The control of motor-vehicle-related air pollution

Motor vehicles are major sources of air pollution in cities. This paper identifies the principal motor-vehicle-related air pollutants, summarizes their harmful effects, and describes ways of reducing their emissions. The relation of emissions reduction measures to measures for reducing congestion and conserving energy also is discussed. Quantitative estimates of the emissions reduction effectiveness of various control measures are presented. It is concluded that transportation and traffic management can achieve large reductions in motor vehicle emissions in small areas within cities. The most effective means of reducing motor vehicle emissions on an urban regional or larger scale are new-vehicle emissions controls and improved maintenance of in-use vehicles.