Limited evidence exists for long-term effects of PM2.5 constituents on mortality. Hence, we aimed to assess associations between all-cause mortality and long-term exposure to PM2.5 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 PM2.5 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/m3) rise in exposure to PM2.5. Comparable or stronger associations were found among PM2.5 constituents with the mortality risk increased by 11.3-14.1% per IQR increase in exposure concentrations. After adjustment for the collinearity between total PM2.5 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 PM2.5 constituents. This cohort study added the novel longitudinal evidence for elevated mortality linked with long-term exposure to PM2.5 constituents among Chinese adults.
Keywords: All-cause mortality; Chinese adults; Chronic effects; Cohort study; Particulate constituents.