Spatiotemporal distribution of ground-level ozone in China at a city level

In recent years, ozone (O₃) pollution in China has shown a worsening trend. Due to the vast territory of China, O₃ pollution is a widespread and complex problem. It is vital to understand the current spatiotemporal distribution of O₃ pollution in China. In this study, we collected hourly data on O₃ concentrations in 338 cities from January 1, 2016, to February 28, 2019, to analyze O₃ pollution in China from a spatiotemporal perspective. The spatial analysis showed that the O₃ concentrations exceeded the limit in seven geographical regions of China to some extent, with more serious pollution in North, East, and Central China. The O₃ concentrations in the eastern areas were usually higher than those in the western areas. The temporal analysis showed seasonal variations in O₃ concentration, with the highest O₃ concentration in the summer and the lowest in the winter. The weekend effect, which occurs in other countries (such as the USA), was found only in some cities in China. We also found that the highest O₃ concentration usually occurred in the afternoon and the lowest was in the early morning. The comprehensive analysis in this paper could improve our understanding of the severity of O₃ pollution in China.