Speed-dependent emission of air pollutants from gasoline-powered passenger cars

In Korea emissions from motor vehicles are a major source of air pollution in metropolitan cities, and in Seoul a large proportion of the vehicle fleet is made up of gasoline-powered passenger cars. The carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NOx) and carbon dioxide (CO ₂) contained in the exhaust emissions from 76 gasoline-powered passenger cars equipped with three-way catalysts has been assessed by vehicle speed, vehicle mileage and model year. The results show that CO, HC, NOx and CO CO ₂ emissions remained almost unchanged at higher speeds but decreased rapidly at lower speeds. While a reduction in CO, HC and NOx emissions was noticeable in vehicles of recent manufacture and lower mileage, CO CO ₂ emissions were found to be insensitive to vehicle mileage, but strongly dependent on gross vehicle weight. Lower emissions from more recent gasoline-powered vehicles arose mainly from improvements in three-way catalytic converter technology following strengthened emission regulations. The correlation between CO CO ₂ emission and fuel consumption has been investigated with a view to establishing national CO CO ₂ emission standards for Korea.