Modeling the effects of urban form on ventilation patterns and traffic-related PM2.5 pollution in a central business area of Bangkok

Traffic-related PM exposure is a significant concern in several cities. This study used ENVI-met simulation to perform the airflow and PM2.5 dispersions in Bangkok's central business district during summer. The impact of urban forms and traffic pollution on airflow and PM2.5 distributions was assessed using correlation analysis. Results showed that during summer, road traffic contributed to urban PM2.5 concentrations. Sky view factor and road area significantly affected wind speeds and PM2.5 concentrations, and these two parameters positively correlated. High wind speeds and PM2.5 concentrations were found in the urban main road, while those levels in the areas far from the road dropped by 50% due to building obstacles. Large open spaces (high sky view factor) could improve wind speeds in inner-city areas by 63%. Based on wind and PM2.5 performance classification, this study introduced new performance-based zoning, including five subzones with design recommendations. Urban planners and architects can use this information to improve pedestrian wind comfort and control air pollution dispersion from road traffic.