 years from the date of signature. Accordingly, for the 2006 revisions to the PM2.5 NAAQS, the SIPs under 110(a)(2) were due on September 21, 2009. On June 9, 2010, EPA issued a notice making findings that states had not submitted SIPs under the 2006 PM2.5 NAAQS by the September 2009 deadline. 75 FR 32673. These findings started a 2-year clock for the promulgation of a FIP by EPA unless, prior to that time, each state makes a submission to meet the requirements of 110(a)(2)(D)(i)(I) and EPA approves the submission. This 2-year period will expire on July 9, 2012. This proposal is designed to provide FIPs for the 2006 standards to ensure that the 110(a)(2)(D)(i)(I) obligation is fully satisfied as it relates to those standards. EPA also notes that under FIPs, reduction requirements are immediately effective and thus FIPs provide for the most expeditious means to implement emissions reduction requirements.

c. Address Transport Requirements With Respect to the 1997 Ozone Standards

This proposed rule, in concert with other actions, largely eliminates upwind state emissions that contribute significantly to nonattainment in, or interfere with maintenance by, any other state with respect to the 1997 8-hour ozone NAAQS. EPA will issue a subsequent proposal for the 1997 8-hour ozone NAAQS to address fully the requirements of CAA Section 110(a)(2)(D)(i)(I). EPA's goal is to fully address transport requirements for the 1997 ozone standards as soon as possible.

d. Provide for a Smooth Transition From Existing Programs

In addressing the Court remand in a way that satisfies the CAA transport requirements, EPA is also mindful of the need to ensure a smooth transition from the existing requirements. Substantial improvements in air quality have resulted from those requirements with associated health benefits. It is important not to lose those benefits as the new requirements move forward. It is also important to move quickly with those portions of the new requirements that provide the greatest benefits.

2. Key Guiding Principles

a. Appropriately Identify Necessary Upwind Reductions

Emissions from upwind states can, alone or in combination with local emissions, result in air quality levels that exceed the NAAQS and jeopardize the health of residents in downwind communities. Each upwind state is required by the “good neighbor provision” to eliminate its individual significant contribution to downwind state nonattainment and to eliminate emissions that interfere with downwind states” maintenance of the air quality standards. The Act does not require upwind states to eliminate all emissions that affect downwind air quality or shift responsibility for attaining the NAAQS to the upwind states. Instead, the “good neighbor provision” requires each upwind state to, within 3 years of promulgation or revision of a NAAQS, submit a SIP to prohibit those emissions that significantly contribute to nonattainment or interfere with maintenance downwind. The prohibition on these emissions is intended to assist downwind states as they design strategies for ensuring that the NAAQS are attained and maintained.

In practice, it is very complex for individual states to address the transport requirements. Generally for transport of ozone, and for transport of sulfate and nitrate fine particles, each downwind area is affected by emissions from multiple upwind states. In addition, in many cases states are simultaneously both upwind and downwind of one another. Further, only emissions that will significantly contribute to nonattainment or interfere with maintenance in another state are prohibited. Thus, an upwind state's obligations are affected by the air quality downwind. Downwind air quality, in turn, is affected by both local emissions and the cumulative impact of emissions from all of the contributing upwind states.

The problem of interstate transport is thus extremely complex and any remedy must acknowledge the inherent complexity of the problem. It is appropriate for EPA in developing such a remedy to be mindful of the interaction between upwind emissions controls and local emissions controls.

The EPA continues to conclude, as it did in developing the CAIR, that it would be difficult if not impossible for many nonattainment areas to reach attainment through local measures alone, and EPA finds no information developed subsequent to development of CAIR to alter this conclusion. At the time of the proposed CAIR rule, EPA conducted a local measures analysis representing an ambitious set of measures and emissions reductions that may in fact be difficult to achieve in practice. (Ref: Section IX of Technical Support Document for the Interstate Air Quality Rule Air Quality Modeling Analyses, January 2004). This analysis was intended to provide illustrative examples of the nature of location measures and possible reductions. This analysis was not intended to precisely identify local emissions control measures that may be available in a particular area. The EPA continues to believe that a strategy based on adopting cost effective controls on sources of transported pollutants as a first step will produce a more reasonable, equitable, and optimal strategy than one beginning with local controls. The local measures analyses we conducted were not, however, intended to develop a specific or “optimal” regional and local attainment strategy for any given area. Rather, the analysis was intended to evaluate whether, in light of available Start Printed Page 45227local measures, it is likely to be necessary to reduce significant regional transport from upwind states. EPA continues to believe that the two local measures analyses that were conducted for the CAIR strongly support the need for regional reductions of SO2 and NOX.

In conclusion, EPA believes that the proposed rule represents the best approach for identifying upwind state emissions that significantly contribute to nonattainment in, or interfere with maintenance by, downwind states.

b. Ensuring That Pollution Controls Operate

The proposed Transport Rule would, by 2012, cap emissions of SO2 and NOX on a state-by-state basis and guarantee that existing and planned pollution controls operate. EPA is convinced that the considerable benefits to air quality and public health that have been achieved must be ensured going forward. Keeping emissions of SO2 and NOX from increasing by 2012 in 27 states and DC assures that recent gains are maintained and that states that significantly contribute to downwind PM2.5 nonattainment and maintenance areas do not increase their contribution to those areas. Further, this proposal would maintain the ozone season emissions reductions achieved since 2005 in 26 states, ensuring that states that significantly contribute to downwind ozone nonattainment and maintenance areas do not increase their contribution to those areas. Tables III.A-2 and III.A-3 in section III.A, previously, show the projected EGU emissions for the 2012 phase of the Transport Rule.

c. Provide Workable Approach for EPA and States

Another important goal in developing the proposed requirements is to provide requirements that can, as a practical matter, be implemented by both EPA and state air quality agencies. Both EPA and state resources are limited and EPA recognizes the importance of developing requirements that make efficient use of limited EPA and state resources. EPA also notes that the air quality improvements brought about by reducing transport can greatly assist states in the development of SIPs and attainment demonstrations.

d. Ensure a Reliable Power Supply

EPA recognizes that requirements for EGUs must be mindful of the variability in the operation of the power grid, and that any requirements for broad reductions should be structured in a way that ensures a reliable power supply.

e. Provide for Cost-Effectiveness

EPA believes that is important to keep both cost-effectiveness and air quality objectives in mind in addressing the CAA transport requirements.

f. Provide Incentives and Flexibility to the Regulated Community

EPA seeks to provide approaches that provide regulated owners/operators of sources with the incentive to achieve all cost-effective reductions. EPA's experience shows that providing this incentive, and the flexibility to seek alternatives to less cost-effective controls, provides for greater environmental protection at reduced cost.

D. Why does this proposed rule focus on the eastern half of the United States?

For this proposal, we identified a 37 state region for the technical analysis, including all states east of the Rockies, from the Dakotas through Texas eastward. Western states also need to address the requirements of section 110(a)(2)(D)(i)(I) of the CAA. However, the transport issues in the eastern United States are analytically distinct and this rule focuses only on that subset of the 110(a)(2)(D)(i)(I) issues.

First, interstate transport of PM2.5 and ozone is a substantial and critical component for attaining the ozone and PM2.5 NAAQS in the eastern United States. The significant reductions in ambient air pollutant concentrations since CAIR, due largely to the large reductions in transported emissions, only serve to reinforce this point.

Second, in developing the CAIR, EPA found that interstate transport (particularly for anthropogenic emissions) made much smaller contributions to exceedances of the 1997 PM2.5 standards in the western United States. At the time, the only exceedances of the 15 μg/m3 in those states were in parts of California, and in Lincoln County (Libby), Montana. The Montana location has subsequently come into attainment.

Technical information developed for EPA's recently completed nonattainment designations suggests that interstate emissions transport makes a relatively small contribution to exceedances in the western United States under the 2006 PM2.5 standards. For these designations, EPA identified several locations in the western U.S. with exceedances of the 24-hour PM2.5 standards. These locations were in California and a few other western states: Alaska, Washington, Oregon, Utah, and Arizona. Technical support information describing the nature of the 24-hour PM2.5 problem at each of these locations is available at: http://www.epa.gov/​pmdesignations/​2006standards/​tech.htm. A review of this information suggests to EPA that the Western nonattainment problems are relatively local in nature with limited interstate transport. EPA requests comment on this assessment.

E. Anticipated Rules Affecting Power Sector

On January 12, 2010, the EPA Administrator outlined seven priorities for the Agency. One of them is to improve air quality. In her description of this priority she said, “EPA will develop a comprehensive strategy for a cleaner and more efficient power sector, with strong but achievable reduction goals for SO2, NOX, mercury, and other air toxics.” In furtherance of this priority goal, and to respond to statutory and judicial mandates, EPA is undertaking a series of regulatory actions over the course of the next 2 years that will affect the power sector in particular.

The rules under the CAA will substantially reduce the emissions of SO2, NOX, mercury, and other air toxics. To the extent that the Agency has the legal authority to do so while fulfilling its obligations under the Act and other relevant statutes, the Agency will also coordinate these utility-related air pollution rules with upcoming regulations for the power sector from EPA's Office of Water (OW) and its Office of Resource Conservation and Recovery (ORCR). EPA expects that this comprehensive set of requirements will yield substantial health and environmental benefits for the public, benefits that can be achieved while maintaining a reliable and affordable supply of electric power across the economy. In developing and promulgating these rules, the Agency will be providing the power industry with a much clearer picture of what EPA will require of it in the next decade. In addition to promulgating the rules themselves, the Agency will engage with other federal, state and local authorities, as well as with stakeholders and the public at large, with the goal of fostering investments in compliance that represent the most efficient and forward-looking expenditure of investor, shareholder, and public funds, resulting, in turn, in the creation of a clean, efficient, and completely modern power sector.

The major CAA rules that will drive these compliance investments are: (1) This transport rule; (2) potential future rules that may be needed to address transport under future revised ozone or fine particle health standards; (3) the Start Printed Page 45228CAA Section 112(d) standards; (4) revisions to the NSPS for coal and oil-fired electric utility steam generating units; and (5) BART requirements and other requirements that address visibility and regional haze. Within the planning and investment horizon for compliance with these rules, the EPA very likely will be compelled to respond a pending petition to set standards for the emissions of greenhouse gases from steam electric generating units under the NSPS program. Furthermore, as set forth in the recently promulgated reinterpretation of the Johnson Memo, beginning in 2011 new and modified sources of GHG emissions, including EGUs, will be subject to permits under the Prevention of Significant Deterioration program requiring them to adopt BACT for their GHGs. Finally, EPA will also pursue with other federal agencies, states, and other groups energy efficiency improvements in the use of electricity throughout the economy that will contribute to additional environmental and public health improvements that the Agency wants to provide while lowering the costs of realizing those improvements.

A brief explanation of these major CAA rulemakings and activities follows.

Transport Rule. This proposed transport rule includes emissions reductions requirements for EGUs to address interstate transport under the 1997 ozone NAAQS, the 1997 PM2.5 NAAQS, and the 2006 PM2.5 NAAQS. After considering public comments on this proposal, EPA will endeavor to issue a final rule in spring 2011.

Rules to Address Transport under Revised Air Quality Health Standards. EPA currently is reconsidering its 2008 national ambient air quality standards for ozone, and is conducting a periodic review of the particulate matter NAAQS, including the fine particle standards. The Act requires EPA to ensure that primary standards are requisite to protect public health with an adequate margin of safety, and to set secondary standards requisite to protect public welfare. The Act requires EPA to review, and revise if appropriate, the primary and secondary NAAQS on a 5-year schedule to ensure that air quality standards reflect the latest scientific information on health and welfare effects. When air quality standards are set or revised, the Act requires revision of SIPs to ensure that these standards to protect public health and welfare are met expeditiously and, in the case of the health-based standards, within timetables in the Act.

If more protective NAAQS are promulgated, further emissions reductions would likely be needed in states where pollution levels exceed air quality standards, and in upwind states with emissions that significantly contribute to the air quality problems in another state. This may result in additional emission reduction requirements for facilities in the power sector, as well as for other sectors. The reconsideration of the March 2008 ozone air quality standards will be completed soon, and the review of particulate matter air quality standards by October 2011. SIP deadlines and attainment deadlines would flow from those dates.

EPA plans to make expeditious determinations of upwind state emissions reduction responsibilities for NAAQS for which interstate transport is an issue. This approach will lead to earlier emissions reductions to protect public health, as well as provide other benefits. In the North Carolina decision, the court made clear that downwind state nonattainment deadlines are legally relevant to the timing of reductions under section 110(a)(2)(D). Thus, expeditious determinations of upwind state responsibilities under section 110(a)(2)(D) can promote upwind reductions in time to help downwind states meet attainment deadlines, enable states and EPA to provide sources with earlier information on their emission reduction responsibilities, and maximize sources lead time to reduce emissions.

If a more protective ozone NAAQS is issued in August, EPA would plan to propose an interstate pollution transport rule for that NAAQS in 2011. We would expect work on that proposal to proceed in parallel with efforts to finalize this Transport Rule for the 1997 and 2006 NAAQS. A final rule to address interstate pollution transport for a reconsidered ozone NAAQS would be anticipated in 2012. In view of the implementation schedule for a reconsidered ozone NAAQS, compliance dates would be later than the compliance dates proposed for this Transport Rule, and would take into account attainment dates for that NAAQS and other factors such, as control cost and installation time. For any revised PM2.5 NAAQS, EPA plans to conduct a similarly expeditious analysis of interstate transport to support a determination as to whether or not further emissions reductions from the power sector are required under section 110(a)(2)(D), in light of the emissions reductions required by other power sector rules.

A revised SO2 NAAQS was issued on June 2 creating a new 1-hour SO2 NAAQS which, when implemented, will protect Americans from asthma and respiratory difficulties associated with short term exposures to SO2. Although EPA does not expect peak SO2 levels to be a long-range transport issue, power plants are among the sources that can contribute to peak SO2 levels and will likely be evaluated by states as they consider control measures to attain the new standards. Anticipated emissions reductions from power plants and other SO2 sources under other Clean Air Act (CAA or Act) requirements (e.g., transport rules, and MACT standards) are expected to play a significant role in attainment of the 1-hour SO2 NAAQS.

Section 112(d) Standards for Utility Units. In 2008, the DC Circuit Court vacated the CAMR and the 112(n) Revision Rule, which removed coal- and oil-fired electric utility steam generating units from the section 112(c) list of sources subject to regulation. EPA is in the early stages of developing regulations under section 112 of the CAA that will require existing and new coal- and oil-fired utility units to meet emissions limits for mercury and other HAPs emitted from these sources. As required by section 112, EPA will issue a set of emissions standards. In part, the section 112(d) rule will require that all existing major sources achieve the emission limits for HAPs which will be at least as stringent as the average emissions reduction currently achieved by the best performing 12 percent of these units. Additionally, any new major source will be required to meet emission limits that are at least as stringent as what is currently achieved by the best-performing single source. Currently, the Agency is seeking data on five categories of HAP emissions: (1) Acid gases (e.g., hydrochloric acid, hydrogen fluoride, and hydrogen cyanide); (2) mercury; (3) Non-Hg metals (e.g., lead, cadmium, selenium, and arsenic); (4) dioxins/furans; and, (5) other organic hazardous air pollutants. EPA expects to receive the requested data, including stack testing results, by September 2010. EPA has agreed to sign the proposed rule by March 16, 2011, and sign the final rule no later than November 16, 2011. EPA may provide existing sources up to 3 years to comply with section 112(d) standards, and the CAA authorizes the permit authority to grant a 1 year extension of the compliance date on a case-by-case basis if such extension is necessary for the installation of controls. The CAA requires new sources to comply on the effective date of the final rule or at startup, whichever is later. If EPA were to provide 3 years for compliance with the section 112(d) standards, Start Printed Page 45229compliance would generally be required by early 2015.

In developing these rules, EPA will endeavor to proceed in a way that provides all stakeholders and other Federal, State and local decision-makers with ongoing, up-to-date information about the full suite of environmental responsibilities that the power sector must undertake. This, in turn, will enable power companies and others whose policies and decisions affect their investment choice to adopt compliance strategies that take full advantage of co-control opportunities and efficiencies and other approaches to maximizing the cost-effectiveness and leveraging benefits of their investments.

New Source Performance Standards. NSPS are administered under section 111 of the CAA. The standards for new, modified, and reconstructed steam EGUs are contained in 40 CFR part 60 subpart Da, which was last amended in 2006. The current structure of subpart Da sets output-based (i.e., lbs of emission/MWh) emission limits for NOX and SO2 and optional output-based standards for particulate matter. EPA is currently re-evaluating the standards in Subpart Da to determine whether they reflect the degree of emission limitation achievable through the application of the best system of emission reduction, which the Administrator determines has been adequately demonstrated. EPA also has a pending voluntary remand to decide whether NSPS standards for this source category should include limits on GHG emissions. EPA is considering the timetable for these actions and decisions in light of legal obligations and policy considerations, including the desirability of the industry knowing its regulatory obligations to inform investment decisions.

Regional Haze/BART. States are required to develop SIPs that address regional haze in scenic areas such as national parks and wilderness areas. EPA regulations for regional haze appear in Chapter 40 of the CFR in sections 51.308 and 51.309. One of the requirements of the regional haze SIPs is to provide for BART for large industrial sources including EGUs. The BART provisions affect EGUs put into operation between 1962 and 1977.

Energy Efficiency. Policies that will promote efficient use of electric power can be an integral, highly cost-effective component of power companies” compliance strategies. Reducing demand for electricity can in itself achieve large emissions reductions and public health benefits, while enhancing the reliability of the grid. It can also lower the cost of emissions reductions for consumers of electricity and for the power industry, as investments are avoided in unnecessary infrastructure.

EPA does not have sole responsibility for the development of energy policy to promote efficiency. To facilitate this component of the power sector's compliance strategy, EPA intends to engage with other federal, state, and local agencies whose policies and actions can make it easier for power companies to adopt, or benefit from, energy efficiency investments in their compliance strategies. EPA will continue to use its authorities to advance energy efficiency by providing incentives for energy efficiency in our regulatory programs (e.g., output-based standards) and through our successful existing voluntary programs such as ENERGY STAR. The Department of Energy (DOE) also has considerable resources to encourage efficient use of electricity. Additional resources have been made available under the American Recovery and Reinvestment Act to both DOE and EPA to promote energy efficiency. State governments, both in their environmental programs and through their public service commissions, which regulate electric utility rates, can promote energy efficiency. Many state governments have been leaders in promoting efficient use of electricity through such mechanisms as energy efficiency standards and demand response, and EPA and DOE are assisting state governments in this effort. Local governments as well, through building codes, zoning, and other actions, can and do promote end-use energy efficiency. The Federal Energy Regulatory Commission (FERC) regulates wholesale electricity markets and sets mandatory reliability standards to assure a safe reliable power system. In carrying out this mission FERC recognizes that energy efficiency is a resource, to be considered along with other energy resources in reliability and economic planning.

All of these entities will need to work in concert to achieve a truly efficient, reliable, cost-effective electric power system. EPA is committed to meeting this challenge.

Non-Air Office Regulations. EPA is also working on three additional rules that will have potential impacts on the power sector. The Office of Solid Waste and Emergency Response is developing revised regulations for coal combustion residues, which are the combustion byproducts associated with the use of coal as a fuel. The Administrator signed the proposed rule on May 4, 2010. Over the next few years, EPA's Office of Water plans to develop two rules affecting electric generating units; the precise timing of these rules is being determined. One will regulate cooling water intake structures. The other will revise the effluent guidelines for wastewater discharges from power plants. Each of these rules has cost implications to the power sector, and the Agency intends to coordinate these regulations with the upcoming air regulations. We intend to maximize reductions in pollution while maintaining cost-effective solutions.

As a first step to carrying out its commitment to promote and facilitate the most cost-effective and forward-looking compliance investments and strategies on the part of the power sector, EPA will conduct extensive outreach concerning the full range of the upcoming environmental responsibilities of the sector as it proposes the Transport Rule. Upon this proposal, the Agency will begin an outreach effort with the public, the regulated community, state air regulators, and others to (1) describe the Transport Rule proposal, and (2) provide information on the 2011 section 112 standards for utility units and other upcoming EPA rulemakings affecting the power sector. The intent will be to inform all stakeholders of the industry's obligations and opportunities for the industry to use investments in SO2 and NOX reductions to help smooth transition to compliance with the Section 112(d) standards applicable to utility units.

At the same time EPA also intends to expand its outreach to others—who can play a significant role in promoting or requiring investment in energy efficiency. EPA intends to continue these efforts over time as more information becomes available in the development of the various rulemakings under development for the power sector.

IV. Defining “Significant Contribution” and “Interference With Maintenance”

This section describes EPA's proposed approach to define emissions that significantly contribute to nonattainment or interfere with maintenance of the PM2.5 and ozone NAAQS downwind. The section begins by providing background on how “significant contribution” and “interference with maintenance” were defined in the past by EPA for the NOX SIP Call and the CAIR, describing past Court opinions on EPA's approach, and presenting an overview of EPA's proposed Transport Rule approach (section IV.A). Next, section IV.B describes the proposed approach to identify upwind contributing states. Section IV.C details the air quality modeling approach and results used for Start Printed Page 45230this proposed rule. Section IV.D provides a detailed description of EPA's proposed approach to quantify emissions that significantly contribute and interfere with maintenance. Section IV.E includes proposed state emissions budgets before accounting for the inherent variability in power system operations. Section IV.F discusses the inherent variability in power system operations, proposes variability limits on the state budgets, and presents projected emissions reduction results. Section IV.G describes how the proposed approach is consistent with judicial opinions. Finally, section IV.H lists alternative approaches to defining significant contribution and interference with maintenance that EPA evaluated but is not proposing.

A. Background

1. Approach Used in NOX SIP Call and the CAIR

a. Significant Contribution

Two rules EPA promulgated that address interstate transport of pollutants are the NOX SIP Call (63 FR 57356; October 27, 1998) and the CAIR (70 FR 25162; May 12, 2005), which are described in section III.B. In both of these rules, EPA used a 2-step approach to quantify significant contribution. The approaches used in both rules were similar.

In the first step, EPA applied an air quality threshold to determine a set of upwind states whose potential for significant contribution should be evaluated further. That is, EPA compared the contributions that individual upwind states make to downwind receptors and identified states whose contributions were greater than the specified threshold amount. EPA referred to these states as significant contributors but did not rely on this first step to quantify or measure the states’ significant contribution.

In the second step, EPA determined the quantity of emissions that the states collectively could remove using highly cost-effective controls. EPA defined this quantity of emissions as the “significant contribution.” The approach used in each rule is described in more detail, later.

NOXSIP Call. EPA addressed the section 110(a)(2)(D)(i)(I) requirement to prohibit emissions that significantly contribute to downwind nonattainment in the NOX SIP Call. To do so, EPA developed a methodology for identifying emissions that constitute upwind states’ “significant contribution.” EPA determined that emissions “contribute” to nonattainment downwind if they have an impact on nonattainment downwind (62 FR 60325). EPA established several criteria or factors for the “significant contribution” test (and further indicated that the same criteria should apply to the “interfere with maintenance” provision).[14]

EPA determined the amount of emissions that significantly contribute to downwind nonattainment from sources in a particular upwind state by: (i) Evaluating, with respect to each upwind state, several air quality related factors, including determining that all emissions from the state have a sufficiently great impact downwind (in the context of the collective contribution nature of the ozone problem); and (ii) determining the amount of that state's emissions that can be eliminated through the application of cost-effective controls (63 FR 57403).

Air Quality Factor. The first factor that EPA used to determine the amount of emissions that significantly contribute to downwind nonattainment was the air quality factor, consisting of an evaluation of the impact on downwind air quality of the upwind state's emissions.

EPA specifically considered three air quality factors with respect to each upwind state:

  • The overall nature of the ozone problem (i.e., “collective contribution”);
  • The extent of the downwind nonattainment problems to which the upwind state's emissions are linked, including the ambient impact of controls required under the CAA or otherwise implemented in the downwind areas; and
  • The ambient impact of the emissions from the upwind state's sources on the downwind nonattainment problems (63 FR 57376).

EPA explained the first factor, collective contribution, by noting,

[V]irtually every nonattainment problem is caused by numerous sources over a wide geographic area * * * [. This] factor suggest[s] that the solution to the problem is the implementation over a wide area of controls on many sources, each of which may have a small or immeasurable ambient impact by itself (63 FR 57377).

The second air quality factor is the extent of downwind nonattainment problems. EPA considered the then-current air quality of the area, the predicted future air quality (assuming implementation of required controls but not the transport requirements that were the subject of the NOX SIP Call), and, when air quality designations had already been made, the boundaries of the area in light of designation status (63 FR 57377).[15]

EPA applied the third air quality factor by projecting the amount of the upwind state's entire inventory of anthropogenic emissions to the year 2007, and then quantifying the impact of those emissions on downwind nonattainment through the appropriate air quality modeling techniques.[16] Specifically, (i) EPA determined the minimum threshold impact that the upwind state's emissions must have on a downwind nonattainment area to be considered potentially to contribute significantly to nonattainment; and then (ii) for states with impacts above that threshold, EPA developed a set of metrics for further evaluating the contribution of the upwind state's emissions on a downwind nonattainment area (63 FR 57378). EPA referred to states with emissions that had a sufficiently great impact as significant contributors; however, the precise amount of their significant contribution was not calculated until the next step. Because the ozone problem is caused by many relatively small contributions, even relatively small contributors must participate in the solution. For this reason, EPA determined that even a relatively small contribution can be significant contribution given the nature of the problem, and established relatively low thresholds.

Cost Factor. The cost factor is the second major factor that EPA applied to determine the significant contribution to nonattainment: “EPA* * * determined whether any amounts of the NOX emissions may be eliminated through controls that, on a cost-per-ton basis, may be considered to be highly cost effective” (63 FR 57377). Applying this cost factor on top of the air quality factor, EPA determined that emissions that both were from states that exceeded Start Printed Page 45231the air quality thresholds and could be eliminated through the application of highly cost-effective controls constituted a given state's significant contribution.

Choice of Highly Cost-Effective Standard. EPA chose the standard of “highly cost-effective” in order to assure state flexibility in selecting control strategies to meet the emissions reduction requirements of the rulemaking. That is, the rulemaking required the states to achieve specified levels of emissions reductions—the levels achievable if states implemented the control strategies that EPA identified as highly cost-effective—but the rulemaking did not mandate those highly cost-effective control strategies, or any other control strategy. Indeed, in calculating the amount of the required emissions reductions by assuming the implementation of highly cost-effective control strategies, EPA assured that other control strategies—ones that were cost-effective, if not highly cost-effective—remained available to the states.

Determination of Highly Cost-Effective Amount. EPA determined the dollar amount considered to be highly cost-effective by reference to the cost-effectiveness of recently promulgated or proposed NOX controls. EPA determined that the average cost-effectiveness of controls ranged up to approximately $1,800 per ton of NOX removed (1990$) on an annual basis. The EPA considered the controls in the reference list to be cost-effective.

EPA established $2,000 per ton (1990$) in average cost-effectiveness for summer ozone season emissions reductions as, at least directionally, the highly cost-effective amount. Identifying this amount on an ozone season basis was appropriate because the NOX SIP Call concerned the ozone standard, for which emissions reductions during only the summer ozone season are necessary. In determining the highly cost-effective amount, EPA analyzed costs on a regionwide basis, and assumed a cap and trade program for EGUs and large non-EGU boilers and turbines.

Source Categories. EPA then determined that the source categories for which highly cost-effective controls were available included EGUs, large industrial boilers and turbines, and cement kilns. At the same time, EPA determined, for those source categories, the level of emissions reductions in each state that would result from the application of all controls that would be highly cost-effective and that would be feasible. The EPA considered other source categories, but found that highly cost-effective controls were not available for various reasons, including the size of the sources, the relatively small amount of emissions from the sources, or the control costs.

Other Factors. EPA also relied on several other, secondary considerations to identify the required amount of emissions reductions. The first concerned the consistency of regional reductions with downwind attainment needs. The second general consideration was “the overall fairness of the control regimes” to which the downwind and upwind areas were subject. The third general consideration was “general cost considerations.” The EPA noted that “in general, areas that currently have, or that in the past have had, nonattainment problems * * * have already incurred ozone control costs.” The next set of controls available to these nonattainment areas would be more expensive than the controls available to the upwind areas. The EPA found that this cost scenario further confirmed the reasonableness of the upwind control obligations (63 FR 57379).

In the NOX SIP Call, EPA considered all of these factors together in determining the level of controls considered to be highly cost-effective. Within the region, the nonattainment areas already had implemented required VOC and NOX controls that covered much of their inventory. However, the upwind states in the region generally had not implemented such controls (except as needed to address their ozone nonattainment areas). In this context, EPA considered it reasonable to impose an additional control burden on the upwind states. Air quality modeling showed that residual nonattainment remained even with this additional level of upwind controls so that further reductions from downwind and/or upwind areas would be necessary.

After ascertaining the controls that qualified as highly cost-effective, EPA developed a methodology for calculating the amount of NOX emissions that each state was required to reduce on grounds that those emissions contribute significantly to nonattainment downwind. The total amount of required NOX emissions reductions was the sum of the amounts that would be reduced by application of highly cost-effective controls to each of the source categories for which EPA determined that such controls were available (63 FR 57378).

Electric Generating Units. The largest of the source categories discussed previously was EGUs. EPA determined the amount of reductions associated with EGU controls by applying the control rate that EPA considered to reflect highly cost-effective controls to each state's EGU heat input (adjusted for projected growth) (70 FR 25173.) In the NOX SIP Call, EPA evaluated the costs of control on a region-wide basis.

CAIR. In the CAIR, EPA again addressed the section 110(a)(2)(D)(i)(I) requirement to prohibit emissions that significantly contribute to downwind nonattainment (70 FR 25162). While the NOX SIP Call had addressed significant contribution with respect to the 1997 ozone NAAQS, the CAIR addressed significant contribution with respect to both the ozone and annual PM2.5 NAAQS promulgated in 1997. In the CAIR, EPA used a methodology to identify states” significant contribution based on and very similar to the methodology used in the NOX SIP Call.

To quantify the amounts of emissions that contribute significantly to nonattainment, EPA explained in the CAIR that the Agency primarily focused on the air quality factor reflecting the upwind state's ambient impact on downwind nonattainment areas, and the cost factor of highly cost-effective controls. See 70 FR 25174.

Air Quality Factor—PM2.5. EPA employed air quality modeling techniques to assess the impact of each upwind state's entire inventory of anthropogenic SO2 and NOX emissions on downwind nonattainment and maintenance for the annual PM2.5 NAAQS.[17] EPA determined that upwind NOX and SO2 emissions contribute significantly to annual PM2.5 nonattainment as of the year 2010.

As in the NOX SIP Call, EPA used a 2-step approach to quantify significant contribution. In the CAIR, in the first step EPA adopted a threshold air quality impact of 0.2 μg/m3 for PM2.5. An upwind state with contributions to downwind nonattainment below this level would not be subject to regulatory requirements, but a state with contributions at or higher than this level would be subject to further evaluation (70 FR 25174-75).

This level reflects the fact that PM2.5 nonattainment, like ozone, is caused by many sources in a broad region and therefore may be solved only by controlling sources throughout the region. As with the NOX SIP Call, the collective contribution condition of PM2.5 air quality is reflected in the relatively low threshold (70 FR 25175).

Air Quality Factor—8-Hour Ozone. EPA employed air quality modeling techniques to assess the impact of each upwind state's inventory of NOX and VOC emissions on downwind nonattainment. The EPA determined Start Printed Page 45232that upwind NOX emissions contribute significantly to 8-hour ozone nonattainment as of the year 2010. Therefore, EPA projected NOX emissions to the year 2010, assuming certain required controls (but not controls required under the CAIR), and then modeled the impact of those projected emissions on downwind 8-hour ozone nonattainment in that year (70 FR 25175).

EPA used the same threshold amounts and metrics for 8-hour ozone that it used in the NOX SIP Call. That is, emissions from an upwind state were found to contribute significantly to nonattainment if the maximum contribution was at least 2 parts per billion, the average contribution greater than one percent, and certain other numerical criteria were met. EPA also evaluated frequency, magnitude, and relative amounts of contribution to determine which linkages were significant before costs were considered.

Cost Factor. The second step in the 2-step process is to apply the cost factor. As in the NOX SIP Call, EPA interpreted this factor as mandating emissions reductions in amounts that would result from application of highly cost-effective controls. In the CAIR, EPA determined the level of costs that would be highly cost-effective on a regional basis by reference to the cost effectiveness of other recent controls. EPA concluded that EGUs were the only source category for which highly cost-effective SO2 and NOX controls were available at the time. EPA determined as highly cost-effective the dollar amount of cost-effectiveness that falls near the low end of a reference range of control costs. See 70 FR 25175. In the CAIR, as in the NOX SIP Call, EPA analyzed the costs of control on a regionwide basis.

