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Emission data were developed from a sample of resident vehicles in Leadville, Colo. at a nominal elevation of 10,000 ft. above sea level. Emissions-concentration sampling was performed on each vehicle in the sample at loaded and unloaded engine operating conditions. Concentration data were then converted to mass data using equations developed from keymode and mass emissions testing of vehicles operating in the Denver area. Mass emissions data were then combined with mass data developed from vehicles operating in a metropolitan area situated near sea level (Chicago) to define the emissions versus altitude relationships for exhaust hydrocarbons (HC), CO, and NOx. Both mass CO emissions and CO emissions at idle were found to be lower from 1967 and older model-year vehicles operating in the Leadville area than from a similar sample of vehicles operating in the Denver area. A minimum HC/CO idle emission standard appears to be impractical for statewide application. /GMRL/

Three production cars and seven cars with various experimental exhaust emission control systems were tested to determine the effect of winter weather ambient temperatures on exhaust emissions. All of the cars were tested at 70, 40, and 20 degrees F, and one was tested at O degrees F using the 1972 EPA test schedule. Modal and bag emission data as well as catalytic converter temperature data were obtained. There was an increase in HC and CO emissions as ambient temperature was reduced. NO emissions emissions did not vary substantially with ambient temperature. /GMRL/

Dispersal of jet aircraft exhaust emissions near airports and of smoke trails in upper atmosphere, assessing pollutant levels near large urban airports