Long-term exposure to ambient air pollution and the risk of urinary tract infections in women: A nationwide cohort study.

Urinary tract infections (UTIs) are common among women, with over half experiencing at least one episode during their lifetime. They are often recurrent and impose a considerable health and economic burden. Although air pollution has been shown to impair mucosal immunity and increase susceptibility to infections, evidence on its long-term effects on UTI risk remains limited. We established a nationwide cohort of 4,384,078 Korean women aged ≥30 years using National Health Insurance Service claims data from 2015 to 2023. A subcohort of 2,245,306 women who underwent general health examinations (GHE) provided detailed information on lifestyle and clinical risk factors. Cox regression models with time-varying covariates were used to estimate hazard ratios (HRs) for incident UTIs per 10 μg/m3 increase in long-term PM2.5 exposure, adjusting for demographic, meteorological, and health-related variables. Over a median follow-up of nine years, 1,386,341 UTI events were recorded. Long-term exposure to PM2.5 was associated with an increased risk of UTI (HR 1.032, 95 % CI 1.022-1.042). The association remained robust after adjustment for lifestyle and clinical factors in the GHE subcohort (HR 1.024, 95 % CI 1.011-1.037). The risk was more pronounced among women with lower income and those engaging in high-risk drinking in both cohorts, highlighting disproportionate vulnerability related to socioeconomic and behavioral factors. Although typically mild, UTIs can negatively impact quality of life, underscoring the need to address environmental health inequities affecting women through air pollution policies.