Abstract: Unlike conventional environmental regulations and policies, the central environmental protection inspection is carried out in a campaign style, so its impact on the environmental quality of the inspected cities is worth studying. In order to explore when the central environmental protection inspection will play its role, this paper focuses the time-lag effect of the central environmental protection inspection. Based on the data of 287 prefecture-level cities in China from 2012 to 2019, the two-way fixed effects model is used to analyze the central environmental protection inspection's time-lag effect and the mechanism of its influence on urban environmental quality. Results show that: (1) there is time-lag effect in policy effect of the central environmental protection inspection and the time-lag effect on the emission reduction of different pollutants is heterogeneous in time and space; (2) the central and western regions show significant characteristics of campaign-style, and the central environmental protection inspection has a U-shaped impact on gaseous pollutants in the central and western regions; and (3) for different pollutants in cities with different scales of economy, the central environmental protection inspection plays its role at different time. Finally, based on the above conclusions, related policy recommendations are put forward.

Key words: the central environmental protection inspection, time-lag effect, urban environmental quality, campaign-style governance