Association between long-term PM2.5 exposure and mortality on Sumatra Island: Indonesian Family Life Survey (IFLS) 2000–2014

The concentration of PM_2.5 (particulate matter with a diameter < 2.5 µm) on Sumatra Island has increased, mainly because of forest and peatland fires, transportation, and industry. Biomass burning releases partially burned carbon into the atmosphere, resulting in a smoky haze containing PM_2.5. Air quality has deteriorated quickly, and PM_2.5 has become a major health hazard in Indonesia. Studies on long-term exposure to PM_2.5 have indicated its associations with both morbidity and mortality. Here, we measured long-term (2000-2014) exposure to PM_2.5 on the basis of satellite-derived aerosol optical depth measurements (1 × 1 km²) used to predict ground-level PM_2.5 concentrations. Additionally, population data on Sumatra Island residents from the fourth wave of the Indonesian Family Life Survey (IFLS) were obtained. We investigated the association between long-term PM_2.5 exposure and mortality with a retrospective cohort study design. A total of 2409 subjects aged ≥ 40 years participated in the IFLS-3 beginning in November 2000, and we examined mortality outcomes until the IFLS-5 in September 2014. We used Cox regression models to calculate hazard ratios (HRs) of mortality associated with PM_2.5 exposure. According to the adjusted model, the mortality HRs per 10 µg/m³ increase in PM_2.5 concentration were 1.10 (95% CI 1.03, 1.17) for all natural causes, 1.17 (95% CI 1.05, 1.25) for cardiovascular causes, and 1.19 (95% CI 1.04, 1.36) for respiratory causes. Long-term exposure to PM_2.5 was associated with all-natural, cardiovascular, and respiratory mortality on Sumatra Island, where PM_2.5 levels exceed the WHO and US-EPA air quality standards.