ON-ROAD CARBON-MONOXIDE EMISSION MEASUREMENT COMPARISONS FOR THE 1988-1989 COLORADO OXY-FUELS PROGRAM

The University of Denver's remote sensor for carbon monoxide has been used to perform a study of CO emissions from in-use vehicles during the State of Colorado's 1988-1989 Oxygenated Fuels program. More than 117000 vehicle exhaust measurements were performed on warm vehicles at two locations in the Denver area, with more than 4900 vehicles identified by make and model year through license plate registration information. The results for the oxygenated fuels period show a statistically significant decrease in average CO emissions of 16 ± 3% at both locations. This decrease is shown to be independent of initial emissions for the dirtiest 25% of the fleet and not significant for the cleanest 75%. The decrease is shown not to be attributable to location, vehicle load, speed, fleet mix, fleet age, or age distribution changes. Less than 10% of the vehicles account for half of the CO emissions. Very few of these (0.3%) are less than 2 model years old, but a sizable fraction (26%) are 1983 model year and newer. © 1990, American Chemical Society. All rights reserved.