This report summarizes air quality monitoring data from Yellowstone National Park during the winter of 2004-2005, and gives a historical perspective of monitoring data. Primarily, it discusses ambient air quality monitoring done at Old Faithful and the West Entrance that measured concentrations of carbon monoxide and particulate matter. The report discusses the trends in air quality that might reflect winter use policy and comparison to the national standards set by the Environmental Protection Agency. Numerous graphs and tables accompany the test.
