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Approval of Air Quality Implementation Plans; California; Imperial County; Ozone Precursor Emissions Inventories

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Environmental Protection Agency.


Direct final rule.


The Environmental Protection Agency (EPA) is approving revisions to California's State Implementation Plan (SIP) for Imperial County that address Clean Air Act (CAA) requirements concerning ozone precursor emissions inventories of volatile organic compounds and oxides of nitrogen. These emissions inventories were submitted by California to meet CAA requirements for Imperial County, which was designated as a moderate nonattainment areas under the 1997 8-hour ozone National Ambient Air Quality Standard.


This action will be effective on December 22, 2014, without further notice, unless EPA receives adverse comments by November 24, 2014. If we receive such comments, we will publish a timely withdrawal in the Federal Register to notify the public that this rule will not take effect and that we will respond to submitted comments and take subsequent final action.


Submit comments, identified by docket number EPA-R09-OAR-2012-0542, by one of the following methods:

1. Federal eRulemaking Portal: Follow the on-line instructions.

2. Email:

3. Mail or delivery: Jerry Wamsley, Air Division (AIR-2), U.S. Environmental Protection Agency—Region 9, 75 Hawthorne Street, San Francisco, CA 94105.

Instructions: All comments will be included in the public docket without change and may be made available online at, including any personal information provided, unless the comment includes Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Information that you consider CBI or otherwise protected should be clearly identified as such and should not be submitted through or email. is an “anonymous access” system, and EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send email directly to EPA, your email address will be automatically captured and included as part of the public comment. 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.

Docket: The docket for this action is available electronically at and in hard copy at EPA Region IX, 75 Hawthorne Street, San Francisco, California. While all documents in the docket are listed in the index, some information may be publicly available only at the hard copy location (e.g., copyrighted material), and some may not be publicly available in either location (e.g., CBI). To inspect the hard copy materials, please schedule an appointment during normal business hours with the contact listed in the FOR FURTHER INFORMATION CONTACT section below.

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Jerry Wamsley, Air Division, U.S. Environmental Protection Agency—Region 9, (415) 947-4111, or via email:

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For the purpose of this document, we are giving meaning to certain words or abbreviations described here. The words or abbreviation “the Act” or “CAA” mean or refer to the Clean Air Act, unless the context indicates otherwise. The terms “we,” “us,” and “our” refer to the United States Environmental Protection Agency.

Table of Contents

I. Background

II. California's Submittal

III. Today's Action

A. Ozone Precursors Emissions Inventories

IV. Final Action

V. Statutory and Executive Order Reviews

I. Background

Ground-level ozone is formed when oxides of nitrogen (NOX) and volatile organic compounds (VOC) react in the presence of sunlight. Referred to as Start Printed Page 63333ozone precursor compounds, these two pollutants are emitted by many types of pollution sources, including on- and off-road motor vehicles and engines, power plants and industrial facilities, and area-wide sources, such as consumer products and lawn and garden equipment. Scientific evidence indicates that adverse public health effects occur following a person's exposure to ozone, particularly children and adults with lung disease. Breathing air containing ozone can reduce lung function and inflame airways, which can increase respiratory symptoms and aggravate asthma or other lung diseases.[1] As a consequence of this scientific evidence, we promulgated the 0.12 part per million (ppm) 1-hour ozone National Ambient Air Quality Standard (NAAQS) in 1979 (44 FR 8202, February 8, 1979).

On July 18, 1997, EPA promulgated a revised ozone NAAQS of 0.08 ppm, averaged over eight hours (62 FR 38855). This standard was determined to be more protective of public health and more stringent than the previous 1979 1-hour ozone standard. On April 30, 2004, we designated areas as attaining or not attaining the 1997 8-hour ozone NAAQS and classified Imperial County as a marginal non-attainment area with an applicable attainment date of June 15, 2007 (69 FR 23858). On February 13, 2008, EPA found that Imperial County failed to attain the 1997 8-hour ozone standard by this June 15, 2007 deadline (73 FR 8209). Consequently, Imperial County was reclassified by operation of law as a moderate ozone non-attainment area with a new attainment date of as expeditiously as practicable, but no later than June 15, 2010.

