EPA Revises Particulate Matter Standards The U.S. Environmental Protection Agency (EPA) recently announced changes to the National Ambient Air Quality Standards (NAAQS) that address fine and coarse particulate matter (PM) limits. The final rule lowers the level of fine particulates (smaller than 2.5 microns) allowed in a designated area by almost half. The new standard lowered the acceptable PM level from 65 µg/m3 to 35 µg/m3 of air averaged over 24 hours. The agency also revoked the existing annual standard for coarse particles (smaller than 10 microns). Each state must develop a State Implementation Plan describing how it will attain and maintain the NAAQS. The new standards will be used to designate attainment and non-attainment regions by November 2009. States must then meet the standards by April 2015 through a variety of mechanisms, such as permits, emissions reductions plans and vehicle emissions limits. For more information, visit www.epa.gov/pm.   [ Back ]