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_2.5) and suicide. However, due to the lack of data from unmonitored areas, it has been difficult to assess heterogeneous impacts of PM_2.5 by urbanicity. This case-crossover study investigated the relationship between short-term PM_2.5 and suicide (2015-2019). In the overall population (65,634 suicide deaths), PM_2.5 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.