Impacts of the differences in PM air quality improvement on regional transport and health risk in Beijing-Tianjin-Hebei region during 2013-2017.

Due to the implementation of different air pollution control measures in the Beijing-Tianjin-Hebei (BTH) region during 2013-2017, the air quality exhibited varied improvements in each province, indicating substantial changes in the interprovincial regional transport of PM. In this study, we investigated these changes by using the Community Multiscale Air Quality (CMAQ) model coupled with the integrated source apportionment method (ISAM) during this period. The results showed that the concentrations of primary particles, SO, and NO decreased by 41.5, 40.8, and 1.8%, respectively due to the air pollutants emission reduction. Local air pollutant emissions were the predominant contributors of PM for each region in BTH, accounting for 41.3-47.6, 38.1-40.6, 50.6-53.6, and 54.0-57.1% of PM in Beijing, Tianjin, and northern and southern Hebei, respectively. Total PM has been mitigated by 7.1-12.3 and 5.1-11.7 μg/m from local and regional emission reduction, respectively in the BTH. Moreover, diverse local meteorological conditions variation increased the PM concentration by 5.3 μg/m in Tianjin and decreased it by 7.6, 2.0, and 4.9 μg/m in Beijing, and northern and southern Hebei, respectively. Estimation by integrated exposure-response function revealed that the number of premature deaths attributable to PM exposure decreased by approximately 3000 in the BTH region during 2013-2017. Additional policies that focus on PM-O coordinated control and stringent regional joint air pollution regulation are required to substantially reduce the health impacts, especially in southern Hebei.