Subsequently, EPA revised the 8-hour ozone NAAQS from 0.08 to 0.075 ppm (73 FR 16436, March 27, 2008). We finalized designations for the 2008 8-hour ozone standard on May 21, 2012 (77 FR 30088). Imperial County was designated marginal for the more stringent 8-hour ozone standard. In a separate and future rulemaking, EPA will finalize the requirements that must be implemented as part of meeting the 2008 8-hour ozone standard.[2] In this action today, however, we are addressing requirements related to the 1997 8-hour ozone NAAQS only.

On December 3, 2009, EPA published our determination that Imperial County had met the 1997 8-hour ozone NAAQS based on certified ambient air monitoring data for the 2006-2008 monitoring period (74 FR 63309).[3] Pursuant to 40 CFR 51.918 and this clean data determination, EPA suspended the requirements for Imperial County and California to submit the following air quality plan elements: An attainment demonstration, reasonably available control measures, a reasonable further progress plan, and contingency measures. These requirements remain suspended for so long as Imperial County continues to attain the 1997 8-hour ozone NAAQS. Under CAA section 172(c)(3), Imperial County is required to submit emissions inventories for VOC and NOX. These ozone precursor emissions inventories are the subject of today's action.

II. California's Submittal

On December 21, 2010, California submitted Imperial County's “Final 2009 1997 8-hour Ozone Modified Air Quality Management Plan” (2009 Ozone AQMP) to EPA for incorporation into the SIP.[4] Imperial County adopted the 2009 Ozone AQMP on July 13, 2010 and the California Air Resources Board (CARB) adopted the plan on November 18, 2010.[5] The Imperial County and CARB adoptions were each preceded by a 30-day public comment period, therefore, the State has met the requirement for adequate public notice.

As explained earlier, the elements of California's 2009 Ozone AQMP that we are acting on today consist of 2002 base year VOC and NOX emissions inventories. These emissions inventories and the 2009 Ozone AQMP as a whole were complete by operation of law on June 21, 2011.[6]

III. Today's Action

EPA is approving the 2002 VOC and NOX emissions inventories elements of the 2009 Ozone AQMP that California submitted to address moderate nonattainment area requirements for Imperial County under the 1997 8-hour ozone NAAQS. Our rationale and basis for this action is discussed below.

A. Ozone Precursors Emissions Inventories

A comprehensive, accurate and current inventory of actual emissions from all sources of the relevant pollutant or pollutants is required by CAA sections 172(c)(3). Imperial County's 2009 Ozone AQMP includes complete VOC and NOX emissions inventories for the base year of 2002.[7] Emissions from different source types vary by season, time of day, or day of the week. The months from May through October are known as the “summer planning inventory” and are the months when ozone formation is pronounced and exceedances of ozone air quality standards are most likely to occur. Consequently, California used the summer planning emissions inventory for the 2009 Ozone AQMP to provide a worst case representation and a daily emissions inventory in tons per day (tpd). This summer planning inventory includes data for the pollutants reactive organic gas (ROG) and NOX, the two primary precursors in the formation of ground-level ozone pollution.[8] We have summarized Imperial County's 2002 base year emissions inventories for ozone precursors in Table 1.

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Table 1—Imperial County, California: 2002 Emissions Inventories for Reactive Organic Gas (ROG) and Oxides of Nitrogen (NOX) by Major Source Category

[Tons per day]

Source categoryROGPercent of totalNOXPercent of total
Stationary Sources:
Fuel combustion0.120.323.579.54
Waste Disposal0.
Cleaning and Surface Coatings0.421.130.000.00
Petroleum Pro. and Marketing0.651.740.000.00
Industrial Processes0.
Area-Wide Sources:
Solvent Evaporation9.0124.140.000.00
Miscellaneous Processes11.8131.650.922.46
Mobile Sources:
Off-Road Vehicles6.4517.2812.7033.93
Totals for Imperial County37.32100.0037.43100.00
Source: 2009 Ozone AQMP, Table 4-1, Page 26.

