A review of surface ozone source apportionment in China

Air pollution caused by particulate matter has significantly improved in China in recent years since the implementation of a series of stringent clean-air regulations. However, surface ozone concentrations have increased, especially in developed city clusters, such as the Beijing–Tianjin–Hebei, Yangtze River Delta, Pearl River Delta, and Sichuan Basin regions. Due to the complexity and nonlinearity of the ozone formation, accurately locating major sources of ozone and its precursors is an important basis for the formulation of cost-effective pollution control strategies. In this paper, the authors systematically summarize the reported results and outcomes of the methods and main conclusions of ozone source apportionment (regions and categories) in China from the published literature, based on observation-based methods and emission-based methods, respectively. The authors aim to provide a comprehensive understanding of ozone pollution and reliable references for the formulation of air pollution prevention policies in China.