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Project at a Glance

Title: On-road motor vehicle emissions including NH3, SO2 and NO2

Principal Investigator / Author(s): Stedman, Donald

Contractor: University of Denver

Contract Number: 07-319

Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels, Monitoring


The three California cities of San Jose, Fresno and west Los Angeles (LA) were visited during March 2008 to remotely collect on-road emission measurements of carbon monoxide (CO), carbon dioxide, hydrocarbons (HC), nitric oxide (NO), sulfur dioxide, ammonia (NH3) and nitrogen dioxide (NO2) from light-duty vehicles. A database for each site was compiled and contains 24,978 records in San Jose, 13,365 records in Fresno and 17,953 records in LA for which the State of California provided registration information. At the San Jose and LA sites repeat measurements of CO, HC and NO show large fuel specific emissions reductions between 1999 and 2008. In Fresno a small fleet of 2007 diesel ambulances was found to have more than 60% of the emitted oxides of nitrogen as NO2. NH3 emissions are again shown to have a strong dependence on model year with NH3 means of 0.49 ± 0.02, 0.49 ± 0.01 and 0.79 ± 0.02 gm/kg of fuel for San Jose, Fresno and LA respectively with the larger in emissions at the LA site likely a result of the more aggressive driving mode.


For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753

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