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Adequacy Status of the Submitted 2005 and 2007 Revised Attainment Demonstration Budgets for the 1-hour Ozone National Ambient Air Quality Standard for Transportation Conformity Purposes for the Chicago, IL Severe Ozone Nonattainment Area

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Environmental Protection Agency (EPA).


Notice of adequacy.


In this notice, EPA is notifying the public that we have found the revised attainment year motor vehicle emissions budgets (“budgets”) for volatile organic compounds (VOC) and nitrogen oxides (NOX) in the submitted revision to the 1-hour ozone attainment demonstration state implementation plan (SIP) for the Chicago, Illinois severe nonattainment area to be adequate for conformity purposes. These attainment year budgets were recalculated using EPA's latest motor vehicle emissions factor model, MOBILE6. On March 2, 1999, the DC Circuit Court ruled that submitted state implementation plan budgets cannot be used for conformity determinations until EPA has affirmatively found them adequate. As a result of our finding, the Chicago, Illinois severe ozone nonattainment area can use the revised 2007 attainment year budgets of VOC and NOX from the submitted revision to the 1-hour ozone attainment demonstration SIP for future conformity determinations. Illinois also submitted an updated 2005 VOC budget as part of the Rate Of Progress requirement. As a result of this finding, the 2005 VOC budget can also be used for conformity determinations in the Chicago, Illinois area.


This finding is effective August 11, 2003.

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Patricia Morris, Environmental Scientist, Regulation Development Section (AR-18J), Air Programs Branch, Air and Radiation Division, United States Environmental Protection Agency, Region 5, 77 West Jackson Boulevard, Chicago, Illinois 60604, (312) 353-8656,

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Throughout this document, whenever “we”, “us” or “our” is used, we mean EPA.


Today's notice is simply an announcement of a finding that we have already made. EPA Region 5 sent a letter to the Illinois Environmental Protection Agency on June 26, 2003, stating that the revised attainment year motor vehicle emissions budgets in the Chicago, Illinois submitted 1-hour ozone attainment demonstration SIP revision (dated April 11, 2003) are adequate for conformity purposes. The purpose of Illinois's April 11, 2003 submittal was to address its enforceable commitment to revise the attainment year budgets using MOBILE6 within two years of the release of the model. This enforceable commitment was approved by EPA on November 13, 2001 (66 FR 56903). EPA's adequacy finding will also be announced on EPA's conformity Web site:​otaq/​traq, (once there, click on the “Conformity” button, then look for “Adequacy Review of SIP Submissions for Conformity”).

Transportation conformity is required by section 176(c) of the Clean Air Act. EPA's conformity rule requires that transportation plans, programs, and projects conform to SIPs and establishes the criteria and procedures for determining whether or not they conform. Conformity to a SIP means that transportation activities will not produce new air quality violations, worsen existing violations, or delay timely attainment of the national ambient air quality standards.

The criteria by which we determine whether a SIP's motor vehicle emission budgets are adequate for conformity purposes are outlined in 40 CFR 93.118(e)(4). Please note that an adequacy review is separate from EPA's completeness review, and it also should not be used to prejudge EPA's ultimate approval of the SIP. Even if we find a budget adequate, the SIP could later be disapproved.

We have described our process for determining the adequacy of submitted SIP budgets in guidance (May 14, 1999 memo titled “Conformity Guidance on Implementation of March 2, 1999 Conformity Court Decision”). We followed this guidance, which can also be found on EPA's Web site at:​otaq/​traq, in making our adequacy determination.

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

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Dated: July 9, 2003.

Bharat Mathur,

Acting Regional Administrator, Region 5.

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[FR Doc. 03-19004 Filed 7-24-03; 8:45 am]