Environmental pollution and population distribution among districts and counties: Evidence from prefecture-level cities in China

China's unprecedented urbanization has come at the cost of environmental degradation, which increasingly appears to be holding back migration to bustling municipal districts. Escaping from Beijing, Shanghai and Guangzhou has become a hot topic in recent years. But in fact, small and medium-sized cities also show signs of population decentralization. The aim of this paper is to reveal the impact of environmental pollution on the decentralization of urban population in China. Based on the panel data of over 227 prefecture-level cities and municipalities directly under the central government, the sensitivity of municipal population to PM2.5 concentration was empirically studied. The results showed that PM2.5 concentrations generally had the effect of driving away the population of municipal districts, but this was most pronounced in first-tier and fourth-tier cities rather than second-tier and third-tier cities. The panel quantile estimates further confirm this finding that megacities and small and micro cities rather than small and medium-sized cities are more vulnerable to environmental pollution, which is a reminder that Chinese policymakers must not focus on the environmental problems of megacities alone, but must prevent environmental degradation from hollowing out the population of small cities and towns.