Emissions From Catalyst Equipped California Cars in Customer Service

The in-use performance of emission control systems on California passenger cars is monitored by annual surveillance programs where consumer-owned cars are emission tested at the California Air Resources Board’s Haagen-Smit Laboratory. Recently, the third catalyst vehicle surveillance program was completed and the Air Resources Board now has sufficient data to update the “emission factors” for the catalyst equipped California cars which have been estimated by the U.S. Environmental Protection Agency. Analysis of in-use surveillance data suggest that the EPA emission factors under-predict hydrocarbon emissions for California cars and that they over-predict carbon monoxide and oxides of nitrogen emissions. In addition, a significant benefit is shown for an annual inspection and maintenance program.