Surface ozone pollution in China: Trends, exposure risks, and drivers

IntroductionWithin the context of the yearly improvement of particulate matter (PM) pollution in Chinese cities, Surface ozone (O-3) concentrations are increasing instead of decreasing and are becoming the second most important air pollutant after PM. Long-term exposure to high concentrations of O-3 can have adverse effects on human health. In-depth investigation of the spatiotemporal patterns, exposure risks, and drivers of O-3 is relevant for assessing the future health burden of O-3 pollution and implementing air pollution control policies in China. MethodsBased on high-resolution O-3 concentration reanalysis data, we investigated the spatial and temporal patterns, population exposure risks, and dominant drivers of O-3 pollution in China from 2013 to 2018 utilizing trend analysis methods, spatial clustering models, exposure-response functions, and multi-scale geographically weighted regression models (MGWR). ResultsThe results show that the annual average O-3 concentration in China increased significantly at a rate of 1.84 mu g/m(3)/year from 2013 to 2018 (160 mu g/m(3)) in China increased from 1.2% in 2013 to 28.9% in 2018, and over 20,000 people suffered premature death from respiratory diseases attributed to O-3 exposure each year. Thus, the sustained increase in O-3 concentrations in China is an important factor contributing to the increasing threat to human health. Furthermore, the results of spatial regression models indicate that population, the share of secondary industry in GDP, NOx emissions, temperature, average wind speed, and relative humidity are important determinants of O-3 concentration variation and significant spatial differences are observed. DiscussionThe spatial differences of drivers result in the spatial heterogeneity of O-3 concentration and exposure risks in China. Therefore, the O-3 control policies adapted to various regions should be formulated in the future O-3 regulation process in China.