Population-level health gains from PM2.5 reduction in an intermediate-pollution region: A multistate analysis of metabolic multimorbidity in Korea

Abstract

Fine particulate matter (PM2.5) is associated with metabolic diseases, but its effects on progression to metabolic multimorbidity remain unclear in regions with intermediate pollution levels. We examined associations between long-term PM2.5 exposure and metabolic disease progression in Korea, where annual mean PM2.5 concentrations range approximately 10-35 & micro;g/m3-exposure levels shared by over 80 countries worldwide-and estimated population-level health gains from PM2.5 reduction. We analyzed 6720 participants aged >= 40 years from the Korean Genome and Epidemiology Study with zero or one metabolic disease (hypertension, diabetes, dyslipidemia) at baseline. One-year average PM2.5 concentrations were estimated using Community Multiscale Air Quality modeling. We fitted multistate Cox models to examine PM2.5 effects on disease transitions across disease states and assessed robustness using nationwide claims data. Dynamic predictions were applied to a nationally representative sample to estimate population-level benefits of reducing PM2.5 to 15, 10, or 5 & micro;g/m3 over 10 years. Each 10 & micro;g/m3 increase in PM2.5 was associated with progression from zero to one disease (hazard ratio 1.61, 95% CI 1.41-1.83) and one disease to multimorbidity (1.26, 1.13-1.40). Among 10.7 million Korean adults aged 45-64 years, reducing PM2.5 to 15, 10, or 5 & micro;g/m3 would prevent 350,000, 560,000, or 740,000 multimorbidity cases over 10 years, respectively. Even below high-exposure thresholds, further reductions could yield substantial population-level benefits by preventing metabolic multimorbidity. These findings provide quantitative support for progressive tightening of air quality standards as a strategy for metabolic disease prevention, particularly across countries with comparable pollution profiles.