Air pollution dispersal in high density urban areas: Research on the triadic relation of wind, air pollution, and urban form

Currently, urban air pollution becoming the major issue of urban physical environment in high density urban area. Many wind-calm zones or vortex zones can be formed where air pollution is retained or concentrated, which affects the environment and human health. To investigate this problem, the authors analyzed changes of wind velocity, direction, and air pollutant flow caused by changes in building height, volume, form, and density using a simulated three-dimensional (3D) conceptual model. The authors conducted an empirical study based on a representative high-density urban area. The results reveal that the actual 3D-simulated environment is complex. The wind environment changes continuously, and the retention or flow of the air pollutants changes drastically as well. The corner wind zones surrounding high-rise buildings may even generate new dust pollution due to the overly high wind speed. In this process, building height volume, layout, and orientation all significantly influence the flow and distribution of air pollution. Based on theoretical and empirical study, this paper discussed spatial planning strategies on the macroscopic city level, mesoscopic block level, and microscopic building level intended to promote the rapid dispersion of air pollutants by controlling the wind environment through optimizing the urban form.