Composition of PM2.5 and PM10 Aerosols in the IMPROVE Network

Abstract PM2.5 and PM10 particulate concentrations measured at 42 sites in the Interagency Monitoring of Protected Visual Environments(IMPROVE) network at Class I visibility areas throughout the United States over the 1993 seasonal year showed well-defined regional patterns. The PM2.5 concentration had a large gradient from West to East, averaging 3 μg/m3 in most of the West compared to 13 μg/m3 in the Appalachian region. Coarse particle concentration (2.5-10 μm) exhibited a small gradient from North to South, but no gradient from West to East. No change in PM2.5 or PM10 was observed from 1988 to 1993 for sites with complete records. The elemental concentration (H, Na-Pb) was determined from all PM2.5 Teflon filters and from the PM10 filters from four sites: an eastern and western urban site (Washington, D.C. and South Lake Tahoe) and the nearest Class I site (Shenandoah and Bliss). Soil was the largest component of the coarse particle concentration. Sulfur accounted for 3% of the coarse particle concentr...