California develops a complete emissions inventory every year and assembles and maintains this inventory in the California Emission Inventory Development and Reporting System (CEIDARS) and the California Emission Forecasting System (CEFS). All reportable sources are categorized as either stationary, area-wide, or mobile. Stationary sources of air pollution include sources such as power plants, refineries, and manufacturing facilities and are facilities that are typically required by California to acquire and maintain a permit to operate. These sources directly report their emissions to California, which in-turn uses this data to compile a complete emissions inventory for air pollution control districts, such as Imperial County.

Area-wide sources of emissions are those where the emissions are spread throughout the nonattainment area, such as consumer products and farming operations. California uses a variety of methods to estimate emissions for approximately 500 area-wide emission sources. A complete compilation of these methodologies can be obtained from​ei/​areasrc/​index0.htm.

Mobile source emissions are further divided into on-road sources and off-road sources. On-road sources include passenger cars, school buses, and trucks. Off-road sources include construction equipment, garden equipment, boats, and outdoor recreational vehicles. California is continually updating and improving its official model to estimate emissions from mobile sources. Although California released its EMFAC2011 model, the State used its EMFAC2007 model to develop the 2002 base year emissions for on-road sources.[9] At the time of the development of this 2002 emissions inventory for ROG and NOX, EMFAC2007 was the latest EPA approved mobile source emissions model. California used its OFFROAD2007 model to develop emissions from off-road sources for the 2002 base year emissions inventory.[10] [11]

We have evaluated Imperial County's base year 2002 emissions inventory shown in Table 1 by verifying this inventory for consistency with past and current emissions inventories and spot-checking the accuracy of the emissions inventory from raw data and accepted emissions factors and estimation methods. We find the 2002 base-year inventory to be a comprehensive and accurate representation of actual emissions and approve it as meeting the requirements of the CAA and EPA guidance.

The on-road motor vehicle emission inventories for VOC and NOX that we are approving today do not change our previous actions concerning the motor vehicle emissions budgets used for determining the conformity of federally-funded transportation plans, programs, and projects in Imperial County, per section 176(c) of the CAA. In May 2008, we found the 2009 motor vehicle emissions budgets within the “Imperial County 8-hour Ozone Early Progress Plan” to be adequate for the purpose of determining transportation conformity: 7 tons per day of VOC; and 17 tons per day of NOX.[12] State transportation and metropolitan planning agencies should continue to use these motor vehicle emissions budgets for determining the conformity of federally funded transportation plans, programs and projects within the Imperial County ozone non-attainment area.

IV. Final Action

EPA is approving the 2002 VOC and NOX emissions inventories within Chapter 4 of Imperial County's 2009 Ozone AQMP. EPA is approving these emissions inventories because they meet the requirements of the CAA and EPA guidance.Start Printed Page 63335

V. Statutory and Executive Order Reviews

This action approves a SIP revision that meets certain emissions inventories requirements for the 1997 8-hour ozone standard. This action would not impose additional requirements beyond those imposed by state law. For that reason, this action:

  • Is not a “significant regulatory action” subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);
  • Does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
  • Is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
  • Does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
  • Does not have Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
  • Is not an economically significant regulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
  • Is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001);
  • Is not subject to requirements of Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because application of those requirements would be inconsistent with the CAA; and
  • Does not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).

In addition, this approval of an emissions inventories SIP revision for the Imperial County non-attainment area of California does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), because the SIP is not approved to apply in Indian country, and EPA notes that it will not impose substantial direct costs on tribal governments or preempt tribal law.

The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule may take effect, the agency promulgating the rule must submit a rule report, which includes a copy of the rule, to each House of the Congress and to the Comptroller General of the United States. EPA will submit a report containing this action and other required information to the U.S. Senate, the U.S. House of Representatives, and the Comptroller General of the United States prior to publication of the rule in the Federal Register. A major rule cannot take effect until 60 days after it is published in the Federal Register.

This action is not a “major rule” as defined by 5 U.S.C. 804(2). Under section 307(b)(1) of the CAA, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by December 22, 2014. Filing a petition for reconsideration by the Administrator of this final rule do not affect the finality of these actions for the purposes of judicial review nor does it extend the time within which a petition for judicial review may be filed, and shall not postpone the effectiveness of such rule or action. This action may not be challenged later in proceedings to enforce its requirements. Parties with objections to this direct final rule are encouraged to file a comment in response to the parallel notice of proposed rulemaking for this action published in the Proposed Rules section of today's Federal Register, rather than file an immediate petition for judicial review of this direct final rule, so that EPA can withdraw this direct final rule and address the comment in the proposed rulemaking. This action may not be challenged later in proceedings to enforce its requirements (see section 307(b)(2) of the CAA.)

