Outline of a novel method for the prediction of atmospheric pollution dispersal from road vehicles

This paper describes a novel method for the prediction of air pollution concentrations from road vehicles. Individual vehicles are considered as moving point sources, and pollution dispersion is considered in the near and far wake regions. The near wake analysis is based upon the wake theory of Eskridge and Hunt and essentially sets the boundary conditions for the far wake region, which is of more practical importance. In the far wake region the pollutant is considered to disperse as a series of puffs emitted at the boundary with the near wake region. The dispersion parameters are taken as being determined by the size of the near wake and by the stability of the atmosphere. By an addition of the solutions for individual vehicles the pollutant distributions due to streams of traffic can be predicted. The formulae thus derived show the effect of vehicle speed and other parameters on ground-level pollution levels, and suggest that decreasing traffic congestion to increase average vehicle speed may not always result in a decrease in the levels of some pollutants. The deposition of pollutant on the ground is also considered using the concept of dry deposition velocity.