This paper considers the importance of road transport as a contributor to air pollution problems. National and international policies to limit traffic pollution have focused on improving the emissions performance by the imposition of stringent standards on road vehicles and the fuels they use. This has achieved considerable success: forecasts of future emissions from road transport indicate that they will reduce substantially and remain well below current levels until well into the next century. It is nevertheless suggested that a number of air pollution problems will continue to be of concern. The paper goes on to discuss the models and procedures available for assessing and forecasting traffic's impacts on air pollution and, in particular, the uncertainties that they contain. These uncertainties are considered in some cases to be substantial, and it is concluded that continuing research and development are necessary to refine the models so that they will provide reliable predictions of air pollution around the road network, giving statistical probabilities of the variation of pollutant concentrations in both time and space. (A)
Abstract