Other Factors. As with the NOX SIP Call, EPA considered other factors that influence the application of the air quality and cost factors, and that confirm the conclusions concerning the amounts of emissions that upwind states must eliminate as contributing significantly to downwind nonattainment. See 70 FR 25175.

b. Interference With Maintenance

Section 110(a)(2)(D)(i)(I) requires that SIPs for national primary and secondary air quality standards contain adequate provisions prohibiting emissions in amounts that “interfere with maintenance by any other state” of any such standard.

In the NOX SIP Call and in the CAIR, EPA gave the term “interfere with maintenance” a meaning much the same as the meaning given to the term “significant contribution.” That approach, which was found inconsistent with the requirements of 110(a)(2)(D)(i)(I), is described later. EPA's proposed new approach to interpreting “interfere with maintenance” is described in section IV.D, later.

NOX SIP Call: In the NOX SIP Call, EPA explained its approach as follows (63 FR 57379-80):

After an area has reached attainment of the 8-hour NAAQS, that area is obligated to maintain that NAAQS. (See sections 110(a)(1) and 175A.) Emissions from sources in an upwind area may interfere with that maintenance. The EPA proposes to apply much the same approach in analyzing the first component of the “interfere-with-maintenance” issue, which is identifying the downwind areas whose maintenance of the NAAQS may suffer interference due to upwind emissions. The EPA has analyzed the “interfere-with-maintenance” issue for the 8-hour NAAQS by examining areas whose current air quality is monitored as attaining the 8-hour NAAQS [or which have no current air quality monitoring], but for which air quality modeling shows nonattainment in the year 2007. This result is projected to occur, notwithstanding the imposition of certain controls required under the CAA, because of projected increases in emissions due to growth in emissions generating activity. Under these circumstances, emissions from upwind areas may interfere with the downwind area's ability to attain. Ascertaining the impact on the downwind area's air quality of the upwind area's emissions aids in determining whether the upwind emissions interfere with maintenance (62 FR 60326).

In today's action, EPA is taking the same positions with respect to the interfere-with-maintenance test as described in the notice of proposed rulemaking.

In addition, the NOX SIP Call preamble stated:

This [interfere-with-maintenance] requirement * * * does not, by its terms, incorporate the qualifier of “significantly.” Even so, EPA believes that for present purposes, the term “interfere” should be interpreted much the same as the term “contribute significantly,” that is, through the same weight-of-evidence approach.

CAIR: In the CAIR, EPA also interpreted “interfere with maintenance” in a limited way. EPA only considered whether upwind state emissions eventually posed a maintenance problem for areas that EPA projected to be in nonattainment in 2010 (the year that was the focus of the analysis of significant contribution to nonattainment). EPA did not examine whether areas in attainment in 2010 might face a maintenance problem either in 2010 or thereafter, so no upwind state controls were considered to assist such areas with maintaining clean air. The CAIR preamble stated (70 FR 25193, footnote 45), “we believe the ‘interfere with maintenance’ prong may come into play only in circumstances where EPA or the state can reasonably determine or project, based on available data, that an [nonattainment] area in a downwind state will achieve attainment, but due to emissions growth or other relevant factors is likely to fall back into nonattainment.” [18]

In responding to comments on the CAIR proposal, we also used this interpretation of the maintenance provision to help support the need for Phase II CAIR reductions. For ozone, we conducted an analysis that looked at (1) the amount by which receptor locations were projected to attain in 2015 and (2) the year-to-year variability in ozone levels due to weather and other factors based on a review of historical monitoring data. This analysis concluded that areas within 3-5 ppb of the standard, and sometimes greater (e.g., Fulton County, Atlanta) had historic variability as great as 8 ppb, and that this variability suggests strongly that upwind states could be interfering with maintenance even if modeling shows attainment by up to these amounts. For PM2.5, while we lacked historical data to support the same variability analysis, we characterized attaining the annual standard by 0.5 μg/m3 as “attaining by a narrow margin” thus giving rise to maintenance concerns, and noted that in past (mobile source) rules we had indicated that attainment by a margin of 10 percent or less could be considered to raise maintenance concerns.

2. Judicial Opinions

a. Significant Contribution

In North Carolina v. EPA, 531 F.3d. 896 (DC Cir. 2008), the Court held that the approach EPA used in CAIR to measure each state's significant contribution was insufficient. EPA, the Court concluded, had failed to “measure[ ] the significant contribution from sources within an individual state to downwind nonattainment areas.” Id. at 907. The Court further reasoned that the lack of a state-specific significant contribution analysis made it impossible for EPA to show that the Start Printed Page 45233trading programs and state budgets established to implement the trading programs, effectuated the section 110(a)(2)(D)(i)(I) statutory mandate to eliminate emissions within the state that significantly contribute to nonattainment or interfere with maintenance in other states.

Specifically, the court rejected the regional scope of EPA's analysis. It reasoned that “because EPA evaluated whether its proposed emissions were ‘highly cost effective’ at the regionwide level assuming a trading program, it never measured the ‘significant contribution’ from sources within an individual state to downwind nonattainment areas.” Id. at 907. In reaching this conclusion, however, the Court also recognized that aspects of EPA's methodology for analyzing significant contribution had been upheld in Michigan v. EPA, 213 F.3d 663 (DC Cir. 2000), and it left those holdings undisturbed. Specifically, the Court acknowledged its prior conclusion that “significance may include cost” North Carolina, 531 F.3d at 919 (citing Michigan 213 F.3d 677-79), and thus it is acceptable for EPA to use cost to “draw the `significant contribution’ line”. Id. The Court also recognized that Michigan approved EPA's decision to apply a uniform emissions control requirement to all upwind states despite different levels of contribution. See North Carolina, 531 F.3d at 908. The Court thus concluded that while EPA must “measure each state's ‘significant contribution’ to downwind nonattainment” that measurement need not “directly correlate with each state's individualized air quality impact on downwind nonattainment relative to other upwind states.” Id. at 908.

In North Carolina, the Court also upheld several aspects of the air quality modeling EPA used in the significant contribution analysis. It upheld EPA's use of whole state modeling, see id. at 923-26, and deferred to EPA's selection of the PM2.5 contribution threshold, see id. at 914-15. With regard to EPA's application of the methodology to individual states, the Court found that EPA had failed to respond to comments by Minnesota Power alleging errors in the application of this methodology to determine Minnesota's contribution to downwind PM2.5 nonattainment areas. See id. at 926-28.

b. Interference With Maintenance

In the CAIR case, the Court also rejected EPA's approach to the second prong of section 110(a)(2)(D)(i)(I), holding that EPA's failure to give independent meaning to the term “interfere with maintenance” was inconsistent with the statutory mandate. See North Carolina, 531 F.3d at 910. The Court rejected the approach used in CAIR reasoning that it “provides no protection for downwind areas that, despite EPA's predictions, still find themselves struggling to meet NAAQS due to upwind interference in 2010.” Id. at 910-11.

3. Overview of Proposed Approach

In this section, EPA will explain how it proposes to identify which states are significantly contributing to downwind non-attainment and/or interfering with maintenance of the NAAQS at downwind sites and to quantify what that contribution is.

In this action, EPA is proposing to use a two step approach to measuring each state's significant contribution. The methodology used is based on the approach used in CAIR and the NOX SIP Call but modified to address the concerns raised by the Court. In the first step of this proposed approach, EPA uses air quality modeling to quantify individual states’ contributions to downwind nonattainment and maintenance sites in 2012. States whose contributions to any downwind sites are greater than 1 percent of the relevant NAAQS are considered “linked” to those sites for the purpose of the second step in the analysis. In the second step, EPA identifies the portion of each state's contribution that constitutes its “significant contribution” and “interference with maintenance.” To do so, EPA uses maximum cost thresholds, informed by air quality considerations. Specifically, for each precursor pollutant (i.e., SO2 and NOX for PM2.5 and NOX for ozone) emitted by the upwind states that EPA has identified as linked to NAAQS nonattainment and maintenance sites downwind, EPA identifies, through this process, the reductions available from EGUs in each individual upwind state at the appropriate maximum cost threshold. These emissions reductions are the amount of the upwind state's significant contribution. The cost thresholds used in this portion of the analysis, in contrast to the thresholds used in CAIR and the NOX SIP Call, are informed by air quality considerations, in addition to a comparison of the cost of control in other regulatory contexts. Specific cost thresholds were developed for annual SO2, annual NOX, and ozone-season NOX. Where appropriate, EPA developed higher and lower cost thresholds, based on the downwind air quality impact of emissions from different groups of states. Although EPA in the past has applied a uniform remedy to all states found to have a significant contribution, in this proposal EPA divides, for individual pollutants, the significantly contributing states into two groups: Those whose significant contribution can be eliminated at a lower cost threshold; and those whose significant contribution is not eliminated (to the extent that it has been identified in this proposal) until they reach the higher cost threshold. The lower cost threshold applies to a state if the reduction in emissions at that threshold eliminates nonattainment and maintenance problems at all “linked” sites.

EPA considers that the maintenance concept has two components: Year-to-year variability in emissions and air quality, and continued maintenance of the air quality standard over time. Both components of maintenance are addressed in this proposal.

Step One: Air Quality Analysis

In step one of this proposed approach, EPA analyzes emissions from 37 states to quantify the impact of those emissions on downwind nonattainment and maintenance sites in 2012 (see section IV.C for a detailed discussion of air quality modeling). To begin this analysis, EPA first identifies all monitors projected to be in nonattainment or, based on historic variability in air quality, projected to have maintenance problems in 2012. This baseline analysis takes into account emissions reductions associated with the implementation of all federal rules promulgated by December 2008 and assumes that the CAIR is not in effect. This baseline presents a unique situation. EPA has been directed to replace the CAIR; yet the CAIR remains in place and has led to significant emissions reductions in many states.

A key step in the process of developing a 110(a)(2)(D)(i)(I) rule involves analyzing existing (base case) emissions to determine which states significantly contribute to downwind nonattainment and maintenance areas. EPA cannot prejudge at this stage which states will be affected by the rule. For example, a state affected by CAIR may not be affected by the new rule and after the new rule goes into effect, the CAIR requirements will no longer apply. For a state covered by CAIR but not covered by the new rule, the CAIR requirements would not be replaced with new requirements, and therefore an increase in emissions relative to present levels could occur in that state. More fundamentally, the court has made clear that, due to legal flaws, the CAIR rule cannot remain in place and must be replaced. If EPA's base case analysis Start Printed Page 45234were to ignore this fact and assume that reductions from CAIR would continue indefinitely, areas that are in attainment solely due to controls required by CAIR would again face nonattainment problems because the existing protection from upwind pollution would not be replaced. For these reasons, EPA cannot assume in its base case analysis, that the reductions required by CAIR will continue to be achieved.

Following this logic, the 2012 base case shows emissions higher than current levels in some states. Because EPA has been directed to replace CAIR, EPA believes that for many states, the absence of the CAIR NOX program will lead to the status quo of the NOX Budget Program, which limits ozone-season NOX emissions and ensures the operation of NOX controls in those states. Also, without the CAIR SO2 program, emission requirements in many areas would revert to the comparatively less stringent requirements of the Title IV Acid Rain Program. As a result, SO2 emissions in many states would increase markedly in the 2012 base case relative to the present. Efforts to comply with ARP rules at the least-cost would occur in many cases without the operation of existing scrubbers through use of readily available, inexpensive Title IV allowances. Notably, all known controls that are required under state laws, NSPS, consent decrees, and other enforceable binding commitments through 2014 are accounted for in the base case. It is against this backdrop that the Transport Rule is analyzed and that significant contribution to nonattainment and interference with maintenance must be addressed.

Step Two: Quantifying Each State's Significant Contribution

In step two, EPA identifies the portion of each state's contributing emissions that constitute the emissions from that state that “significantly contribute to, or interfere with maintenance by” another state. To do so with respect to the 1997 ozone NAAQS, EPA analyzes the costs and associated air quality impacts of reductions in ozone-season NOX. To do so with respect to the 1997 and 2006 PM2.5 NAAQS, EPA analyzes the costs and associated air quality impacts of reductions in annual SO2 and annual NOX. The analysis uses cost thresholds, informed by air quality considerations and applied on a state specific basis. EPA considered a number of factors, including air quality and cost factors because the circumstances that lead to nonattainment and maintenance problems at downwind sites are extremely complex. By using both cost and air quality factors, EPA's analysis can address the different circumstances influencing the linkages between upwind and downwind states. As such, EPA believes it is appropriate to consider these factors in identifying the emissions that must be prohibited.

While we believe it is important to consider cost, we also recognize that we can't “just pick a cost for the region and deem ‘significant’ any emissions that sources can eliminate more cheaply.” North Carolina, 531 F.3d at 918. In contrast to the approach used in CAIR and the NOX SIP Call, the cost thresholds EPA uses in this proposed approach are informed by air quality considerations and applied on a state specific basis. EPA first develops state-specific costs curves showing what level of emissions reductions could be achieved at different cost levels in 2012 and 2014. EPA then uses a simplified air quality assessment tool to examine the impact of the reductions at specific cost levels on downwind nonattainment and maintenance sites. This approach allows EPA to identify specific cost breakpoints based on air quality considerations (such as the cost at which the air quality assessment analysis projects large numbers of downwind sites maintenance and nonattainment problems would be resolved) or cost criteria (such as being a cost where large emissions reductions occur because a particular technology is widely implemented at that cost). EPA then evaluated the reasonableness of the cost breakpoints using a number of criteria to determine which of the breakpoints appropriately represented a cost threshold with which to define significant contribution.

These thresholds are then applied on a state-specific basis to quantify each individual state's significant contribution.

The remainder of this section provides further detail on the specific methodology developed by EPA and the application of this methodology to identify emissions that significantly contribute to or interfere with maintenance of the 1997 ozone NAAQS and the 1997 and 2006 PM2.5 NAAQS.

B. Overview of Approach To Identify Contributing Upwind States

This section describes EPA's proposal to require reductions in upwind emissions of SO2 and NOX to address PM2.5 transport and to require reductions in upwind emissions of NOX to address ozone-related transport. In addition, this section provides an overview of EPA's approach to identifying which states are subject to the proposed rule, and which states are not subject to the rule because their sources’ emissions were found to not significantly contribute to nonattainment of the PM2.5 or 8-hour ozone standards or interfere with maintenance of those standards, in downwind states.

The EPA assessed individual upwind states” 2012 projected ambient impacts on downwind nonattainment and maintenance receptors for a 37-state region in the eastern U.S., and established threshold values for PM2.5 and ozone to identify those states whose impact does not constitute a significant contribution to air quality violations in the downwind states. EPA used these same threshold values in considering the potential for upwind state emissions to interfere with maintenance of the PM2.5 and 8-hour ozone NAAQS in downwind areas. The EPA used air quality modeling of emissions in each state to estimate the ambient impacts. The air quality modeling platform and approach to quantifying interstate contributions to PM2.5 and ozone are discussed in section IV.C.

As noted previously, EPA considers that the maintenance concept has two components: Year-to-year variability in emissions and air quality, and continued maintenance of the air quality standard over time. The way that EPA defined maintenance based on year-to-year variability is discussed in section IV.C., and directly affects the proposed requirements of this rule. EPA also considered whether further reductions were necessary to ensure continued lack of interference with maintenance of the NAAQS over time. EPA concluded that in light of projected emission trends, and also considering the emissions reductions from this proposed rule, no further reductions are required solely for this purpose at PM and ozone receptors for which we are partially or fully determining significant contribution for the current NAAQS. (See discussion of emissions trends in Chapter 7 of TSD entitled “Emission Inventories,” included in the docket for this proposal.)

1. Background

a. For the CAIR, how did EPA determine which pollutants were necessary to control to address interstate transport for PM2.5?

Section II of the January 2004 CAIR proposal summarized key scientific and technical aspects of the occurrence, formation, and origins of PM2.5, as well as findings and observations relevant to formulating control approaches for reducing the contribution of transport to Start Printed Page 45235fine particle problems (69 FR 4575-87). Key concepts and provisional conclusions drawn from this discussion were summarized as follows in the preamble to the final CAIR:

(1) Fine particles (measured as PM2.5 for the NAAQS) consist of a diverse mixture of substances that vary in size, chemical composition, and source. The PM2.5 includes both “primary” particles that are emitted directly to the atmosphere as particles, and “secondary” particles that form in the atmosphere through chemical reactions from gaseous precursors. The major components of fine particles in the eastern U.S. can be grouped as follows: Carbonaceous material (including both primary and secondary organic carbon and black carbon); sulfates; nitrates; ammonium; and crustal material, which includes suspended dust as well as some other directly emitted materials. The major gaseous precursors of PM2.5 include SO2, NOX, NH3, and certain volatile organic compounds.

(2) Examination of urban and rural monitors indicate that in the eastern U.S., sulfates, carbonaceous material, nitrates, and ammonium associated with sulfates and nitrates are typically the largest components of transported PM2.5, while crustal material tends to be only a small fraction.

(3) Atmospheric interactions among particulate ammonium sulfates and nitrates and gas phase nitric acid and ammonia vary with temperature, humidity, and location. Both ambient observations and modeling simulations suggest that regional SO2 reductions are effective at reducing sulfate and associated ammonium, and, therefore, PM2.5. Under certain conditions reductions in particulate ammonium sulfates can release ammonia as a gas, which then reacts with gaseous nitric acid to form nitrate particles, a phenomenon called “nitrate replacement.” In such conditions SO2 reductions would be less effective in reducing PM2.5, unless accompanied by reductions in NOX emissions to address the potential increase in nitrates.

(4) Reductions in ammonia can reduce the ammonium, but not the sulfate portion of sulfate particles. The relative efficacy of reducing nitrates through NOX or ammonia control varies with atmospheric conditions; the highest particulate nitrate concentrations in the East tend to occur in cooler months and regions. At present, our knowledge about sources, emissions, control approaches, and costs is greater for NOX than for ammonia. Measures to reduce NOX from stationary and mobile sources have been implemented for more than 20 years. From a chemical perspective, as NOX reductions accumulate relative to ammonia, the atmospheric chemical system would move towards an equilibrium in which ammonium nitrate reductions become more responsive to further NOX reductions relative to ammonia reductions.

(5) Much less is known about the sources of regional transport of carbonaceous material. Key uncertainties include how much of this material is due to biogenic as compared to anthropogenic sources, and how much is directly emitted as compared to formed in the atmosphere.

Based on the understanding of current scientific and technical information, as well as EPA's air quality modeling, as summarized in the CAIR proposal, EPA concluded that it was both appropriate and necessary to focus on control of SO2 and NOX emissions as the most effective approach to reducing the contribution of interstate transport to PM2.5.

For the CAIR, the EPA did not include emissions controls that affect other components of PM2.5, noting that “current information relating to sources and controls for other components identified in transported PM2.5 (carbonaceous particles, ammonium, and crustal materials) does not, at this time, provide an adequate basis for regulating the regional transport of emissions responsible for these PM2.5 components.” (69 FR 4582). For all of these components, the lack of knowledge of and ability to quantify accurately the interstate transport of these components limited EPA's ability to include these components in the CAIR.

b. For the CAIR, how did EPA determine which pollutants were necessary to control to address interstate transport for ozone?

In the notice of proposed rulemaking for the CAIR, EPA provided the following characterization of the origin and distribution of 8-hour ozone air quality problems:

The ozone present at ground level as a principal component of photochemical smog is formed in sunlit conditions through atmospheric reactions of two main classes of precursor compound: VOCs and NOX (mainly NO and NO2). The term “VOC” includes many classes of compounds that possess a wide range of chemical properties and atmospheric lifetimes, which help determine their relative importance in forming ozone. Sources of VOCs include man-made sources such as motor vehicles, chemical plants, refineries, and many consumer products, but also natural emissions from vegetation. Nitrogen oxides contributing to ozone formation are emitted by motor vehicles, power plants, and other combustion sources, with lesser amounts from natural processes including lightning and soils. Key aspects of current and projected inventories for NOX and VOC are summarized in section IV of the proposal notice and EPA Web sites (e.g., http://www.gov/​ttn/​chief.) The relative importance of NOX and VOC in ozone formation and control varies with local- and time-specific factors, including the relative amounts of VOC and NOX present. In rural areas with high concentrations of VOC from biogenic sources, ozone formation and control is governed by NOX. In some urban core situations, NOX concentrations can be high enough relative to VOC to suppress ozone formation locally, but still contribute to increased ozone downwind from the city. In such situations, VOC reductions are most effective at reducing ozone within the urban environment and immediately downwind. The formation of ozone increases with temperature and sunlight, which is one reason ozone levels are higher during the summer. Increased temperature also increases emissions of volatile man-made and biogenic organics and can indirectly increase NOX as well (e.g., increased electricity generation for air conditioning). Summertime conditions also bring increased episodes of large-scale stagnation, which promote the build-up of direct emissions and pollutants formed through atmospheric reactions over large regions. Authoritative assessments of ozone control approaches have concluded that, for reducing regional scale ozone transport, a NOX control strategy would be most effective, whereas VOC reductions are most effective in more dense urbanized areas.

Studies conducted in the 1970s established that ozone occurs on a regional scale (i.e., 1,000s of kilometers) over much of the eastern U.S., with elevated concentrations occurring in rural as well as metropolitan areas. While substantial progress has been made in reducing ozone in many urban areas, regional scale ozone transport is still an important component of high ozone concentrations during the extended summer ozone season. A series of more recent progress reports discussing the effect of the NOX SIP Call reductions can be found on EPA's Web site at: http://www.epa.gov/​airmarkets/​progress/​progress-reports.html.

In the notice of proposed rulemaking for CAIR, EPA noted that we continue to rely on the assessment of ozone Start Printed Page 45236transport made in great depth by the OTAG in the mid-1990s. As indicated in the NOX SIP Call proposal, the OTAG Regional and Urban Scale Modeling and Air Quality Analysis Work Groups concluded that regional NOX emissions reductions are effective in producing ozone benefits; the more NOX reduced, the greater the benefit.

More recent assessments of ozone, for example those conducted for the Regulatory Impact Analysis for the ozone standards in 2008, continue to show the importance of NOX transport. Information on these analyses can be found at EPA's Web site at: http://www.epa.gov/​ttn/​ecas/​regdata/​RIAs/​452_​R_​08_​003.pdf.

For addressing interstate ozone transport in the CAIR, EPA addressed NOX emissions, but did not include requirements for VOCs. EPA believes that VOCs from some upwind states do indeed have an impact in some nearby downwind states, particularly over short transport distances. The EPA expects that states will need to examine the extent to which VOC emissions affect ozone pollution levels across state lines, and identify areas where multi-state VOC strategies might assist in meeting the 8-hour standard, in planning for attainment.

c. For the CAIR, which thresholds were used to identify states included under the rule?

(1) Fine Particles

In the CAIR, EPA used as the metric for identifying a state as significantly contributing (depending upon further consideration of costs) to downwind nonattainment, the predicted change, due to the upwind state's NOX and SO2 emissions, in annual[19] PM2.5 concentration in the downwind nonattainment area that receives the largest ambient impact. The EPA proposed this metric in the form of a range of alternatives for a “bright line,” that is, air quality impacts at or greater than the chosen threshold level indicated that the upwind state's emissions do contribute significantly (depending on cost considerations), and that air quality impacts below the threshold indicate that the upwind state's emissions do not contribute significantly to nonattainment.

This metric addresses how much each state contributes to a downwind neighbor. EPA does not believe that a particular upwind state must contribute to multiple downwind receptors to be required to make emissions reductions under CAA section 110(a)(2)(D). Under this provision, an upwind state must include in the SIP adequate provisions that prohibit that state's emissions that “contribute significantly to nonattainment in * * * any other State * * *” 42 U.S.C. 7410(a)(2)(D)(i)(I). Our interpretation of this provision is that the emphasized terms make clear that the upwind state's emissions must be controlled as long as they contribute significantly to a single nonattainment area.

As discussed in section II of the preamble to the final CAIR, EPA's approach to evaluating a state's impact on downwind nonattainment considered the entirety of the state's SO2 and NOX emissions, rather than treating them separately. We believed this approach was consistent with the chemical interactions in the atmosphere of SO2 and NOX in forming PM2.5. The contributions of SO2 and NOX emissions are generally not additive, but rather are interrelated due to complex chemical reactions.

In the CAIR proposal, EPA proposed to establish a state-level annual average PM2.5 contribution threshold from anthropogenic SO2 and NOX emissions that was a small percentage of the annual air quality standard of 15.0 μg/m3. The EPA based this proposal on the general concept that an upwind state's contribution of a relatively low level of ambient impact should be regarded as significant (depending on the further assessment of the control costs). We based our reasoning on several factors. The EPA's modeling indicates that at least some nonattainment areas will find it difficult to attain the standards without reductions in upwind emissions. In addition, our analysis of base case PM2.5 transport shows that, in general, PM2.5 nonattainment problems result from the combined impact of relatively small contributions from many upwind states, along with contributions from in-state sources and, in some cases, substantially larger contributions from a subset of particular upwind states. In the NOX SIP Call rulemaking, we termed this pattern of contribution—which is also present for ozone nonattainment—“collective contribution.”

In the case of PM2.5, we have found collective contribution to be a pronounced feature of the PM2.5 transport problem, in part because the annual nature of the PM2.5 NAAQS means that throughout the entire year and across a range of wind patterns—rather than during just one season of the year or on only the few worst days during the year which may share a prevailing wind direction—emissions from many upwind states affect the downwind nonattainment area.

As a result, to address the transport affecting a given nonattainment or maintenance area, many upwind states must reduce their emissions, even though their individual contributions may be relatively small. As a result, for the CAIR EPA determined that a relatively low value for the PM2.5 transport contribution threshold was appropriate. For the final CAIR EPA decided to apply a threshold of 0.20 μg/m3, such that any model result that is below this value (0.19 or less) indicates a lack of significant contribution, while values of 0.20 or higher exceeded the threshold.

(2) Ozone

For the CAIR ozone program, in assessing the contribution of upwind states to downwind 8-hour ozone nonattainment, EPA followed the approach used in the NOX SIP Call and employed the same contribution metrics, but with an updated model and updated inputs.

The air quality modeling approach we proposed to quantify the impact of upwind emissions included two different methodologies: Zero-out and source apportionment. EPA applied each methodology to estimate the impact of all of the upwind state's anthropogenic NOX and VOC emissions on each downwind nonattainment area.

The EPA's first step in evaluating the results of these methodologies was to remove from consideration those states whose upwind contributions were very low. Specifically, EPA considered an upwind state not to contribute significantly to a downwind nonattainment area if the state's maximum contribution to the area was either (1) less than 2 ppb; or (2) less than one percent of total nonattainment in the downwind area; as indicated by either of the two modeling techniques.

If the upwind state's impact exceeded these thresholds, then EPA conducted a further evaluation to determine if the impact was high enough to meet the air quality portion of the “contribute significantly” standard. In doing so, EPA organized the outputs of the two modeling techniques into a set of “metrics.” The metrics reflect three key contribution factors:

  • The magnitude of the contribution (actual amount of ozone contributed by emissions in the upwind state to nonattainment in the downwind area);
  • The frequency of the contribution (how often contributions above certain thresholds occur); and
  • The relative amount of the contribution ( the total ozone Start Printed Page 45237contributed by the upwind state compared to the total amount of nonattainment ozone in the downwind area).

2. Approach for Proposed Rule

a. Which pollutants do we propose to control?

For the proposed rule, EPA believes that the conclusions and findings in the final CAIR regarding the nature of pollutant contributions are still appropriate. EPA proposes to continue to focus the PM2.5 transport requirements on SO2 and NOX transport, and the ozone transport requirements on NOX.

EPA recognizes that, in some circumstances, the state's NOX contribution to PM2.5 in downwind states may be considerably smaller than the state's SO2 contribution to PM2.5 in downwind states. In addition, for monitors in EPA's speciation trends network that are located in southern states with warmer climates, the level of monitored nitrates can be very small. For these states, it is possible that annual NOX controls, within levels that could realistically be achieved, would result in a very small change in ambient PM2.5 levels. EPA considered identifying states where this was the case. For a number of reasons, we propose not to take this course of action. First, these states can impact downwind states in cooler climates, and thus impact nitrate formation in those downwind states. For example, EPA modeling results show that Georgia's emissions are linked to Ohio, Maryland, New Jersey, and Pennsylvania where monitored nitrates are higher. Second, EPA is concerned with the possibility for the “nitrate replacement” effect described previously. That is, there is a possibility for increases in nitrate particles if SO2 emissions decrease without accompanying decreases in NOX. Third, EPA believes that there would be important disbenefits to relaxing annual NOX requirements in those states. If for those states, EPA were to relax the annual NOX requirements currently required for their contribution to PM2.5, annual NOX emissions would increase, with potentially harmful effects on visibility and nitrogen deposition.

b. Thresholds

For the proposed rule, as for CAIR, EPA uses air quality thresholds to identify states whose contributions do not warrant transport requirements. We propose air quality thresholds for annual PM2.5, 24-hour PM2.5, and 8-hour ozone. Each threshold is based on 1 percent of the NAAQS.

As we found at the time of the CAIR, EPA's analysis of base case PM2.5 transport shows that, in general, PM2.5 nonattainment problems result from the combined impact of relatively small contributions from many upwind states, along with contributions from in-state sources and, in some cases, substantially larger contributions from a subset of particular upwind states. For ozone, as we found in the CAIR and the SIP call, we also found important contributions from multiple upwind states. In short, EPA continues to find an upwind “collective contribution” that is important to both PM2.5 and ozone.

A second reason that low threshold values are warranted, as EPA discussed in the notices for the CAIR, is that there are adverse health impacts associated with ambient PM2.5 and ozone even at low levels. See relevant portions of the CAIR proposal notice (63 FR 4583-84) and the CAIR final rule notice (70 FR 25189-25192).

For annual PM2.5 for the final CAIR, as noted previously, EPA decided to use a single-digit value, 0.2 μg/m3, rather than the two-digit value in the proposed CAIR, 0.15 μg/m3. The rationale for the single digit value for the final rule was that a single digit is consistent with the EPA monitoring requirements in part 50, appendix N, section 4.3. The reporting requirements for annual PM2.5 require that:

Annual PM2.5 standard design values shall be rounded to the nearest 0.1 μg/m3 (decimals 0.05 and greater are rounded up to the next 0.1, and any decimal lower than 0.05 is rounded down to the nearest 0.1).

Because the design value is to be reported only to the nearest 0.1 μg/m3, EPA deemed it preferable for the final CAIR to select the threshold value at the nearest 0.1 μg/m3 as well, and hence one percent of the 15 μg/m3, rounded to the nearest 0.1 μg/m3 became 0.2 μg/m3.

For the 24-hour standard of 35 μg/m3, we attempted to apply the same rationale for determining a single-digit air quality threshold. That is, we applied rounding conventions in Part 50, Appendix N to a value representing one percent of the NAAQS. The rounding requirements for the 24-hour standard are indicated in section 4.3 as follows:

24-hour PM2.5 standard design values shall be rounded to the nearest 1 μg/m3 (decimals 0.5 and greater are rounded up to the nearest whole number, and any decimal lower than 0.5 is rounded down to the nearest whole number).

One percent of the 24-hour standard is 0.35 μg/m3, and rounding to the nearest whole μg/m3 would yield an air quality threshold of zero. Thus applying the same rationale for the final CAIR, there would be no air quality threshold for 24-hour PM2.5, which EPA believes to be counterintuitive and unworkable as an approach for assessing interstate contributions.

For the proposed rule, EPA proposes to decouple the precision of the air quality thresholds with the monitoring reporting requirements, and to use 2-digit values representing one percent of the NAAQS, that is, 0.15 μg/m3 for the annual standard, and 0.35 μg/m3 for the 24-hour standard. EPA believes there are a number of considerations favoring this approach. First, it provides for a consistent approach for the annual and 24-hour standards. Second, the approach is readily applicable to any current and future NAAQS. For example, if EPA were to retain the CAIR approach for the annual standard, any future lowering of the PM2.5 NAAQS to below 15 μg/m3 would reduce the air quality threshold to 0.1 μg/m3. This would occur because any value less than 0.15 μg/m3 (e.g., 0.14 μg/m3) would be rounded down to 0.1 μg/m3. EPA finds it within its discretion to adjust its approach to account for the additional considerations that were not in existence at the time of the final CAIR.

For the proposal, EPA is proposing to take a more straightforward approach to air quality thresholds for ozone than the multi-factor approach we used for the NOX SIP Call or for the CAIR. The proposed approach uses a single “bright line” threshold for ozone that is one percent of the 1997 8-hour ozone standard of 0.08 ppm. As described later in section IV.C, the 1 percent threshold is averaged over multiple model days. EPA believes this to be a robust metric compared to previous metrics which might have relied on the maximum contribution on a single day. Under this approach, one percent of the NAAQS is a value of 0.8 ppb. State contributions of 0.8 ppb and higher are above the threshold; ozone contributions less than 0.8 ppb are below the threshold. EPA believes that this approach is preferable because it is a robust metric, it is consistent with the approach for PM2.5, and because it provides for a consistent approach that takes into account, and is applicable to, any future ozone standards below 0.08 ppm.

