Vehicle emissions and evaporative emission control: Secondary pollutant air quality

Abstract

Currently, understanding of the role of motor vehicle exhaust and evaporative emissions in the environment is expanding rapidly. Advantage has been taken of this progress to improve and extend assessments of the impact of motor vehicle emissions on secondary pollutant air quality using a photochemical trajectory model. The results confirm that the Stage I and II provisions of the Luxembourg Agreement dealing with vehicle exhaust emissions will be important to stem further deterioration in secondary pollutant air quality in the future, taking into account growth in vehicle usage. A detailed treatment of vehicle evaporative emissions has been implemented in the photochemical trajectory model. Controlling evaporative emissions will indeed lead to reductions in peak secondary pollutant concentrations but the benefits are likely to be significantly smaller than from exhaust emission controls. The results of the computer modelling studies are presented for a wide range of photochemically-generated secondary pollutants, including ozone, PAN and hydrogen peroxide, formed in an air parcel as it is carried across the southern British Isles over London in a westerly direction.