Revealing the impacts of transboundary pollution on PM2.5-related deaths in China.

Long-range transport of air pollutants may cause significant health impacts in the receptor regions. In this study, we calculated the transboundary health impact from different foreign regions using a state-of-the-art air quality model at hemispheric scale. Our results reveal that transboundary PM2.5 pollution from outside China was of great significance, causing 100 thousand (95% CI, 45 thousand-200 thousand) premature deaths in China in 2015, which accounted for 9.60% PM2.5 related premature death in China. The impact of transboundary pollution in China was most significant in winter, in which the average PM2.5 concentration increased by 3.7 μg/m3, and was least significant in summer, with the average PM2.5 concentration increasing by 0.5 μg/m3. Liaoning and Yunnan provinces were extremely susceptible to transboundary pollution, whose annual average PM2.5 concentrations were increased by 10.2 and 11.4 μg/m3 respectively. Among all foreign regions, the impact from South Asia was most significant, causing 30 thousand (95% CI, 12 thousand-62 thousand) premature deaths annually in China. This study only reveals the transboundary impact under the integrated exposure-response (IER) model and fixed meteorology field in 2015. Further studies are needed to investigate how different exposure-response functions and meteorology affect the transboundary PM2.5 pollution and its related death.