Clean Air Act Determination of Attainment for PM10 Nonattainment Areas; Montana and Colorado

Résumé

EPA is finalizing determinations of attainment for the particulate matter with an aerodynamic diameter less than or equal to a nominal 10 microns (PM 10 ) national ambient air quality standards (NAAQS) for the Whitefish, Montana, Thompson Falls, Montana and Steamboat Springs, Colorado moderate PM 10 nonattainment areas. The Whitefish, Montana nonattainment area was required by the Clean Air Act Amendments (CAAA) of 1990 to attain the PM 10 NAAQS by December 31, 1999. This final determination is based on complete, quality assured ambient air quality monitoring data for the years 1997, 1998, and 1999. The Thompson Falls, Montana and Steamboat Springs, Colorado nonattainment areas were required by the Clean Air Act Amendments (CAAA) of 1990 to attain the PM 10 NAAQS as of December 31, 2000. These final determinations are based on complete, quality assured ambient air quality monitoring data for the years 1998, 1999, and 2000.