Comprehensive Insights Into O3 Changes During the COVID-19 From O3 Formation Regime and Atmospheric Oxidation Capacity

Economic activities and the associated emissions have significantly declined during the 2019 novel coronavirus (COVID-19) pandemic, which has created a natural experiment to assess the impact of the emitted precursor control policy on ozone (O₃) pollution. In this study, we utilized comprehensive satellite, ground-level observations, and source-oriented chemical transport modeling to investigate the O₃ variations during the COVID-19 pandemic in China. Here, we found that the significant elevated O₃ in the North China Plain (40%) and Yangtze River Delta (35%) were mainly attributed to the enhanced atmospheric oxidation capacity (AOC) in these regions, associated with the meteorology and emission reduction during lockdown. Besides, O₃ formation regimes shifted from VOC-limited regimes to NO_x-limited and transition regimes with the decline of NO_x during lockdown. We suggest that future O₃ control policies should comprehensively consider the effects of AOC on the O₃ elevation and coordinated regulations of the O₃ precursor emissions.