EPA seeks comment on the pollutants and air quality thresholds used for identifying states to be included under the proposed rule. In particular, EPA requests comment on alternatives to the 1 percent threshold. In addition, EPA requests comment on whether EPA should use the same rounding Start Printed Page 45238convention that was used in the final CAIR for the 15 μg/m3 annual PM2.5 standard, or whether commenters agree with EPA's approach that does not use this rounding convention. To identify the potential effect of alternative thresholds for the annual PM2.5 standard, see Table IV.C-13 (showing state specific contributions to areas with annual PM2.5 nonattainment and maintenance issues) and Table IV.C-16 (showing state specific contributions to areas with 24-hour PM2.5 nonattainment and maintenance issues).

C. Air Quality Modeling Approach and Results

1. What air quality modeling platform did EPA use?

a. Introduction

In this section, we describe the air quality modeling performed to support the proposed rule. We used air quality modeling to (1) identify locations where we expect there to be nonattainment or maintenance problems for annual average PM2.5, 24-hour PM2.5, and/or 8-hour ozone for the analytic years chosen for this proposal, (2) quantify the impacts (i.e., air quality contributions) of SO2 and NOX emissions from upwind states on downwind annual average and 24-hour PM2.5 concentrations at monitoring sites projected to be nonattainment or have maintenance problems in 2012 for the 1997 annual and 2006 24-hour PM2.5 NAAQS, respectively, (3) quantify the impacts of NOX emissions from upwind states on downwind 8-hour ozone concentrations at monitoring sites projected to be nonattainment or have maintenance problems in 2012 for the 1997 ozone NAAQS, and (4) assess the health and welfare benefits of the emissions reductions expected to result from this proposal. This section includes information on the air quality model applied in support of the proposed rule, the meteorological and emissions inputs to these models, the evaluation of the air quality model compared to measured concentrations, and the procedures for projecting ozone and PM2.5 concentrations for future year scenarios. We also provide in this section the interstate contributions for annual average and 24-hour PM2.5, and 8-hour ozone. The Air Quality Modeling Technical Support Document (AQMTSD) contains more detailed information on the air quality modeling aspects of this rule.

To support the proposal, air quality modeling was performed for four emissions scenarios: A 2005 base year, a 2012 “no CAIR” base case, a 2014 “no CAIR” base case, and a 2014 control case that reflects the emissions reductions expected from the proposed FIPs. The remedy proposed for inclusion in the FIPs is described in section V.D. The modeling for 2005 was used as the base year for projecting air quality for each of the 3 future year scenarios. The 2012 base case modeling was used to identify future nonattainment and maintenance locations and to quantify the contributions of emissions in upwind states to annual average and 24-hour PM2.5 and 8-hour ozone. The 2014 base case and 2014 control case modeling were used to quantify the benefits of this proposal.

For CAIR, EPA used the Comprehensive Air Quality Model with Extensions (CAMx) version 5 [20] to simulate ozone and PM2.5 concentrations for the 2005 base year and the 2012 and 2014 future year scenarios. In contrast, for the CAIR EPA used two air quality models, CAMx version 3.1 for modeling ozone and the Community Multiscale Air Quality Model (CMAQ) version 4.3 for modeling PM2.5. Both CAMx and CMAQ are grid cell-based, multi-pollutant photochemical models that simulate the formation and fate of ozone and fine particles in the atmosphere. The use of one model for both pollutants, as we have done for this proposal, provides a more scientifically integrated “one atmosphere” approach versus using different models for ozone and PM2.5. In addition, using a single model rather than two models is computationally more efficient. The CAMx model applications were designed to cover states in the central and eastern U.S. using a horizontal resolution of 12 x 12 km.[21] The modeling region (i.e., modeling domain) extends from Texas northward to North Dakota and eastward to the East Coast and includes 37 states and the District of Columbia. A map of the air quality modeling domain is provided in the AQMTSD.

Both CAMx and CMAQ contain certain source apportionment tools that are designed to quantify the contribution of emissions from various sources and areas to ozone and PM2.5 component species in other downwind locations. The CAMx model was chosen for use in this proposal because the source apportionment tools in this model have had extensive use and evaluation by states and industry. Also, the source apportionment tools in CAMx received favorable comments in a recent peer review.[22]

The 2005-based air quality modeling platform used for the proposal includes 2005 base year emissions and 2005 meteorology for modeling ozone and PM2.5 with CAMx. This platform provides an update to the now more historical data in the 2001-based platform used for CAIR that included 2001 emissions, 2001 meteorology for modeling PM2.5, and 1995 meteorology for modeling ozone. In the remainder of this section we provide an overview of (1) the emissions and meteorological components of the 2005-based platform, (2) the methods for projecting future nonattainment and maintenance along with a list of 2012 base case nonattainment and maintenance locations, (3) the approach to developing metrics to measure interstate contributions to annual and 24-hour PM2.5 and ozone, and (4) the predicted interstate contributions to downwind nonattainment and maintenance. We also identify which predicted interstate contributions are at or above the air quality impact thresholds described previously in section IV.B.

b. Emissions Inventories

Emissions estimates were made for a 2005 base year and for 2012 and 2014. All inventories include emissions from EGUs, nonEGU point sources, stationary nonpoint sources, onroad mobile sources, and nonroad mobile sources. When emissions were only available at annual or monthly temporal resolutions, emissions modeling steps were applied to estimate hourly emissions. Point source emissions were assigned to modeling grid cells based on latitude and longitude in the inventory, and county total emissions were allocated to grid cells. Emissions of NOX, VOCs and PM2.5 were split into their component species using other data sources, to provide the modeling species needed by CAMx. Elevated point sources were identified for simulating releases of emissions from those sources in layers 2 and higher in CAMx. In addition to the anthropogenic emission sources described previously, hourly, gridded biogenic emissions were estimated for individual modeling days using the BEIS model version 3.14.[23 24] The same Start Printed Page 45239biogenic emissions data were used in all scenarios modeled.

(1) Development of 2005 Base Year Emissions

Emissions inventory inputs representing the year 2005 were developed to provide a base year for forecasting future air quality, described in section IV.C.2. The 2005 National Emission Inventory (NEI), version 2 from October 6, 2008, was the starting point for the U.S. inventories used for the 2005 air quality modeling. This inventory includes 2005-specific data for point and mobile sources, while most nonpoint data were carried forward from version 3 of the 2002 NEI. In addition, a 2006 Canadian inventory and a 1999 Mexican inventory were used for the portions of Canada and Mexico within the modeling domains. Additional details on these inventories and the augmentation described here are available from the Emissions Inventory Technical Support Document (EITSD) for the Transport Rule.

The onroad and nonroad emissions were primarily based on the National Mobile Inventory Model (NMIM) monthly, county, process level emissions from the 2005 NEI v2. The 2005 onroad mobile emissions were augmented for onroad gasoline emissions sources with emissions based on a draft version of the Motor Vehicle Emissions Simulator (MOVES) for carbon monoxide (CO), NOX, VOC, PM2.5, and particulate matter less than ten microns (PM10). While these data were preliminary, they more closely reflect the PM2.5 emissions from the final release of MOVES 2010. To account for the temperature dependence of PM2.5, MOVES-based temperature adjustment factors were applied to gridded, hourly emissions using gridded, hourly meteorology. Additional information on this approach is available in the EITSD.

The annual NOX and SO2 emissions for EGUs in the 2005 NEI v2 are based primarily on data from EPA's Clean Air Markets Division's Continuous Emissions Monitoring (CEM) program, with other pollutants estimated using emission factors and the CEM annual heat input. For EGUs without CEMs, data were obtained from the states as included in the NEI. For modeling, the 2005 EGU emissions for SO2 and NOX were augmented by using hourly CEM data to develop a temporal allocation approach of the 2005 NEI v2 emissions. The annual emissions themselves were unchanged, and match closely with data from the CEM program except where states have provided data for partial CEM and non-CEM units. The 2005 EGUs were identified as all units in 2005 that map to the units modeled by the version of the Integrated Planning Model (IPM) used for this proposal, and include records both with and without data submitted to the CEM program. Temporal profiles were used instead of the actual 2005 CEM data so that the temporal allocation approach could be consistent in the future year modeling.

For the 2005 base year, the annual EGU NEI emissions were allocated to hourly emissions values needed for modeling based on the 2004, 2005, and 2006 CEM data. The NOX CEM data were used to create NOX-specific profiles, the SO2 data were used to create SO2-specific profiles, and the heat input data were used to allocate all other pollutants. The 3 years of data were used to create state-specific profiles to allocate from annual to monthly values and from daily to hourly values. Only the 2005 data were used to create state-specific factors for allocation from month to day, which is intended to preserve an appropriate level of daily temporal variability needed for this type of modeling.

Other significant augmentations were also made to the 2005 NEI and include the following. The nonpoint inventory was augmented with the oil and gas exploration inventory [25] which includes emissions in several states within the eastern U.S. 12 km modeling domain and additional states within the national 36 km modeling domain. The commercial marine category 3 (C3) vessel emissions were augmented with gridded 2005 emissions from the previous modeling efforts for the rule called “Control of Emissions from New Marine Compression-Ignition Engines at or Above 30 Liters per Cyl inder.” The 2005 point source daily wildfire and prescribed burning emissions were replaced with average-year county-based inventories. Additionally, the inventories were processed to provide the hourly, gridded, model-species needed by CAMx.

Tables IV.C-1 and IV.C-2 provide summaries of SO2 and NOX emissions by state by sector for the 2005 base year for those states within the eastern 12 km modeling domain. Emissions for other states within the 36 km modeling domain are available in the EISTD. In the tables, the EGU column summarizes all units matched to the IPM model and the nonEGU column is for other point source units. The Nonpoint column shows emissions for all nonpoint stationary sources. The Nonroad column summarizes emissions for nonroad mobile sources, including aircraft, locomotive, and marine sources including the C3 commercial marine. The Onroad column summarizes emissions for the combined NEI and draft MOVES-based emissions, in which emissions from the draft MOVES were used when available, and NEI emissions based on MOBILE6 were used for the remainder. Finally, the Fires column represents the average-year fire emissions for wildfires and prescribed burning mentioned previously.

Table IV.C-1—2005 Base Case SO2 Emissions (Tons/Year) for Eastern States by Sector

StateEGUNonEGUNonpointNonroadOnroadFiresTotal
Alabama460,12370,34652,3256,3973,199983593,372
Arkansas66,38413,06627,2605,6781,632728114,749
Connecticut10,3561,83118,4552,5481,128434,320
Delaware32,37834,8595,85911,648422685,173
District of Columbia1,0826861,55941417203,914
Florida417,32157,47570,49093,54310,2857,018656,131
Georgia616,05456,11656,82913,3315,6902,010750,031
Illinois330,382156,1545,39519,3025,71620516,969
Indiana878,97895,20059,7759,4363,981241,047,396
Iowa130,26461,24119,8328,8381,70225221,902
Kansas136,52013,14236,3818,0351,824103196,005
Start Printed Page 45240
Kentucky502,73125,81134,2296,9422,711364572,787
Louisiana109,851165,7372,37873,2332,399892354,489
Maine3,88718,5199,9693,72583415037,084
Maryland283,20534,98840,86417,8192,96632379,874
Massachusetts85,76819,62025,26125,3352,16893158,245
Michigan349,87776,51042,06614,5337,20491490,280
Minnesota101,66625,16914,74710,4102,558631155,181
Mississippi74,11729,8926,7966,0032,1581,051120,016
Missouri284,38478,30744,57310,4644,251186422,165
Nebraska74,9556,42929,5759,1991,326105121,589
New Hampshire51,4453,2457,4088056303863,571
New Jersey57,0447,64010,72623,4842,48661101,441
New York180,84758,562125,15820,9085,628113391,216
North Carolina512,23166,15022,02042,7435,341696649,181
North Dakota137,3719,4586,4555,98644366159,779
Ohio1,116,084118,46819,81015,6156,293221,276,292
Oklahoma110,08140,4827,5425,0152,699469166,288
Pennsylvania1,002,20285,41168,34911,9725,363321,173,328
Rhode Island1762,7433,3652,49420818,987
South Carolina218,78231,49530,01620,4772,976646304,393
South Dakota12,2151,69810,3473,41251149828,682
Tennessee266,14878,20632,7146,2884,834277388,468
Texas534,949223,625109,21552,74913,4701,178935,187
Vermont99025,385385305497,036
Virginia220,24869,44032,92318,4203,829399345,259
West Virginia469,45648,31414,5892,1331,095215535,802
Wisconsin180,20066,8076,3697,1293,11070263,685
Grand total10,019,7741,953,7451,117,009596,847123,54719,34513,380,267

Table IV.C-2—2005 Base Case NOX Emissions (Tons/Year) for Eastern States by Sector

StateEGUNonEGUNonpointNonroadOnroadFiresTotal
Alabama133,05174,83032,02461,623142,2213,814447,562
Arkansas35,40737,47821,45363,49381,0142,654241,499
Connecticut6,8655,82412,55421,78569,64514116,688
Delaware11,9175,5673,25915,56722,5692358,902
District of Columbia4925011,7403,4949,677015,904
Florida217,26353,77829,533277,888460,47425,6001,064,537
Georgia111,01753,29738,91995,175279,4497,955585,812
Illinois127,92397,50447,645223,697276,50771773,347
Indiana213,50373,64730,185110,100187,42688614,949
Iowa72,80639,29915,15092,96591,79590312,105
Kansas90,22070,78542,28686,55376,062378366,285
Kentucky164,74335,43217,55790,669127,4351,326437,163
Louisiana63,791165,16227,559301,170112,8893,254673,824
Maine1,10018,3097,42313,37938,46956679,246
Maryland62,57424,62121,71555,812129,796137294,656
Massachusetts25,61818,42934,37374,419118,148341271,327
Michigan120,00594,13943,499101,087279,816330638,876
Minnesota83,83664,43856,700115,873146,1382,300469,286
Mississippi45,16653,98512,21279,39498,0603,833292,649
Missouri127,43138,60432,910123,228183,022678505,873
Nebraska52,42612,15613,820107,18058,643381244,607
New Hampshire8,8273,24111,2359,24632,53713765,223
New Jersey30,11420,59826,39388,486157,736223323,550
New York63,46555,12287,608121,363282,072412610,042
North Carolina111,57644,50218,869135,936225,75611,424548,064
North Dakota76,3817,54510,04659,63521,575240175,422
Ohio258,68771,71541,466173,988270,38381816,321
Oklahoma86,20473,46594,57455,424117,2401,709
Pennsylvania176,87089,20853,435118,774266,649117705,053
Rhode Island5452,1642,9647,79813,456426,930
South Carolina53,82329,06920,28168,146128,7652,357302,441
South Dakota15,6505,0355,76630,32424,8501,81783,442
Tennessee102,93460,35318,67682,331207,4101,012472,717
Texas176,170292,806274,338377,246615,7154,8901,741,166
Vermont2977993,4383,95113,31617921,980
Virginia62,51260,10153,60591,298194,1731,456463,145
West Virginia159,80436,91314,51932,73950,040785294,801
Start Printed Page 45241
Wisconsin72,17040,68821,99475,981147,952256359,042
Grand total3,223,1841,931,1111,301,7263,647,2155,758,88080,93115,943,047

(2) Development of Future Year Emissions

The future base case scenarios represent predicted emissions in the absence of any further controls beyond those federal measures already promulgated. For EGUs, all state and other programs available at the time of modeling have been included. For mobile sources, all national measures available at the time of modeling have been included. For nonEGU point and nonpoint stationary sources, any local control programs that may be necessary for areas to attain the annual PM2.5 NAAQS and the ozone NAAQS are not included in the future base case projections. The future base case scenarios do reflect projected economic changes and fuel usage for EGU and mobile sectors, as described in the EITSD.

Tables IV.C-3 through IV.C-6 provide 2012 and 2014 summaries of emissions data for 2012 and 2014 modeling for all sectors for SO2 and NOX for states included in the 12 km modeling domain. The EITSD provides summaries for additional pollutants with additional detail and for all states in the nationwide 36 km modeling domain.

Table IV.C-3—2012 Base Case SO2 Emissions (Tons/Year) for Eastern States by Sector

StateEGUNonEGUNonpointNonroadOnroadFiresTotal
Alabama335,73470,34652,3152,333585983462,297
Arkansas85,06813,05427,257818336728127,259
Connecticut5,4931,83118,4431,292330427,392
Delaware7,84110,9745,85814,19398638,970
District of Columbia06861,559104102,296
Florida228,36057,49170,482102,0762,0727,018467,498
Georgia552,00756,12256,8177,9841,2532,010676,193
Illinois724,657133,2015,3841,9601,17420866,396
Indiana829,98895,20159,76787177524986,626
Iowa169,03961,24219,82148234625250,954
Kansas59,56713,04836,376518302103109,915
Kentucky718,98025,81334,2141,368510364781,249
Louisiana100,239159,7222,37378,051455892341,731
Maine15,75918,5199,9503,92615615048,460
Maryland49,07834,98840,85417,11260832142,672
Massachusetts16,29919,62225,24229,8255759391,657
Michigan287,80776,45842,0667,6361,07491415,132
Minnesota53,59625,10014,7331,34259663195,997
Mississippi46,43224,4266,7882,0943751,05181,166
Missouri445,64378,31044,5501,307765186570,761
Nebraska120,7906,43029,571817209105157,921
New Hampshire7,2903,2457,396721423818,183
New Jersey37,7466,74710,71525,2867726181,327
New York144,07458,566125,18712,3361,541113341,818
North Carolina126,62066,12822,00048,861935696265,240
North Dakota77,3839,4586,451288766693,722
Ohio946,667105,40619,8103,4561,131221,076,493
Oklahoma156,03236,9127,536341502469201,791
Pennsylvania966,13679,14268,3304,9381,135321,119,712
Rhode Island02,7433,3642,8798219,069
South Carolina149,51531,45230,00522,697532646234,846
South Dakota13,4531,69810,342659149826,147
Tennessee596,98777,59532,701828795277709,182
Texas327,873162,915109,19937,1092,4091,178640,682
Vermont09025,381694496,432
Virginia145,45269,16632,90415,158883399263,963
West Virginia588,39241,81714,583443197215645,646
Wisconsin107,36566,4526,37092864670181,830
Grand total9,243,3621,802,9271,116,694451,70524,59519,34512,658,628

Table IV.C-4—2012 Base Case NOX Emissions (Tons/Year) for Eastern States by Sector

StateEGUNonEGUNonpointNonroadOnroadFiresTotal
Alabama121,80974,83231,95849,62282,1353,814364,171
Arkansas43,22237,47921,42948,34946,9592,654200,092
Connecticut2,7705,83012,47515,86537,8471474,801
Start Printed Page 45242
Delaware4,6395,5673,24815,51110,7002339,687
District of Columbia25011,7392,7044,85709,802
Florida195,67355,01729,475282,147275,60325,600863,515
Georgia78,01153,31738,82576,901158,7717,955413,780
Illinois77,92092,44047,564167,046157,91571542,957
Indiana203,10773,65130,12583,760114,39688505,127
Iowa66,31639,30115,06472,03158,92090251,721
Kansas70,82370,75142,24966,89743,914378295,012
Kentucky149,17934,87517,44672,28971,2841,326346,399
Louisiana44,773161,72427,525285,56264,0743,254586,912
Maine3,13918,3097,29513,35421,89656664,559
Maryland17,37624,62421,64753,58064,368137181,731
Massachusetts6,31218,44734,24575,14957,417341191,911
Michigan96,87493,95343,39280,900163,505330478,955
Minnesota51,28564,25056,58192,08086,1982,300352,694
Mississippi37,51752,45412,15164,13852,7093,833222,801
Missouri77,57138,61032,73196,197108,298678354,085
Nebraska52,82012,15913,78881,17733,907381194,233
New Hampshire2,5143,24311,1537,30819,71013744,067
New Jersey15,98718,99626,32081,90676,979223220,410
New York25,75555,16787,776100,212154,260412423,582
North Carolina61,64344,51418,715133,476126,08111,424395,854
North Dakota59,5477,54410,01846,64912,111240136,110
Ohio159,62769,07541,378133,650149,13481552,945
Oklahoma86,85871,80894,52843,05771,2071,709369,167
Pennsylvania193,03285,16853,28992,594142,217117566,418
Rhode Island2212,1682,9597,4688,120420,940
South Carolina47,76228,95320,27363,56475,9942,357238,903
South Dakota15,4935,0355,73324,11714,9571,81767,151
Tennessee68,42559,59418,57365,209126,3531,012339,166
Texas159,738287,831274,203313,204303,4534,8901,343,319
Vermont08003,4063,07710,32817917,790
Virginia36,03660,10153,49679,717111,5831,456342,389
West Virginia102,72535,69814,47326,04027,694785207,415
Wisconsin49,35140,69421,97958,95186,315256257,546
Grand Total2,485,8561,904,4811,299,2243,075,4593,232,16880,93212,078,120

Table IV.C-5—2014 Base Case SO2 Emissions (Tons/Year) for Eastern States by Sector

StateEGUNonEGUNonpointNonroadOnroadFiresTotal
Alabama322,13069,15052,3131,873605983447,053
Arkansas88,18713,05527,256142347728129,714
Connecticut5,5121,83418,4401,294340427,423
Delaware7,80610,9745,85714,891101639,635
District of Columbia06861,55944202,291
Florida192,90357,52170,480108,5792,1597,018438,658
Georgia173,21056,01456,8138,2631,3072,010297,618
Illinois200,475133,1095,3813901,22120340,596
Indiana804,29495,03759,76419381024960,123
Iowa163,96660,19519,8178536025244,448
Kansas65,12513,04836,37554313103115,018
Kentucky739,59223,80434,210258528364798,755
Louisiana94,824151,2162,37278,097470892327,871
Maine11,65018,5209,9454,21516015044,640
Maryland42,63534,99440,85116,96663132136,109
Massachusetts16,29919,62425,23732,0435949393,890
Michigan275,63776,43742,0667,5361,10791402,874
Minnesota61,44725,11214,728468618631103,005
Mississippi48,14924,4276,7851,2803851,05182,077
Missouri500,64977,08644,543214796186623,473
Nebraska115,6956,43129,57055217105152,072
New Hampshire6,6083,2467,393451483817,476
New Jersey37,6696,75610,71226,5897996182,585
New York141,35458,584125,19610,8531,594113337,694
North Carolina140,58566,04621,99452,897961696283,180
North Dakota80,3209,4585,76335786695,720
Ohio841,194105,12319,8102,0851,17122969,405
Oklahoma165,77336,9247,53445524469211,268
Pennsylvania972,97776,25668,3244,1171,169321,122,876
Start Printed Page 45243
Rhode Island02,7453,3643,1288519,323
South Carolina156,09631,45330,00224,380551646243,129
South Dakota13,4591,69910,298229449826,070
Tennessee600,06677,60532,696173829277711,647
Texas373,950155,720109,19436,1092,5111,178678,662
Vermont09035,3807101496,439
Virginia135,74169,17732,89915,624918399254,758
West Virginia496,30741,81714,58196201215553,218
Wisconsin117,25366,4566,37063867570191,461
Grand Total8,209,5361,778,2441,116,600453,74225,51619,34511,602,982

Table IV.C-6—2014 Base Case NOX Emissions (Tons/Year) for Eastern States by Sector

StateEGUNonEGUNonpointNonroadOnroadFiresTotal
Alabama118,42074,62231,93945,93267,0113,814341,738
Arkansas44,79237,49121,42244,29938,9652,654189,623
Connecticut2,8215,85412,45114,41031,5341467,084
Delaware4,5135,5673,24515,2708,7362337,353
District of Columbia15011,7382,3983,92908,568
Florida180,80155,34329,457278,920225,47825,600795,599
Georgia48,09153,55738,79771,011130,2407,955349,650
Illinois80,22893,05947,540151,373131,40371503,676
Indiana200,89973,52330,10776,02494,21788474,858
Iowa68,14638,83115,03865,75148,83690236,692
Kansas78,92070,73042,23861,61335,950378289,829
Kentucky148,50934,97917,41365,80557,7591,326325,791
Louisiana45,457161,76627,515274,69752,3603,254565,049
Maine2,53518,3167,25713,16918,06156659,903
Maryland19,99024,68721,62652,50153,040137171,980
Massachusetts6,61918,52734,20775,65446,748341182,095
Michigan97,45594,07943,36073,939135,806330444,969
Minnesota51,85964,37256,54584,04071,1612,300330,278
Mississippi37,14252,44012,13358,55942,5253,833206,633
Missouri82,97938,74432,67788,23390,001678333,312
Nebraska52,97012,17313,77975,25227,856381182,410
New Hampshire2,5153,25511,1296,58716,26013739,884
New Jersey16,26819,08926,29878,87563,254223204,007
New York28,35055,35987,82692,841129,376412394,165
North Carolina61,74744,57318,669133,455104,15011,424374,018
North Dakota59,5567,5493,96942,9729,925240130,252
Ohio164,94569,15741,352120,900122,42681518,861
Oklahoma81,12272,52594,51339,53958,3821,709347,790
Pennsylvania196,15184,11153,24683,885118,122117535,631
Rhode Island2812,1862,9577,3846,772419,585
South Carolina47,51228,96920,27162,40062,9962,357224,505
South Dakota15,5145,0395,15722,02112,2541,81762,368
Tennessee68,77959,69418,54259,145104,7111,012311,882
Texas166,177282,509274,163289,605241,0094,8901,258,354
Vermont08033,3972,7718,56317915,713
Virginia32,11560,21653,46475,46192,2911,456315,002
West Virginia100,10335,70014,45923,79822,863785197,708
Wisconsin53,77440,72921,97453,84871,163256241,743
Grand total2,468,0571,900,6241,298,4732,884,3382,656,13480,93211,288,558

Development of Future-Year Emissions Inventories for Electric Generating Units

Future year 2012 and 2014 base case EGU emissions used for the air quality modeling runs that predicted ozone and PM2.5 were obtained from version 3.02 EISA of the IPM (http://www.epa.gov/​airmarkt/​progsregs/​epa-ipm/​index.html). The IPM is a multiregional, dynamic, deterministic linear programming model of the U.S. electric power sector; version 3.02 EISA features an updated Title IV SO2 allowance bank assumption, reflects state rules and consent decrees through February 3, 2009, and incorporates updates related to the Energy Independence and Security Act of 2007. Units with advanced controls (e.g., scrubber, SCR) that were not required to run for compliance with Title IV, New Source Review (NSR), state settlements, or state-specific rules were allowed in IPM to decide on the basis of economic efficiency whether to operate those controls. Further details on the EGU emissions inventory used for this proposal can be found in the IPM Documentation. Also note that as explained in section IV.A.3, the baseline used in this analysis assumes no CAIR. If EPA's base case analysis were to Start Printed Page 45244assume that reductions from CAIR would continue indefinitely, areas that are in attainment solely due to controls required by CAIR would again face nonattainment problems because the existing protection from upwind pollution would not be replaced. As explained in that section, EPA believes that this is the most appropriate baseline to use for purposes of determining whether an upwind state has an impact on a downwind monitoring site in violation of section 110(a)(2)(D).

Development of Future-Year Emissions Inventories for Mobile Inventories

Mobile source inventories of onroad and nonroad mobile emissions were created for 2012 and 2015 using a combination of the NMIM and draft MOVES models. Mobile source emissions were further interpolated between 2012 and 2015 to estimate 2014 emissions. Emissions for these years reflect onroad mobile control programs including the Light-Duty Vehicle Tier 2 Rule, the Onroad Heavy-Duty Rule, and the Mobile Source Air Toxics (MSAT) final rule. Nonroad mobile emissions reductions for these years include reductions to locomotives, various nonroad engines including diesel engines and various marine engine types, fuel sulfur content, and evaporative emissions standards. A more comprehensive list of control programs included for mobile sources is available in the EITSD.

The onroad emissions were primarily based on the NMIM monthly, county, process level emissions. For both 2012 and 2015, emissions from onroad gasoline sources were augmented with emissions based on the same preliminary version of MOVES as was used for 2005. MOVES-based emissions were computed for CO, NOX, VOC, PM2.5, and PM10. The same MOVES-based PM2.5 temperature adjustment factors were also applied as in 2005.

Nonroad mobile emissions were created only with NMIM using a consistent approach as was used for 2005, but emissions were calculated using NMIM future-year equipment population estimates and control programs for 2012 and 2014. Emissions from 2012 and 2015 were used for locomotives and category 1 and 2 (C1 and C2) commercial marine vessels, based on emissions published in OTAQ's Locomotive Marine Rule, Regulatory Impact Assessment, Chapter 3. For category 3 (C3) commercial marine vessels, a coordination strategy of emissions reductions is ongoing that includes NOX, VOC, and CO reductions for new C3 engines as early as 2011 and fuel sulfur limits that could go into affect as early as 2012. However, given the uncertainty about the timing for parts of these emissions reductions and the fact that the 2012 modeling was conducted well in advance of the December 2009 publication of the rule, we have not used the controlled emissions in modeling supporting this proposal.

Development of Future-Year Emissions Inventories for Other Inventory Sources

Other inventory sources include nonEGU point sources, stationary nonpoint sources, and emissions in Canada and Mexico. Emissions from Canada and Mexico for all source sectors (including EGUs) in these countries were held constant for all cases. This approach reflects the unavailability of future-year emissions from Canada and Mexico for the future years of interest in time to support the modeling for this proposal.

The future year emissions for other sectors are described next. For all sector projections, EPA seeks comment on growth and control approaches, particularly where a control measure has not been included. The EITSD provides more details on these projections for additional review and we have included in the EITSD a table for the public to provide more detailed control data to EPA.

For nonEGU point sources, emissions were projected by including emissions reductions and increases from a variety of sources. For nonEGUs, emissions were not grown using economic growth projections and emissions reductions were applied through plant closures, refinery and other consent decrees, and reductions stemming from several MACT standards. Since aircraft at airports were treated as point emissions sources in the 2005 NEI v2, we also applied projection factors based on activity growth projected by the Federal Aviation Administration Terminal Area Forecast (TAF) system, published December 2008. Controls from the NOX SIP Call were assumed to have been implemented by 2005 and captured in the 2005 NEI v2.

For stationary nonpoint sources, refueling emissions were projected using the refueling results from the NMIM runs performed for the onroad mobile sector. Portable fuel container emissions were projected using estimates from previous OTAQ rulemaking inventories. Emissions of ammonia and dust from animal operations were projected based on animal population data from the Department of Agriculture and EPA. Residential wood combustion was projected by replacement of obsolete woodstoves with new woodstoves and a 1 percent annual increase in fireplaces. Landfill emissions were projected using MACT controls. All other nonpoint sources were held constant between 2005 and the future years.

(3) Preparation of Emissions for AQ Modeling

The annual and summer day emissions inventory files were processed through the Sparse Matrix Operator Kernel Emissions (SMOKE) Modeling System version 2.6 to produce the gridded model-ready emissions for input to CAMx. Emissions processing using SMOKE was performed to create the hourly, gridded data of CAMx species required for air quality modeling for all sectors, including biogenic emissions. Additional information on the development of the emissions data sets for modeling is provided in the EITSD. Details about preparation of emissions for contribution modeling are described in the Transport Rule AQ Modeling TSD.

c. Preparation of Meteorological and Other Air Quality Modeling Inputs

The gridded meteorological input data for the entire year of 2005 were derived from simulations of the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model. This model, commonly referred to as MM5, is a limited-area, nonhydrostatic, terrain-following system that solves for the full set of physical and thermodynamic equations which govern atmospheric motions.[26] The meteorological outputs from MM5 were processed to create model-ready inputs for CMAQ using the MM5-to-CAMx preprocessor (ref CAMx user's guide).

The 2005 MM5 meteorological predictions for selected variables were compared to measurements as part of several performance evaluations of the predicted data. The evaluation approach included a combination of qualitative and quantitative analyses to assess the adequacy of the MM5 simulated fields. The qualitative aspects involved comparisons of the model-estimated synoptic patterns against observed patterns from historical weather chart archives. Additionally, the evaluations compared spatial patterns of monthly average rainfall and monthly maximum planetary boundary layer (PBL) heights. The operational evaluation included Start Printed Page 45245statistical comparisons of model/observed pairs (e.g., mean normalized bias, mean normalized error, index of agreement, root mean square errors, etc.) for multiple meteorological parameters. For this portion of the evaluation, five meteorological parameters were investigated: Temperature, humidity, shortwave downward radiation, wind speed, and wind direction. The three individual MM5 evaluations are described elsewhere.[27 28 29 ] It was ultimately determined that the bias and error values associated with the 2005 meteorological data were generally within the range of past meteorological modeling results that have been used for air quality applications. Additional details on the meteorological inputs can be found in the AQMTSD.

