Spatiotemporal trends of PM2.5 concentrations and typical regional pollutant transport during 2015–2018 in China

Abstract China has suffered extremely serious and sustained haze in recent years, and this haze has led to growing public concern about air quality. Based on the data from 1497 national environmental monitoring stations, the kriging interpolation method and HYSPLIT model was used to analyze spatiotemporal trends and typical regional pollutant transport in China from 2015 to 2018. The results indicated that the average PM2.5 concentration in China reached 44.43 μg·m−3, and the proportion of areas with levels below Chinese Ambient Air Quality Standards (CAAQS) Grade II (35 μg·m−3) increased in the past 4 years from 31.70% to 53.70%, particularly in the North China Plain (NCP). The PM2.5 concentrations in country and divisions of NCP, Junggar Basin (JB), other regions of China (ORC) showed a U-shaped seasonal and monthly trend of high values in winter and low values in summer and a yearly trend of continuous decline. Tarim Basin (TB) was affected by increasing dust fall with the highest values in spring, and the Fenwei Plain (FWP) was affected by combustion and topography with increases in spring and winter during study period. Furthermore, SJZ (Shijiazhuang) and XA (Xi'an) were selected as representative cities in the NCP and FWP to study regional pollutant transport. And the pollution in the XA mainly comes from local sources in all seasons, while the pollution in the SJZ is mainly from Shanxi Province in winter and from local sources in summer. The findings provide a useful reference for improving regional air quality management.