Spatiotemporal patterns and quantitative analysis of influencing factors of PM2.5 and O3 pollution in the North China Plain

Abstract

It is of great significance to reveal the spatial-temporal patterns of PM2.5 and O3 collaborative pollution, and the main influencing factors of these two air pollutants in the North China Plain (NCP). Hourly PM2.5 and O3 observations in 355 ground-based sites from 2015 to 2020 was utilized to reveal the spatiotemporal patterns of PM2.5 and O3 collaborative pollution. Subsequently, PM2.5 and O3 ground-based observations and their relative influencing factors were used to build the O3 and PM2.5 estimation model using eXtreme Gradient Boosting model. Then the contribution of each variable was quantitatively evaluated and revealed. The results revealed that PM2.5 and O3 collaborative pollution was mainly concentrated in the central NCP. Daily scale PM2.5 and O3 collaborative pollution mainly occurs in summer, with the highest pollution level occurring in May, June, and July. Hourly-scale PM2.5 and O3 collaborative pollution peaks mainly between 14:00 and 18:00 p.m. In addition, PM2.5 and O3 collaborative pollution level in the NCP decreased by 91.8% from 2015 to 2020. The most leading influencing factors for O3 pollution in the NCP were VOCs and NOX, which contributed 33.13% and 10.57%, respectively, while the top two principal variables for PM2.5 pollution were SOX and NOX, which contributed 13.12% and 12.72% respectively. Generally, the most critical measures to control O3 and PM2.5 pollution in the NCP are to reduce VOCs, NOX and SOX emitted by human activities.