PM-10 exhaust samples collected during IM-240 dynamometer tests of in-service vehicles in Nevada

Twenty-three vehicles that were recruited by remote sensing and roadside inspection and maintenance (I/M) checks during the 1994 Clark and Washoe Remote Sensing Study (CAWRSS) were tested on the IM240 cycle using a transportable dynamometer. Six of these vehicles emitted visible smoke. Total gas-phase hydrocarbon (HC), carbon monoxide (CO), and nitrogen oxides (NOx) exhaust concentrations were continuously measured in the diluted exhaust stream from the constant Volume sampler (CVS) during IM240 testing. Two isokinetic PM-10 samples were collected simultaneously using cyclones and filter holders connected to a dilution tube. Teflon filters were collected for total mass and then extracted for chloride, nitrate, and sulfate ions. Quartz filters were analyzed by the thermal/optical reflectance method for organic and elemental carbon. The quartz filters and backup vapor traps were then extracted and analyzed by GC/MS far 28 separate polynuclear aromatic hydrocarbons. Mass emission rates of PM-10 per vehicle ranged from 5.6 to over 1300 mg/ml, with most of the mass attributable to carbon. Except far one vehicle with high sulfate emissions, the ion emissions were relatively low. Total PAH emissions were in the range of 10-200 mg/ml.