As noted previously, the CAMx simulations for this proposal were performed using a spatial resolution of 12 x 12 km. The concentrations of pollutants transported into this eastern U.S. modeling region were obtained from air quality model simulations performed at coarser 36 x 36 km resolution for a modeling domain covering the lower 48 states and portions of northern Mexico and southern Canada. The 12 x 12 km model simulations were also initialized with air quality predictions from the coarse scale modeling. Pollutant concentrations at the boundaries of the coarse scale modeling domain were obtained from a three-dimensional global atmospheric chemistry model, the GEOSChem [30] model (standard version 7-04-11 [31] ). The global GEOSChem model simulates atmospheric chemical and physical processes driven by assimilated meteorological observations from the NASA's Goddard Earth Observing System (GEOS). This model was run for 2005 with a grid resolution of 2.0 degrees x 2.5 degrees (latitude-longitude). The predictions were used to provide one-way dynamic boundary conditions at three-hour intervals and an initial concentration field for the coarse scale simulations.

d. Model Performance Evaluation for Ozone and PM2.5

The 2005 base year model predictions for ozone and fine particulate sulfate, nitrate, organic carbon, elemental carbon, and crustal material were compared to measured concentrations in order to evaluate the performance of the modeling platform for replicating observed concentrations. This evaluation was comprised principally of statistical assessments of paired modeled and observed data. Details on the evaluation methodology and the calculation of performance statistics are provided in the AQMTSD. The results indicate that, overall, the predicted patterns and day-to-day variations in regional ozone levels are similar to what was observed with measured data. The normalized mean bias for 8-hour daily maximum ozone concentrations was −2.9 percent and the normalized mean error was 13.2 percent for the months of May through September 2005, based on an aggregate of observed-predicted pairs within the 12 km modeling domain. The two PM2.5 species that are most relevant for this proposal are sulfate and nitrate. For the summer months of June though August, when observed sulfate concentrations are highest in the East, the model predictions of 24-hour average sulfate were lower than the corresponding measured values by 7 percent at urban sites and by 9 to 10 percent at rural sites in the IMPROVE [32] and CASTNET [33] monitoring networks, respectively. For the winter months of December through February, when observed nitrate concentrations are highest in the East, the model predictions of 24-hour average particulate nitrate were lower than the corresponding measured values by 12 percent at urban sites and by 4 percent at rural sites in the IMPROVE monitoring network. The model performance statistics by season for ozone and PM2.5 component species are provided in the AQMTSD.

2. How did EPA project future nonattainment and maintenance for annual PM2.5, 25-Hour PM2.5, and 8-hour ozone?

In this section we describe the approach for projecting future concentrations of ozone and PM2.5 to identify locations that are expected to be nonattainment or have a maintenance problem in 2012. The nonattainment and maintenance locations are based on projections of future air quality at existing ozone and PM2.5 monitoring sites. These sites are used as the “receptors” for quantifying the contributions of emissions in upwind states to nonattainment and maintenance in downwind locations. For this analysis we are using the air quality modeling results in a “relative” sense to project future concentrations. In this approach, the ratio of future year model predictions to base year model predictions are used to adjust ambient measured data up or down depending on the relative (percent) change in model predictions for each location.

a. How did EPA process ambient ozone and PM2.5 data for the purpose of projecting future year concentrations?

In this analysis we use measurements of ambient ozone and PM2.5 data that come from monitoring networks consisting of more than one thousand ozone monitors and one thousand PM2.5 monitors located across the country. The monitors are sited according to the spatial and temporal nature of ozone and PM2.5, and to best represent the actual air quality in the United States. The ambient data used in this analysis were obtained from EPA's Air Quality System (AQS).

In order to use the ambient data, the raw measurements must be processed into a form pertinent for useful interpretations. For this action, the ozone data were processed consistent with the formats associated with the NAAQS for ozone. The resulting estimates are used to indicate the level of air quality relative to the NAAQS. For ozone air quality indicators, we developed estimates for the 1997 8-hour ozone standard. The level of the 1997 8-hour O3 NAAQS is 0.08 ppm. The 8-hour ozone standard is not met if the 3-year average of the annual 4th highest daily maximum 8-hour O3 concentration is greater than 0.08 ppm (0.085 ppm when rounded up). This 3-year average is referred to as the design value.

The PM2.5 ambient data were processed consistent with the formats associated with the NAAQS for PM2.5. The resulting estimates are used to Start Printed Page 45246indicate the level of air quality relative to the NAAQS. For PM2.5, we evaluated concentrations of both the annual average PM2.5 NAAQS and the 24-hour PM2.5 NAAQS. The annual PM2.5 standard is met when the 3-year average of the annual mean concentration is 15.0 μg/m 3 or less. The 3-year average annual mean concentration is computed at each site by averaging the daily Federal Reference Method (FRM) samples by quarter, averaging these quarterly averages to obtain an annual average, and then averaging the three annual averages. The 3-year average annual mean concentration is referred to as the annual design value.

The 24-hour average standard is met when the 3-year average of the annual 98th percentile PM2.5 concentration is 35 μg/m 3 or less. The 3-year average mean 98th percentile concentration is computed at each site by averaging the 3 individual annual 98th percentile values at each site. The 3-year average 98th percentile concentration is referred to as the 24-hour average design value.

As described later, the approach for projecting future ozone and PM2.5 design values involved the projection of an average of up to 3 design value periods which include the years 2003-2007 (design values for 2003-2005, 2004-2006, and 2005-2007). The average of the 3 design values creates a “5-year weighted average” value. The 5-year weighted average values were then projected to the future years that were analyzed for this proposed rule. The 2003-2005, 2004-2006, and 2005-2007 design values are accessible at http://www.epagov/​airtrends/​values.html.

The procedures for projecting annual average PM2.5 and 8-hour ozone conform to the methodology in the final attainment demonstration modeling guidance [34] . In the CAIR analysis, EPA did not project 24-hour PM2.5 design values [35] . The analysis for this proposed rule, in contrast, uses the 24-hour PM2.5 methodology outlined in the modeling guidance.

b. Projection of Future Annual and 24-Hour PM2.5 Nonattainment and Maintenance

Annual PM2.5 modeling was performed for the 2005 base year emissions and for the 2012 base case as part of the approach for projecting which locations (i.e., monitoring sites) are expected to be in nonattainment and/or have difficulty maintaining the PM2.5 standards in 2012. We refer to these areas as nonattainment sites and maintenance sites respectively.

In general, the projection methodology involves using the model in a relative sense to estimate the change in PM2.5 between 2005 and the future 2012 base case as recommended in the modeling guidance. Rather than use the absolute model-predicted future year ozone and PM2.5 concentrations, the base year and future year predictions are used to calculate a (relative) percent change in ozone and PM2.5 concentrations. For a particular location, the percent change in modeled concentration is multiplied by the corresponding observed base period ambient concentration to estimate the future year design value for that location. The use of observed ambient data as part of the calculation helps to constrain the future year design value predictions, even if the absolute model concentrations are over-predicted or under-predicted.

Concentrations of PM2.5 in 2012 were estimated by applying the 2005 to 2012 relative change in model-predicted PM2.5 species to the (2003-2007) PM2.5 design values. The choice of base period design values is consistent with EPA's modeling guidance which recommends using the average of the three design value periods centered about the emissions projection year. Since 2005 was the base emissions year, we used the design value for 2003-2005, 2004-2006, and 2005-2007 to represent the base period PM2.5 concentrations. For each FRM PM2.5 monitoring site, all valid design values (up to 3) from this period were averaged together. Since 2005 is included in all three design value periods, this has the effect of creating a 5-year weighted average, where the middle year is weighted 3 times, the 2nd and 4th years are weighted twice, and the 1st and 5th years are weighted once. We refer to this as the 5-year weighted average concentration.

The 5-year weighted average concentrations were used to project concentrations for the 2012 base case in order to determine which monitoring sites are expected to be nonattainment in this future year. We projected 2012 design values for each of 3 year periods (i.e., 2003-2005, 2004-2006, and 2003-2007) and used the highest of these projections to determine which sites are expected to have maintenance problems in 2012.

For the analysis of both nonattainment and maintenance, monitoring sites were included in the analysis if they had at least one complete design value in the 2003-2007 period.[36] There were 721 monitoring sites in the 12 km modeling domain which had at least one complete design value period for the annual PM2.5 NAAQS, and 736 sites which met this criteria for the 24-hour NAAQS.[37]

EPA followed the procedures recommended in the modeling guidance for projecting PM2.5 by projecting individual PM2.5 component species and then summing these to calculate the concentration of total PM2.5. The model predictions are used in a relative sense to estimate changes expected to occur in each of the major PM2.5 species. The PM2.5 species are sulfate, nitrate, ammonium, particle bound water, elemental carbon, salt, other primary PM2.5, and organic aerosol mass by difference. Organic aerosol mass by difference is defined as the difference between FRM PM2.5 and the sum of the other components. The procedure for calculating future year PM2.5 design values is called the SMAT. The SMAT approach is codified in a software tool available from EPA called MATS. The software (including documentation) is available at: http://www.epa.gov/​scram001/​modelingapps_​mats.htm.

(1) Methodology for Projecting Future Annual PM2.5 Nonattainment and Maintenance

The following is a brief summary of the future year annual PM2.5 calculations. Additional details are provided in the modeling guidance, MATS documentation, and the AQMTSD.

We are using the base period (i.e., 2003 2007) FRM data for projecting future design values since these data are used to determine attainment status. In order to apply SMAT to the FRM data, information on PM2.5 speciation is needed for the location of each FRM monitoring site. Since co-located PM2.5 speciation data are only available at about 15 percent of FRM monitoring sites, spatial interpolation techniques are used to calculate species concentrations for each FRM monitoring site. Speciation data from the IMPROVE and Chemical Speciation Network Start Printed Page 45247(CSN) were interpolated to each FRM monitor location using the Voronoi Neighbor Averaging (VNA) technique (using MATS). Additional information on the VNA interpolation techniques and data handling procedures can be found in the MATS User's Guide. After the species fractions are calculated for each FRM site, the following procedures were used to estimate future year design values:

Step 1: Calculate quarterly mean concentrations for each of the major species components of PM2.5 (i.e., sulfate, nitrate, ammonium, elemental carbon, organic carbon mass, particle bound water, salt, and blank mass). This is done by multiplying the monitored quarterly mean concentration of FRM-derived total PM2.5 by the monitored fractional composition of PM2.5 species for each quarter averaged over 3 years [38] (e.g., 20 percent sulfate fraction multiplied by 15 μg/m3 PM2.5 equals 3 μg/m3 sulfate).

Step 2: For each quarter, calculate the ratio of future year to base year model predictions for each of the component species. The result is a set of species-specific relative response factors (RRF) (e.g., assume that the model-predicted 2005 base year sulfate for a particular location is 10.0 μg/m[3] and the 2012 future concentration is 8.0 μg/m[3] , then RRF for sulfate is 0.8). The RRFs are calculated based on the modeled concentrations averaged over the nine grid cells [39] centered at the location of the monitor.

Step 3: For each quarter and each of the species, multiply the base year quarterly mean component concentration (Step 1) by the species-specific RRF obtained in Step 2. This results in an estimated future year quarterly mean concentration for each species (e.g., 3 μg/m3 sulfate multiplied by 0.8 equals a future sulfate concentration of 2.4 μg/m3).

Step 4: The future year concentrations for the remaining species are then calculated.[40] The future year ammonium is calculated based on the calculated future year sulfate and nitrate concentrations, using a constant value for the degree of neutralization of sulfate (from the ambient data). The future year particle bound water concentration is calculated from an empirical formula. The inputs to the formula are the future year concentrations of sulfate, nitrate, and ammonium (from step 3).

Step 5: Average the four quarterly mean future concentrations to obtain the future year annual design value concentration for each of the component species. Sum the species concentrations to obtain the future year annual average design value for PM2.5.

Step 6: Calculate the maximum future design value by processing each of the three base design value periods (2003-2005, 2004-2006, and 2005-2007) separately. The highest of the three future values is the maximum design value. The maximum design values are used to determine future year maintenance sites.

The preceding procedures for determining future year PM2.5 concentrations were applied for each FRM site. The calculated annual PM2.5 design values are truncated (i.e., discarded) after the second decimal place.[41] This is consistent with the truncation and rounding procedures for the annual PM2.5 NAAQS. Any value that is greater than or equal to 15.05 μg/m3 is rounded to 15.1 μg/m3 and is considered to be violating the NAAQS. Thus, sites with future year annual PM2.5 design values of 15.05 μg/m3 or greater, based on the projection of 5-year weighted average concentrations, are predicted to be nonattainment sites. Sites with future year maximum design values of 15.05μg/m3 or greater are predicted to be maintenance sites. Note that nonattainment sites are also maintenance sites because the maximum design value is always greater than or equal to the 5-year weighted average. For ease of reference we use the term “nonattainment sites” to refer to those sites that are projected to exceed the NAAQS based on both the average and maximum design values. Those sites that are projected to be attainment based on the average design value but exceed the NAAQS based on the maximum design value are referred to as maintenance sites. The monitoring sites that we project to be nonattainment and/or maintenance for the annual PM2.5 NAAQS in the 2012 base case are the nonattainment/maintenance receptors used for assessing the contribution of emissions in upwind states to downwind nonattainment and maintenance of the annual PM2.5 NAAQS as part of this proposal.

Table IV.C-7 contains the 2003-2007 base case period average and maximum annual PM2.5 design values and the corresponding 2012 base case average and maximum design values for sites projected to be nonattainment of the annual PM2.5 NAAQS in 2012. Table IV.C-8 contains this same information for projected 2012 maintenance sites.

Table IV.C-7—Average and Maximum 2003-2007 and 2012 Base Case Annual PM2.5 Design Values (μg/m3) at Projected Nonattainment Sites

Monitor IDStateCountyAverage design value 2003-2007Maximum design value 2003-2007Average design value 2012Maximum design value 2012
10730023AlabamaJefferson18.4818.6717.1517.33
10732003AlabamaJefferson17.0717.4515.9916.35
130210007GeorgiaBibb16.4716.7815.3315.62
130630091GeorgiaClayton16.4716.7115.0715.29
131210039GeorgiaFulton17.4317.4716.0116.04
170310052IllinoisCook15.7516.0215.1615.43
171191007IllinoisMadison16.7217.0116.5616.85
171630010IllinoisSaint Clair15.5815.7415.4815.63
180190006IndianaClark16.4016.6015.9616.16
180372001IndianaDubois15.1815.6815.0715.57
180970078IndianaMarion15.2615.4315.1815.36
Start Printed Page 45248
180970081IndianaMarion16.0516.3615.9316.25
180970083IndianaMarion15.9016.2715.7716.15
211110043KentuckyJefferson15.5315.7515.1915.41
261630015MichiganWayne15.8816.4015.0515.55
261630033MichiganWayne17.5018.1616.5717.19
390170016OhioButler15.7416.1115.2515.61
390350038OhioCuyahoga17.3718.116.2616.95
390350045OhioCuyahoga16.4716.9815.4215.91
390350060OhioCuyahoga17.1117.6616.0216.55
390610014OhioHamilton17.2917.5316.6916.93
390610042OhioHamilton16.8517.2516.3316.71
390610043OhioHamilton15.5515.8215.0515.32
390617001OhioHamilton16.1716.5615.6516.03
390618001OhioHamilton17.5417.9016.9317.27
420030064PennsylvaniaAllegheny20.3120.7518.9019.31
420031301PennsylvaniaAllegheny16.2616.5715.1315.42
420070014PennsylvaniaBeaver16.3816.4515.2315.30
420710007PennsylvaniaLancaster16.5517.4615.1916.01
421330008PennsylvaniaYork16.5217.2515.2515.94
540110006West VirginiaCabell16.3016.5715.2515.50
540391005West VirginiaKanawha16.5216.5915.2815.34

Table IV.C-8—Average and Maximum 2003-2007 and 2012 Base Case Annual PM2.5 Design Values (μ/m3) at Projected Maintenance-Only Sites

Monitor IDStateCountyAverage design value 2003-2007Maximum design value 2003-2007Average design value 2012Maximum design value 2012
170313301IllinoisCook15.2415.5914.7315.06
170316005IllinoisCook15.4816.0714.9215.48
211110044KentuckyJefferson15.3115.4714.9315.09
360610056New YorkNew York16.1817.0214.9815.74
390350027OhioCuyahoga15.4616.1314.5015.13
390350065OhioCuyahoga15.9716.4414.9615.40
390610040OhioHamilton15.5015.8815.0315.40
390811001OhioJefferson16.5117.1714.9515.54
391130032OhioMontgomery15.5415.9215.0115.37
391510017OhioStark16.1516.5914.9915.40
420110011PennsylvaniaBerks15.8216.1914.7715.11
482011035TexasHarris15.4215.8414.7415.14
540030003West VirginiaBerkeley15.9316.1914.9515.20
540090005West VirginiaBrooke16.5216.8014.9515.22
540291004West VirginiaHancock15.7616.6414.3415.15
540490006West VirginiaMarion15.0315.2514.9615.18

(2) Methodology for Projecting Future 24-Hour PM2.5 Nonattainment and Maintenance

The following is a brief summary of the procedures used for calculating future year 24-hour PM2.5 design values. Additional details are provided in the modeling guidance, MATS documentation, and the AQMTSD. Similar to the annual PM2.5 calculations, we are using the 2003-2007 base period FRM data for projecting future year design values. The 24-hour PM2.5 calculations are computationally similar to the annual average calculations. The main difference is that the base period 24-hour 98th percentile PM2.5 concentrations are projected to the future year, instead of the annual average concentrations. Also, the PM2.5 species fractions and relative response factors are calculated from observed and modeled high concentration days, instead of quarterly average data.

Both the annual PM2.5 and 24-hour PM2.5 calculations are performed on a calendar quarter basis. Since all years and quarters are averaged together in the annual PM2.5 calculations, the individual years can be averaged together early in the calculations. However, in the 24-hour PM2.5 calculations, only the high quarter from each year is used in the final calculations. This represents the 98th percentile value, which can come from any of the 4 quarters in any year. Therefore all quarters and years must be carried through to near the end of the calculations when the individual future year high quarter values are selected. To calculate final future year design values, the high quarter for each year is identified and then a five year weighted average of the high quarters for each site was calculated to derive the future year design value.

The following are the steps followed for calculating the 2012 base case 24-hour PM2.5 design values:

Step 1: At each FRM monitoring site, we identify the maximum 24-hour PM2.5 concentration in each quarter that is less Start Printed Page 45249than or equal to the 98th percentile value over the entire year. This results in a data set for each year (for up to 5 years) for each site containing one quarter with the observed 98th percentile value and three quarters with the maximum highest values from each quarter that are less than or equal to the 98th percentile value for the year. All 20 quarters (i.e., 4 quarters in each of 5 years) of data are carried through the calculations until the high future year quarter value is identified in step 6.

Step 2: In this step we calculate quarterly ambient concentrations on “high” [42] days for each of the major component species of PM2.5 (sulfate, nitrate, ammonium, elemental carbon, organic carbon mass, particle bound water, salt, and blank mass). This calculation is performed by multiplying the monitored concentrations of FRM-derived total PM2.5 mass on the 10 percent highest days from each quarter, by the monitored fractional composition of PM2.5 species on the 10 percent highest PM2.5 days for each quarter, averaged over 3 years [43] (e.g., 20 percent sulfate fraction multiplied by 40 μg/m3 PM2.5 equals 8 μg/m3 sulfate).

Step 3: For each quarter, we calculate the ratio of future year (i.e., 2012) to base year (i.e., 2005) predictions for each component species for the top 10 percent of days based on predicted concentrations of 24-hour PM2.5. The result is a set of species-specific relative response factors (RRF) for the high PM2.5 days in each quarter (e.g., assume that the 2005 predicted sulfate concentration on the 10 percent highest PM2.5 days for a quarter for a particular location is 20 μg/m3 and the 2012 base case concentration is 16 μg/m3, then RRF for sulfate is 0.8). The RRFs are calculated based on the modeled concentrations at the single grid cell where the monitor is located.

Step 4: For each quarter, we multiply the quarterly species concentration (step 2) by the quarterly [44] species-specific RRF obtained in step 3. This leads to an estimated future quarterly concentration for each component. (e.g., 21.0 μg/m3 nitrate × 0.75 = future nitrate of 15.75 μg/m3).

Step 5: The future year concentrations for the remaining species are then calculated.[45] The future year ammonium is calculated based on the calculated future year sulfate and nitrate concentrations, using a constant value for the degree of neutralization of sulfate (from the ambient data). The future year particle bound water concentration is calculated from an empirical formula. The inputs to the formula are the calculated future year concentrations of sulfate, nitrate, and ammonium (from step 4).

Step 6: We sum the species concentrations to obtain quarterly PM2.5 values. This step is repeated for each quarter and for each of the 5 years of ambient data. The highest daily value (from the 4 quarterly values) for each year at each monitor is considered to be the estimated future year 98th percentile 24-hour design value for that year.

Step 7: The estimated 98th percentile values for each of the 5 years are averaged over 3 year intervals to create the 3 year average design values. These design values are averaged to create a 5 year weighted average for each monitoring site.

Step 8: The maximum future design value is calculated by following the previous steps for each of the three base design value periods (2003-2005, 2004-2006, and 2005-2007) separately. The highest of the three future values is the maximum design value. This maximum value is used to identify the 24-hour PM2.5 maintenance receptors.

The preceding procedures for determining future year 24-hour PM2.5 concentrations were applied for each FRM site. The 24-hour PM2.5 design values are truncated after the first decimal place. This approach is consistent with the truncation and rounding procedures for the 24-hour PM2.5 NAAQS. Any value that is greater than or equal to 35.5 μg/m3 is rounded to 36 μg/m3 and is violating the NAAQS. Sites with future year 5 year weighted average design values of 35.5 μg/m3 or greater, based on the projection of 5-year weighted average concentrations, are predicted to be nonattainment. Sites with future year maximum design values of 35.5 μg/m3 or greater are predicted to be maintenance sites. Note that nonattainment sites for the 24-hour NAAQS are also maintenance sites because the maximum design value is always greater than or equal to the5-year weighted average. For ease of reference we use the term “nonattainment sites” to refer to those sites that are projected to exceed the NAAQS based on both the average and maximum design values. Those sites that are projected to be attainment based on the average design value but exceed the NAAQS based on the maximum design value are referred to as maintenance sites. The monitoring sites that we project to be nonattainment and/or maintenance for the 24-hour PM2.5 NAAQS in the 2012 base case are the nonattainment/maintenance receptors used for assessing the contribution of emissions in upwind states to downwind nonattainment and maintenance of 24-hour PM2.5 NAAQS as part of this proposal.

Table IV.C-9 contains the 2003-2007 base period average and maximum 24-hour PM2.5 design values and the 2012 base case average and maximum design values for sites projected to be 2012 nonattainment of the 24-hour PM2.5 NAAQS in 2012. Table IV.C-10 contains this same information for projected 2012 24-hour maintenance sites.

Table IV.C-9—Average and Maximum 2003-2007 and 2012 Base Case 24-Hour PM2.5 Design Values (μg/m3) at Projected Nonattainment Sites

Monitor IDStateCountyAverage design value 2003-2007Maximum design value 2003-2007Average design value 2012Maximum design value 2012
10730023AlabamaJefferson44.044.240.040.7
10732003AlabamaJefferson40.340.838.138.9
90091123ConnecticutNew Haven38.340.335.736.6
170310052IllinoisCook40.241.438.539.7
Start Printed Page 45250
170310057IllinoisCook37.338.635.737.0
170310076IllinoisCook38.039.136.337.3
170311016IllinoisCook43.046.341.044.1
170312001IllinoisCook37.740.635.638.2
170313103IllinoisCook39.640.338.138.7
170313301IllinoisCook40.243.338.241.0
170316005IllinoisCook39.141.837.439.8
171190023IllinoisMadison37.338.139.440.2
171191007IllinoisMadison39.140.140.040.6
171192009IllinoisMadison34.935.937.238.2
171193007IllinoisMadison34.034.636.537.3
180190006IndianaClark37.539.438.140.2
180372001IndianaDubois35.336.936.538.0
180830004IndianaKnox35.936.335.936.5
180890022IndianaLake38.944.037.342.1
180890026IndianaLake38.441.336.339.3
180970042IndianaMarion34.235.336.337.2
180970043IndianaMarion38.439.940.542.0
180970066IndianaMarion38.339.640.341.8
180970078IndianaMarion36.637.638.739.7
180970079IndianaMarion35.636.737.238.3
180970081IndianaMarion38.239.240.141.1
180970083IndianaMarion36.637.039.039.3
181570008IndianaTippecanoe35.636.735.936.9
191630019IowaScott37.137.136.836.8
210590005KentuckyDaviess33.833.837.037.0
211110043KentuckyJefferson35.436.135.836.4
211110044KentuckyJefferson36.136.636.036.5
211110048KentuckyJefferson36.437.235.636.4
245100040MarylandBaltimore City39.040.936.338.3
245100049MarylandBaltimore City38.138.135.535.5
261150005MichiganMonroe38.839.637.038.0
261250001MichiganOakland39.940.437.938.4
261470005MichiganSt. Clair39.640.638.439.4
261610008MichiganWashtenaw39.440.838.139.8
261630015MichiganWayne40.140.638.539.1
261630016MichiganWayne42.945.440.643.0
261630019MichiganWayne40.941.438.639.1
261630033MichiganWayne43.844.242.142.6
261630036MichiganWayne37.137.936.336.9
290990012MissouriJefferson33.434.235.736.5
291831002MissouriSaint Charles33.134.735.537.1
295100007MissouriSt. Louis City33.133.536.036.3
295100087MissouriSt. Louis City34.334.736.436.9
340171003New JerseyHudson39.040.535.736.1
340172002New JerseyHudson41.441.438.238.2
340390004New JerseyUnion40.441.436.737.2
360050080New YorkBronx38.840.235.936.2
360610056New YorkNew York39.740.637.138.0
360610128New YorkNew York39.441.836.238.0
390170003OhioButler39.241.140.342.3
390170016OhioButler37.137.737.537.8
390170017OhioButler37.937.938.538.5
390171004OhioButler37.138.137.838.6
390350038OhioCuyahoga44.247.041.244.0
390350045OhioCuyahoga38.541.536.039.0
390350060OhioCuyahoga42.145.739.442.8
390350065OhioCuyahoga38.641.036.538.9
390490024OhioFranklin38.539.736.637.6
390490025OhioFranklin38.439.136.136.4
390610006OhioHamilton37.637.638.038.0
390610014OhioHamilton38.239.437.538.5
390610040OhioHamilton36.737.735.836.8
390610042OhioHamilton37.338.237.238.0
390610043OhioHamilton35.936.236.036.4
390617001OhioHamilton38.839.637.738.1
390618001OhioHamilton40.640.939.640.3
390811001OhioJefferson41.945.536.539.9
391130032OhioMontgomery37.840.036.338.5
Start Printed Page 45251
391530017OhioSummit38.039.635.637.2
420030008PennsylvaniaAllegheny39.439.935.936.3
420030064PennsylvaniaAllegheny64.268.258.862.3
420030093PennsylvaniaAllegheny45.651.541.146.2
420030116PennsylvaniaAllegheny42.542.537.137.1
420031008PennsylvaniaAllegheny41.342.838.039.3
420031301PennsylvaniaAllegheny40.342.436.638.6
420070014PennsylvaniaBeaver43.444.637.739.1
420110011PennsylvaniaBerks37.739.135.837.0
420210011PennsylvaniaCambria39.039.440.340.7
420430401PennsylvaniaDauphin38.039.035.737.1
420710007PennsylvaniaLancaster40.844.037.740.1
421330008PennsylvaniaYork38.240.735.938.8
471251009TennesseeMontgomery36.337.536.637.9
540090011West VirginiaBrooke43.944.939.940.8
550790010WisconsinMilwaukee38.640.037.739.0
550790026WisconsinMilwaukee37.341.336.340.1
550790043WisconsinMilwaukee39.940.838.839.7
550790099WisconsinMilwaukee37.738.736.837.7

Table IV.C-10—Average and Maximum 2003-2007 and 2012 Base Case 24-Hour PM2.5 Design Values (μg/m3) at Projected Maintenance-Only Sites

Monitor IDStateCountyAverage design value 2003-2007Maximum design value 2003-2007Average design value 2012Maximum design value 2012
110010041Washington DCWashington DC36.337.834.035.6
110010042Washington DCWashington DC34.937.033.035.6
170310022IllinoisCook36.638.634.936.6
170310050IllinoisCook36.138.034.135.8
170314007IllinoisCook34.336.433.635.7
171630010IllinoisSaint Clair33.734.135.335.9
171971002IllinoisWill36.437.135.135.8
180390003IndianaElkhart34.436.333.835.6
180431004IndianaFloyd33.234.534.335.7
181670023IndianaVigo34.836.135.136.5
191390015IowaMuscatine36.037.734.536.0
210290006KentuckyBullitt34.635.835.036.3
211451004KentuckyMcCracken33.635.934.436.8
212270007KentuckyWarren33.135.133.736.3
240031003MarylandAnne Arundel35.537.433.836.7
245100035MarylandBaltimore (City)37.739.234.735.5
261630001MichiganWayne37.840.135.437.8
295100085MissouriSt. Louis City33.233.835.335.7
360610062New YorkNew York38.841.635.337.0
360610079New YorkNew York37.940.234.236.4
390350027OhioCuyahoga36.638.834.536.6
390350034OhioCuyahoga36.537.933.735.7
390810017OhioJefferson40.742.435.336.8
390950024OhioLucas36.338.634.236.5
390950026OhioLucas34.936.733.635.6
390990014OhioMahoning36.838.234.235.8
391130031OhioMontgomery35.737.134.335.6
391351001OhioPreble32.833.934.335.5
391550007OhioTrumbull36.237.833.935.6
420030095PennsylvaniaAllegheny38.740.734.336.6
420033007PennsylvaniaAllegheny37.543.133.838.5
420410101PennsylvaniaCumberland38.040.235.337.0
421255001PennsylvaniaWashington38.139.933.935.5
471650007TennesseeSumner33.634.535.136.0
540090005West VirginiaBrooke39.441.533.936.1
550250047WisconsinDane35.536.935.136.1
550790059WisconsinMilwaukee35.537.034.836.3
551330027WisconsinWaukesha35.436.234.935.6
Start Printed Page 45252

(3) Methodology for Projecting Future 8-Hour Ozone Nonattainment and Maintenance

The following is a brief summary of the future year 8-hour average ozone calculations. Additional details are provided in the modeling guidance, MATS documentation, and the AQMTSD.

We are using the base period 2003-2007 ambient ozone design value data for projecting future year design values. The ozone projection procedure is relatively simple, since ozone is a single species. It is not necessary to interpolate ambient ozone data, since ambient ozone design values and gridded, modeled ozone is all that is needed for the projections.

To project 8-hour ozone design values we used the 2005 base year and 2012 future base case model-predicted ozone concentrations to calculate relative response factors. The methodology we followed is consistent with the attainment demonstration modeling guidance. The RRFs were applied to the 2003-2007 ozone design values through the following steps:

Step 1: For each monitoring site we calculate the average concentration across all days with 8-hour daily maximum predictions greater than or equal to 85 ppb [46] using the predictions in the nine grid cells that include or surround the location of the monitoring site. The RRF for a site is the ratio of the mean prediction in the future year to the mean prediction in the 2005 base year. The RRFs were calculated on a site-by-site basis.

Step 2: The RRF for each site is then multiplied by the 2003-2007 5-year weighted average ambient design value for that site, yielding an estimate of the future year design value at that particular monitoring location.

Step 3: We calculate the maximum future design value by projecting design values for each of the three base periods (2003-2005, 2004-2006, and 2005-2007) separately. The highest of the three future values is the maximum design value. This maximum value is used to identify the 8-hour ozone maintenance receptors.

The preceding procedures for determining future year 8-hour average ozone design values were applied for each ozone monitoring site. The future year design values are truncated to integers in units of ppb. This approach is consistent with the truncation and rounding procedures for the 8-hour ozone NAAQS. Future year design values that are greater than or equal to 85 ppb are considered to be violating the NAAQS. Sites with future year 5-year weighted average design values of 85 ppb or greater are predicted to be nonattainment. Sites with future year maximum design values of 85 ppb or greater are predicted to be future year maintenance sites. Note that, as described previously for the annual and 24-hour PM2.5 NAAQS, nonattainment sites for the ozone NAAQS are also maintenance sites because the maximum design value is always greater than or equal to the 5-year weighted average. For ease of reference we use the term “nonattainment sites” to refer to those sites that are projected to exceed the NAAQS based on both the average and maximum design values. Those sites that are projected to be attainment based on the average design value but exceed the NAAQS based on the maximum design value are referred to as maintenance sites. The monitoring sites that we project to be nonattainment and/or maintenance for the ozone NAAQS in the 2012 base case are the nonattainment/maintenance receptors used for assessing the contribution of emissions in upwind states to downwind nonattainment and maintenance of ozone NAAQS as part of this proposal.

Table IV.C-11 contains the 2003-2007 base period average and maximum 8-hour ozone design values and the 2012 base case average and maximum design values for sites projected to be 2012 nonattainment of the 8-hour ozone NAAQS in 2012. Table IV.C-12 contains this same information for projected 2012 8-hour ozone maintenance sites.

