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Transportation Conformity: Chronological List of Rulemakings

EPA has published several rule amendments in the Federal Register since transportation conformity was enacted as part of the 1990 Clean Air Act. These previous rulemakings include preamble text that explain rule provisions that remain in place today and can be accessed here.

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Transportation Conformity Rule Restructuring Amendments

This final rule restructures several sections of the existing transportation conformity rule so that the rule applies to any new or revised NAAQS EPA establishes.

Transportation Conformity Rule:  MOVES Regional Grace Period Extension

This final rule extends the grace period before the MOtor Vehicle Emission Simulator model (currently MOVES2010a) is required for regional emissions analyses for transportation conformity determinations (“regional conformity analyses”). This final rule provides an additional year to the previously established two-year conformity grace period, which is now extended to March 2, 2013.

PM Amendments

Transportation Conformity Rule PM2.5 and PM10 Amendments (published March 24, 2010)
This PM amendments final rule amends the conformity regulation to reflect the October 17, 2006 final rule that strengthened the 24-hour PM2.5 national ambient air quality standard (NAAQS) and revoked the annual PM10 NAAQS. The final PM amendments rule also addresses a court remand concerning hot-spot analyses; this portion of the rule applies to PM2.5 and PM10 and carbon monoxide nonattainment and maintenance areas.

SAFETEA-LU Rulemaking

Transportation Conformity Rule Amendments to Implement Provisions Contained in the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (published January 24, 2008)
EPA has updated the transportation conformity rule to make it consistent with the Clean Air Act as amended by SAFETEA-LU.

Rulemakings that Address 8-hour Ozone and Particulate Matter Air Quality Standards

August 6, 2002, Final Rule

July 28, 2000, Federal Register Supplemental Notice of Proposed Rule

April 10, 2000, Final Rule

March 18, 1999, Final Rule

1997 Conformity Rule

November 1995 Rule Amendments

August 1995 Rule Amendments

1993 Conformity Rule

For further information or assistance regarding this Web page, contact Astrid Terry at 734-214-4812 or

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