ABSTRACT

Pollution from motor vehicles has become an issue simply because of the steady increase both in the number of vehicles in use and the distance travelled by each vehicle each year. During the past 50 years, mobile sources have taken over from static combustion of fossil fuel as the major threat to air quality. There are four main polluting emissions from motor vehicles: carbon monoxide, nitrogen oxide, hydrocarbons and particles. This chapter discusses the sources and control of motor vehicle emissions as a group, because the pollutants are emitted together. When the mixture of hydrocarbons and air in the combustion zone is burned, reactions proceed at different rates for the different components. The chemical reactions occurring on the catalyst surfaces are combustions, and the temperature has to be high enough for these to occur. Vehicle maintenance is a major factor in emission control. In extreme cases, contamination of the catalyst by lead can render the converter useless very quickly.