Twenty-four properly functioning and six high carbon monoxide emission light-duty gasoline vehicles were emission tested in Denver, CO, using the Federal Test Procedure (FTP), a hot start Unified Cycle (UC), and the REPOS driving cycles at 35 °F. All were 1990-1997 model year vehicles tested on both an oxygenated and a nonoxygenated fuel. PM10 emission rates for the properly functioning vehicles using oxygenated fuel averaged 6.1, 3.6, and 12.7 mg/mi for the FTP, UC, and REPOS, respectively. The corresponding values for the high emitters were 52, 28, and 24 mg/mi. Use of oxygenated fuel significantly reduces PM{sub}10 on the FTP, with all the reduction occurring during the cold start. MOUDI impactor samples showed that 33 and 69 of the PM mass was smaller than 0.1 μm for the FTP and REPOS cycles, respectively, when collected under standard laboratory conditions. Particle number counts were much higher on the REPOS than the FTP. Counts were obtained using secondary dilution of samples drawn from the standard dilution tunnel. FTP PM{sub}10 was mostly carbonaceous material, 36 of which was classified as organic. For the REPOS, as much as 20 of the PM{sub}10 was sulfate and associated water. Forty-five percent of the REPOS PM carbon emissions was classified as organic. Driving cycle had a significant impact on the distribution of the emitted polynuclear aromatic hydrocarbons.
展开▼
