Environmental exposure and risk of death by suicide, attempted suicide and suicide ideation: a systematic review and meta-analysis.

BACKGROUND: The impact of environmental exposure on suicide risk is poorly understood. We investigated the relationship between four environmental exposures-air, noise, light and water pollution-and the risk of death by suicide, attempted suicide and suicide ideation. METHODS: We searched three electronic databases for empirical studies (2010-2024) investigating the relationship between environmental exposures and death by suicide, attempted suicide or suicide ideation. Random effect meta-analyses and narrative synthesis were performed. Risk of bias was assessed with the Newcastle Ottawa Scale. RESULTS: This review included 45 studies, 29 in the meta-analysis and 16 in the narrative review. Short-term exposure to PM2.5 (n=13 studies, OR 1.0139, 95% CI 1.0001 to 1.0279) and PM10 (n=7 studies, OR 1.0100, 95% CI 1.0007 to 1.0195), and long-term exposure to PM2.5 (n=6 studies, OR 1.5254, 95% CI 1.1351 to 2.0481) and NO2 (n=7 studies, OR 1.3173, 95% CI 1.0641 to 1.6308) had statistically significant positive associations with risk of suicide, attempted suicide and suicide ideation. The narrative review found potential positive associations for other air pollutants (including SO2 and O3) and noise pollution. Meta-analysis was not possible for water and light pollution; however, narrative review findings showed conflicting and unclear results. CONCLUSION: This meta-analysis shows statistically significant positive associations between short-term exposure to PM2.5 and PM10, long-term exposure to PM2.5 and NO2, and risk of death by suicide, attempted suicide and suicide ideation. The narrative review also suggests that positive associations exist for other air pollutants and for noise pollution. The results highlight the importance of considering environmental exposures as modifiable risk factors in suicide prevention.