Table IV.C-11—Average and Maximum 2003-2007 and 2012 Base Case 8-Hour Ozone Design Values (ppb) at Projected Nonattainment Sites

Monitor IDStateCountyAverage design value 2003-2007Maximum design value 2003-2007Average design value 2012Maximum design value 2012
220330003LouisianaEast Baton Rouge929687.891.6
361030002New YorkSuffolk909186.387.2
361030009New YorkSuffolk90.39185.185.8
421010024PennsylvaniaPhiladelphia90.39185.386
480391004TexasBrazoria94.79788.891
482010051TexasHarris939888.493.1
482010055TexasHarris100.710395.797.9
482010062TexasHarris95.79990.593.7
482010066TexasHarris92.39689.993.5
482011039TexasHarris96.310090.593.9
484391002TexasTarrant93.39585.186.7

Table IV.C-12—Average and Maximum 2003-2007 and 2012 Base Case 8-Hour Ozone Design Values (ppb) at Projected Maintenance-Only Sites

Monitor IDStateCountyAverage design value 2003-2007Maximum design value 2003-2007Average design value 2012Maximum design value 2012
90010017ConnecticutFairfield889083.185
90011123ConnecticutFairfield92.39484.886.4
90013007ConnecticutFairfield909284.586.4
Start Printed Page 45253
90093002ConnecticutNew Haven90.39382.985.4
130890002GeorgiaDeKalb88.79381.685.6
131210055GeorgiaFulton91.79484.486.5
361192004New YorkWestchester87.79084.786.9
420170012PennsylvaniaBucks889281.885.6
481130069TexasDallas879082.985.8
481130087TexasDallas878884.685.6
482010024TexasHarris889283.387.1
482010029TexasHarris91.79384.485.6
482011015TexasHarris899683.790.3
482011035TexasHarris86.3958290.3
482011050TexasHarris89.39283.986.5
484392003TexasTarrant93.7958485.2

3. How did EPA assess interstate contributions to nonattainment and maintenance?

This section documents the procedures used by EPA to quantify the impact of emissions in specific upwind states on air quality concentrations in projected downwind nonattainment and maintenance locations for annual PM2.5, 24-hour PM2.5, and 8-hour ozone. These procedures are the first of the two-step approach for determining significant contribution, as described previously in section IV.A.3.

EPA used CAMx photochemical source apportionment modeling to quantify the impact of emissions in specific upwind states on projected downwind nonattainment and maintenance receptors for both PM2.5 and 8-hour ozone. Details of the modeling techniques and post-processing procedures are described in this section.

CAMx employs enhanced source apportionment techniques which track the formation and transport of ozone and particulate matter from specific emissions sources and calculates the contribution of sources and precursors to ozone and PM2.5 for individual receptor locations. The strength of the photochemical model source apportionment technique is that all modeled ozone and/or PM2.5 mass at a given receptor location in the modeling domain is tracked back to specific sources of emissions and boundary conditions to fully characterize culpable sources. This type of emissions apportionment is useful to understand the types of sources or regions that are contributing to ozone and PM2.5 estimated by the model.

Source apportionment is an alternative approach to zero-out modeling [47] and other methods to track pollutant formation in photochemical models. Source apportionment completely characterizes source contributions to model-estimated ozone and PM2.5, which is not possible with an emissions sensitivity approach such as zero-out, since the change in emissions leads to changes in pollutant concentrations, meaning the sum of estimated ozone or PM2.5 in all zero-out simulations may not exactly match the ozone or PM2.5 estimated in the base model simulation. Photochemical model source apportionment has the additional advantage over emissions sensitivity-based approaches of being more computationally efficient. There is currently no technical evidence showing that one technique is clearly superior to the other for evaluating contributions to ozone and PM2.5 from various emission sources. However, since source apportionment explicitly tracks the formation and transport of all ozone and PM2.5 mass, it is particularly well suited for quantifying interstate contributions as part of this proposal. More details on the implementation of photochemical source apportionment in CAMx can be found in the CAMx user's guide. In the analysis performed for CAIR, EPA conducted zero-out modeling for PM2.5, and both zero-out and source apportionment modeling for ozone. The CAIR modeling was conducted at 36 km resolution for PM2.5 and 12 km resolution for ozone. In contrast, the analysis for the Transport Rule was performed at 12 km resolution for both ozone and PM2.5. When choosing the modeling techniques to use for the Transport Rule, we carefully considered all of the pros and cons of each technique, including the lengthy model run times and large file sizes of the 12 km eastern U.S. modeling domain. Due to the scientific credibility of the source apportionment technique and significant time and resource savings compared to zero-out modeling, we chose to perform the modeled contribution analyses for PM2.5 and ozone with photochemical source apportionment.

The EPA performed source apportionment modeling for both ozone and PM2.5 for the 2012 base case emissions. In this modeling we tracked the ozone and PM2.5 formed from emissions from sources in each upwind state in the 12 km modeling domain. The results were used to calculate the contributions of these upwind emissions to downwind nonattainment and maintenance receptors. The states EPA analyzed using source apportionment for ozone and for PM2.5 are: Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, Washington DC, and Wisconsin. There were also several other states that are only partially contained within the 12 km modeling domain (i.e., Colorado, Montana, New Mexico, and Wyoming). However, EPA did not individually track the emissions Start Printed Page 45254or assess the contribution from emissions in these states.

In contrast to CAIR, all contributions to downwind nonattainment and maintenance receptors for the Transport Rule were calculated using a relative approach. This is similar to the approach used to calculate future year design values, as described in section IV.C.2.a. In CAIR we used absolute and relative metrics to examine air quality contributions. Although absolute contributions are useful for certain applications, there are advantages of examining the relative contributions for both ozone and PM2.5. The main advantage of relative contributions is that they help to minimize biases introduced by model over-predictions and under-predictions. Also, the relative approach constrains the total contributions to the measurements of ozone and PM2.5 species concentrations at each downwind receptor. Since model performance is variable across the domain, EPA judged the relative approach to be the most appropriate technique for the Transport Rule.

a. Annual and 24-Hour PM2.5 Contribution Modeling Approach

EPA used the CAMx Particulate Source Apportionment Technique (PSAT) to calculate downwind PM2.5 contributions to nonattainment and maintenance. The CAMx PSAT is capable of “tagging” (i.e., tracking) source category emissions for certain PM species and precursor emissions. For this proposal, we ran PSAT to tag emissions of NOX, SO2, and primary PM2.5 from the individual states listed previously. Due to small modeled concentrations of secondary organic aerosols (SOA), and the relatively large runtime penalty of the SOA PSAT mechanism, we chose not to track SOA. Through emissions pre-processing procedures, EPA tagged all of the anthropogenic NOX, SO2, and primary PM2.5 emissions in each upwind state. Each state was a separate tag, and the tagged emissions followed state boundaries (not grid cells).

In the PSAT simulation NOX emissions are tracked to particulate nitrate concentrations, SO2 emissions are tracked to particulate sulfate concentrations, and primary particulates (organic carbon, elemental carbon, and other PM2.5) are tracked as primary particulates. As described earlier in section IV.B., the nitrate and sulfate contributions were combined and used to evaluate interstate contributions of PM2.5, as described in section IV.C.4, later.

We developed and applied several post-processing steps to transform the PSAT modeling outputs to PM2.5 downwind contributions. The approach involved processing the PSAT model outputs using MATS along with other post-processing software to calculate the contribution of each upwind state to each downwind nonattainment and/or maintenance receptor. This process involved calculating a ratio which uses the PSAT-predicted absolute contribution for each species (e.g., sulfate) coupled with the CAMx-predicted absolute 2012 base case concentration of the same species. The PSAT-derived ratios were then multiplied by the corresponding species component concentrations comprising the 2012 base case PM2.5 design value. For calculating annual contributions, we included the PSAT data for each day of the modeled year. For 24-hour calculations, the contributions are based on the 10 percent highest of the days in each quarter, as predicted for each receptor in the 2012 base case. In the 24-hour calculations, only the upwind contribution to the highest quarter at each receptor was used (i.e., highest quarter based on 2012 PM2.5 mass). For both annual and 24-hour PM2.5, the total PM2.5 mass contribution was calculated by summing the contributions of sulfate, nitrate, ammonium, and particle bound water. [48] Details on the procedures for calculating the contribution metrics are provided in the AQMTSD.

b. 8-Hour Ozone Contribution Modeling Approach

EPA used the CAMX Ozone Source Apportionment Technique (OSAT) in order to calculate downwind 8-hour ozone contributions to nonattainment and maintenance. OSAT tracks the formation of ozone from NOX and VOC emissions. Through emissions pre-processing procedures, EPA tagged all of the NOX and VOC emissions in each upwind state. A separate tag was created for each state, and the tagged emissions followed state boundaries (not grid cells).

All anthropogenic sources of NOX and VOC were tracked in the OSAT simulation. Upwind NOX and VOC emissions were tracked to downwind ozone concentrations. There are several post-processing steps needed to transform the raw model outputs to ozone downwind contributions. We developed and applied several post-processing steps to transform the OSAT modeling outputs to ozone contributions at downwind receptors. The approach for ozone was similar to the approach for PM2.5 in that the OSAT model outputs were processed using MATS along with other post-processing software to calculate the contribution of each upwind state to each downwind nonattainment and/or maintenance receptor. This process involved calculating a ratio which uses the OSAT-predicted absolute contribution of ozone coupled with the CAMx-predicted absolute 2012 base case ozone concentration. The OSAT-derived ratios were then multiplied by the corresponding 2012 base case ozone design value. The contributions to each downwind receptor are averaged across all days with modeled 2012 base case concentrations greater than 85 ppb [49] (at the given receptor). Details on the procedures for calculating the contribution metrics are provided in the AQMTSD.

c. Use of Projected Nonattainment and Maintenance Contributions

The previous steps provide the details for calculating 8-hour ozone and annual and 24-hour PM2.5 contributions to all downwind receptors. After the post-processing of the model results is complete, we then evaluate the contributions of each upwind state to nonattainment and maintenance receptors. The nonattainment receptors are those monitoring sites which are projected to exceed the NAAQS in the 2012 base case, based on 5-year weighted average design values. The maintenance receptors are those monitoring sites which are projected to exceed the NAAQS in the 2012 base case based on the highest design value period. The upwind ozone and PM2.5 contributions from each state are calculated for each downwind receptor. Contributions to nonattainment and maintenance receptors are evaluated independently for each state to determine if they are above the 1 percent threshold criteria.

For each upwind state, the maximum contribution to nonattainment is calculated based on the single largest Start Printed Page 45255contribution to a future year (2012) downwind nonattainment receptor. The maximum contribution to maintenance is calculated based on the single largest contribution to a future year (2012) downwind maintenance receptor. Since the contributions are calculated independently for each receptor, the upwind contribution to maintenance can sometimes be larger than the contribution to nonattainment, and vice versa. This also means that maximum contributions to nonattainment can be below the threshold while maximum contributions to maintenance may be at or above the threshold, or vice versa.

4. What are the estimated interstate contributions to annual PM2.5, 24-Hour PM2.5, and 8-Hour ozone nonattainment and maintenance?

a. Contributions to Annual and 24-Hour PM2.5 Nonattainment and Maintenance

In this section, we present the interstate contributions from emissions in upwind states to downwind nonattainment and maintenance sites for the annual PM2.5 NAAQS. We also present the interstate contributions from emissions in upwind states to downwind nonattainment and maintenance sites for the 24-hour PM2.5 NAAQS. As described previously in section IV.B., states which contribute 0.15 μg/m3 or more to annual PM2.5 nonattainment or maintenance in another state are identified as states with contributions to downwind attainment and maintenance sites large enough to warrant further analysis. For 24-hour PM2.5, states which contribute 0.35 μg/m3 or more to 24-hour PM2.5 nonattainment or maintenance in another state are identified as states with contributions to downwind attainment and maintenance sites large enough to warrant further analysis. As described previously in section IV.C.3, we performed air quality modeling to quantify the contributions to annual and 24-hour PM2.5 from emissions in each of the following 37 states individually: Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland combined with the District of Columbia, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, and Wisconsin.

For annual PM2.5, we calculated each state's contribution to each of the 32 monitoring sites that are projected to be nonattainment and each of the 16 sites that are projected to have maintenance problems for the annual PM2.5 NAAQS in the 2012 base case. The largest contribution from each state to annual PM2.5 nonattainment in downwind sites is provided in Table IV.C-13. The largest contribution from each state to annual PM2.5 maintenance in downwind sites is also provided in Table IV.C-13. The contributions from each state to all projected 2012 nonattainment and maintenance sites for the annual PM2.5 NAAQS are provided in the AQMTSD.

Table IV.C-13—Largest Contribution to Downwind Annual PM2.5 (μg/m3) Nonattainment and Maintenance for Each of 37 States

Upwind stateLargest downwind contribution to nonattainment for annual PM2.5 (μg/m3)Largest downwind contribution to maintenance for annual PM2.5 (μg/m3)
Alabama0.460.18
Arkansas0.090.04
Connecticut0.040.09
Delaware0.200.14
Florida0.290.07
Georgia0.630.18
Illinois1.010.63
Indiana2.091.78
Iowa0.310.30
Kansas0.090.05
Kentucky1.681.01
Louisiana0.110.34
Maine0.010.02
Maryland/Washington, D.C.0.630.56
Massachusetts0.070.13
Michigan0.720.71
Minnesota0.190.17
Mississippi0.070.03
Missouri1.380.27
Nebraska0.080.06
New Hampshire0.010.02
New Jersey0.340.68
New York0.490.47
North Carolina0.190.11
North Dakota0.050.05
Ohio1.492.03
Oklahoma0.080.05
Pennsylvania0.831.60
Rhode Island0.010.01
South Carolina0.260.04
South Dakota0.020.02
Tennessee0.680.64
Texas0.130.06
Vermont0.000.00
Virginia0.360.37
Start Printed Page 45256
West Virginia0.981.17
Wisconsin0.460.42

Based on the state-by-state contribution analysis, there are 22 states and the District of Columbia [50] which contribute 0.15 μg/m3 or more to downwind annual PM2.5 nonattainment. These states are: Alabama, Delaware, the District of Columbia, Florida, Georgia, Illinois, Indiana, Iowa, Kentucky, Maryland, Michigan, Minnesota, Missouri, New Jersey, New York, North Carolina, Ohio, Pennsylvania, South Carolina, Tennessee, Virginia, West Virginia, and Wisconsin. In Table IV.C-14, we provide a list of the downwind nonattainment sites to which each upwind state contributes 0.15 μg/m3 or more (i.e., the upwind state to downwind nonattainment “linkages”).

There are 19 states and the District of Columbia [51] which contribute 0.15 μg/m3 or more to downwind annual PM2.5 maintenance. These states are: Alabama, the District of Columbia, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maryland, Michigan, Minnesota, Missouri, New Jersey, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin. In Table IV.C-15, we provide a list of the downwind maintenance sites to which each upwind state contributes 0.15 μg/m3 or more (i.e., the upwind state to downwind maintenance “linkages”).

Start Printed Page 45257

Table IV.C-14—Upwind State to Downwind Nonattainment Site “Linkages” for Annual PM2.5

Upwind StateNumber of linkages
Counties containing downwind 24-hour PM2.5 nonattainment sites (monitoring site ID)
Alabama6Bibb, GA (130210007)Clayton, GA (130630091)Fulton, GA (131210039)Clark, IN (180190006)Dubois, IN (180372001)Jefferson, KY (211110043)
Delaware2Lancaster, PA (420710007)York, PA (421330008)
Florida3Jefferson, AL (10730023)Bibb, GA (130210007)Clayton, GA (130630091)
Georgia7Jefferson, AL (10730023)Jefferson, AL (10732003)Clark, IN (180190006)Dubois, IN (180372001)Jefferson, KY (211110043)Kanawha, WV (540391005)Cabell, WV (540110006)
Illinois29Jefferson, AL (10730023)Jefferson, AL (10732003)Fulton, GA (131210039)Bibb, GA (130210007)Clayton, GA (130630091)Clark, IN (180190006)Dubois, IN (180372001)
Marion, IN (180970078)Marion, IN (180970081)Marion, IN (180970083)Jefferson, KY (211110043)Wayne, MI (261630015)Wayne, MI (261630033)Butler, OH (390170016)
Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Hamilton, OH (390610014)Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)
Hamilton, OH (390618001)Allegheny, PA (420030064)Allegheny, PA (420031301)Beaver, PA (420070014)Lancaster, PA (420710007)York, PA (421330008)Cabell, WV (540110006)
Kanawha, WV (540391005)
Indiana27Jefferson, AL (10730023)Jefferson, AL (10732003)Bibb, GA (130210007)Clayton, GA (130630091)Fulton, GA (131210039)Cook, IL (170310052)Madison, IL (171191007)
Saint Clair, IL (171630010)Jefferson, KY (211110043)Wayne, MI (261630015)Wayne, MI (261630033)Butler, OH (390170016)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)
Cuyahoga, OH (390350060)Hamilton, OH (390618001)Hamilton, OH (390610014)Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)Allegheny, PA (420030064)
Allegheny, PA (420031301)Beaver, PA (420070014)Lancaster, PA (420710007)York, PA (421330008)Cabell, WV (540110006)Kanawha, WV (540391005)
Iowa4Cook, IL (170310052)Madison, IL (171191007)Saint Clair, IL (171630010)Dubois, IN (180372001)
Kentucky31Jefferson, AL (10730023)Jefferson, AL (10732003)Bibb, GA (130210007)Clayton, GA (130630091)Fulton, GA (131210039)Cook, IL (170310052)Madison, IL (171191007)
Saint Clair, IL (171630010)Clark, IN (180190006)Dubois, IN (180372001)Marion, IN (180970078)Marion, IN (180970081)Marion, IN (180970083)Wayne, MI (261630015)
Wayne, MI (261630033)Butler, OH (390170016)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Hamilton, OH (390610014)Hamilton, OH (390610042)
Hamilton, OH (390610043)Hamilton, OH (390617001)Hamilton, OH (390618001)Allegheny, PA (420030064)Allegheny, PA (420031301)Beaver, PA (420070014)Lancaster, PA (420710007)
York, PA (421330008)Cabell, WV (540110006)Kanawha, WV (540391005)
Maryland2Lancaster, PA (420710007)York, PA (421330008)
Michigan25Cook, IL (170310052)Madison, IL (171191007)Saint Clair, IL (171630010)Clark, IN (180190006)Dubois, IN (180372001)Marion, IN (180970078)Marion, IN (180970081)
Marion, IN (180970083)Jefferson, KY (211110043)Butler, OH (390170016)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Hamilton, OH (390610014)
Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)Hamilton, OH (390618001)Allegheny, PA (420030064)Allegheny, PA (420031301)Beaver, PA (420070014)
Lancaster, PA (420710007)York, PA (421330008)Cabell, WV (540110006)Kanawha, WV (540391005)
Minnesota1Cook, IL (170310052)
Missouri17Cook, IL (170310052)Madison, IL (171191007)Saint Clair, IL (171630010)Clark, IN (180190006)Dubois, IN (180372001)Marion, IN (180970078)Marion, IN (180970081)
Marion, IN (180970083)Jefferson, KY (211110043)Butler, OH (390170016)Hamilton, OH (390610014)Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)
Hamilton, OH (390618001)Cabell, WV (540110006)Kanawha, WV (540391005)
New Jersey2Lancaster, PA (420710007)York, PA (421330008)
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New York8Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Allegheny, PA (420030064)Allegheny, PA (420031301)Beaver, PA (420070014)Lancaster, PA (420710007)
York, PA (421330008)
North Carolina3Bibb, GA (130210007)Clayton, GA (130630091)Fulton, GA (131210039)
Ohio23Jefferson, AL (10730023)Jefferson, AL (10732003)Bibb, GA (130210007)Clayton, GA (130630091)Fulton, GA (131210039)Cook, IL (170310052)Madison, IL (171191007)
Saint Clair, IL (171630010)Clark, IN (180190006)Dubois, IN (180372001)Marion, IN (180970078)Marion, IN (180970081)Marion, IN (180970083)Jefferson, KY (211110043)
Wayne, MI (261630015)Wayne, MI (261630033)Allegheny, PA (420030064)Allegheny, PA (420031301)Beaver, PA (420070014)Lancaster, PA (420710007)York, PA (421330008)
Cabell, WV (540110006)Kanawha, WV (540391005)
Pennsylvania25Bibb, GA (130210007)Clayton, GA (130630091)Fulton, GA (131210039)Cook, IL (170310052)Madison, IL (171191007)Saint Clair, IL (171630010)Clark, IN (180190006)
Dubois, IN (180372001)Marion, IN (180970078)Marion, IN (180970081)Marion, IN (180970083)Jefferson, KY (211110043)Wayne, MI (261630015)Wayne, MI (261630033)
Butler, OH (390170016)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Hamilton, OH (390610014)Hamilton, OH (390610042)Hamilton, OH (390610043)
Hamilton, OH (390617001)Hamilton, OH (390618001)Cabell, WV (540110006)Kanawha, WV (540391005)
South Carolina3Bibb, GA (130210007)Clayton, GA (130630091)Fulton, GA (131210039)
Tennessee29Jefferson, AL (10730023)Jefferson, AL (10732003)Bibb, GA (130210007)Clayton, GA (130630091)Fulton, GA (131210039)Clark, IN (180190006)Madison, IL (171191007)
Saint Clair, IL (171630010)Dubois, IN (180372001)Marion, IN (180970078)Marion, IN (180970081)Marion, IN (180970083)Jefferson, KY (211110043)Wayne, MI (261630015)
Wayne, MI (261630033)Butler, OH (390170016)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Hamilton, OH (390610014)Hamilton, OH (390610042)
Hamilton, OH (390610043)Hamilton, OH (390617001)Hamilton, OH (390618001)Allegheny, PA (420030064)Allegheny, PA (420031301)Beaver, PA (420070014)Cabell, WV (540110006)
Kanawha, WV (540391005)
Virginia4Lancaster, PA (420710007)York, PA (421330008)Cabell, WV (540110006)Kanawha, WV (540391005)
West Virginia25Fulton, GA (131210039)Bibb, GA (130210007)Clayton, GA (130630091)Clark, IN (180190006)Marion, IN (180970078)Marion, IN (180970081)Marion, IN (180970083)
Dubois, IN (180372001)Jefferson, KY (211110043)Wayne, MI (261630015)Wayne, MI (261630033)Butler, OH (390170016)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)
Cuyahoga, OH (390350060)Hamilton, OH (390610014)Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)Hamilton, OH (390618001)Allegheny, PA (420030064)
Allegheny, PA (420031301)Beaver, PA (420070014)Lancaster, PA (420710007)York, PA (421330008)
Wisconsin8Cook, IL (170310052)Dubois, IN (180372001)Marion, IN (180970078)Marion, IN (180970081)Marion, IN (180970083)Wayne, MI (261630015)Wayne, MI (261630033)
Cuyahoga, OH (390350045)
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Table IV.C-15—Upwind State to Downwind Maintenance Site “Linkages” for Annual PM2.5

Upwind StateNumber of linkages
Counties containing downwind 24-hour PM2.5 nonattainment sites (monitoring site ID)
Alabama1Jefferson, KY (211110044)
Georgia1Jefferson, KY (211110044)
Illinois13Jefferson, KY (211110044)Cuyahoga, OH (390350027)Cuyahoga, OH (390350065)Hamilton, OH (390610040)Jefferson, OH (390811001)Montgomery, OH (391130032)Stark, OH (391510017)
Berks, PA (420110011)Harris, TX (482011035)Berkeley, WV (540030003)Brooke, WV (540090005)Hancock, WV (540291004)Marion, WV (540490006)
Indiana16Cook, IL (170313301)Cook, IL (170316005)Jefferson, KY (211110044)New York, NY (360610056)Cuyahoga, OH (390350027)Cuyahoga, OH (390350065)Hamilton, OH (390610040)
Jefferson, OH (390811001)Montgomery, OH (391130032)Stark, OH (391510017)Berks, PA (420110011)Harris, TX (482011035)Berkeley, WV (540030003)Brooke, WV (540090005)
Hancock, WV (540291004)Marion, WV (540490006)
Iowa2Cook, IL (170313301)Cook, IL (170316005)
Kentucky12Cook, IL (170313301)Cook, IL (170316005)Cuyahoga, OH (390350027)Cuyahoga, OH (390350065)Hamilton, OH (390610040)Jefferson, OH (390811001)Montgomery, OH (391130032)
Stark, OH (391510017)Berkeley, WV (540030003)Brooke, WV (540090005)Hancock, WV (540291004)Marion, WV (540490006)
Louisiana1Harris, TX (482011035)
Maryland2Berks, PA (420110011)Berkeley, WV (540030003)
Michigan15Cook, IL (170313301)Cook, IL (170316005)Jefferson, KY (211110044)New York, NY (360610056)Cuyahoga, OH (390350027)Cuyahoga, OH (390350065)Hamilton, OH (390610040)
Jefferson, OH (390811001)Montgomery, OH (391130032)Stark, OH (391510017)Berks, PA (420110011)Berkeley, WV (540030003)Brooke, WV (540090005)Hancock, WV (540291004)
Marion, WV (540490006)
Minnesota1Cook, IL (170316005)
Missouri6Cook, IL (170313301)Cook, IL (170316005)Jefferson, KY (211110044)Hamilton, OH (390610040)Montgomery, OH (391130032)Stark, OH (391510017)
New Jersey2New York, NY (360610056)Berks, PA (420110011)
New York9Cuyahoga, OH (390350027)Cuyahoga, OH (390350065)Jefferson, OH (390811001)Stark, OH (391510017)Berks, PA (420110011)Berkeley, WV (540030003)Brooke, WV (540090005)
Hancock, WV (540291004)Marion, WV (540490006)
Ohio9Cook, IL (170313301)Cook, IL (170316005)Jefferson, KY (211110044)New York, NY (360610056)Berks, PA (420110011)Berkeley, WV (540030003)Brooke, WV (540090005)
Hancock, WV (540291004)Marion, WV (540490006)
Pennsylvania14Cook, IL (170313301)Cook, IL (170316005)Jefferson, KY (211110044)New York, NY (360610056)Cuyahoga, OH (390350027)Cuyahoga, OH (390350065)Hamilton, OH (390610040)
Jefferson, OH (390811001)Montgomery, OH (391130032)Stark, OH (391510017)Berkeley, WV (540030003)Brooke, WV (540090005)Hancock, WV (540291004)Marion, WV (540490006)
Tennessee10Jefferson, KY (211110044)Cuyahoga, OH (390350027)Cuyahoga, OH (390350065)Hamilton, OH (390610040)Jefferson, OH (390811001)Montgomery, OH (391130032)Stark, OH (391510017)
Brooke, WV (540090005)Hancock, WV (540291004)Marion, WV (540490006)
Virginia4New York, NY (360610056)Berks, PA (420110011)Berkeley, WV (540030003)Marion, WV (540490006)
West Virginia9Jefferson, KY (211110044)New York, NY (360610056)Cuyahoga, OH (390350027)Cuyahoga, OH (390350065)Hamilton, OH (390610040)Jefferson, OH (390811001)Montgomery, OH (391130032)
Stark, OH (391510017)Berks, PA (420110011)
Start Printed Page 45260
Wisconsin2Cook, IL (170313301)Cook, IL (170316005)
Start Printed Page 45261

For 24-hour PM2.5, we calculated each state's contribution to each of the 92 monitoring sites that are projected to be nonattainment and each of the 38 sites that are projected to have maintenance problems for the 24-hour PM2.5 NAAQS in the 2012 base case. The largest contribution from each state to 24-hour PM2.5 nonattainment in downwind sites is provided in Table IV.C-16. The largest contribution from each state to 24-hour PM2.5 maintenance in downwind sites is also provided in Table IV.C-16. The contributions from each state to all projected 2012 nonattainment and maintenance sites for the 24-hour PM2.5 NAAQS are provided in the AQMTSD.

Table IV.C-16—Largest Contribution to Downwind 24-Hour PM2.5 (μg/m3) Nonattainment and Maintenance for Each of 37 States

Upwind StateLargest downwind contribution to nonattainment for 24-hour PM2.5 (μg/m3)Largest downwind contribution to maintenance for 24-hour PM2.5 (μg/m3)
Alabama0.480.32
Arkansas0.200.17
Connecticut0.410.70
Delaware0.500.36
Florida0.080.08
Georgia0.950.41
Illinois7.286.57
Indiana9.918.94
Iowa1.871.67
Kansas0.770.45
Kentucky6.536.91
Louisiana0.230.18
Maine0.190.19
Maryland/Washington, DC2.631.82
Massachusetts0.670.71
Michigan2.353.35
Minnesota0.910.86
Mississippi0.090.04
Missouri5.034.82
Nebraska0.620.39
New Hampshire0.210.23
New Jersey2.694.74
New York5.821.17
North Carolina0.500.45
North Dakota0.270.15
Ohio5.845.56
Oklahoma0.160.21
Pennsylvania3.674.86
Rhode Island0.050.06
South Carolina0.190.19
South Dakota0.130.09
Tennessee3.924.70
Texas0.210.28
Vermont0.060.07
Virginia1.322.26
West Virginia3.514.83
Wisconsin0.801.01

Based on the state-by-state contribution analysis, there are 24 states and the District of Columbia [52] which contribute 0.35 μg/m3 or more to downwind 24-hour PM2.5 nonattainment. These states are: Alabama, the District of Columbia, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin. In Table IV.C-17, we provide a list of the downwind nonattainment counties to which each upwind state contributes 0.35 μg/m3 or more (i.e., the upwind state to downwind nonattainment “linkages”).

