Policy Effect Evaluation of the Centralization of Environmental Supervision Authority: Evidence from China’s Central Environmental Protection Inspection

The Central Environmental Protection Inspection (CEPI) represents a landmark institutional arrangement for the centralization of environmental supervision authority from local governments to the central government. It has played a significant role in correcting the distortion of local government incentives for environmental governance under decentralized management. However, the persistence and spatial heterogeneity of its policy effects remain to be further examined. This paper treats the CEPI, which was progressively implemented from 2016, as a quasi-natural experiment of centralizing environmental supervision authority. Using daily city-level panel data from 333 Chinese cities over the period 2015–2022, we employ a multi-cutoff time regression discontinuity design in time to evaluate its policy effects. The findings are threefold. First, the CEPI significantly reduces urban concentrations of AQI, PM2.5, PM10, SO2, NO2, and CO, while O3 concentrations increase significantly over the same period, indicating that the centralization of supervision authority is effective in mitigating conventional primary pollutants but faces limitations in addressing secondary pollutants. Second, the policy effects vary across inspection rounds, with the first round and the “look-back” generating larger short-run coefficients than the second round. These differences in short-run inspection-period coefficients across rounds indicate that marginal policy responsiveness diminishes as the inspection program becomes institutionalized. Third, the policy effects display significant spatial heterogeneity: cities in northern regions, resource-based cities, and cities with historically moderate air quality experience more pronounced improvements, while the grouping effect of administrative hierarchy is not statistically significant for most pollutants. This indicates that the governance effects of centralizing supervision authority vary across city characteristics but do not simply follow an administrative hierarchy gradient. This study provides empirical evidence for understanding the boundary of the effectiveness of centralizing environmental supervision authority and offers policy implications for optimizing the vertical allocation of environmental governance responsibilities.