In-use light-duty gasoline vehicle particulate matter emissions on three driving cycles

Twenty-four properly functioning and six high carbon monoxide emission ligh t-duty gasoline vehicles were emission tested in Denver, CO, using the Fede ral Test Procedure (FTP), a hot start Unified Cycle (UC), and the REP05 dri ving cycles at 35 degreesF. All were 1990-1997 model year vehicles tested o n 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 REP05, respectively. The corresponding valu es for the high emitters were 52, 28, and 24 mg/mi. Use of oxygenated fuel significantly reduces PM10 on the FTP, with all the reduction occurring dur ing the cold start. MOUDI impactor samples showed that 33 and 69% of the PM mass was smaller than 0.1 mum for the FTP and REP05 cycles, respectively, when collected under standard laboratory conditions. Particle number counts were much higher on the REP05 than the FTP. Counts were obtained using sec ondary dilution of samples drawn from the standard dilution tunnel. FTP PM1 0 was mostly carbonaceous material, 36% of which was classified as organic. For the REP05, as much as 20% of the PM10 was sulfate-and associated water . Forty-five percent of the REP05 PM carbon emissions was classified as org anic. Driving cycle had a significant impact on the distribution of the emi tted polynuclear aromatic hydrocarbons.