This final rule, published by EPA on May 6, 2005, adds the following transportation-related PM2.5 precursors to the transportation conformity regulations: nitrogen oxides (NOx), volatile organic compounds (VOCs), sulfur oxides (SOx), and ammonia (NH3). The final rule also specifies when each of these precursors must be considered in conformity determinations in PM2.5 nonattainment and maintenance areas before and after PM2.5 state air quality implementation plans (SIPs) are submitted. This final rule is part of EPA's overall strategy for implementing the new ozone and PM2.5 standards.

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• Federal Register Notice of Final Rule: Transportation Conformity Rule Amendments for the New PM2.5 National Ambient Air Quality Standard: PM2.5 Precursors (PDF)(13 pp, 230K, May 6, 2005).
• Federal Register Correction Notice: Corrects two minor errors in the preamble to the May 6, 2005 final rule (PDF)(1 pp, 54K, June 1, 2005). This notice corrects preamble language by providing greater detail and updated reference information for data and analyses obtained from the PM Supersites Program. The notice also updates a footnote in the May 6 final rule to provide the most recent reference information.
• Fact Sheet: Final Rule to Add PM2.5 Precursors to the Transportation Conformity Rule (PDF)(EPA-420-F-05-005, 2 pp, 148 K, April 2005)  This document provides general information about the final rule.
• Federal Register Notice: Proposed Rulemaking - Transportation Conformity Rule Amendments for the New 8-hour Ozone and PM2.5 National Ambient Air Quality Standards and Miscellaneous Revisions for Existing Areas (PDF)(41 pp, 372K, published November 5, 2003)

For further information or assistance regarding this Web page, contact Rudy Kapichak, at 734-214-4574 or email: kapichak.rudolph@epa.gov