How Effective Is Traffic and Production Restriction for Air Pollution? Evidence From a Quasi-natural Experiment in China

Abstract Air pollution seriously affects human health. The traffic and production restriction is widely used for controlling heavy air pollution. However, the effectiveness of these two policies has not been scientifically verified through a city-level study. COVID-19 pandemic caused lockdowns in many cities, which makes it possible to verify the effectiveness of these two policies. Taken Wuhan as the study area, this study firstly verifies the existence of lockdown effect on air pollution and analyzes the evolution rule of six air pollutants (PM 2.5 , PM 10 , NO 2 , SO 2 , CO and O 3 ) using statistical methods. Then the structural break points in six air pollutants are detected with the regression discontinuity design model. Because Spring Festival overlapping COVID-19 may also affect the air pollution, in order to avoid the disturbance of Spring Festival on the results, the Spring Festival effect is also validated. The results illustrate that the effects of traffic and production restriction on six air pollutants are obviously different, in which the concentrations of PM 2.5 , PM 10 and NO 2 decrease significantly, while traffic and production restriction has no apparent effects on SO 2 , CO and O 3 . Moreover, the structural break points are verified in the four air pollutants (PM 2.5 , PM 10 , NO 2 and CO), and the structural break points are caused by lockdown instead of Spring Festival. This study revealed how the traffic and production restriction affected the air pollution at a city level, and provided strong implementation basis to the air pollution control policy.