Associations between long-term exposure to fine particulate matter and osteoporotic fracture risks in South Korea

The prevalence of osteoporotic fracture is increasing globally due to rapid population growth and aging. Current evidence suggests adverse impacts of air pollution on bone mineral density loss and osteoporosis, but population-based evidence for the associations between fine particulate matter (particulate matter no larger than 2.5 μm in diameter [PM2.5]) and osteoporotic fracture is limited due to the small number of studies. This longitudinal study assessed the associations between long-term exposure to PM2.5 and osteoporotic fracture incidence in adults aged ⩾40 years, who enrolled in the National Health Insurance Service-National Sample Cohort data in 2002–2019 in South Korea. A time-varying moving window of past exposures of PM2.5 up to ten past years was estimated for participants’ residential addresses using modeled PM2.5. We used Cox proportional hazard models to estimate hazard ratios (HRs) of time-variant moving concentrations of PM2.5 exposure and osteoporotic fracture. The Cox models calculated HRs for an interquartile range (IQR) increase in PM2.5 exposure, adjusting for age, sex, body mass index, health behaviors, medications, disease history, income, and urbanicity. We assessed 161 831 participants over 993 104 person-year of follow-up. Results suggested linear and positive exposure-response associations for past PM2.5 exposure in the prior four years or more. The IQR increase in 5-year moving average PM2.5 was significantly associated with increased osteoporotic risk (HR = 1.079, 95% CI: 1.001, 1.164). The HRs were significant in women (1.102, 95% CI: 1.011, 1.200) and the subset of women aged 50–74 years (1.105, 95% CI: 1.005, 1.214) but not in men overall or by age groups. The association was not significantly different by income, physical activities, urbanicity, or diet. Overall, long-term PM2.5 exposure was associated with increased osteoporotic fracture risks in Korean adults, especially women.