Black Carbon Air Pollution and Incident Mortality among the Advance-Aged Adults in China: A Prospective Cohort Study

Abstract

Background We aimed to assess associations between black carbon (BC) and non-accidental mortality among advance-aged adults in China. Methods We conducted a prospective cohort study in 22 provinces of Chinese Longitudinal Healthy Longevity Survey. We calculated concentrations of 3-year average BC, fine particulate matter (PM2.5), and other PM2.5 components (SO42-, NO3-, NH4+, and organic matter) at individual levels. We used Cox proportional hazards models to assess dose-response BC exposure on non-accidental mortality, adjusted for total PM2.5, green space, temperature, humidity, and demographic covariates. Results We studied 12,873 participants, with a median age of 88 years and 57.4% females. For a median follow-up of 4 years, we observed 7,426 mortality events. The mean 3-year average BC and total PM2.5 exposure concentrations were 3.49 and 66.97 μg/m3, respectively. An increase of 1 μg/m3 in BC was associated with a 39% increase in mortality risks (HR: 1.39, 95% CI: 1.36, 1.43), notably higher than the corresponding increase in mortality risks linked to total PM2.5 (HR: 1.003, 95% CI: 1.002, 1.004). The stratified analyses show that people living in rural areas, with lower social and leisure activity index, and lower physical activity, were at greater risk from BC exposure. Conclusions BC is a strong predictor of mortality, with a higher effect estimate compared with total PM2.5 and other PM2.5 components, particularly in rural populations. While total PM2.5 has been a target indicator of clean air policy interventions, our results indicate that BC concentration should be routinely measured, reported, and studied to improve public health.