Investigating the relationship between air pollution variation and urban form

Air quality in megacities and its correlation with urban form have become a priority, since numerous cities worldwide are encountering a development bottleneck due to air pollution. This paper analyzed the spatial variations in 8 air pollutants among 18 ambient air monitoring stations across Shanghai based on continuously hourly mass concentration data from 28 days in February 2017. In each of the 18 stations, we created a buffer zone with a radius of 1 km, and derived 18 quantified features of the urban form including points of interest and environmental information by the geographic information system and the Baidu Map program interface. Then, the 18 stations were clustered into 3-level groups by using the k-nearest neighbor method according to every pollutant and urban form. Results showed that the spatial variation differed per pollutant, as did urban form. PM_2.5 concentrations were high in the western and low in the eastern of Shanghai, which can be explained by regional influences and the distance from East China Sea. PM₁₀ showed a relatively high level in the developed urban areas, and high buildings with a similar height in these areas significantly restrain the dispersion of PM₁₀. The spatial variations of the 6 gaseous pollutants mainly depend on local human activities and transport-related emissions. The distance to primary road, standard deviation of building floors, and average building floors were the top 3 urban form features influencing the spatial variations of all pollutants. Wind ventilation was identified as a critical index for air quality-oriented urban design.