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List of Subjects in 40 CFR Part 52

  • Environmental protection
  • Air pollution control
  • Incorporation by reference
  • Intergovernmental relations
  • Oxides of nitrogen
  • Ozone
  • Volatile organic compounds
  • Reporting and recordkeeping requirements
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Dated: September 24, 2014.

Jared Blumenfeld,

Regional Administrator, EPA Region 9.

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Part 52, Chapter I, Title 40 of the Code of Federal Regulations is amended as follows:

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1. The authority citation for part 52 continues to read as follows:

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Authority: 42 U.S.C. 7401 et seq.

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Subpart F—California

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2. Section 52.220 is amended by adding paragraph (c)(445) to read as follows:

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Identification of plan.
* * * * *

(c) * * *

(445) A plan revision submitted on December 21, 2010 by the Governor's Designee.

(i) [Reserved]

(ii) Additional materials.

(A) State of California Air Resources Board.

(1) California Air Resources Board Resolution No. 10-35, adopted November 18, 2010.

(B) Imperial County Air Pollution Control District.

(1) Imperial County Air Pollution Control Board, Minute Order No. 15, adopted July 13, 2010.

(2) Chapter 4—Emission Inventory, in “Imperial County 2009 1997 8-Hour Ozone Modified Air Quality Management Plan”, adopted on July 13, 2010.

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1.  See “Fact Sheet, Proposal To Revise the National Ambient Air Quality Standards for Ozone,” January 6, 2010 and 75 FR 2938, January 19, 2010.

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2.  EPA published the proposed rule concerning implementation of the 8-hour 2008 ozone NAAQS on June 6, 2013, (78 FR 34178). The public comment period on this implementation rule closed on August 5, 2013. EPA is reviewing comments and intends to publish a final rule in the near future.

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3.  For further discussion of our clean data determination and application of our Clean Data Policy, see our proposed rule at 74 FR 48495, (September 23, 2009).

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4.  See letter from Lynn Terry (for James Goldstene), California Air Resources Board to Jared Blumenfeld, EPA-Region 9, dated December 21, 2010, included in the docket for this rulemaking.

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5.  See the Imperial County Board of Supervisor's “Minute Order of the Air Pollution Control Board”, Number 15, dated July 13, 2010, and California Air Resources Board, Resolution 10-35, dated November 18, 2010, included in the docket for this rulemaking.

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6.  If we do not determine a submittal to be complete within 6 months of its submittal, it is deemed to be complete by operation of law. See 40 CFR part 51, appendix V for the completeness criteria applied to SIP submittals.

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7.  2002 is the designated base year for SIP planning purposes under the 1997 8-hour ozone NAAQS. See Memorandum of November 18, 2002, from Lydia Wegman and Peter Tsirigotis, “2002 Base Year Emission Inventory SIP Planning: 8-hour Ozone, PM2.5 and Regional Haze Programs” and 70 FR 71612, (November 29, 2005), EPA's Phase II implementation rule for the 1997 8-hour ozone NAAQS.

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8.  The California Air Resources Board (CARB) uses the term reactive organic gases (ROG) for planning and inventory purposes and uses it synonymously with its own definition of “volatile organic compound” for regulatory purposes.

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9.  On January 18, 2008, EPA approved and announced the availability of EMFAC 2007 Motor Vehicle Emission Factor Model for use in SIP development in the State of California (73 FR 3464).

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10.  The OFFROAD2007 model is now replaced by category specific methods and inventory models developed for specific regulatory support projects.

11.  Further information on California's official mobile source inventory models, as well as links to the mobile source emissions databases, can be obtained from​msei/​msei.htm.

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12.  See 73 FR 24594, (May 5, 2008).

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[FR Doc. 2014-24753 Filed 10-22-14; 8:45 am]