[20201223]IF11288_臭氧和颗粒物空气标准：EPA审查.pdf

https:/crsreports.congress.gov Updated December 23, 2020Ozone and Particulate Matter Air Standards: EPA ReviewThe Clean Air Act (CAA) requires the U.S. Environmental Protection Agency (EPA) to review standards for national ambient air quality every five years. In 2018, EPA announced strategies to expedite the National Ambient Air Quality Standard (NAAQS) review while concurrently disbanding a pollutant-specific scientific review panel that has historically advised agency staff during their reviews. Although the CAA allows the EPA Administrator to specify the procedures for review of the NAAQS, past EPA reviews and revisions have garnered considerable congressional oversight. In December 2020, EPA completed the particulate matter (PM) NAAQS review and retained the standards. This In Focus discusses the recently completed PM NAAQS review and the ongoing ozone review. Background on Ozone and Particulate Matter Ozone and PM are two of six principal pollutants referred to as “criteria pollutants” for which EPA has promulgated NAAQS under the CAA (42 U.S.C. 7408(a)(1). Ground-level ozone, the primary component of smog, is formed when nitrogen oxides (NOx) react with volatile organic com