Directional spatial spillover effects and driving factors of haze pollution in North China Plain
Haze pollution is one of the most serious environmental problems in China and wind direction plays a crucial role in the process of pollution transport. Upwind and downwind cities interact with each other differently, so the directions of spillover effects should be emphasized in empirical study. With the panel data of 44 cities in North China Plain from 2013 to 2017, we constructed a novel wind direction weight matrix to analyze the spatial variations of PM2.5 concentration. The matrix was then incorporated into a spatial panel model to quantitatively evaluate the impacts of socioeconomic and natural factors on PM2.5 concentration. We found that wind direction dominates the distribution of PM2.5 concentration. The increase of GDP per capita reduces PM2.5 concentration while the increase of the other socioeconomic factors raises it. Natural factors directly or indirectly affect PM2.5 concentration. Particularly, the spillover effects of socioeconomic factors are greater than their local effects. Therefore, investment of air pollution control in a neighboring area may be more effective than in the local city itself. The mechanism of pollutant transport should be fully considered in the fields such as the construction of urban air ducts, industrial layout, and eco-compensation.