Is atmospheric oxidation capacity better in indicating tropospheric O formation?

Tropospheric ozone (O) concentration is increasing in China along with dramatic changes in precursor emissions and meteorological conditions, adversely affecting human health and ecosystems. O is formed from the complex nonlinear photochemical reactions from nitrogen oxides (NO = NO + NO) and volatile organic compounds (VOCs). Although the mechanism of O formation is rather clear, describing and analyzing its changes and formation potential at fine spatial and temporal resolution is still a challenge today. In this study, we briefly summarized and evaluated different approaches that indicate O formation regimes. We identify that atmospheric oxidation capacity (AOC) is a better indicator of photochemical reactions leading to the formation of O and other secondary pollutants. Results show that AOC has a prominent positive relationship to O in the major city clusters in China, with a goodness of fit ( ) up to 0.6. This outcome provides a novel perspective in characterizing O formation and has significant implications for formulating control strategies of secondary pollutants.