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

Objectives: This study aimed to evaluate the association between long-term exposure to fine particulate matter (PM2.5) and cause-specific mortality among older adults in South Korea, providing insights into the evolving public health burden in an aging society.

Methods: We analyzed national insurance claims data from the Republic of Korea 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, 1.040-1.097); stroke, 1.023 (95% CI, 1.003-1.043); ALRI, 1.050 (95% CI, 1.026-1.076); COPD, 1.114 (95% CI, 1.072-1.157); T2DM, 1.046 (95% CI, 1.007-1.086); and LC, 0.972 (95% CI, 0.948-0.996). Excess deaths attributable to long-term PM2.5 exposure were estimated at 4,888 (95% CI, 2,304-7,323) in 2010 and 5,179 (95% CI, 2,585-7,648) in 2019.

Conclusion: Although PM2.5 levels in South 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.