Fine particulate matter, suicide, and urbanicity in South Korea: A nationwide time-stratified cases-crossover study.

Previous studies reported a link between exposure to ambient fine particulate matter (PM) and suicide. However, due to the lack of data from unmonitored areas, it has been difficult to assess heterogeneous impacts of PM by urbanicity. This case-crossover study investigated the relationship between short-term PM and suicide (2015-2019). In the overall population (65,634 suicide deaths), PM was marginally associated with suicide risk (odds ratio [OR]: 1.008, 95% confidence interval [CI]: 0.997-1.020). However, the association was stronger in rural areas (OR: 1.044, 95% CI: 0.996-1.095) and individuals aged 0-44 years (OR: 1.025, 95% CI: 1.002-1.048) compared to metropolitan/urban areas and older age groups. Metropolitan women aged 45-64 years (OR: 1.067, 95% CI: 1.013-1.124) and rural men aged 0-44 years (OR: 1.129, 95% CI: 0.988-1.289) showed the highest OR estimates than other subpopulations. These findings provide evidence to support more targeted suicide intervention strategies.