Particulate Matter (Pm2.5): Implementation of the 1997 National Ambient Air Quality Standards (Naaqs)

Particulate matter (PM), including fine particulate matter (PM 2.5 ) and larger, but still inhalable particles (PM 10 ), 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).EPA most recently revised the particulates NAAQS in October 2006, but is due to propose revised standards in February 2011 and promulgate them by October 2011.While currently much of the interest in the particulates NAAQS is focused on reviewing the NAAQS and speculation as to the degree of stringency of any new standards, implementing revised standards can take many years.EPA and states are in the early stages of implementing the 2006 revised standards, and have not finalized implementation of the standards promulgated in 1997 after years of litigation and other delays.This report outlines the implementation process for the 1997 PM 2.5 NAAQS and describes issues raised as EPA and states developed and employed implementation strategies for achieving attainment.The EPA's final designation of 39 areas, consisting of 205 counties in 20 states and the District of Columbia, as "nonattainment" (out of compliance) areas for the 1997 PM 2.5 NAAQS became effective in April 2005.A combined population of almost 90 million resides in these areas.States with PM 2.5 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 PM 2.5 NAAQS by April 2008, but EPA did not begin receiving most submissions until July 2008.On November 27, 2009, EPA published its findings that three states failed to meet the deadline for submitting complete SIPs.For the remaining designated areas, states either submitted a complete SIP or EPA made a final approval that the area attained the 1997 PM 2.5 NAAQS based on 2006-2008 air quality data.