Mortality Risk Associated with Short-Term Exposure to Particulate Matter in China: Estimating Error and Implication

Most previous studies used a specific size of particulate matter (PMx) for dosimetry estimation when determining particulate matter (PM)-associated risk, which precluded the impact of other sizes of PM. Here, we used a multiple-path particle dosimetry model to determine the deposition of PM in human airways and further estimated the associated mortality risk in 205 cities in China. Results showed that the fractions of PM1, PM1-2.5, and coarse PM (PM2.5-10) deposited in the tracheobronchial (TB) and pulmonary airways were estimated in ranges of 11.06-12.83, 19.9-26.37, and 5.35-9.81%, respectively. Each 10 μg/m3 increase in deposited PM was significantly associated with a nationwide increment of 1.12% (95% confidence interval, CI, 0.77-1.49%) for total nonaccidental mortality. Short-term exposure to PM during 2014-2017 resulted in a nationwide mortality of 98 826 cases/year, with contributions from PM1, PM1-2.5, coarse PM of 37.7, 43.1, and 19.2%, respectively. Our study demonstrated that the estimated mortality counts may be associated with the coefficient of variation of dosimetry estimations. In addition, we revealed the caution should be exercised when interpreting PMx-associated risk and further reinforced the importance of size distribution in relevant research.