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Summary:
Particulate matter (PM), including fine particulate matter (PM2.5) and larger, but still inhalable particles (PM10), is one of the six principal pollutants for which the U.S. Environmental Protection Agency (EPA) has set National Ambient Air Quality Standards (NAAQS) under the Clean Air Act (CAA). Primary NAAQS are designed to protect human health, with an adequate margin of safety. After years of litigation and other delays, EPA is implementing the NAAQS for PM2.5 promulgated in 1997. This report outlines the implementation process for the 1997 PM2.5 NAAQS and describes issues raised as EPA and states develop implementation strategies. The EPA's final designation of 38 areas, consisting of 205 counties in 20 states and the District of Columbia, as "nonattainment" (out of compliance) areas for the 1997 PM2.5 NAAQS became effective in April 2005. A combined population of almost 90 million resides in these areas. States with PM2.5 nonattainment areas are required to develop comprehensive implementation plans, referred to as State Implementation Plans (SIPs), demonstrating how attainment will be reached by a designated deadline. SIPs include pollution control measures that rely on models of the impact on air quality of projected emission reductions to demonstrate attainment. States were required to submit SIPs for the 1997 PM2.5 NAAQS by April 2008, but EPA did not begin receiving most of them until July 2008. States must be in compliance by 2010, unless they are granted an extension. A number of issues will continue to be debated as the implementation of the 1997 PM2.5 NAAQS progresses. The U.S. Court of Appeals for the D.C. Circuit's July 11, 2008, decision (North Carolina v. EPA) to vacate the Clean Air Interstate Rule (CAIR) could further delay implementation, which has heightened interest in Congress. CAIR was expected to assist states in addressing upwind emission contributions for achieving attainment of the 1997 PM2.5 NAAQS. In addition, other EPA rulemakings promulgated and proposed that influence various aspects of regulating air quality could affect the PM2.5 NAAQS implementation process. EPA's April 25, 2007, final "PM2.5 implementation" rule to provide guidance and procedures for establishing controls to achieve and maintain attainment has raised concerns. Six petitions for review of the rule were filed with the D.C. Circuit, and two petitions for reconsideration have been filed with EPA. Additionally, as required under the CAA, EPA reviewed the PM2.5 and PM10 NAAQS, and on October 17, 2006, promulgated final revisions that included a strengthening of the 1997 PM2.5 standard. Pending judicial actions regarding these new PM NAAQS could affect implementation of the 1997 PM2.5 NAAQS. Many questions and concerns remain, including whether special provisions can be made for meeting attainment deadlines, particularly for areas affected by upwind pollution, and how nonattainment designation might affect economic development.
