ABSTRACT
Several major classes of air pollutants have the potential to affect the health of populations. These pollutants result either from primary emissions or atmos pheric transformation. Motor vehicles are the major source of a number of these pollutants, in particular, carbon monoxide, nitrogen oxides, unbumed hydrocarbons and lead and, in smaller proportions, suspended particulate matter, sulphur dioxide and volatile organic compounds.They also contribute via atmospheric transformation to increases in ozone and other photochemical oxidants (HEI, 1988). With growing urbanisation and increases in vehicle density, urban air pollution has become a crucial problem, compounded by the great expense of pollution control, and it is now urgent to undertake risk assess ments in order to evaluate and prioritise control strategies.
