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Summary:
Particulate matter (PM), including fine particulate matter (PM2.5), 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). NAAQS are designed to protect human health within an adequate margin of safety. After years of litigation and other delays, the EPA is moving to implement the NAAQS for PM2.5 promulgated in 1997. This report provides information on the designation process for PM2.5 "attainment" and "nonattainment" areas. It also discusses issues that have been raised as EPA, the states, and nonattainment areas develop implementation strategies. EPA's final designation of 39 areas, consisting of 208 counties in 20 states and the District of Columbia, as nonattainment areas for the 1997 PM2.5 NAAQS became effective April 2005. The EPA published a final rule on April 14, 2005, amending designated geographical areas for 1997 PM2.5 standards, which were originally published in January 2005. The agency's amendments were based on a review of supplemental 2004 air monitoring data submitted by several states. 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. EPA published a proposed "PM2.5 implementation" rule on November 1, 2005, that provides guidance and procedures for establishing controls to achieve and maintain attainment. States are required to submit SIPs for how they will meet the 1997 PM2.5 NAAQS by April 2008 (three years after the effective date for the final geographic designations), and must be in compliance by 2010, unless they are granted a five-year extension. A number of issues will continue to be debated as the implementation of the 1997 PM2.5 NAAQS progresses. Some areas that have not been designated as nonattainment under implementation of other NAAQS have been designated "nonattainment" for the first time. Questions and concerns include the following: what criteria were used to determine nonattainment; whether special provisions can be made for meeting attainment deadlines, particularly for areas affected by upwind pollution; what grants or other funding might be available to help areas reach attainment; and how nonattainment designation might affect economic development and transportation planning in an area. Legislation and EPA rulemaking that affect aspects of regulating air quality could influence the implementation process. Court challenges that followed the release of the eight-hour ozone designations, and EPA's periodic review of PM NAAQS, as required under the CAA, could also affect implementation of the 1997 PM2.5 NAAQS. As part of the CAA review process, on September 21, 2006, the EPA Administrator signed a final revision to NAAQS for particulate matter (both PM2.5 and PM10) that included a strengthening of the 1997 PM2.5 standard.
