With the rapid industrial development and urbanisation in China, nitrogen dioxide (NO 2) pollution has become a severe environmental problem that threatens public health. Based on hourly concentration monitoring data of the six main air pollutants in mainland China, a space–time Bayesian hierarchy model was employed to analyse the spatiotemporal trends of the absolute and relative NO 2 concentrations (i.e., the proportion of NO 2 in the six main air pollutants: CO , NO 2 , PM 2.5 , PM 10 , O 3 , and SO 2 ). Both the absolute and relative NO 2 concentrations were higher in the autumn and winter of each year during the study period. Four regions in particular—the North China Plain, the Yangtze River Delta, the Sichuan Basin, and the Pearl River Delta—experience the largest amounts of NO 2 pollution, with a high local magnitude of more than 1.0 relative to the overall absolute and relative NO 2 concentrations; this affects an area with a human population of 571.85 million, which is 42.47% of the total population. Central China (i.e., the Shaanxi–Shanxi–Henan region) and the Tarim Basin (northwest of Xinjiang) were heavily polluted by NO 2 and other pollutants throughout the year, with a high local magnitude of more than 1.0 relative to the overall absolute NO 2 concentration. The NO 2 pollution in most of the cities in western and southern China is less serious, along with cities in the northeast. Local trends reveal that in general, cities with high NO 2 pollution are accompanied by upward trends. Specifically, except for in the summer, there were about 86 cities showing the increasing trend, of which 66 cities are located in areas with higher absolute and relative NO 2 concentrations. Taiyuan, for example, represents the maximal local trend, with an average annual increase of 4.39 (95% CI 1.61–7.43) μ g / m 3 and 0.43 (95% CI 0.16–0.73) %, respectively, which will lead to further increases in the population exposure-risk in heavily polluted areas. [ABSTRACT FROM AUTHOR]
Copyright of Environmental Monitoring & Assessment is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