There are 23 states and the District of Columbia which contribute 0.35 μg/m3 or more to downwind 24-hour PM2.5 maintenance. These states are: Connecticut, Delaware, the District of Columbia, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin. In Table IV.C-18, we provide a list of the downwind maintenance sites to which each upwind state contributes 0.35 μg/m3 or more (i.e., the upwind state to downwind maintenance “linkages”).Start Printed Page 45262

Table IV.C-17—Upwind State to Downwind Nonattainment Site “Linkages” for 24-Hour PM2.5

Upwind StateNumber of linkages
Counties containing downwind 24-hour PM2.5 nonattainment sites (monitoring site ID)
Alabama5Monroe, MI (261150005)Wayne, MI (261630015)Hamilton, OH (390610006)Hamilton, OH (390610014)Hamilton, OH (390618001)
Connecticut3Hudson, NJ (340172002)New York, NY (360610056)New York, NY (360610128)
Delaware2Union, NJ (340390004)Dauphin, PA (420430401)
Georgia12Jefferson, AL (10730023)Jefferson, AL (10732003)Baltimore City, MD (245100040)Baltimore City, MD (245100049)Union, NJ (340390004)Butler, OH (390170016)
Butler, OH (390171004)Hamilton, OH (390610006)Hamilton, OH (390610014)Hamilton, OH (390618001)Montgomery, OH (391130032)York, PA (421330008)
Illinois70Jefferson, AL (10730023)Jefferson, AL (10732003)New Haven, CT (90091123)Clark, IN (180190006)Dubois, IN (180372001)Knox, IN (180830004)
Lake, IN (180890022)Lake, IN (180890026)Marion, IN (180970042)Marion, IN (180970043)Marion, IN (180970066)Marion, IN (180970078)
Marion, IN (180970079)Marion, IN (180970081)Marion, IN (180970083)Tippecanoe, IN (181570008)Scott, IA (191630019)Daviess, KY (210590005)
Jefferson, KY (211110043)Jefferson, KY (211110044)Jefferson, KY (211110048)Monroe, MI (261150005)Oakland, MI (261250001)St. Clair, MI (261470005)
Washtenaw, MI (261610008)Wayne, MI (261630015)Wayne, MI (261630016)Wayne, MI (261630019)Wayne, MI (261630033)Wayne, MI (261630036)
Jefferson, MO (290990012)Saint Charles, MO (291831002)St. Louis City, MO (295100007)St. Louis City, MO (295100087)Union, NJ (340390004)New York, NY (360610128)
Butler, OH (390170003)Butler, OH (390170016)Butler, OH (390170017)Butler, OH (390171004)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)
Cuyahoga, OH (390350060)Cuyahoga, OH (390350065)Franklin, OH (390490024)Franklin, OH (390490025)Hamilton, OH (390610006)Hamilton, OH (390610014)
Hamilton, OH (390610040)Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)Hamilton, OH (390618001)Jefferson, OH (390811001)
Montgomery, OH (391130032)Summit, OH (391530017)Allegheny, PA (420030064)Allegheny, PA (420030093)Allegheny, PA (420030116)Allegheny, PA (420031008)
Allegheny, PA (420031301)Beaver, PA (420070014)Berks, PA (420110011)Cambria, PA (420210011)Montgomery, TN (471251009)Brooke, WV (540090011)
Milwaukee, WI (550790010)Milwaukee, WI (550790026)Milwaukee, WI (550790043)Milwaukee, WI (550790099)
Indiana75Jefferson, AL (10730023)Jefferson, AL (10732003)New Haven, CT (90091123)Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)
Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313103)Cook, IL (170313301)Cook, IL (170316005)Madison, IL (171190023)
Madison, IL (171191007)Madison, IL (171192009)Madison, IL (171193007)Scott, IA (191630019)Daviess, KY (210590005)Jefferson, KY (211110043)
Jefferson, KY (211110044)Jefferson, KY (211110048)Monroe, MI (261150005)Oakland, MI (261250001)St. Clair, MI (261470005)Washtenaw, MI (261610008)
Wayne, MI (261630015)Wayne, MI (261630016)Wayne, MI (261630019)Wayne, MI (261630033)Wayne, MI (261630036)Jefferson, MO (290990012)
Saint Charles, MO (291831002)St. Louis City, MO (295100007)St. Louis City, MO (295100087)Hudson, NJ (340171003)Union, NJ (340390004)Bronx, NY (360050080)
New York, NY (360610056)New York, NY (360610128)Butler, OH (390170003)Butler, OH (390170016)Butler, OH (390170017)Butler, OH (390171004)
Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Cuyahoga, OH (390350065)Franklin, OH (390490024)Franklin, OH (390490025)
Hamilton, OH (390610006)Hamilton, OH (390610014)Hamilton, OH (390610040)Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)
Hamilton, OH (390618001)Jefferson, OH (390811001)Montgomery, OH (391130032)Summit, OH (391530017)Allegheny, PA (420030008)Allegheny, PA (420030064)
Allegheny, PA (420030093)Allegheny, PA (420030116)Allegheny, PA (420031008)Allegheny, PA (420031301)Beaver, PA (420070014)Berks, PA (420110011)
Cambria, PA (420210011)Dauphin, PA (420430401)York, PA (421330008)Montgomery, TN (471251009)Brooke, WV (540090011)Milwaukee, WI (550790010)
Milwaukee, WI (550790026)Milwaukee, WI (550790043)Milwaukee, WI (550790099)
Iowa17Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313103)
Cook, IL (170313301)Cook, IL (170316005)Madison, IL (171191007)Lake, IN (180890022)Lake, IN (180890026)Jefferson, MO (290990012)
St. Louis City, MO (295100007)Milwaukee, WI (550790010)Milwaukee, WI (550790026)Milwaukee, WI (550790043)Milwaukee, WI (550790099)
Kansas3Milwaukee, WI (550790010)Milwaukee, WI (550790026)Milwaukee, WI (550790099)
Kentucky81Jefferson, AL (10730023)Jefferson, AL (10732003)New Haven, CT (90091123)Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)
Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313103)Cook, IL (170313301)Cook, IL (170316005)Madison, IL (171190023)
Madison, IL (171191007)Madison, IL (171192009)Madison, IL (171193007)Clark, IN (180190006)Dubois, IN (180372001)Knox, IN (180830004)
Lake, IN (180890026)Marion, IN (180970042)Marion, IN (180970043)Marion, IN (180970066)Marion, IN (180970078)Marion, IN (180970079)
Marion, IN (180970081)Marion, IN (180970083)Tippecanoe, IN (181570008)Scott, IA (191630019)Monroe, MI (261150005)Oakland, MI (261250001)
Start Printed Page 45263
St. Clair, MI (261470005)Washtenaw, MI (261610008)Wayne, MI (261630015)Wayne, MI (261630016)Wayne, MI (261630019)Wayne, MI (261630033)
Wayne, MI (261630036)Jefferson, MO (290990012)Saint Charles, MO (291831002)St. Louis City, MO (295100007)St. Louis City, MO (295100087)Hudson, NJ (340171003)
Union, NJ (340390004)Bronx, NY (360050080)New York, NY (360610128)Butler, OH (390170003)Butler, OH (390170016)Butler, OH (390170017)
Butler, OH (390171004)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Cuyahoga, OH (390350065)Franklin, OH (390490024)
Franklin, OH (390490025)Hamilton, OH (390610006)Hamilton, OH (390610014)Hamilton, OH (390610040)Hamilton, OH (390610042)Hamilton, OH (390610043)
Hamilton, OH (390617001)Hamilton, OH (390618001)Jefferson, OH (390811001)Montgomery, OH (391130032)Summit, OH (391530017)Allegheny, PA (420030008)
Allegheny, PA (420030064)Allegheny, PA (420030093)Allegheny, PA (420030116)Allegheny, PA (420031008)Allegheny, PA (420031301)Beaver, PA (420070014)
Berks, PA (420110011)Cambria, PA (420210011)York, PA (421330008)Montgomery, TN (471251009)Brooke, WV (540090011)Milwaukee, WI (550790010)
Milwaukee, WI (550790026)Milwaukee, WI (550790043)Milwaukee, WI (550790099)
Maryland11New Haven, CT (90091123)Hudson, NJ (340171003)Hudson, NJ (340172002)Union, NJ (340390004)Bronx, NY (360050080)New York, NY (360610056)
New York, NY (360610128)Berks, PA (420110011)Dauphin, PA (420430401)Lancaster, PA (420710007)York, PA (421330008)
Massachusetts3New Haven, CT (90091123)New York, NY (360610056)New York, NY (360610128)
Michigan48Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313103)
Cook, IL (170313301)Cook, IL (170316005)Madison, IL (171190023)Madison, IL (171191007)Madison, IL (171192009)Madison, IL (171193007)
Knox, IN (180830004)Lake, IN (180890022)Lake, IN (180890026)Scott, IA (191630019)Jefferson, MO (290990012)Saint Charles, MO (291831002)
St. Louis City, MO (295100007)St. Louis City, MO (295100087)New York, NY (360610128)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)
Cuyahoga, OH (390350065)Franklin, OH (390490024)Franklin, OH (390490025)Hamilton, OH (390610014)Hamilton, OH (390617001)Hamilton, OH (390618001)
Jefferson, OH (390811001)Montgomery, OH (391130032)Summit, OH (391530017)Allegheny, PA (420030008)Allegheny, PA (420030064)Allegheny, PA (420030093)
Allegheny, PA (420030116)Allegheny, PA (420031008)Allegheny, PA (420031301)Beaver, PA (420070014)Cambria, PA (420210011)Dauphin, PA (420430401)
Montgomery, TN (471251009)Brooke, WV (540090011)Milwaukee, WI (550790010)Milwaukee, WI (550790026)Milwaukee, WI (550790043)
Milwaukee, WI (550790099)
Minnesota4Milwaukee, WI (550790010)Milwaukee, WI (550790026)Milwaukee, WI (550790043)Milwaukee, WI (550790099)
Missouri56Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313103)
Cook, IL (170313301)Cook, IL (170316005)Madison, IL (171190023)Madison, IL (171191007)Madison, IL (171192009)Madison, IL (171193007)
Clark, IN (180190006)Dubois, IN (180372001)Knox, IN (180830004)Lake, IN (180890022)Lake, IN (180890026)Marion, IN (180970042)
Marion, IN (180970043)Marion, IN (180970066)Marion, IN (180970078)Marion, IN (180970079)Marion, IN (180970081)Marion, IN (180970083)
Tippecanoe, IN (181570008)Scott, IA (191630019)Daviess, KY (210590005)Jefferson, KY (211110043)Jefferson, KY (211110044)Jefferson, KY (211110048)
Monroe, MI (261150005)Oakland, MI (261250001)Washtenaw, MI (261610008)Wayne, MI (261630015)Wayne, MI (261630033)Wayne, MI (261630036)
Butler, OH (390170003)Butler, OH (390170016)Butler, OH (390170017)Butler, OH (390171004)Franklin, OH (390490024)Franklin, OH (390490025)
Hamilton, OH (390610006)Hamilton, OH (390610014)Hamilton, OH (390610040)Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)
Hamilton, OH (390618001)Montgomery, OH (391130032)Allegheny, PA (420030116)Montgomery, TN (471251009)Milwaukee, WI (550790010)Milwaukee, WI (550790026)
Milwaukee, WI (550790043)Milwaukee, WI (550790099)
Nebraska3Milwaukee, WI (550790010)Milwaukee, WI (550790026)Milwaukee, WI (550790099)
New Jersey9New Haven, CT (90091123)Baltimore City, MD (245100049)Bronx, NY (360050080)New York, NY (360610056)New York, NY (360610128)Berks, PA (420110011)
Dauphin, PA (420430401)Lancaster, PA (420710007)York, PA (421330008)
New York23New Haven, CT (90091123)Baltimore City, MD (245100040)Baltimore City, MD (245100049)St. Clair, MI (261470005)Washtenaw, MI (261610008)Wayne, MI (261630016)
Wayne, MI (261630019)Wayne, MI (261630033)Wayne, MI (261630036)Hudson, NJ (340171003)Hudson, NJ (340172002)Union, NJ (340390004)
Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Cuyahoga, OH (390350065)Franklin, OH (390490024)Franklin, OH (390490025)
Summit, OH (391530017)Berks, PA (420110011)Dauphin, PA (420430401)Lancaster, PA (420710007)York, PA (421330008)
Start Printed Page 45264
North Carolina11Baltimore City, MD (245100040)Baltimore City, MD (245100049)Hudson, NJ (340171003)Hudson, NJ (340172002)Union, NJ (340390004)Bronx, NY (360050080)
New York, NY (360610056)Berks, PA (420110011)Dauphin, PA (420430401)Lancaster, PA (420710007)York, PA (421330008)
Ohio72Jefferson, AL (10730023)Jefferson, AL (10732003)New Haven, CT (90091123)Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)
Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313103)Cook, IL (170313301)Cook, IL (170316005)Madison, IL (171190023)
Madison, IL (171191007)Madison, IL (171192009)Madison, IL (171193007)Clark, IN (180190006)Dubois, IN (180372001)Knox, IN (180830004)
Lake, IN (180890022)Lake, IN (180890026)Marion, IN (180970042)Marion, IN (180970043)Marion, IN (180970066)Marion, IN (180970078)
Marion, IN (180970079)Marion, IN (180970081)Marion, IN (180970083)Tippecanoe, IN (181570008)Scott, IA (191630019)Daviess, KY (210590005)
Jefferson, KY (211110043)Jefferson, KY (211110044)Jefferson, KY (211110048)Baltimore City, MD (245100040)Baltimore City, MD (245100049)Monroe, MI (261150005)
Oakland, MI (261250001)St. Clair, MI (261470005)Washtenaw, MI (261610008)Wayne, MI (261630015)Wayne, MI (261630016)Wayne, MI (261630019)
Wayne, MI (261630033)Wayne, MI (261630036)Jefferson, MO (290990012)Saint Charles, MO (291831002)St. Louis City, MO (295100007)St. Louis City, MO (295100087)
Hudson, NJ (340171003)Hudson, NJ (340172002)Union, NJ (340390004)Bronx, NY (360050080)New York, NY (360610056)New York, NY (360610128)
Allegheny, PA (420030008)Allegheny, PA (420030064)Allegheny, PA (420030093)Allegheny, PA (420030116)Allegheny, PA (420031008)Allegheny, PA (420031301)
Beaver, PA (420070014)Berks, PA (420110011)Cambria, PA (420210011)Dauphin, PA (420430401)Lancaster, PA (420710007)York, PA (421330008)
Montgomery, TN (471251009)Brooke, WV (540090011)Milwaukee, WI (550790010)Milwaukee, WI (550790026)Milwaukee, WI (550790043)Milwaukee, WI (550790099)
Pennsylvania77Jefferson, AL (10730023)Jefferson, AL (10732003)New Haven, CT (90091123)Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)
Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313103)Cook, IL (170313301)Cook, IL (170316005)Madison, IL (171191007)
Madison, IL (171192009)Madison, IL (171193007)Madison, IL (171190023)Clark, IN (180190006)Dubois, IN (180372001)Knox, IN (180830004)
Lake, IN (180890026)Marion, IN (180970042)Marion, IN (180970043)Marion, IN (180970066)Marion, IN (180970078)Marion, IN (180970079)
Marion, IN (180970081)Marion, IN (180970083)Tippecanoe, IN (181570008)Scott, IA (191630019)Jefferson, KY (211110043)Jefferson, KY (211110044)
Jefferson, KY (211110048)Baltimore City, MD (245100040)Baltimore City, MD (245100049)Monroe, MI (261150005)Oakland, MI (261250001)St. Clair, MI (261470005)
Washtenaw, MI (261610008)Wayne, MI (261630015)Wayne, MI (261630016)Wayne, MI (261630019)Wayne, MI (261630033)Wayne, MI (261630036)
Jefferson, MO (290990012)Saint Charles, MO (291831002)St. Louis City, MO (295100007)St. Louis City, MO (295100087)Hudson, NJ (340171003)Hudson, NJ (340172002)
Union, NJ (340390004)Bronx, NY (360050080)New York, NY (360610056)New York, NY (360610128)Butler, OH (390170003)Butler, OH (390170016)
Butler, OH (390170017)Butler, OH (390171004)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Cuyahoga, OH (390350065)
Franklin, OH (390490024)Franklin, OH (390490025)Hamilton, OH (390610006)Hamilton, OH (390610014)Hamilton, OH (390610040)Hamilton, OH (390610042)
Hamilton, OH (390610043)Hamilton, OH (390617001)Hamilton, OH (390618001)Jefferson, OH (390811001)Montgomery, OH (391130032)Summit, OH (391530017)
Montgomery, TN (471251009)Brooke, WV (540090011)Milwaukee, WI (550790026)Milwaukee, WI (550790043)Milwaukee, WI (550790099)
Tennessee61Jefferson, AL (10730023)Jefferson, AL (10732003)New Haven, CT (90091123)Madison, IL (171190023)Madison, IL (171191007)Madison, IL (171192009)
Madison, IL (171193007)Clark, IN (180190006)Dubois, IN (180372001)Knox, IN (180830004)Marion, IN (180970042)Marion, IN (180970043)
Marion, IN (180970066)Marion, IN (180970078)Marion, IN (180970079)Marion, IN (180970081)Marion, IN (180970083)Tippecanoe, IN (181570008)
Scott, IA (191630019)Daviess, KY (210590005)Jefferson, KY (211110043)Jefferson, KY (211110044)Jefferson, KY (211110048)Monroe, MI (261150005)
Oakland, MI (261250001)St. Clair, MI (261470005)Washtenaw, MI (261610008)Wayne, MI (261630015)Wayne, MI (261630033)Wayne, MI (261630036)
Jefferson, MO (290990012)Saint Charles, MO (291831002)St. Louis City, MO (295100007)St. Louis City, MO (295100087)Union, NJ (340390004)New York, NY (360610128)
Butler, OH (390170003)Butler, OH (390170016)Butler, OH (390170017)Butler, OH (390171004)Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)
Cuyahoga, OH (390350065)Franklin, OH (390490024)Franklin, OH (390490025)Hamilton, OH (390610006)Hamilton, OH (390610014)Hamilton, OH (390610040)
Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)Hamilton, OH (390618001)Jefferson, OH (390811001)Montgomery, OH (391130032)
Summit, OH (391530017)Allegheny, PA (420030093)Allegheny, PA (420030116)Allegheny, PA (420031008)Allegheny, PA (420031301)Cambria, PA (420210011)
York, PA (421330008)
Virginia13New Haven, CT (90091123)Baltimore City, MD (245100040)Baltimore City, MD (245100049)Hudson, NJ (340171003)Hudson, NJ (340172002)Union, NJ (340390004)
Start Printed Page 45265
Bronx, NY (360050080)New York, NY (360610056)New York, NY (360610128)Berks, PA (420110011)Dauphin, PA (420430401)Lancaster, PA (420710007)
York, PA (421330008)
West Virginia84Jefferson, AL (10730023)Jefferson, AL (10732003)New Haven, CT (90091123)Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)
Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313301)Cook, IL (170316005)Madison, IL (171190023)Madison, IL (171191007)
Madison, IL (171192009)Madison, IL (171193007)Clark, IN (180190006)Dubois, IN (180372001)Lake, IN (180890026)Marion, IN (180970042)
Marion, IN (180970043)Marion, IN (180970066)Marion, IN (180970078)Marion, IN (180970079)Marion, IN (180970081)Marion, IN (180970083)
Tippecanoe, IN (181570008)Scott, IA (191630019)Jefferson, KY (211110043)Jefferson, KY (211110044)Jefferson, KY (211110048)Baltimore City, MD (245100040)
Baltimore City, MD (245100049)Monroe, MI (261150005)Oakland, MI (261250001)St. Clair, MI (261470005)Washtenaw, MI (261610008)Wayne, MI (261630015)
Wayne, MI (261630016)Wayne, MI (261630019)Wayne, MI (261630033)Wayne, MI (261630036)Jefferson, MO (290990012)Saint Charles, MO (291831002)
St. Louis City, MO (295100007)St. Louis City, MO (295100087)Hudson, NJ (340171003)Hudson, NJ (340172002)Union, NJ (340390004)Bronx, NY (360050080)
New York, NY (360610056)New York, NY (360610128)Butler, OH (390170003)Butler, OH (390170016)Butler, OH (390170017)Butler, OH (390171004)
Cuyahoga, OH (390350038)Cuyahoga, OH (390350045)Cuyahoga, OH (390350060)Cuyahoga, OH (390350065)Franklin, OH (390490024)Franklin, OH (390490025)
Hamilton, OH (390610006)Hamilton, OH (390610014)Hamilton, OH (390610040)Hamilton, OH (390610042)Hamilton, OH (390610043)Hamilton, OH (390617001)
Hamilton, OH (390618001)Jefferson, OH (390811001)Montgomery, OH (391130032)Summit, OH (391530017)Allegheny, PA (420030008)Allegheny, PA (420030064)
Allegheny, PA (420030093)Allegheny, PA (420030116)Allegheny, PA (420031008)Allegheny, PA (420031301)Beaver, PA (420070014)Berks, PA (420110011)
Cambria, PA (420210011)Dauphin, PA (420430401)Lancaster, PA (420710007)York, PA (421330008)Montgomery, TN (471251009)Milwaukee, WI (550790043)
Wisconsin12Cook, IL (170310052)Cook, IL (170310057)Cook, IL (170310076)Cook, IL (170311016)Cook, IL (170312001)Cook, IL (170313103)
Cook, IL (170313301)Cook, IL (170316005)Lake, IN (180890022)Lake, IN (180890026)Scott, IA (191630019)Wayne, MI (261630016)

Table IV.C-18—Upwind State to Downwind Maintenance Site “Linkages” for 24-Hour PM2.5

Upwind StateNumber of linkages
Counties containing downwind 24-hour PM2.5 nonattainment sites (monitoring site ID)
Connecticut1New York, NY (360610062)
Delaware2Cumberland, PA (420410101)New York, NY (360610079)
Georgia3Baltimore City, MD (245100035)Lucas, OH (390950026)Preble, OH (391351001)
Illinois29District of Columbia (110010041)District of Columbia (110010042)Elkhart, IN (180390003)Floyd, IN (180431004)Vigo, IN (181670023)Muscatine, IA (191390015)
Bullitt, KY (210290006)McCracken, KY (211451004)Warren, KY (212270007)Wayne, MI (261630001)St. Louis City, MO (295100085)New York, NY (360610079)
Cuyahoga, OH (390350027)Cuyahoga, OH (390350034)Jefferson, OH (390810017)Lucas, OH (390950024)Lucas, OH (390950026)Mahoning, OH (390990014)
Montgomery, OH (391130031)Preble, OH (391351001)Trumbull, OH (391550007)Allegheny, PA (420030095)Allegheny, PA (420033007)Washington, PA (421255001)
Sumner, TN (471650007)Brooke, WV (540090005)Dane, WI (550250047)Milwaukee, WI (550790059)Waukesha, WI (551330027)
Indiana34District of Columbia (110010041)District of Columbia (110010042)Cook, IL (170310022)Cook, IL (170310050)Cook, IL (170314007)Saint Clair, IL (171630010)
Will, IL (171971002)Muscatine, IA (191390015)Bullitt, KY (210290006)McCracken, KY (211451004)Warren, KY (212270007)Anne Arundel, MD (240031003)
Wayne, MI (261630001)St. Louis City, MO (295100085)New York, NY (360610062)New York, NY (360610079)Cuyahoga, OH (390350027)Cuyahoga, OH (390350034)
Jefferson, OH (390810017)Lucas, OH (390950024)Lucas, OH (390950026)Mahoning, OH (390990014)Montgomery, OH (391130031)Preble, OH (391351001)
Trumbull, OH (391550007)Allegheny, PA (420030095)Allegheny, PA (420033007)Cumberland, PA (420410101)Washington, PA (421255001)Sumner, TN (471650007)
Brooke, WV (540090005)Dane, WI (550250047)Milwaukee, WI (550790059)Waukesha, WI (551330027)
Iowa9Cook, IL (170310022)Cook, IL (170310050)Cook, IL (170314007)Will, IL (171971002)Elkhart, IN (180390003)St. Louis City, MO (295100085)
Start Printed Page 45266
Dane, WI (550250047)Milwaukee, WI (550790059)Waukesha, WI (551330027)
Kansas2Muscatine, IA (191390015)Milwaukee, WI (550790059)
Kentucky33District of Columbia (110010041)District of Columbia (110010042)Cook, IL (170310022)Cook, IL (170310050)Cook, IL (170314007)Saint Clair, IL (171630010)
Will, IL (171971002)Elkhart, IN (180390003)Floyd, IN (180431004)Vigo, IN (181670023)Muscatine, IA (191390015)Anne Arundel, MD (240031003)
Wayne, MI (261630001)St. Louis City, MO (295100085)New York, NY (360610062)New York, NY (360610079)Cuyahoga, OH (390350027)Cuyahoga, OH (390350034)
Jefferson, OH (390810017)Lucas, OH (390950024)Lucas, OH (390950026)Mahoning, OH (390990014)Montgomery, OH (391130031)Preble, OH (391351001)
Trumbull, OH (391550007)Allegheny, PA (420030095)Allegheny, PA (420033007)Washington, PA (421255001)Sumner, TN (471650007)Brooke, WV (540090005)
Dane, WI (550250047)Milwaukee, WI (550790059)Waukesha, WI (551330027)
Maryland5District of Columbia (110010041)District of Columbia (110010042)New York, NY (360610062)New York, NY (360610079)Cumberland, PA (420410101)
Massachusetts1New York, NY (360610062)
Michigan28District of Columbia (110010041)Cook, IL (170310022)Cook, IL (170310050)Cook, IL (170314007)Saint Clair, IL (171630010)Will, IL (171971002)
Elkhart, IN (180390003)Vigo, IN (181670023)Muscatine, IA (191390015)Warren, KY (212270007)St. Louis City, MO (295100085)Cuyahoga, OH (390350027)
Cuyahoga, OH (390350034)Jefferson, OH (390810017)Lucas, OH (390950024)Lucas, OH (390950026)Mahoning, OH (390990014)Montgomery, OH (391130031)
Preble, OH (391351001)Trumbull, OH (391550007)Allegheny, PA (420030095)Allegheny, PA (420033007)Washington, PA (421255001)Sumner, TN (471650007)
Brooke, WV (540090005)Dane, WI (550250047)Milwaukee, WI (550790059)Waukesha, WI (551330027)
Minnesota4Muscatine, IA (191390015)Dane, WI (550250047)Milwaukee, WI (550790059)Waukesha, WI (551330027)
Missouri20Cook, IL (170310022)Cook, IL (170310050)Cook, IL (170314007)Saint Clair, IL (171630010)Will, IL (171971002)Elkhart, IN (180390003)
Floyd, IN (180431004)Vigo, IN (181670023)Muscatine, IA (191390015)Bullitt, KY (210290006)McCracken, KY (211451004)Warren, KY (212270007)
Jefferson, OH (390810017)Lucas, OH (390950026)Montgomery, OH (391130031)Preble, OH (391351001)Sumner, TN (471650007)Dane, WI (550250047)
Milwaukee, WI (550790059)Waukesha, WI (551330027)
Nebraska2Muscatine, IA (191390015)Milwaukee, WI (550790059)
New Jersey5District of Columbia (110010041)Anne Arundel, MD (240031003)New York, NY (360610062)New York, NY (360610079)Cumberland, PA (420410101)
New York9District of Columbia (110010041)District of Columbia (110010042)Anne Arundel, MD (240031003)Baltimore City, MD (245100035)Cuyahoga, OH (390350027)Cuyahoga, OH (390350034)
Lucas, OH (390950024)Lucas, OH (390950026)Cumberland, PA (420410101)
North Carolina3Baltimore City, MD (245100035)New York, NY (360610062)New York, NY (360610079)
Ohio29District of Columbia (110010041)District of Columbia (110010042)Cook, IL (170310022)Cook, IL (170310050)Cook, IL (170314007)Saint Clair, IL (171630010)
Will, IL (171971002)Elkhart, IN (180390003)Floyd, IN (180431004)Vigo, IN (181670023)Muscatine, IA (191390015)Bullitt, KY (210290006)
McCracken, KY (211451004)Warren, KY (212270007)Anne Arundel, MD (240031003)Baltimore City, MD (245100035)Wayne, MI (261630001)St. Louis City, MO (295100085)
New York, NY (360610062)New York, NY (360610079)Allegheny, PA (420030095)Allegheny, PA (420033007)Cumberland, PA (420410101)Washington, PA (421255001)
Sumner, TN (471650007)Brooke, WV (540090005)Dane, WI (550250047)Milwaukee, WI (550790059)Waukesha, WI (551330027)
Pennsylvania32District of Columbia (110010041)District of Columbia (110010042)Cook, IL (170310022)Cook, IL (170310050)Cook, IL (170314007)Saint Clair, IL (171630010)
Will, IL (171971002)Elkhart, IN (180390003)Floyd, IN (180431004)Vigo, IN (181670023)Muscatine, IA (191390015)Bullitt, KY (210290006)
Warren, KY (212270007)Anne Arundel, MD (240031003)Baltimore City, MD (245100035)Wayne, MI (261630001)New York, NY (360610062)New York, NY (360610079)
Cuyahoga, OH (390350027)Cuyahoga, OH (390350034)Jefferson, OH (390810017)Lucas, OH (390950024)Lucas, OH (390950026)Mahoning, OH (390990014)
Montgomery, OH (391130031)Preble, OH (391351001)Trumbull, OH (391550007)Sumner, TN (471650007)Brooke, WV (540090005)Dane, WI (550250047)
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Milwaukee, WI (550790059)Waukesha, WI (551330027)
Tennessee21Cook, IL (170314007)Saint Clair, IL (171630010)Will, IL (171971002)Elkhart, IN (180390003)Floyd, IN (180431004)Vigo, IN (181670023)
Muscatine, IA (191390015)Bullitt, KY (210290006)McCracken, KY (211451004)Warren, KY (212270007)Wayne, MI (261630001)St. Louis City, MO (295100085)
Jefferson, OH (390810017)Lucas, OH (390950024)Lucas, OH (390950026)Mahoning, OH (390990014)Montgomery, OH (391130031)Preble, OH (391351001)
Trumbull, OH (391550007)Allegheny, PA (420033007)Washington, PA (421255001)
Virginia7District of Columbia (110010041)District of Columbia (110010042)Anne Arundel, MD (240031003)Baltimore City, MD (245100035)New York, NY (360610062)New York, NY (360610079)
Cumberland, PA (420410101)
West Virginia35District of Columbia (110010041)District of Columbia (110010042)Cook, IL (170310050)Cook, IL (170314007)Saint Clair, IL (171630010)Will, IL (171971002)
Elkhart, IN (180390003)Floyd, IN (180431004)Vigo, IN (181670023)Muscatine, IA (191390015)Bullitt, KY (210290006)Warren, KY (212270007)
Anne Arundel, MD (240031003)Baltimore City, MD (245100035)Wayne, MI (261630001)St. Louis City, MO (295100085)New York, NY (360610062)New York, NY (360610079)
Cuyahoga, OH (390350027)Cuyahoga, OH (390350034)Jefferson, OH (390810017)Lucas, OH (390950024)Lucas, OH (390950026)Mahoning, OH (390990014)
Montgomery, OH (391130031)Preble, OH (391351001)Trumbull, OH (391550007)Allegheny, PA (420030095)Allegheny, PA (420033007)Cumberland, PA (420410101)
Washington, PA (421255001)Sumner, TN (471650007)Dane, WI (550250047)Milwaukee, WI (550790059)Waukesha, WI (551330027)
Wisconsin6Cook, IL (170310022)Cook, IL (170310050)Cook, IL (170314007)Will, IL (171971002)Elkhart, IN (180390003)Muscatine, IA (191390015)

b. Results of 8-Hour Ozone Contribution Modeling

In this section, we present the interstate contributions from emissions in upwind states to downwind nonattainment and maintenance sites for the ozone NAAQS. As described previously in section IV.B., states which contribute 0.8 ppb or more to 8-hour ozone nonattainment or maintenance in another state are identified as states with contributions to downwind attainment and maintenance sites large enough to warrant further analysis. We performed air quality modeling to quantify the contributions to 8-hour ozone from emissions in each of the following 37 states individually: Alabama, Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland combined with the District of Columbia, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Vermont, Virginia, West Virginia, and Wisconsin.

We calculated each state's contribution to each of the 11 monitoring sites that are projected to be nonattainment and each of 14 [53] sites that are projected to have maintenance problems for the 8-hour ozone NAAQS in the 2012 Base Case. The largest contribution from each state to 8-hour ozone nonattainment in downwind sites is provided in Table IV.C-19. The largest contribution from each state to 8-hour ozone maintenance in downwind sites is also provided in Table IV.C-19. The contributions from each state to all projected 2012 nonattainment and maintenance sites for the 8-hour ozone NAAQS are provided in the AQMTSD.

Table IV.C-19—Largest Contribution to Downwind 8-Hour Ozone Nonattainment and Maintenance for Each of 37 States

Upwind StateLargest downwind contribution to nonattainment for ozone (ppb)Largest downwind contribution to maintenance for ozone (ppb)
Alabama4.74.7
Arkansas1.41.8
Connecticut1.71.6
Delaware3.32.5
Florida0.82.1
Georgia2.11.7
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Illinois0.80.6
Indiana1.11.0
Iowa0.30.3
Kansas0.60.8
Kentucky2.31.8
Louisiana11.410.6
Maine0.00.0
Maryland/Washington, DC6.14.2
Massachusetts0.60.5
Michigan0.90.5
Minnesota0.10.2
Mississippi5.22.5
Missouri0.70.6
Nebraska0.20.2
New Hampshire0.10.1
New Jersey16.815.8
New York0.422.7
North Carolina1.72.0
North Dakota0.10.0
Ohio2.82.6
Oklahoma2.12.7
Pennsylvania8.98.1
Rhode Island0.10.1
South Carolina0.60.8
South Dakota0.00.0
Tennessee1.63.0
Texas1.60.6
Vermont0.00.1
Virginia4.24.5
West Virginia2.72.3
Wisconsin0.30.2

Based on the state-by-state contribution analysis, there are 22 states and the District of Columbia [54] which contribute 0.8 ppb or more to downwind 8-hour ozone nonattainment. These states are: Alabama, Arkansas, Connecticut, Delaware, the District of Columbia, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Maryland, Michigan, Mississippi, New Jersey, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Texas, Virginia, and West Virginia. In Table IV.C-20, we provide a list of the downwind nonattainment counties to which each upwind state contributes 0.8 ppb or more (i.e., the upwind state to downwind nonattainment “linkages”).

There are 22 states and the District of Columbia which contribute 0.8 ppb or more to downwind 8-hour ozone maintenance. These states are: Alabama, Arkansas, Connecticut, Delaware, the District of Columbia, Florida, Georgia, Indiana, Kansas, Kentucky, Louisiana, Maryland, Mississippi, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Virginia, and West Virginia. In Table IV.C-21, we provide a list of the downwind nonattainment counties to which each upwind state contributes 0.8 ppb or more (i.e., the upwind state to downwind nonattainment “linkages”).

