Effect of ambient temperature and E-10 fuel on primary exhaust particulate matter emissions from light duty vehicles

During the winter of 1994-1995, the State of Alaska Department of Environmental Conservation conducted a multifaceted program designed to evaluate the impact of switching from regular gasoline to an E-10 fuel (gasoline with 10% ethanol) in Fairbanks. As part of that program, 10 in-use vehicles were tested on a chassis dynamometer at temperatures of 20, 0, and -20 degrees F using both fuels. Three of these vehicles were retested in the EPA facilities at Research Triangle Park, NC, under the same conditions. Vehicles were driven over the Urban Dynamometer Driving Schedule of the Federal Test Procedure during testing. PM-10 exhaust emission samples were collected at Fairbanks, and total particulate samples were obtained at the EPA. Results from both parts of this study indicate that particulate matter (PM) emission rates increased with decreasing temperature for both fuels. The increase occurred primarily during cold starting and is assumed to be due to enrichment. Particulate matter emission rates during operation on the E-10 fuel were lower relative to rates obtained during operation on the base gasoline. Exhaust hydrocarbon and PM emissions were well correlated, suggesting that fully phased-in Federal Tier 1 vehicle emission standards will reduce PM emissions from new vehicles and that rich-operating, high emitters can be expected to have high PM emissions.