Assessment of the policy effectiveness of Central Inspections of Environmental Protection on improving air quality in China

Abstract

To address the problems of environmental pollution, from 2015, the Chinese government launched its most stringent environmental supervision program in history, Central Inspections of Environmental Protection, and completed the first round nationwide inspections by the end of 2017. This paper focuses on the impact of this policy shock on air quality based on daily data from 286 cities in China and uses a regression discontinuity design to test the effectiveness of the policy on improving air quality. Cross-city analyses suggest that, the overall reduction effects on Air Quality Index (AQI) were not significant. Of the examined pollutants, more substantial reductions in SO2 and PM10 concentrations, by 6.3%–7.7% and 3.3%–5.4%, respectively, were observed immediately after the policy implementation. However, the reduction effects on PM2.5, CO, and NO2 were not significant, and no reduction effect was observed for O3. City-specific analyses show that most of the cities that experienced statistically significant policy effects are located in North China and feature high baseline pollutant concentration levels. The early warning effect and persistence of the effect of the policy were also discussed. On the one hand, significant reductions in NO2, CO, and SO2 occurred 6 weeks, 4 weeks, and 2 weeks, respectively, prior to the entry dates of the inspection team. On the other hand, the policy effects decayed significantly immediately after the “on-site” inspection ended. This study implies that a sustainable environmental governance system is necessary and that applying a regression discontinuity design based on high-density time series data is valid for environmental policy evaluation.