Table IV.C-20—Upwind State to Downwind Nonattainment “Linkages” for 8-Hour Ozone

Upwind StateNumber of linkages
Counties containing downwind 24-hour PM2.5 nonattainment sites (monitoring site ID)
Alabama8East Baton Rouge, LA (220330003)Brazoria, TX (480391004)Harris, TX (482010051)Harris, TX (482010055)Harris, TX (482010062)Harris, TX (482010066)
Harris, TX (482011039)Tarrant, TX (484391002)
Arkansas3East Baton Rouge, LA (220330003)Brazoria, TX (480391004)Tarrant, TX (484391002)
Start Printed Page 45269
Connecticut1Suffolk, NY (361030009)
Delaware3Suffolk, NY (361030002)Suffolk, NY (361030009)Philadelphia, PA (421010024)
Florida2Harris, TX (482010062)Tarrant, TX (484391002)
Georgia7Brazoria, TX (480391004)Harris, TX (482010051)Harris, TX (482010055)Harris, TX (482010062)Harris, TX (482010066)Harris, TX (482011039)
Tarrant, TX (484391002)
Illinois2Suffolk, NY (361030009)Harris, TX (482010055)
Indiana3Suffolk, NY (361030002)Suffolk, NY (361030009)Philadelphia, PA (421010024)
Kentucky6Suffolk, NY (361030002)Philadelphia, PA (421010024)Harris, TX (482010051)Harris, TX (482010055)Harris, TX (482010062)Harris, TX (482011039)
Louisiana7Brazoria, TX (480391004)Harris, TX (482010051)Harris, TX (482010055)Harris, TX (482010062)Harris, TX (482010066)Harris, TX (482011039)
Tarrant, TX (484391002)
Maryland3Suffolk, NY (361030002)Suffolk, NY (361030009)Philadelphia, PA (421010024)
Michigan1Suffolk, NY (361030009)
Mississippi8East Baton Rouge, LA (220330003)Brazoria, TX (480391004)Harris, TX (482010051)Harris, TX (482010055)Harris, TX (482010062)Harris, TX (482010066)
Harris, TX (482011039)Tarrant, TX (484391002)
New Jersey3Suffolk, NY (361030002)Suffolk, NY (361030009)Philadelphia, PA (421010024)
North Carolina3Suffolk, NY (361030002)Suffolk, NY (361030009)Philadelphia, PA (421010024)
Ohio3Suffolk, NY (361030002)Suffolk, NY (361030009)Philadelphia, PA (421010024)
Oklahoma1Tarrant, TX (484391002)
Pennsylvania2Suffolk, NY (361030002)Suffolk, NY (361030009)
Tennessee7Philadelphia, PA (421010024)Brazoria, TX (480391004)Harris, TX (482010051)Harris, TX (482010055)Harris, TX (482010062)Harris, TX (482010066)
Harris, TX (482011039)
Texas1East Baton Rouge, LA (220330003)
Virginia3Suffolk, NY (361030002)Suffolk, NY (361030009)Philadelphia, PA (421010024)
West Virginia3Suffolk, NY (361030002)Suffolk, NY (361030009)Philadelphia, PA (421010024)

Table IV.C-21—Upwind State to Downwind Maintenance “Linkages” for 8-Hour Ozone

Upwind StateNumber of linkages
Counties containing downwind 24-hour PM2.5 nonattainment sites (monitoring site ID)
Alabama6DeKalb, GA (130890002)Fulton, GA (131210055)Harris, TX (482010024)Harris, TX (482010029)Harris, TX (482011050)Tarrant, TX. (484392003).
Arkansas4Dallas, TX (481130069)Dallas, TX (481130087)Harris, TX (482011050)Tarrant, TX (484392003)
Connecticut1Westchester, NY (361192004)
Delaware1Bucks, PA (420170012)
Florida4DeKalb, GA (130890002)Fulton, GA (131210055)Harris, TX (482010024)Harris, TX (482010029)
Georgia4Harris, TX (482010024)Harris, TX (482010029)Harris, TX (482011050)Tarrant, TX (484392003)
Indiana4Fairfield, CT (90010017)New Haven, CT (90093002)Westchester, NY (361192004)Bucks, PA (420170012)
Kansas1Dallas, TX (481130069)
Kentucky6Fairfield, CT (90010017)Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Westchester, NY (361192004)Bucks, PA. (420170012).
Start Printed Page 45270
Louisiana6Dallas, TX (481130069)Dallas, TX (481130087)Harris, TX (482010024)Harris, TX (482010029)Harris, TX (482011050)Tarrant, TX. (484392003).
Maryland6Fairfield, CT (90010017)Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Westchester, NY (361192004)Bucks, PA. (420170012).
Mississippi7DeKalb, GA (130890002)Fulton, GA (131210055)Dallas, TX (481130087)Harris, TX (482010024)Harris, TX (482010029)Harris, TX. (482011050).
Tarrant, TX (484392003)
New Jersey6Fairfield, CT (90010017)Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Westchester, NY (361192004)Bucks, PA. (420170012).
New York5Fairfield, CT (90010017)Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Bucks, PA (420170012)
North Carolina5Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Westchester, NY (361192004)Bucks, PA (420170012)
Ohio6Fairfield, CT (90010017)Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Westchester, NY (361192004)Bucks, PA. (420170012).
Oklahoma3Dallas, TX (481130069)Dallas, TX (481130087)Tarrant, TX (484392003)
Pennsylvania5Fairfield, CT (90010017)Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Westchester, NY (361192004)
South Carolina2Fulton, GA (131210055)Harris, TX (482010029)
Tennessee5DeKalb, GA (130890002)Fulton, GA (131210055)Bucks, PA (420170012)Harris, TX (482010024)Harris, TX (482011050)
Virginia6Fairfield, CT (90010017)Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Westchester, NY (361192004)Bucks, PA. (420170012).
West Virginia6Fairfield, CT (90010017)Fairfield, CT (90011123)Fairfield, CT (90013007)New Haven, CT (90093002)Westchester, NY (361192004)Bucks, PA. (420170012).

D. Proposed Methodology To Quantify Emissions That Significantly Contribute or Interfere With Maintenance

In this section, EPA explains its general approach to quantifying the amount of emissions that represent significant contribution and interference with maintenance. EPA then applies that approach for the three different NAAQS being addressed in today's notice: The 1997 ozone NAAQS, the 1997 annual PM2.5 NAAQS and the 2006 24-hour PM2.5 NAAQS.

With respect to the 1997 ozone NAAQS, we apply this methodology to fully quantify the significant contribution and interference with maintenance for 16 states. We also use the methodology to quantify, for 10 additional states, NOX emissions reductions that are necessary to make measurable progress towards eliminating their significant contribution and interference with maintenance. Additional information gathering and analysis is needed to determine the extent to which further reductions from these states may be needed to fully eliminate significant contribution and interference with maintenance with the ozone NAAQS. As is further explained in section IV.D.2.b EPA will fully address this issue in a future rulemaking as quickly as possible.

With respect to the annual PM2.5 NAAQS, this proposal finds that 24 eastern states have SO2 and NOX emission reduction responsibilities. We apply the proposed methodology to fully quantify the SO2 and NOX emissions from each of these states that significantly contribute to or interfere with maintenance in downwind areas.

With respect to the 24-hour PM2.5 NAAQS, this proposal finds that 25 eastern states have emission reduction responsibilities. We use the proposed methodology to quantify emissions reductions that these states must achieve to make, at a minimum, measurable progress towards eliminating the state's significant contribution and interference with maintenance. Further analysis will be needed to determine if these reductions are sufficient to fully eliminate any or all of these states' significant contribution and interference with maintenance for purposes of the 24-hour PM2.5 standard. As is explained in greater detail in section IV.D.2.a, EPA intends to finalize, to the extent possible a determination of the complete amount of emissions that represents significant contribution and interference with maintenance. If further analysis shows that the amounts of emissions proposed in today's notice include all emissions that significantly contribute or interfere with maintenance of the 24-hour PM2.5 standard or that more SO2 emissions should be included, we believe that we will be able to issue a supplemental proposal and finalize a rule fully quantifying significant contribution and interference with maintenance with respect to the 24-hour PM2.5 standard. If further analysis shows that other reductions should be considered as part of significant contribution or interference with maintenance with respect to the 24-hour PM2.5 standard these emissions would be fully addressed in a separate rulemaking effort.

1. Explanation of Proposed Approach To Quantify Significant Contribution

After using air quality analysis to identify upwind states that are “linked” to downwind air quality monitoring sites with nonattainment and maintenance problems because the upwind states' emissions contribute one percent or more to the air quality value at the downwind site, EPA quantifies the portion of each state's contribution that constitutes its “significant contribution” and “interference with maintenance.”

This section describes the methodology developed by EPA for this analysis and then explains how that methodology is applied to measure significant contribution and interference with maintenance with respect to the PM2.5 NAAQS and the ozone NAAQS. For this portion of the analysis, EPA expands upon the methodology used in the NOX SIP Call and CAIR, but modifies it in significant respects. In the NOX SIP Call and CAIR, EPA's Start Printed Page 45271methodology relied upon defining significant contribution as those emissions that could be removed with the use of “highly cost effective” controls. In this action, rather than relying solely on determining reductions based on “highly cost effective” controls, EPA uses a number of factors that account for both cost and air quality improvement. Furthermore, unlike the NOX SIP Call and CAIR where EPA only defined an amount of reductions needed to address significant contribution to nonattainment, EPA is proposing to define an amount of emissions reductions that addresses both significant contribution to nonattainment and interference with maintenance.

The methodology takes into account both the DC Circuit Court's determination that EPA may consider cost when measuring significant contribution, Michigan, 213 F.3d at 679, and its rejection of the manner in which cost was used in the CAIR analysis, North Carolina, 531 F.3d at 917. It also recognizes that the Court accepted—but did not require—EPA's use of a single, uniform cost threshold to measure significant contribution. Michigan, 213 F.3d at 679.

The methodology defines each state's significant contribution and interference with maintenance as the emissions that can be eliminated for a specific cost. Unlike the NOX SIP Call and CAIR, where EPA's significant contribution analysis had a regional focus, the methodology used in today's proposal focuses on state-specific factors. The methodology uses a multi-step process to analyze costs and air quality impacts, identify appropriate cost thresholds, quantify reductions available from EGUs in each state at those thresholds, and consider the impact of variability in EGU operations.

In step one, EPA identifies what emissions reductions are available at various costs, quantifying emissions reductions that would occur within each state at ascending costs per ton of emissions reductions. For purposes of this discussion, we refer to these as “cost curves”.

In step two, EPA uses an air quality assessment tool to estimate the impact that the combined reductions available from upwind contributing states and the downwind state, at different cost-per-ton levels, would have on air quality at downwind monitor sites that had nonattainment and/or maintenance problems.

In step three, EPA examines cost and air quality information to identify cost “breakpoints.” Breakpoints are the places where there is a noticeable change on one of the cost curves, such as a point where a large reduction occurs because a certain type of emissions control becomes cost-effective. EPA then uses a multi-factor assessment to determine the amount of emissions that represents significant contribution to nonattainment and interference with maintenance. The factors considered include both the air quality and cost considerations used in developing the breakpoints along with additional air quality and cost considerations. This assessment is performed for each transported NAAQS pollutant or precursor which EPA has concluded must be regulated due to its impact on downwind receptors. In this rule, as discussed in section IV.B, EPA is proposing to regulate SO2 and NOX. The methodology also allows EPA, where appropriate, to define multiple cost thresholds that vary for a particular pollutant for different upwind states.

In step four, EPA quantifies the emissions reductions available in each “linked” state at the appropriate cost threshold. This information is then used to develop a state “budget,” representing the remaining emissions for the state in an average year, and to identify a variability limit associated with that budget. These budgets and variability limits are used to develop enforceable requirements under the proposed and two alternative remedy options. State emissions budgets are discussed in section IV.E and the variability limit is discussed in section IV.F.

EPA's proposed methodology considers both cost and air quality factors to address complex circumstances. We believe it is important to consider both factors because circumstances related to different downwind receptors can vary and consideration of multiple factors can help EPA appropriately identify each state's significant contribution under different circumstances. For instance, there may be cases when upwind states contributing to a specific downwind nonattainment area have already done a great deal to reduce emissions while the downwind state in which the nonattainment area is located has done very little. Conversely, the downwind state may have made large reductions while one or more contributing upwind states may have done very little. There may be cases where some states (upwind or downwind) have large emissions (and a correspondingly large impact downwind) not because their sources are poorly controlled, but because they have a greater number of sources—the operation of which is critical to the reliability of the electric grid. Conversely, there may be cases where a state (upwind or downwind) contributes less in total emissions because it has a smaller number of plants, but those plants are poorly controlled and could be better controlled at a relatively low cost.

Air quality factors alone are not able to discern these types of differences. Using both air quality and cost factors allows EPA to consider the full range of circumstances and state-specific factors that affect the relationship between upwind emissions and downwind nonattainment and maintenance problems. For example, considering cost takes into account the extent to which existing plants are already controlled as well as the potential for, and relative difficulty of, additional emissions reductions. Therefore, EPA believes that it is appropriate to consider both cost and air quality metrics when quantifying each state's significant contribution.

This methodology is consistent with the statutory mandate in section 110(a)(2)(D)(i)(I) which requires upwind states to prohibit emissions that significantly contribute to nonattainment or interfere with maintenance in another state, but does not shift the responsibility for achieving or maintaining the NAAQS to the upwind state.

In developing and implementing this methodology, EPA was cognizant of a number of factors. First, in many areas, transported emissions are a key component of the downwind air quality problem. Second, there are large amounts of low cost emission reduction opportunities in upwind states. Third, EPA recognizes that section 110(a)(2)(D) does not grant EPA authority to require emissions reductions solely because they provide large health and environmental benefits: reductions required pursuant to section 110(a)(2)(D)(i)(I) must be related to the goal of eliminating upwind state emissions that significantly contribute to nonattainment or interfere with maintenance of the NAAQS in downwind areas.

Fourth, EPA is cognizant of the relationship between the upwind and downwind state requirements in the Act. The Act requires upwind states to eliminate significant interstate pollution transport under section 110(a)(2)(D). It also requires each state to assure attainment and maintenance of the NAAQS within its borders. Thus, a downwind state must adopt controls to demonstrate timely attainment of the NAAQS despite any pollution transport from upwind states that is not eliminated under section 110(a)(2)(D). Start Printed Page 45272Given this structure, interpreting significant contribution and interfere with maintenance inherently involves a policy decision on how much emissions control responsibility should be assigned to upwind states, and how much responsibility should be left to downwind states. In virtually all areas, PM2.5 and ozone problems result from a combination of local, in-state, and upwind state emissions. EPA's proposed methodology for determining what portion of a state's total contribution is its significant contribution and interference with maintenance is intended to assign a substantial but reasonable amount of responsibility to upwind states.

There are several reasons that EPA believes upwind state sources contributing to air quality degradation in a downwind state should bear substantial responsibility to control their emissions. First, the plain language of this good neighbor provision requires upwind states to prohibit emissions that significantly contribute to nonattainment or interfere with maintenance in a downwind state. Second, interstate pollution transport increases pollution levels and health risks in the downwind state. Third, the influx of pollution from upwind states raises the pollution level in a downwind state, making it necessary for the downwind state to obtain deeper pollution reductions to attain and maintain air quality standards, which increases costs of control in the downwind state. Fourth, from the standpoint of a downwind state, the pollution contribution of each upwind state adds up to a larger, cumulative degradation of the downwind state's air quality. Fifth, reducing interstate pollution enhances prospects that attainment in downwind states can be achieved within the Act's deadlines and as expeditiously as practicable. All of these points support the position that upwind state sources should bear substantial responsibility to control their emissions.

On the other hand, the proposed methodology ensures that upwind states are not required to shoulder the entire responsibility for the downwind state's attainment and maintenance of the NAAQS. Among other things, our methodology implicitly assumes controls at the same cost per ton level in the downwind state as in the upwind contributing states.[55] In addition, in almost all cases, states with downwind nonattainment and maintenance areas are also required to reduce emissions based on the fact that they are also upwind states that are “linked” to other downwind states with nonattainment and maintenance problems.

The proposed methodology also directly ties each state's reduction requirements to EPA's analysis of that state's significant contribution and interference with maintenance. The required reductions would provide very substantial air quality improvements. For the annual PM2.5 standard, EPA projects that this rule will help assure that all but one area in the East attain the standard by 2014. It will also help a number of areas achieve the standard earlier. The methodology provides similar assistance for ozone, assuring upwind reductions that will mitigate the amount that downwind states may need to do. It reduces ozone concentration levels in 2012 and helps assure that even absent this additional local control, all but 3 areas' nonattainment and maintenance problems are resolved by 2014. Air quality in the few areas with remaining problems will be improved, providing both health benefits and assistance for these local areas in meeting the NAAQS requirements.

a. Step 1. Emissions Reductions Cost Curves

The first step in EPA's methodology for determining the quantity of emissions that represents each state's significant contribution is to identify reductions available at different costs. To do so, EPA developed a set of cost curves that show, at various cost increments, the available emissions reductions for EGUs in a state. In other words, EPA determined for specific cost per ton thresholds, the emissions reductions that would be achieved in a state if all EGUs in that state used all emission controls and emission reduction measures available at that cost threshold. The zero point of the curve shows what emissions would occur absent any additional investment in emissions reductions (i.e., the base case emissions). Additional points on the curves show the emissions that would occur after the installation of all controls that could be installed at specific cost levels (dollars per ton of emissions reduced). In developing these cost curves, EPA used IPM to identify costs for reducing emissions from EGUs by modeling emissions reductions available at multiple cost increments. EPA also applied the same cost constraint for each state in each modeling iteration. For example, in one iteration, all covered sources in the states examined were constrained to emit at levels achievable by the application of all controls available for $100/ton. In a second iteration, all states examined were assumed to achieve all reductions in each state that were available at $200/ton. The resulting cost curves for SO2 and annual NOX can be found in section IV.D.2.a of this preamble and the curves for ozone season NOX in section IV.D.2.b. For more detail on the development of the cost curves, see the TSD, “Analysis to Quantify Significant Contribution,” in the docket for this rule.

Although the cost curves presented in this proposal only include EGU reductions, EPA also conducted a preliminary assessment of reductions available for source categories other than EGUs. This preliminary assessment suggested that there likely would be very large emissions reductions available from EGUs before costs reach the point for which non-EGU sources have available reductions. EPA therefore initially created cost curves based solely on reductions from EGUs and determined appropriate cost thresholds based on that analysis. EPA then re-examined non-EGUs to determine the accuracy of its initial assumptions that there were little or no reductions available from non-EGUs at costs lower than the thresholds that EPA had chosen. EPA's analysis of the costs of and opportunities for non-EGU emissions reductions is discussed in more detail in section IV.D.3, later. For the reasons explained in that section, EPA believes there are little or no non-EGU reductions available at the cost thresholds used in this rule. Therefore, EPA believes it is reasonable at this time to use cost curves that include only EGU reductions. However, EPA is continuing to conduct analyses and believes that it will be necessary to further consider non-EGU emission reduction opportunities in future transport rules.

To develop cost curves, emissions available at various costs were assessed in 2012 for ozone season NOX and 2014 for annual NOX and SO2. As described in section V.C, EPA coordinated the deadlines for eliminating significant contribution and interference with maintenance with the NAAQS attainment deadlines for downwind states and determined that all significant contribution and interference with maintenance with respect to the 1997 and 2006 PM2.5 NAAQS must be eliminated by 2014, or as expeditiously as practicable. The cost curves show, among other things, that the amount of emissions reductions that can be achieved for a given cost varies over Start Printed Page 45273time. This is true because, among other things, control options that are available in a longer timeframe may not be available in a shorter timeframe. For instance, it takes approximately 27 months to build a flue gas desulfurization unit (FGD, or “scrubber”) to reduce SO2 emissions (Boilermaker Labor Analysis and Installation Timing, USEPA, March 2005), so if this rule is finalized in mid-2011, emissions reductions from scrubbers by 2012 or 2013 can only reasonably be achieved if that scrubber either exists today, or if it is currently under construction. However, by 2014, additional reductions could be obtained from the construction of new scrubbers. It takes approximately 21 months to construct a selective catalytic reduction (SCR) unit to reduce emissions of NOX. (Boilermaker Labor Analysis and Installation Timing, USEPA, March 2005).

There are approximately 30 months between mid-2011 (when the Agency anticipates finalizing this rule) and January 2014 (the proposed Phase 2 compliance deadline). EPA believes this is sufficient time for sources to install the advanced emissions controls projected to be retrofit. EPA expects about 14 GW of FGD and less than 1 GW of SCR capacity to be retrofit for Phase 2 of this rule. This is significantly less than the capacity that was retrofit in the same length of time after CAIR was finalized. EPA is not aware of problems or issues with sources meeting the CAIR compliance deadlines, either in equipment deliveries or labor availability. EPA believes the proposed Transport Rule compliance deadlines are reasonable, and will result in emissions reductions as quickly as practicable, delivering health benefits to the public and aiding states with NAAQS attainment deadlines.

EPA requests comment on the schedule for scrubber and SCR installations, the availability of boilermaker labor, and any comment on whether there might be alternative post-combustion cost-effective technologies that could reduce SO2 and/or NOX emissions. We also solicit comment on whether advanced coal preparation processes might provide emissions reductions at the significant contribution cost levels identified in this proposal, whether such processes have been commercialized, and what the costs will be. In addition, EPA seeks comment on, whether other factors, such as other EPA regulatory actions, will create an increase in boilermaker demand earlier than today's proposal, in 2010 and beyond. We solicit comments on whether other factors might increase demand for boilermakers or control equipment, and what these factors would be. Comments in support of or opposed to the proposed compliance deadlines should include information to support the commenter's position.

Unlike add-on pollution controls such as scrubbers and SCRs, EPA believes that low-NOX burners could be installed by 2012. See TSD, “Installation Timing for Low NOX Burners,” in the docket for this rule.

EPA also believes that sources can switch coals by 2012. Eastern bituminous coals used for power generation typically have more than sufficient sulfur content to facilitate highly efficient collection of fly ash in a cold-side electrostatic precipitator (ESP). Some ESPs that operate at acceptably high collection efficiency when using a high-or medium-sulfur bituminous coal may experience some loss in collection efficiency when a lower sulfur coal is used. Whether this occurs on a specific unit, and the extent to which it occurs, would depend on the design margins built into the existing ESP, the percentage change in coal sulfur content, and other factors. Relatively inexpensive practices to maintain high ESP performance on lower sulfur bituminous coals are available and are being used successfully where necessary. These include a range of upgrades to ESP components and flue gas conditioning.

EPA assumes in the Transport Rule analysis that it will not be necessary for units that switch from higher to lower sulfur bituminous to make a costly replacement of the ESP. EPA's analysis therefore does not add capital or operations and maintenance costs for coal switching from higher to lower sulfur bituminous coals.

EPA's analysis does not allow a unit designed for bituminous to switch to (very low sulfur) subbituminous coal unless the unit has demonstrated that capability in the past. EPA assumes units with that capability have already made any investments needed to handle a switch to subbituminous coals. EPA therefore assumes that any modeled coal switching from bituminous to subbituminous has no cost or schedule impact.

EPA requests comment on the reasonableness of EPA's assumption that coal switching within the bituminous coal grades will have relatively little cost or schedule impact on most units.

b. Step 2. Performing the Air Quality Assessment

In the second step, EPA uses an air quality assessment tool to estimate the impact of the upwind emissions reductions on downwind ambient concentrations.[56] This tool is useful for identifying cost breakpoints for significant improvements in downwind air quality changes, including estimated effects on downwind attainment. While less rigorous than the air quality models used for attainment demonstrations, EPA believes this air quality assessment tool is acceptable for assessing the impact of numerous options on upwind reductions in the process of identifying upwind state significant contribution. It allows the Agency to analyze many more potential scenarios than the time- and resource-intensive more refined air quality modeling would permit. This tool assesses the impact that reductions at a given cost breakpoint from all of the contributing states (as well as the state with the nonattainment area itself) had on pollutant concentrations at that downwind area. The resulting information is used in step three. For each downwind area with a nonattainment and/or maintenance problem, it shows the total improvement in air quality for each cost level and associated pollutant reduction, the amount of the remaining problem caused by each upwind state (by constituent), and the amount of the remaining problem caused by sources within the state (by constituent). It also shows, overall, how much of the downwind air quality problem had been addressed at different cost levels. More detail on the tool itself, what EPA has done to verify the underlying assumptions, and the specific application of the tool to examining significant contribution for ozone and PM2.5 can be found in the TSD, “Analysis to Quantify Significant Contribution,” in the docket for this rule.

c. Step 3. Identifying Appropriate Cost Thresholds

In the third step of this analysis, EPA examines the information developed in the first two steps to identify potential cost thresholds. It then uses a multi-factor assessment to identify which cost Start Printed Page 45274threshold [57] or thresholds should be used to quantify states’ significant contribution and interference with maintenance. This new methodology responds to the Court's statements in North Carolina v. EPA both criticizing the manner in which cost was used in the CAIR rule and acknowledging its prior acceptance (in Michigan v. EPA, 213 F.3d 663) of EPA's use of a uniform cost threshold and the uniform control requirements associated with the use of such a cost threshold. See North Carolina v. EPA, 531 F.3d at 908, 917.920. In both the NOX SIP Call and CAIR, EPA evaluated the cost of controls relative to the cost of controls required by other CAA regulations to identify a single cost threshold referred to as the “highly-cost-effective” threshold. In contrast, in this proposed rule, EPA considers multiple factors to identify appropriate cost thresholds, allowing EPA to give greater weight to air quality considerations and making it possible to tailor the significant contribution measurement more closely to different conditions in different groups of states.

This step of the analysis begins with an examination of the cost and air quality data to identify breakpoints on the emissions reductions cost curves developed in steps 1 and 2 related to (1) air quality (e.g., points at which all areas (other than those with an unusually predominant local pollution problem) reach attainment and have maintenance fully addressed), and/or (2) cost (e.g., points at which significant reductions are available because a certain technology is widely deployed). EPA identifies potential breakpoints and then uses a multi-factor assessment to evaluate whether one or more of the potential breakpoints represent a reasonable cost at which to define significant contribution for some or all upwind states. The factors in this multi-factor assessment can be divided into two broad categories: Those that focus on air quality considerations and those that focus on cost considerations. Air quality considerations include, for example, how much air quality improvement in downwind states results from upwind state emissions reductions at different levels; whether, considering upwind emissions reductions and assumed local (in-state) reductions, the downwind air quality problems would be resolved; and the components of the remaining downwind air quality problem (e.g., is it a predominantly local or in-state problem, or does it still contain a large upwind component). Cost considerations include, for example, how the cost per ton compares with the cost per ton of existing federal and state rules for the same pollutant, and whether the cost per ton is consistent with the cost per ton of technologies already widely deployed (similar to the highly-cost-effective criteria used in both the NOX SIP Call and CAIR); the cost increase required to achieve the next increment of air quality improvement; and whether, given timing considerations, emissions reductions requirements could be more costly than indicated in the modeling because sources could choose one short-term solution and then switch to another long-term solution (e.g., switching coals can involve plant modifications. While these costs are low when amortized over a number of years, if a source quickly installs controls, and switches coals again, costs may be higher than projected).

Because upwind state sources should bear substantial responsibility for controlling emissions that contribute to air quality degradation in downwind states, EPA believes that cost per ton levels that are consistent with widely deployed existing controls, or are within the cost per ton range of controls already required by existing and proposed Federal and State rules (i.e., similar to the highly cost effective concept in the NOX SIP Call and CAIR), are reasonable for upwind states from a cost standpoint. Higher cost per ton levels also may be reasonable for upwind states based on examination of air quality and cost factors. One reason is that achieving attainment and maintenance of the air quality standard may require controls in upwind and downwind states that are more costly than previous controls (particularly if it is a new standard).

Based on this multi-factor assessment, EPA identifies a specific cost per ton threshold for quantifying the amount of significant contribution from each state for each precursor pollutant. While we continue to believe that under certain circumstances it may be appropriate for us to use a single uniform cost per ton threshold to quantify significant contribution for all states, we believe it is also important to retain the flexibility to use multiple cost thresholds. For example, we believe it is appropriate to use multiple thresholds where one group of states can, for a lower cost, eliminate nonattainment and maintenance for all the downwind nonattainment and maintenance areas to which they are linked.

d. Step 4. Identify Required Emissions Reductions

In the final step of this analysis, EPA uses the cost thresholds identified in the previous step to determine, on a state-by-state basis, the amount of emissions that could be reduced at a specific cost. The results of this analysis are used to develop the state budgets and variability limits, which are in turn used to implement the requirements to eliminate significant contribution and interference with maintenance. See sections IV.E and IV.F.

2. Application

The discussion that follows explains how the methodology described previously was applied to quantify significant contribution with respect to the 1997 and 2006 PM2.5 NAAQS and the 1997 ozone NAAQS. EPA also believes that the methodology proposed today could also be used to address transport concerns under other NAAQS, including revisions to the ozone and PM2.5 NAAQS.

All of the air quality considerations included in the multi-factor assessment are based on analysis using the air quality assessment tool. EPA believes that it is appropriate to use this tool because of the advantages it has over more refined air quality modeling to perform analysis of a large number of scenarios very quickly (more refined air quality modeling can take several months, while multiple scenarios can be evaluated using the air quality assessment tool in a single day). EPA has done more refined air quality modeling of the proposed emissions budgets. The more refined air quality modeling confirms EPA's overall methodology, but does suggest that, in the case of daily PM2.5, the air quality assessment tool slightly over-predicts the air quality benefit of the proposed reductions.

For this reason, EPA is also requesting comment on whether we should modify our conclusions regarding the amount of specific states' significant contribution and interference with maintenance; whether there are ways to use our air quality modeling in conjunction with the air quality assessment tool to carry out the significant contribution analysis in a way that would not extend the time needed to complete this rulemaking; and whether there are ways to improve the air quality assessment tool. Start Printed Page 45275

a. Specific Application to PM2.5

(1) Year for Quantifying Significant Contribution

EPA's significant contribution analysis for PM2.5 used a multi-factor assessment to identify cost thresholds for 2014. EPA believes this is the most appropriate year to consider because it is consistent with attainment dates for both the annual and daily PM2.5 standards. Furthermore, EPA believes that 2014 provides sources sufficient lead time to install emissions controls or take other actions necessary to achieve the required reductions. After determining the amount of emissions that represents each state's significant contribution, EPA then considers whether it would be appropriate to establish an interim compliance deadline to ensure that the reductions are achieved as expeditiously as practicable. For this part of the analysis, EPA focused on determining what portion of each state's significant contribution could be eliminated by 2012, the first year in which it would be possible to get reductions following promulgation of this rule in 2011. EPA believes it is possible to achieve much of the required emissions reductions by 2012. EPA also believes that it is important to get the reductions as expeditiously as practicable and to coordinate the compliance dates both with the downwind states” maximum attainment deadlines and with the requirement that they eliminate nonattainment as expeditiously as practicable.

(2) Step 1. Emissions Reductions Cost Curves

This subsection provides more detail on the cost curves that EPA developed to assess the costs of reducing SO2 and NOX to address transport related to PM2.5. It summarizes the information from the curves and then provides EPA's interpretation of that information. EPA uses the information from the cost curves in step 3 to quantify the cost per ton of emissions reductions which should be used to calculate each state's significant contribution and interference with maintenance, and the resulting state-specific emissions budgets.

To measure significant contribution and interference with maintenance with respect to the PM2.5 NAAQS, EPA developed cost curves showing the annual NOX and annual SO2 reductions available in 2014 at different cost increments. Specifically, EPA developed cost curves that show reductions available in 2014 from EGUs at various costs (in 2006 $) up to $2,500/ton for annual NOX, $5,000/ton for ozone season NOX, and $2,400/ton for SO2. For example, this means that EPA examined reductions of annual NOX that are available at a cost of $2,500 per ton or less. For SO2, the projected cost considered for reducing a ton of emissions is $2,400 or less.

Table IV.D-1 shows the annual NOX emissions from EGUs at various levels of control cost for 2014.

Table IV.D-1—2014 Annual NOX Emissions From Electric Generating Units for Each State in the Transport Region at Various Costs

[(2006 $) per ton (thousand tons)]

Marginal cost per tonBase case level$500$1,500$2,500
Alabama119626250
Connecticut8888
Delaware6666
Florida19613811380
Georgia48464545
Illinois80565656
Indiana201114114107
Iowa68565047
Kansas79383635
Kentucky149727271
Louisiana46373728
Maryland36363636
Massachusetts13131313
Michigan99686866
Minnesota55383838
Missouri83826155
Nebraska53342828
New Jersey27232320
New York36353231
North Carolina63636261
Ohio1651049888
Pennsylvania20512312286
South Carolina48363635
Tennessee69292929
Virginia38373736
West Virginia100544945
Wisconsin55444341
Total2,1441,4551,3751,241

Before applying the information in the cost curves in step 3 of the analysis, EPA evaluated the cost curves to better understand how reductions at various cost levels reflect changes in the generation mix (e.g., dispatch changes, fuel use changes, or installation or operation of controls). From the cost curves, EPA concluded that in 2014, there are large NOX reductions available at approximately $500/ton. At costs above $500/ton and up to at least $2,500/ton, potential reductions increase slowly. This is because the base case assumed that sources would not Start Printed Page 45276run their SCR units unless they are required to run those SCR units pursuant to mandates other than CAIR (which will be replaced by this rule when it is finalized). This is especially relevant for winter use of SCRs. Even without CAIR, the NOX SIP Call will provide an incentive to run many SCRs during the ozone season.

The cost curves demonstrate that many of these sources would operate their SCR units when emissions reductions that cost $500/ton are required. In addition, at this $500/ton level some additional units would likely install advanced combustion control technology. Below $500/ton, there are very few other NOX reductions. Significant additional reductions would not be achieved without application of controls costing more than $2,500/ton. In 2014, more reductions could be achieved with installation of additional add-on controls, such as SCR.

The cost curves for SO2 show the same effect as those for NOX (large emissions reductions at relatively low costs and additional reductions at relatively high costs) but the effect was not as pronounced. In 2014, more than 1,000,000 tons of SO2 reductions can be achieved at a cost of less than $200 per ton. Most of these reductions can be achieved by requiring companies to operate existing scrubbers that they would not have an incentive to run absent the requirements of CAIR. Additional reductions can be achieved at higher costs. For instance, in many cases, companies are currently using lower sulfur coals to comply with CAIR, but there is no guarantee they will continue to do so. Many, but not all, of these reduction opportunities (e.g., operating current equipment and continued use of low sulfur coal) are available at below $500/ton.

