Enhancing Air Quality in High-Density Cities: Investigating the Link Between Traffic-Related Air Pollution Distribution and Urban Ventilation

Urban traffic-related air pollution has emerged as a significant concern for the physical environment in densely populated urban areas. This study numerically investigates the dispersion of air pollutants and ventilation within typical urban blocks in Shanghai, considering the prevailing annual winds—northerly in winter (4.64 m/s) and easterly in summer (5.85 m/s). Multiple factors influence the dispersion of urban pollution. In this research, we examine the effects of viaducts and urban ventilation corridors, alongside the impact of urban parameters on pedestrian-level ventilation, by analyzing variations in building forms along residential streets in Shanghai. A novel approach for analyzing pollution dispersion is proposed, which involves performing a sensitivity analysis on the buffer radius and mapping various radii onto the C* parameter. The results indicate that: (1) enhancing air fluidity in regions with stagnant winds can be achieved by introducing vertical turbulence; (2) the prevailing wind direction, urban ventilation corridors, and urban permeability play a crucial role in determining the direction of pollutant dispersion at pedestrian levels in densely populated urban environments; (3) the contribution of pollutants released at ground level is significantly higher than those from viaducts at pedestrian height (248.58%). Drawing on both theoretical and experimental research, this study explores the spatial dispersion of air pollutants across various scales, including city-wide, block-level, and building-specific perspectives. The findings provide recommendations for the design of environmentally sustainable urban streets in residential areas.