Directional spatial spillover effects and driving factors of haze pollution in North China Plain

Haze pollution is a serious interregional problem for many countries and wind direction plays a crucial role in the process of pollution transport. Upwind cities have obviously greater impacts on downwind cities due to atmospheric transport. Hence the directions of pollution spillover effects should be emphasized in empirical study to avoid model bias. 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. The results show that wind direction dominates the distribution of PM2.5 concentration. The growth of per capita GDP facilitates the reduction of PM2.5 pollution while the increase of the other socioeconomic factors aggravates haze pollution. Besides, natural factors directly or indirectly affect PM2.5 concentration. Particularly, the spillover effects of socioeconomic factors are greater than their local effects. Based on the results, we suggested that 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.