Urban configuration and PM_2.5 concentrations: Evidence from 330 Chinese cities

Preventing high concentrations of fine particulate (PM_2.5) to realize the goal of sustainable development is becoming a challenge for rapidly urbanized cities. Increasing vehicle emission due to inefficient urban form is thought to be the main cause of traffic congestion and increased PM_2.5 concentrations. Previous efforts attributing PM_2.5 concentrations to urban forms are yet to reach consistent conclusions on practical environmental protection strategies. In this study, we considered urban compositions and their spatial configuration to propose a new measurement-urban configuration-and document the effects of urban configuration on PM_2.5 concentrations. Using 330 Chinese cities as our sample, we found that the areas of two types of urban facilities, namely, residence and industry, are positively related to PM_2.5 concentrations, and the area of public service facilities is negatively related to PM_2.5 concentrations. Regarding the spatial configuration of different urban compositions, we documented that residence-industry accessibility is a key factor of PM_2.5 concentrations and plays a more important role than the residence-commerce accessibility. We also compared the influence of two accessibility indices (distance- and gravity-based accessibilities) and further found that the effect of reducing the residence-industry distance is more remarkable than the effect of increasing residential or industrial area on reducing PM_2.5 concentrations. Our results indicate that the key to reaching sustainable urban expansion is to synchronize urban constructions with spatial configuration optimization. For Chinese cities, a 7.52% increase in residence area requires at least 1% decrease in the average residence-industry distance to eliminate the incremental effects of newly constructed residential region on PM_2.5 concentrations. This study casts new light on the relationship between urban configuration and PM_2.5 concentration and provides decision makers practical and realistic approaches in realizing sustainable development goals.