Particulate Matter (PM2.5) Trends
Under the Clean Air Act, the EPA sets national ambient air quality standards (NAAQS) for particulate matter (PM) at levels that are safe for public health and the environment. PM2.5 describes fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller. Air quality monitors operated by federal, state, local and tribal agencies throughout the country collect ambient measurements of PM2.5 concentrations to ensure that the NAAQS are being met. The charts below based on this measurement data show that nationally, PM2.5 concentrations have decreased over the years. For information on PM standards, sources, health effects, and programs to reduce PM pollution, please see our Particulate Matter Pollution page.
