Revisiting the environmental Kuznets curve of PM2.5 concentration: evidence from prefecture-level and above cities of China.

In this paper, the panel data of China's four municipalities and 223 prefecture-level cities were used to investigate whether the EKC hypothesis for urban PM2.5 concentration was satisfied, considering such factors as urbanization population, electricity consumption, innovation capacity, and foreign direct investment in the cities. Assuming that the level of economic development directly affects the PM2.5 concentration, and the PM2.5 concentration will continue to increase at the early stage. Once the urban economy develops to a certain extent, the PM2.5 concentration will start to decline, and the environmental quality will be improved. Therefore, we attempt to construct the standard EKC by incorporating the quadratic and cubic terms of GDP per capita. The empirical results show that, except for the four municipalities of Beijing, Tianjin, Shanghai, and Chongqing, economic growth has a complex impact on PM2.5 concentration in most cities during the study period, rather than a simple inverted U-shaped pattern. Moreover, only in recent years has smog pollution shown an average decrease. But if the sources of smog are difficult to explore, it is worth considering the possibility of adjusting economic structure to meet environmental targets.