Pollution status and spatio-temporal variations of ozone in China during 2015—2016

In order to further understand the general characteristics of temporal and spatial changes of O₃ pollution in mainland China, the analysis of 336 cities in O₃ routine monitoring during 2015 to 2016 was analyzed by means of time-space statistical analysis and GIS technology. The temporal and spatial distribution of O₃ concentration and different pollution days were analyzed. And the differences of O₃ concentration inside and outside the area of "three districts and ten groups" were especially compared. The results show that the annual mean O₃ concentration of 258 cities in 2016 is higher than that in 2015, and formed a new O₃ pollution spatial pattern. That is, O₃ pollution in the Beijing-Tianjin-Hebei region, Shandong urban agglomeration, Yangtze River Delta region, Henan urban agglomeration, and Wuhan and surrounding urban agglomeration is obviously aggravated (especially, Yangtze River Delta region and Shandong urban agglomeration are China's O₃ core pollution areas); the concentration of O₃ in several rural areas such as Tibet Plateau, Yunnan-Guizhou Plateau and the west bank of the Straits is always low; but at the same time, Shaanxi Guanzhong city group, Shanxi city group and Anhui city group formed a new O₃ heavily polluted space pattern. The spatial distribution of O₃ shows strong correlation with the spatial distribution of NO_x emission and O₃-NO_x-VOCs sensitivity. Previous studies showed that the O₃ generation control of most areas in China belonged to the VOCs control type, while the suburban spots in the North China Plain and Sichuan basin were NO_x control type. The results of the study are helpful to evaluate the differences of O₃ pollution characteristics inside and outside the national air pollution prevention and control area directly from the macroscopic point of view, so as to carry out the prevention and control of environmental pollution.