Urban Form and Environmental Characteristics as Drivers of Air Pollution Exposure Variability and Inequality in Fujian Province, China.

Air pollution, particularly fine particulate matter, poses significant health and environmental risks, with exposure levels exhibiting considerable spatial inequality. However, few studies have comprehensively examined how urban form and environmental factors influence air pollution exposure and its spatial inequality. This study investigates how urban and environmental factors affect particulate matter pollution (PM, PM, and PM) and its spatial inequality across 85 counties in Fujian, China. Twelve indicators across urban form, socio-economic, and environmental domains were analyzed using principal component analysis and partial correlation networks. Our results show that while overall air pollution levels exhibit substantial variability, spatial inequality in exposure does not always correlate directly with these levels. Notably, while urbanized counties display higher pollution exposure, significant disparities in pollution distribution are observed within regions of similar pollution levels. Urban and socio-economic features such as population density and road density are strongly correlated with higher pollution exposure, especially in more urbanized areas. In contrast, environmental factors, such as vegetation coverage and precipitation, significantly mitigate pollution levels. Principal component analysis reveals that development density and environmental changes primarily drive overall pollution levels, while economic activity and segregation contribute to the spatial inequality of exposure. Network analysis further corroborates that high-density urban development exacerbates pollution exposure, while socio-economic segregation contributes to uneven distribution across the population. Our findings underscore the need for integrated urban planning strategies that address these urban and environmental factors to reduce air pollution inequality and promote more equitable urban environments.