Association of suicide with short-term exposure to air pollution at different lag times: A systematic review and meta-analysis.

Davoudi, Mojtaba; Barjasteh-Askari, Fateme; Amini, Homayoun; Lester, David; Mahvi, Amir Hossein; Ghavami, Vahid; Rezvani Ghalhari, Mohammad

BACKGROUND Suicide is a major public health problem, with some environmental risk factors. OBJECTIVES This meta-analysis study explored the association between short-term exposure to air pollution and suicide mortality, with an emphasis on different lag times. METHODS A systematic search was used to find relevant studies in databases including Scopus, Web of Knowledge, Pubmed, and Embase published up to 19 May 2020. The inclusion criteria included case-crossover or time-series studies assessing the association of criteria air pollutants with suicide mortality at different Lag Days of 0-7 (LD0 to LD7) and Cumulative Lags of 1-7 days (CL1 to CL7). Odds ratios (OR) were calculated with 95% confidence intervals (CI). RESULTS Of 1436 retrieved articles, 11 were eligible for data extraction, representing data on 283,550 suicides published between 2010 and 2019. The odds of suicide death increase with each 10 μg/m3 increase in the mean concentrations of NO2 at CL1 (1.013: 1.006-1.021), CL2 (1.028: 1.003-1.053), CL3 (1.035: 1.001-1.070), and LD2 (1.011: 1.001-1.022), SO2 at CL1 (1.024: 1.014-1.034), CL2 (1.030: 1.012-1.048), CL3 (1.029: 1.009-1.049), and CL4 (1.027: 1.005-1.049), O3 at CL6 (1.008: 1.000-1.016), PM10 at CL1 (1.004: 1.000-1.008), and PM2.5 at CL1 (1.017: 1.003-1.031). Besides, the odds of suicide death increases with each 0.5 mg/m3 increase in the mean concentration of CO at LD6 (1.005: 1.000-1.011). However, it decreased with increased O3 exposure at LD3 (0.997: 0.994-1.000). CONCLUSION The study supports a positive association between air pollution and suicide mortality. No immediate risk was elucidated but the possible effects seem to be exerted cumulatively.