Abstract |
Ambient air samples from 44 sites in 39 U.S. urban areas were collected in electropolished, stainless steel canisters on week days from 6 to 9 am during June through September of 1984, 1985, and 1986. Not all sites were sampled all years. Samples were analyzed by capillary gas chromatography with flame ionization detection to determine C2 to C12 volatile hydrocarbon composition. Benzene, which is carcinogenic and present in automobile exhaust and gasoline, was present in every sample. Individual sample concentrations ranged from 1.0 parts-per-billion as carbon (ppbC) to 273 ppbC. The benzene median concentrations by site and year ranged from 4.8 ppbC to 35.0 ppbC with the overall median being 12.6 ppbC. |