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

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.