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May 6, 2005, Transportation Conformity Rule That Addresses PM2.5 Precursors

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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