Impact of spatial structure of urban agglomerations on PM2.5 pollution：Based on resource misallocation.

The spatial structure of urban agglomerations affects the economic development and environmental conditions of urban agglomerations. Severe air pollution makes green development an empty talk, and how the spatial structure of urban agglomerations affects air pollution is an urgent problem to be solved in pursuit of high-quality economic development. The panel data of 20 urban agglomerations in China from 2002 to 2017 are used to test how the spatial structure of urban agglomerations affects regional PM2.5 concentration in resource misallocation mediation effect. The empirical results show that (1) most urban agglomerations are polycentric, and only Guanzhong, Poyang Lake Ring, Wuhan and Nanqin Beifang urban agglomerations are monocentric. (2) The spatial structure and PM2.5 concentration have U-shaped characteristics, with the inflection point of centrality equal to 1. To reduce PM2.5 concentration in polycentric urban agglomerations can be achieved by increasing the centrality, while the opposite is true for monocentric urban agglomerations. (3) Improving the resource allocation of urban agglomerations can reduce PM2.5 concentration. The spatial structure of urban agglomerations with a limited degree of centrality can improve the resource allocation of urban agglomerations and further reduce PM2.5 pollution. This also indicates to a certain extent that a reasonable spatial structure of urban agglomerations is conducive to optimizing resource allocation and improving air pollution.