How does the impact of a two-stage air pollution control policy on air quality different? Evidence from 258 cities in China

Air pollution control has become a core task in the construction of China's ' s " ecological civilization". " . From 2013 to 2020, the Chinese government successively implemented two consecutive environmental management policies targeting air pollution, namely the Air Pollution Prevention and Control Action Plan (APPCAP) and the Blue Sky Defense War (BSDW). To compare and analyze the effects of these two consecutive policies on air pollution control and their differences in governance mechanisms, this paper employs daily air pollution data from 258 cities in China from January 2013 to September 2020 for empirical analysis. We examines the direct impact of the two-stage policies on air pollution and explores the impact mechanisms from three aspects: technological effects, structural effects, and scale effects. The results indicate: (1) Both APPCAP and BSDW significantly reduced AQI, PM2.5, 2.5 , PM10, 10 , SO2, 2 , nitrogen dioxide, and CO. (2) Compared to APPCAP, BSDW had a stronger effect on reducing nitrogen dioxide and managed O3 3 in coordination. (3) APPCAP did not have significant impacts on technology, scale, and structure effects, whereas BSDW significantly promoted technological innovation and industrial restructuring but significantly suppressed the scale effect. Our work provides new empirical evidence for the policy heterogeneity in air pollution control and offers useful policy implications for improving air quality and coordinated pollution control.