Ground-level ozone pollution in China: a synthesis of recent findings on influencing factors and impacts

Ozone (O-3) in the troposphere is an air pollutant and a greenhouse gas. In mainland China, after the Air Pollution Prevention and Action Plan was implemented in 2013-and despite substantial decreases in the concentrations of other air pollutants-ambient O-3 concentrations paradoxically increased in many urban areas. The worsening urban O-3 pollution has fuelled numerous studies in recent years, which have enriched knowledge about O-3-related processes and their impacts. In this article, we synthesise the key findings of over 500 articles on O-3 over mainland China that were published in the past six years in English-language journals. We focus on recent changes in O-3 concentrations, their meteorological and chemical drivers, complex O-3 responses to the drastic decrease in human activities during coronavirus disease 2019 lockdowns, several emerging chemical processes, impacts on crops and trees, and the latest government interventions.