Mortality burden attributable to long-term exposure to fine particulate matter among older adults in Korea

OBJECTIVES: This study aimed to evaluate the association between long-term exposure to particulate matter with an aerodynamic diameter <2.5 μm (PM2.5) and cause-specific mortality among older adults in Korea, providing insights into the evolving public health burden in an aging society. METHODS: We analyzed national insurance claims data spanning 2010-2019. Modeled PM2.5 concentrations were assigned to participants according to their residential districts. We employed time-varying Cox proportional hazard models, using age as the time scale, adjusted for potential confounders. Six cause-specific mortalities were considered: ischemic heart disease (IHD), stroke, chronic obstructive pulmonary disease (COPD), acute lower respiratory infection (ALRI), lung cancer (LC), and type 2 diabetes mellitus (T2DM). Annual excess deaths attributable to long-term PM2.5 exposure were calculated. RESULTS: A total of 5,360,032 older adults were followed from 2010 to 2019. Hazard ratios (HRs) per 10 μg/m3 increase in 12-month PM2.5 concentration were as follows: IHD, 1.068 (95% CI, 1.040 to 1.097); stroke, 1.023 (95% CI, 1.003 to 1.043); ALRI, 1.050 (95% CI, 1.026 to 1.076); COPD, 1.114 (95% CI, 1.072 to 1.157); T2DM, 1.046 (95% CI, 1.007 to 1.086); and LC, 0.972 (95% CI, 0.948 to 0.996). Excess deaths attributable to long-term PM2.5 exposure were estimated at 4,888 (95% CI, 2,304 to 7,323) in 2010 and 5,179 (95% CI, 2,585 to 7,648) in 2019. CONCLUSIONS: Although PM2.5 levels in Korea have shown a declining trend over the past decade, mortality among older adults associated with long-term PM2.5 exposure has not significantly decreased, likely due to the rapid aging of the population.