Effects of air environmental audit on reducing air pollutant emissions: evidence from China

In order to mitigate air pollution, governments have implemented various active measures for air pollution prevention and control, among which the air environmental audit is an essential supervision initiative of air environmental regulation policy. This study aims to focus on and investigate the role of air environmental audit in national governance systems by collecting panel data on air environmental audits and air pollutant emissions from 261 prefecture-level cities across China between 2004 and 2018. Using difference-in-differences (DID) models, we empirically analyzed the policy effects of air environmental audits on reducing air pollutant emissions. The results indicate that air environmental audits have a significant impact on reducing air pollutant emissions, which is robust under multiple scenarios, including propensity score matching and placebo tests. The effect of air environmental audits varies significantly among different air pollutants, with the most significant and rapid effect observed on PM2.5 concentration, while industrial sulfur dioxide and industrial smoke (dust) emissions exhibit a time lag. Moreover, the promotion effect of air environmental audits on air pollution control displays strong heterogeneity based on local economic levels, initial environmental quality, and government competition. Therefore, it is of great significance to intensify the implementation of air environmental audits for air pollution control and to promote and improve the audit work according to pollutant classification and local conditions, thereby fully leveraging the audit's role and further improving air quality continuously.