Table IV.D-2 shows that in 2014 there are increased SO2 emission reduction opportunities beyond just operating existing scrubbers and switching to low sulfur coal. Installation of new scrubbers becomes feasible by 2014, thus increasing reduction opportunities at costs between $500/ton and $2,000/ton (and above).

Table IV.D-2—2014 SO2 Emissions From Electric Generating Units for Each State in the Transport Region at Various Costs

[(2006$) per ton (thousand tons)]

Marginal cost per tonBase case level$100$200$500$1,000$1,400$1,800$2,000$2,400
Alabama3223072571711661461018471
Connecticut666663333
Delaware899999988
Florida195178171117113111797470
Georgia173166136133117101928667
Illinois200185165165164165161155143
Indiana804478433328291284242227190
Iowa16414013010610510410210170
Kansas656456494646333124
Kentucky740275270248196178127115100
Louisiana959595959595958236
Maryland454545454545424240
Massachusetts171818101010996
Michigan276254253214209207177163116
Minnesota625755494848484846
Missouri50128923821321221219618394
Nebraska116119113747371694533
New Jersey404027212120181714
New York1431421431351181141007063
North Carolina141141141130114104999163
Ohio841583553408294260236221203
Pennsylvania975825441337202175154145125
South Carolina15613813713412583785742
Tennessee60015413112712610810810079
Virginia13713413410910693655445
West Virginia49617917016116014313211998
Wisconsin117111108979289878164
Total7,4365,1334,4353,6923,2633,0252,6602,4101,912

(3) Step 2. Air Quality Assessment of Potential Emissions Reductions

After developing cost curves to show the state-by-state cost-effective emissions reductions available, EPA used the air quality assessment tool to evaluate the impact these upwind reductions would have on air quality in “linked” downwind nonattainment and maintenance areas. This section summarizes the results of that evaluation and provides analysis that informs EPA's multi-factor assessment, explained in step 3, later.

EPA performed air quality analysis for each downwind receptor with a nonattainment and/or maintenance problem. For each receptor, EPA assessed the air quality improvement resulting when a group of states, consisting of the upwind states that are “linked” to the downwind receptor (i.e., EPA modeling showed that they exceeded the one percent contribution threshold, based on it's 2012 linkage analysis), and the downwind state where the receptor is located, all made the emissions reductions that EPA identified as available at each cost threshold (as described previously). This analysis did not assume any reductions in upwind states covered by this rule but not “linked” to the downwind receptor (even if the state was “linked” to a different receptor), beyond those assumed in the base case.

The percent emissions reductions (and percent air quality improvement) Start Printed Page 45277that could be made by each upwind state in 2014 at different cost per ton levels are shown in Figures IV.D-1 through IV.D-4, later. These figures show the percent reduction in SO2 emissions as a function of cost (using the emissions at zero dollars per ton in 2014 as the baseline reference). A percentage reduction of zero means that emissions are not reduced from the levels that exist at the 2014 zero dollar per ton (base case) cost level. It is assumed that reductions in SO2 emissions are linearly and directly proportional to downwind sulfate contributions. In other words, it is assumed that a specific percent reduction in SO2 emissions would lead to the same percent reduction in air quality sulfate contribution from that upwind state. For example, if a state made a 50 percent reduction in SO2 emissions, its sulfate contribution to any monitor downwind is assumed to be reduced by 50 percent.

EPA determines the cumulative air quality improvement that could be expected at a particular downwind receptor by multiplying each upwind state's percent reduction by its air quality contribution and summing the results for all upwind states. In EPA's air quality analysis of each downwind receptor, all air quality improvements are measured relative to baseline emissions and air quality contributions in 2012.

Figures IV.D-1 through IV.D-4 show that at increased costs, there are substantial increased emissions reductions. As explained previously, each decrease in emissions is assumed to lead to a corresponding improvement in downwind air quality. These changes apply to both the daily and annual PM2.5 NAAQS. While the pattern differs from state to state, many states see noticeable decreases in sulfate contribution for costs of $500/ton or less. Reductions in downwind contribution level off, then many states start to see an additional decrease in contribution at higher costs (in general about $1,500/ton).

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EPA also identified the overall air quality reductions projected by the air quality assessment tool at downwind nonattainment and maintenance receptor locations. As explained previously, the multi-factor assessment in step 3 analyzed the results from the downwind receptor analysis in step 2 for the annual and daily PM2.5 standards. Tables IV.D-3 and IV.D-4 show the air quality improvements in 2014 from the emissions reductions projected to occur at various costs. Table IV.D-4 also shows the average decrease in ambient daily PM2.5 for different sets of downwind sites for various reductions in SO2.

Table IV.D-3—Estimated Number of Nonattainment and/or Maintenance Monitor Sites in 2014 for Annual PM2.5

[As a function of SO2 cost-per-ton levels]

Marginal cost per ton20142014
Number of remaining nonattainment monitor sitesNumber of remaining nonattainment and maintenance monitor sites
>$01219
>$10036
>$20023
>$30023
>$40012
>$50012
>$60011
>$80011
>$1,00011
>$1,20011
>$1,40011
>$1,60011
>$1,80001
>$2,00001
>$2,40001

Table IV.D-4—Daily Air Quality Impacts vs. SO2 Cost per Ton Levels in 2014

Marginal SO2 cost per tonNumber of remaining nonattainment and maintenance monitor sitesAir quality improvement (average μg/m⁁3 Reduction) relative to 2014 base case (zero dollars/ton)
All sites in 2012 base6 selected sites *3 selected sites **
>$0640.00.00.0
>$100163.72.01.8
>$200124.42.42.1
>$30084.72.62.3
>$400* 65.02.92.6
>$50065.13.02.6
>$60065.33.12.8
>$80065.43.32.9
>$1,00065.63.43.0
>$1,20065.73.43.0
>$1,40065.83.53.1
>$1,60056.03.63.2
>$1,80046.23.73.3
>$2,000** 36.43.93.4
>$2,40016.84.13.7
* The six sites are: Allegheny County, PA (2 sites); Baltimore County, MD; Wayne County, MI; Lake County, IN; Cook County, IL.
** The three sites are: Lake County, IN; Cook County, IL; Allegheny County, PA.

A number of conclusions can be drawn from Tables IV.D-3 and IV.D-4. Very low cost SO2 reductions result in significant air quality benefits.[58] As explained previously, this is because there are significant reductions available from sources that operate existing scrubbers and, in a number of cases, use relatively low cost, lower sulfur coal. At the same time, in 2014 enough lead time exists for considerable emission reduction opportunities from new scrubber installations. Other programs are also achieving reductions (for example, some state rules and enforcement consent decrees require SO2 and NOX reductions in 2013 and 2014). The analysis also shows that higher cost reductions continue to provide downwind air quality improvements.

Start Printed Page 45281

(4) Identifying Cost Thresholds

(a) Considerations for 2014

For PM2.5, EPA considered three cost breakpoints for SO2 and one for NOX. First EPA looked at a point at which EGUs operated all installed controls, continued to burn coals with sulfur contents consistent with what they were burning in 2009, and operated any additional controls they are currently planning to install by 2014. For NOX, this point is similar to the $500/ton cost. For SO2, it is similar to the $300 to $400 cost. EPA believes this is an appropriate starting point, because if a state is “linked” to a downwind state (i.e., if our air quality analysis showed it was contributing above the 1 percent threshold), EPA believes it is appropriate to prohibit that state from increasing its emissions which could worsen downwind air quality problems. EPA then considered what additional cost thresholds should be considered. For SO2 EPA considered two breakpoints: (1) $2,000/ton SO2 and (2) $2,400/ton SO2. EPA's state-by-state cost modeling at that point indicates that scrubbers would be installed on units generating about 20 GW of electricity. Since slightly over 21 GWs of scrubbers were installed in both 2008 and 2009 (see EPA Analysis of Alternative SO2 and NOX Caps for Senator Carper—July 31, 2009   Appendix B, page 15), EPA believes that it is clearly possible for the power sector to install at least that quantity of scrubbers by 2014. The $2,400/ton SO2 breakpoint represents the point where analysis from the air quality assessment tool projects that both nonattainment and maintenance concerns would be fully addressed in all areas, except for Allegheny County, Pennsylvania, when considering reductions from only states that contribute more than 1 percent.[59] As is explained later in this section, EPA believes that the monitor in Allegheny County that remains in nonattainment is in an area where the air quality problem is primarily local. Since EPA's analysis suggests that the only remaining nonattainment problem is primarily local, EPA did not consider higher cost thresholds.

EPA did not consider additional cost thresholds for NOX beyond $500/ton because there are minimal additional NOX reductions until one considers cost levels higher than $2,400/ton, and SO2 reductions are generally more effective than NOX reductions at reducing PM2.5. EPA did not consider lower cost thresholds than $2,000/ton for SO2 because: There are clearly continued air quality benefits at higher costs (as evidenced by increases in average air quality improvements in downwind sites); there is very little change in the number of downwind nonattainment and/or maintenance sites, indicating that the number of upwind states contributing would not be expected to change much; and costs of up to $2,000/ton of SO2 are reasonable in comparison to other existing regulations.

First EPA assessed $2,000/ton. Reductions at $2,000/ton would improve air quality at several locations with nonattainment and/or maintenance problems. We also believe that, as explained in the introduction to this section, it is reasonable to require a substantial level of control of upwind state emissions that significantly contribute to nonattainment or maintenance problems in another state. We believe that $2,000/ton is reasonable for SO2 considering that this cost per ton level is based on EGU control technologies that are proven and already widely deployed. Furthermore, compared to other control measures that address SO2, this cost per ton level is relatively low. A survey of the control options that EPA examined in the PM2.5 RIA shows that non-EGU SO2 reduction opportunities cost from $2,270/ton to over $16,000/ton.

While analysis with the air quality assessment tool shows that a site in Allegheny County, Pennsylvania would be in nonattainment and two other sites—Lake County, Indiana and Cook County, Illinois—would have maintenance problems, if we assume reductions at $2,000/ton and additional reductions made by states because of their contribution to other downwind sites that do not contribute to these three problem areas, the maintenance problems in Lake County, Indiana and Cook County, Illinois would be resolved and only Allegheny County, Pennsylvania, would continue to have a nonattainment/maintenance problem. Because reductions at $2,000/ton continue to have significant air quality benefit for downwind sites with nonattainment and/or maintenance problems, it has been demonstrated historically that the amount of control equipment that is projected to be needed at $2,000/ton could be installed in the timeframe required and these costs are reasonable when compared to other options to reduce SO2. Therefore, EPA believes that requiring a cost threshold of at least $2,000/ton would be appropriate for determining significant contribution.

Because our analysis shows that one area (Allegheny County, Pennsylvania) would have continuing nonattainment and maintenance problems, EPA continued to perform its multi-factor assessment for the higher $2,400/ton breakpoint to see if any additional emissions should also be considered significant. For this receptor monitor, EPA considered the local circumstances in the Liberty-Clairton area in Allegheny County that were leading to continued nonattainment. It is well-established that, in addition to being impacted by regional sources, the Liberty-Clairton area is significantly affected by a large increment of local emissions from a sizable coke production facility and other nearby sources. (See http://www.epa.gov/​pmdesignations/​2006standards/​final/​TSD/​tsd_​4.0_​4.3_​4.3.3_​r03_​PA_​2.pdf). High concentrations of organic carbon indicate the unique local problem for this location.

Because the remaining PM2.5 problem is more local in nature than the problem at other receptors, EPA does not believe that it is appropriate to establish a higher cost threshold solely for states that are “linked” to this monitor.

(b) Amount of Reductions That Could Be Achieved by 2012

After determining that the amount of emissions that could be reduced for $2,000/ton in 2014 is an appropriate quantification of a state's significant contribution, EPA considered whether any of these emissions reductions could be achieved prior to 2014. For the reasons that follow, EPA concluded that significant reductions could be achieved by 2012 and that it is important to require all such reductions by 2012 to ensure that they are achieved as expeditiously as practicable. While EPA believes that it is not possible to require the installation of post-combustion SO2 controls (scrubbers) or post-combustion NOX controls (SCRs) before 2014 (because it takes about 27 months to install a scrubber and 21 months to install an SCR), EPA believes that there are significant reductions that can occur earlier. For SO2, reductions from operating existing scrubbers up to their design removal efficiencies and from the use of lower sulfur coals are possible by 2012. For NOX, reductions from operating existing SCRs on a year-round basis and up to their design removal efficiencies and the installation of limited amounts of low NOX burners are possible by 2012. For this reason, EPA believes it is appropriate to require these emissions to be removed in 2012, Start Printed Page 45282consistent with the Act's requirement that downwind states attain the NAAQS as expeditiously as practicable. Section IV.E explains how these 2012 emissions reductions requirements are defined.

(c) Off-Ramp for States That Eliminate Their Significant Contribution for Less Than $2,000/Ton

Table IV.D.4, previously, shows that for large numbers of monitoring sites where there are nonattainment and or maintenance problems, those problems are fully resolved before all states achieve all of the emissions reductions that could be achieved at or below $2,000/ton. EPA used the air quality assessment tool to analyze the impact of requiring all states linked to the downwind state site with an air quality problem, as well as the downwind state, to reduce emissions consistent with the levels discussed for 2012 in section IV.D.2.a(2), previously. The air quality assessment tool shows that those 2012 reductions will resolve the nonattainment and maintenance problems for all of the areas to which the following states are linked: Alabama, Connecticut, Delaware, the District of Columbia, Florida, Kansas, Louisiana, Maryland, Massachusetts, Minnesota, Nebraska, New Jersey and South Carolina (referred to as group 2 states). EPA also assessed whether, in 2014, the combination of this level of reduction from the group 2 states and the remaining states (referred to as group 1 states) continued to result in all downwind areas—except for Allegheny County, Pennsylvania—fully addressing their nonattainment and or/maintenance problems, and determined that it did.

The states in group 1 and group 2 are rationally grouped considering air quality and cost. EPA proposes that it would not be appropriate to assign the same cost per ton to group 2 and group 1 states because a significantly lower cost per ton was sufficient to resolve air quality problems at all downwind receptors linked to the group 2 states. Although states are linked to different sets of downwind receptors, our analysis indicated that the cost per ton needed to resolve downwind air quality problems varied only to a limited extent among states within group 1 and among states within group 2. The cost per ton did vary greatly between the group 1 and group 2 states. Limitations on the accuracy of our cost and air quality analyses, and the ruling in the Michigan decision accepting EPA's prior use of a uniform cost approach, support the decision to use uniform costs for a group of states.

(d) Proposed Cost Thresholds for PM2.5

Summary of methodology. In summary, EPA determined that SO2 emissions that could be reduced for $2,000/ton in 2014 should be considered a state's significant contribution, unless EPA determined that a lesser reduction would fully resolve the nonattainment and/or maintenance problem for all the downwind monitoring sites to which a particular state might be linked. For these “group 2 states” EPA is determining that a lesser reduction of SO2, based on the amount of SO2 reductions that can be reasonably achieved by 2012 is appropriate. EPA also determined that all states linked to downwind PM2.5 nonattainment and maintenance problems should be required to achieve those emissions reductions that can be reasonably achieved by 2012. Finally, EPA determined that all states linked to downwind PM2.5 nonattainment (see Table IV.D-5) and maintenance problems should, by 2012, remove all NOX emissions that can be reduced for $500/ton in 2012.

Table IV.D-5—States Covered for SO2 Group 1, SO2 Group 2, and NOX Annual

States coveredSO2 group 1SO2 group 2NOX annual
AlabamaXX
ConnecticutXX
DelawareXX
District of ColumbiaXX
FloridaXX
GeorgiaXX
IllinoisXX
IndianaXX
IowaXX
KansasXX
KentuckyXX
LouisianaXX
MarylandXX
MassachusettsXX
MichiganXX
MinnesotaXX
MissouriXX
NebraskaXX
New JerseyXX
New YorkXX
North CarolinaXX
OhioXX
PennsylvaniaXX
South CarolinaXX
TennesseeXX
VirginiaXX
West VirginiaXX
WisconsinXX
Totals151328
Start Printed Page 45283

After completing the process to propose appropriate state-by-state cost thresholds, EPA used these thresholds to develop the specific state-by-state budgets. This step in the process is fully described in section IV.E.

(e) Request for Comment on Issues Related to EPA's Modeling Methods

EPA believes that the methodology described previously is a sound and analytically efficient approach to addressing the requirements of 110(a)(2)(D)(i)(I) for the PM2.5 standards. While it would be possible for EPA to add additional analytical steps to the methodology, and such analyses would provide more information, EPA believes that the methodology selected strikes an appropriate balance between the competing requirements of comprehensive analysis and timely action. EPA believes that the technical analysis completed provides a sound basis for action. EPA also seeks to avoid burdensome technical analyses which could prevent EPA from fulfilling our obligation to the Court to act in a timely way. In this section, EPA generally requests comment on issues related to its efforts to strike an appropriate balance. EPA identifies several areas of recognized limitations on our methodology, and requests comments both on the implications of these limitations and on possible options for addressing these limitations without unduly delaying necessary action.

(f) Use of Air Quality Assessment Tool; Results of More Detailed Air Quality Modeling Used To Evaluate the Tool

As discussed previously, EPA uses a simplified air quality assessment tool, rather than actual air quality modeling, to identify air quality impacts of the options considered. This assessment tool enables efficient evaluation of multiple options quickly. We did, however, conduct more refined air quality modeling of the select emissions budgets and this more detailed modeling serves as a check on the appropriateness of the method. This check confirmed the directional conclusions of the air quality assessment tool and largely confirmed the more detailed results of the air quality assessment tool, but raised several issues on which EPA is requesting comment.

For the annual PM2.5 standard, the air quality assessment tool projected that, after implementation of the proposed FIPs, only one area (Allegheny County, PA) would have a continuing NAAQS air quality problem under the maintenance criteria. The results of the refined air quality modeling are very similar. This modeling projects similar annual PM2.5 reductions in downwind states and projects that Allegheny County, PA would remain in nonattainment and that Birmingham, AL would exceed the threshold for “maintenance” by a slight amount (less than 0.1 ug/m 3). Given the unique local nature of the Allegheny County, PA receptor (see discussion previously), EPA does not believe that the fact that the air quality assessment tool projects the area to have only a maintenance problem, while the refined air quality modeling suggests that the area would remain in nonattainment, raises any serious issues about the conclusions regarding significant contribution to nonattainment and interference with maintenance with the annual PM2.5 standard. Similarly, because the refined air quality modeling projects that Birmingham, AL will exceed the maintenance criteria by only an extremely slight amount and because reductions from nearby point sources will reduce local emissions in the area, EPA does not believe the refined air quality modeling demonstrates that upwind reductions beyond those in the proposed FIPs are required to address significant contribution and interference with maintenance of the annual PM2.5 NAAQS in Birmingham. For these reasons, EPA does not believe that the more refined air quality modeling for the annual PM2.5 standard changes any of EPA's conclusions with respect to reductions required to eliminate significant contribution and interference with maintenance with respect to this standard. EPA is, however, taking comment on whether Florida, the one group 2 state that was identified as linked to Birmingham, should be moved from group 2 to group 1. EPA notes that no group 2 states are linked to Allegheny County, PA.

For the 24-hour PM2.5 standard, the simplified air quality assessment tool results suggest that under EPA's proposed FIPs, only one problem site, Allegheny County, PA, would remain. In contrast, the more refined CAMx air quality modeling results show a greater 24-hour PM2.5 problem, with 10 nonattainment and 4 maintenance areas. As described later, EPA is evaluating the impact of this refined air quality modeling on the methodology used and the conclusions it has reached regarding significant contribution and interference with maintenance with regard to the 24-hour PM2.5 NAAQS.

EPA has completed some preliminary analysis of the difference between the air quality assessment tool and CAMx results (see the TSDs “Analysis to Quantify Significant Contribution” and “Air Quality Modeling”). This analysis suggests that the main difference is that in the winter months, the CAMx modeling shows smaller air quality reductions compared to the assessment tool. This is because the CAMx air quality modeling more accurately reflects the complex nature of the winter portion of the 24-hour PM2.5 problem. Unlike summer days, for which sulfate is the dominant contributor to PM2.5, sulfate concentrations are typically a lesser contributor to the overall PM2.5 concentrations on winter days. Moreover, for winter days, reductions in this already reduced amount of sulfate appear to be less responsive to reductions in SO2 emissions than for summer days. That is, while for the summer a 50 percent reduction in SO2 emissions would likely yield a nearly 50 percent reduction in sulfate concentrations, in the winter such a reduction in SO2 would reduce sulfate by less than 50 percent. Thus, EPA believes that more study of the winter portion of the problem is warranted to address the issues raised by the CAMx modeling. EPA believes it is important to understand the degree to which these winter exceedances are transport-related or locally generated, and the degree to which upwind states' emissions of NOX, SO2, and other transported pollutants are significantly contributing to these winter exceedances.

Because the CAMx results indicate additional nonattainment and maintenance areas compared to the air quality assessment tool, EPA requests comment on whether the $2,000/ton cost cutoff for SO2 resulting from the assessment tool should be raised to a higher cost cutoff. While the CAMx results may suggest that it would be appropriate to use a cutoff greater than $2,000/ton, the results do not suggest that the cutoff could be less than $2,000/ton. Instead, the results confirm the importance of achieving, at a minimum, all reductions available at the $2,000/ton cost threshold.

Additionally, EPA is requesting comment on whether some group 2 states should be moved to group 1. These group 2 states are: Connecticut, Kansas, Maryland, Massachusetts, Minnesota, Nebraska, and New Jersey. These states were all placed in group two because the air quality assessment tool indicates that the 2012 reductions will resolve the nonattainment or maintenance problems at all areas to which they are linked. However, for these states, the CAMx modeling indicates that one or more of the states to which they are linked will have continuing nonattainment and Start Printed Page 45284maintenance problems after the implementation of the 2012 reductions.

EPA also notes that during the winter, PM2.5 contains a larger nitrate component than in summer months. One reason for this is that some nitrates that are particles in cooler weather volatize and exist as gases during warmer weather. Given this larger contribution from nitrates in the winter, EPA is also taking comment on whether there should be a higher cost threshold for annual nitrogen oxides. This may be appropriate for states that have been identified as contributing significantly to sites that the CAMx air quality modeling continues to show as having a residual nonattainment and/or maintenance concern in 2014.

Finally, EPA requests comment on how and whether EPA should incorporate the use of detailed models such as CAMx into our methodology for significant contribution and interference with maintenance.

(g) Possibility for Emissions Increases in Noncontributing States

EPA also evaluated whether the proposed rule could cause changes in operation of electric generating units in states not regulated under the proposal (that is states not listed in table IV.D-5). Specifically, EPA evaluated whether such changes could lead to increases in emissions in those states, potentially affecting whether they would exceed the 1 percent contribution thresholds used to identify linkages between upwind and downwind states. (See sections IV.B and IV.C previously for more discussion of the 1 percent thresholds). Such changes are possible in part because of the interconnected nature of the country's energy system (including both the electricity grid and coal and natural gas supplies). In addition, our models project that the rule affects the cost of coal (generally lowering the cost of higher sulfur coals and raising the cost of lower sulfur coals). If these price effects took place and if the rule is finalized as proposed, sources in states not covered by the proposed rule might choose to use higher sulfur coals. Increased use of such coals could thus increase SO2 emissions in those states. EPA's modeling confirms this, projecting that, after the proposed rule is implemented in states regulated for SO2, emissions in some states not covered by the proposed rule would increase (i.e., their emissions are greater in the control case modeling than in the base case modeling). As shown in table IV.D-6, Arkansas, Mississippi, North Dakota, South Dakota, and Texas all exhibit 2012 SO2 emissions increases over the base case and above 5,000 tons.[60] For reference, we also include the statewide 2012 base case emissions from all sources within the state.

Table IV.D-6—Unregulated States With More Than 5,000 Tons of Projected SO2 Increases Under the Proposed Transport Rule

State2012 SO2 increase from base case (thousand tons)2012 SO2 base case emissions from all sources (thousand tons)
Arkansas32127
Mississippi1880
North Dakota1194
South Dakota626
Texas136640

Further analysis with the air quality assessment tool indicates that these projected increases in the Texas SO2 emissions would increase Texas's contribution to an amount that would exceed the 0.15 μg/m3 threshold for annual PM2.5. For this reason, EPA takes comment on whether Texas should be included in the program as a group 2 state.

(h) Providing Downwind States Full Relief From Upwind Emissions

EPA takes very seriously its responsibility to ensure that upwind reductions are made in a timely way so that downwind states can meet their attainment obligations.

EPA recognizes, as discussed previously, that while this proposal fully addresses the annual PM2.5 standard, it may not fully address the 24-hour PM2.5 standard. Where this may be the case, as explained previously, EPA's air quality modeling shows that the remaining component of non-attainment is almost entirely occurring in the winter months. Also as noted previously the atmospheric chemistry related to secondary particle formation, and the relative importance of particle species such as sulfate and nitrate, is quite different between summer and winter. Because of this, EPA is moving ahead with further efforts, before the final rule is published, to determine the extent to which this winter problem is caused by emissions transported from upwind states and, if this is the case, to identify the total amount of emissions that represents significant contribution and interference with maintenance. To the extent possible, EPA plans to finalize a rule that fully defines this amount.

Based on the information that EPA currently has, EPA believes there are a number of possible outcomes of this further study. Possible outcomes include:

(1) Identification of the additional amount of SO2 emissions reductions needed to eliminate significant contribution and interference with maintenance from upwind states contributing to the residual 24-hour PM2.5 problem sites.

(2) Identification of the additional amount of NOX emissions reductions needed to eliminate significant contribution and interference with maintenance from upwind states contributing to the residual 24-hour PM2.5 problem sites.

(3) Identification of another pollutant that should be considered part of significant contribution and interference with maintenance for states that Start Printed Page 45285contribute to the residual 24-hour PM2.5 problem sites.

(4) Determination that the reductions proposed in today's rulemaking would fully address significant contribution and interference with maintenance at these sites.

If EPA determines that more SO2 emissions should be considered part of this amount based on the analysis performed for today's proposal, EPA believes that the next set of emissions that can be reduced above the $2,000/ton threshold would likely still come from the power sector. If EPA determines that more SO2 emissions reductions are required or that the amount of emissions of SO2 and NOX that it has proposed as significantly contributing to nonattainment are the appropriate amounts to address this winter portion of the problem, EPA intends to supplement today's proposal and finalize a rule that would fully addresses emissions that significantly contribute to or interfere with maintenance of the 2006 daily PM2.5 standard.

To the extent that EPA determines that more NOX reductions are needed or that reductions of another pollutant are needed, EPA believes that we could provide the greatest assistance to states in addressing transport by finalizing this rule quickly and promulgating a separate rule to achieve any necessary additional NOX reductions. This is because those emissions reductions would likely involve placing reduction requirements on sources other than EGUs and that additional approaches would need to be addressed. EPA believes that developing supplemental information to address these sources and concepts would substantially delay publication of a final rule, beyond the anticipated publication of spring 2011.

EPA plans to move forward aggressively in the event that these further reductions are needed. We do not, however, intend to delay the reductions in this proposed rule because those reductions have a substantial impact on states' abilities to attain the NAAQS in the required time period and have large health benefits.

b. Specific Application to Ozone

This section discusses, for the 1997 ozone standards, how EPA applies its multi-step methodology for defining each state's significant contribution. For some aspects of the methodology, further work is needed to complete the methodology for ozone and this further work will be completed in a separate proposal.

(1) Years for Quantifying Significant Contribution

In this subsection, we discuss how EPA identifies for ozone the years to analyze for eliminating significant contribution. Similar to the previous discussion for PM2.5, EPA believes that the selection of the year for eliminating significant contribution is informed by the attainment deadline and by the Act's requirement to attain the NAAQS “as expeditiously as practicable.”

As noted earlier, the 2012 ozone season is the last ozone season before the 2013 attainment deadline for ozone areas classified as “serious” for the 1997 ozone air quality standards. Thus, for any states “linked” to “serious area” locations for which 2012 is the latest ozone season prior to their attainment deadline, EPA believes that 2012 is the appropriate year for eliminating significant contribution, to the extent that purpose can be achieved given the short time period. Because this proposed rule would not be finalized until 2011, the year 2012 also represents the earliest time by which emissions reductions could be achieved, which is consistent with statutory provisions calling for downwind states to achieve attainment “as expeditiously as practicable.” This also is relevant for certain other areas with lower ozone classifications that are projected in our analysis to have continuing air quality problems and to be affected by transported pollution from certain upwind states in amounts greater than the 1 percent threshold.[61]

EPA is concerned that the timing of this rule presents difficult challenges in eliminating significant contribution and interference with maintenance with regard to the 1997 ozone NAAQS by the attainment date. For states with a 2012 (or earlier) attainment date for which we project continuing ozone problems, we are concerned that strict adherence to a 2012 date for reductions could be viewed as an artificial constraint on our ability to require appropriate reductions. EPA believes that the current situation for ozone, involving a transport rulemaking within months of the attainment date (and in a number of cases, after the current attainment date) is a unique situation created by the Court's remand of the CAIR. Under normal circumstances adhering to the CAA schedule for addressing transport within 3 years after a NAAQS is promulgated, transport requirements would be in place years before the attainment date. For purposes of our analysis of ozone for areas with a 2012 attainment date, EPA proposes that we should not be constrained to only considering those reductions that are possible by 2012.

Another reason that it would be inappropriate to limit upwind state responsibility based on the downwind area's current attainment date is that the statute contains provisions for extension of attainment dates. To the extent that downwind states have continuing ozone air quality problems after 2012, the Act requires that they be reclassified, which allows the downwind area to qualify for a later attainment date that is as expeditious as practicable but no later than 2019 (2018 emissions year).[62] In addition, two 1-year attainment date extensions can be granted if an area comes close to attaining, based on specific criteria. In addition, history shows many examples of states not meeting air quality standards by their attainment deadlines, often due in part to interstate pollution transport. Even if a downwind area attains on time, further upwind reductions may be important to assure continued maintenance of the standard.

If in determining upwind state reduction responsibilities EPA were to automatically assume that downwind states will attain on time despite pollution transport, this assumption would have the effect of absolving the upwind state of responsibility for any reductions in pollution transport that could not be achieved by the downwind area's current attainment date. EPA does not believe this would be appropriate. This would transfer emissions control responsibility from the upwind state to the downwind state in any case when the area did not attain by its current attainment date, and could delay for years the date when the public would breathe air that meets health-based standards.

Accordingly, for all the reasons discussed previously, we address both 2012 and 2014 in our analysis, and we do not believe that examining 2012 only would be appropriate. EPA has chosen to examine 2014 air quality results because, based on a conservative estimate, 2014 is the earliest year for which significantly more stringent NOX limits (e.g., reflecting SCR) could conceivably be considered in a swift, subsequent rulemaking.

One area in the eastern half of the U.S. covered by this proposal, Houston, Start Printed Page 45286is classified as “severe.” For Houston, it is relevant to consider both that (1) the latest permissible attainment date for severe areas is June 2019, which would require emissions reductions by the 2018 ozone season, and (2) the state implementation plan must provide for attainment as expeditiously as practicable. In light of this, EPA may select a year between 2012 and 2018 that is as expeditious as practicable as the appropriate year for eliminating significant contribution. Because, as explained later, further analysis is needed to quantify any additional reductions necessary to eliminate significant contribution to Houston, EPA requests comment on which year we should select within this 2012 to 2018 time period for this analysis.

(2) Step 1. Emissions Reductions Cost Curves for EGU Ozone Season NOX

Using IPM, EPA developed cost curves for 2012 for ozone season NOX, showing the ozone season (May-September) NOX reductions available in 2012 at different cost increments. Specifically, EPA developed cost curves that show reductions available in 2012 from EGUs at various costs (in 2006 $) up to $5,000/ton. These EGU cost curves are presented in Table IV.D-7. Generally, projected emissions reductions for 2012 are modest because, by 2012, it is not feasible to install add-on equipment. Some highly effective and widely employed NOX control technologies such as SCR could not be planned and installed in significant numbers within a 1-year time period (i.e., because a single SCR unit on average takes 21 months to install,[63] SCR-based limits in 2012, if feasible at all, would require an unacceptably steep cost premium).

For some states (particularly those which are not regulated by the NOX SIP Call) EPA identified potential reductions from the installation of some combustion controls/low NOX burners and the use of existing SCR units that, in the absence of CAIR, would not be required to operate. These reductions are available at approximately $500/ton in 2012. There were very few emissions reductions available below this cost.

Table IV.D-7—2012 Ozone-Season NOX Emissions From Electric Generating Units for Each State at Various Costs (2006$) per Ton (Thousand Tons)

Marginal cost per ton$0$500$1,000$1,500$2,000$2,500$3,000$3,500$5,000
Alabama303030303030302929
Arkansas211111111111111111
Connecticut333333333
Delaware222222222
Florida1017460595959595857
Georgia3533333333333333