Donald H. Stedman

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A multiyear, on-road emission measurement program carried out in the cities of Chicago, Illinois; Denver, Colorado; Los Angeles (LA), California; and Phoenix, Arizona shows large, fuel-specific tailpipe emissions reductions at all of the sites for carbon monoxide (CO), hydrocarbons (HC), and nitric oxide (NO). CO emissions decreased between 56% (Denver) and(More)
Acid deposition and photochemical smog are urban air pollution problems, and they remain localized as long as the sulfur, nitrogen, and hydrocarbon pollutants are confined to the lower troposphere (below about 1-kilometer altitude) where they are short-lived. If, however, the contaminants are rapidly transported to the upper troposphere, then their(More)
The University of Denver has completed the first five years of a multi-year remote sensing study in the Chicago area, with measurements made in the first four and sixth years. The remote sensor used in this study is capable of measuring the ratios of CO, HC, and NO to CO 2 in motor vehicle exhaust. From these ratios, we calculate the percent concentrations(More)
Emission inventories from mobile sources have traditionally been obtained through computational modeling. This method, however, has intrinsic shortcomings in that the factors used incorporate only a limited amount of real-world observations. The agreement between model predictions and measurements has often been poor. Recently, a fuel-based method of(More)
Increases in the number of winter visitors to Yellowstone National Park during the past decade have raised concerns over the environmental impacts of snowmobiling in the park. During the 1998-99 season, more than 62,000 snowmobile and 1300 snow coach trips entered the park. Using the University of Denver's vehicle exhaust remote-sensing equipment, 1385(More)
The University of Denver conducted a five-day remote sensing study in the Chicago area in the fall of 1997. The remote sensor used in this study is capable of measuring the ratios of CO, HC, and NO to CO 2 in motor vehicle exhaust. From these ratios, we calculate the percent concentrations of CO, CO 2 , HC and NO in motor vehicle exhaust which would be(More)
Recent U.S. Environmental Protection Agency emissions regulations have resulted in lower emissions of particulate matter and oxides of nitrogen from heavy-duty diesel trucks. To accelerate fleet turnover the State of California in 2008 along with the Ports of Los Angeles and Long Beach (San Pedro Bay Ports) in 2006 passed regulations establishing timelines(More)