The influence of roadside green belts and street canyon aspect ratios on air pollution dispersion and personal exposure

Abstract

Vehicle exhaust emissions are major sources of air pollution in urban areas. This study investigates the influence of roadside green belts, spatial urban street layout, and wind speed on the dispersion of vehicle exhaust emissions in street canyons using numerical simulations. Personal daily mean pollutant intake was calculated to assess the extent of exhaust exposure in street canyons. Results showed that pollutant levels decreased with tree spacing, with the optimal spacing being 0.4 times the building height. The recommended aspect ratio of street canyons was less than 0.67. Setting green belts in the center of roads and near the leeward side of buildings is beneficial for pollutant dispersion from street canyons. These results can be used to effectively improve the air quality in street microenvironments, provide pollution protection for low-rise dwellers and pedestrians, and provide a basis for reconstructing and modifying old street buildings.