Abstract |
Studies of human exposure to acid aerosols have been underway for several years, leading to the need to intercompare measurement methods for acidic aerosol concentrations. Over the past few years the U.S. EPA has sponsored several intercomparisons of the methods in use. The studies have included single component aerosols of sulfuric acid and ammonium bisulfate, photochemical aerosols, a sequence of compounds chosen to test for on-filter neutralization by ammonium nitrate, the addition of alkaline dust, laboratory-spiked samples, and atmospheric aerosol samples. These studies were designed to establish both intra- and interlaboratory precision and to attempt to separate the effects of differences in flow rate, extraction, and analysis. |