Longitudinal Impacts of PM 2.5 Constituents on Adult Mortality in China.

Limited evidence exists for long-term effects of PM 2.5 constituents on mortality. Hence, we aimed to assess associations between all-cause mortality and long-term exposure to PM 2.5 constituents in China. We designed a nationwide cohort study of 30524 adults from 162 prefectural areas across mainland China with follow-ups through years 2010-2017. Cox proportional hazards models with time-varying exposures were employed to quantify associations between all-cause mortality and long-term exposure to PM 2.5 and constituents. A total of 1210 deaths occurred during 172297.7 person-years. A multiadjusted Cox model estimated an hazard ratio (HR) of 1.125 (95% confidence interval: 1.058-1.197) for all-cause mortality, associated with an interquartile range (IQR = 26.7 μg/m 3 ) rise in exposure to PM 2.5 . Comparable or stronger associations were found among PM 2.5 constituents with the mortality risk increased by 11.3-14.1% per IQR increase in exposure concentrations. After adjustment for the collinearity between total PM 2.5 and constituents, effect estimates for nitrate, ammonium, and sulfate remained significant and became larger. Urban residents, alcohol drinkers, smokers, and men were more susceptible to chronic impacts from ambient PM 2.5 constituents. This cohort study added the novel longitudinal evidence for elevated mortality linked with long-term exposure to PM 2.5 constituents among Chinese adults.