- By:
- Peluso, Alina ; Lamichhane, Dirga; VanDerslice, James; Lurmann, Fred; Pavlovic, Nathan; Staley, Michael; Tharp, Douglas; Byrwa hill, Brandy; Zhang, Yue; Docherty, Anna; Coon, Hilary; Bakian, Amanda V
- Journal Name:
- Environment International
- Page Number:
- 110152
- Volume:
- 209
- Publication Date:
- July 23, 2026
- View DOI Listing:
- https://doi.org/10.1016/j.envint.2026.110152
Abstract
Background: Individual components of the ambient environment, such as temperature and air pollution, exist as part of a complex mixture and have been associated with suicide; however, their interactive effects remain poorly understood. This study examined the independent and interactive effects of wet bulb globe temperature (WBGT), nitrogen dioxide (NO2), and fine particulate matter (PM2.5) on suicide mortality. Methods: We identified 7,551 suicide cases in Utah, USA, from 2000 to 2016 and assigned exposure to daily maximum WBGT (sourced from the European Center for Medium-Range Weather Forecasts) and PM2.5 and NO2 concentrations (sourced from a national spatiotemporal ensemble model) using decedent’s residential address at the time of death. A case-crossover design with conditional logistic regression was used to estimate the independent and interactive effects of WBGTmax, PM2.5, and NO2 on suicide. For exposure windows, we considered single days preceding suicide (lag 0 to 6) and their averages across preceding days (lag 0–1, 0–3, and 0–6). Analyses were stratified by season. Results: We identified a significant association between WBGTmax and suicide across all seasons (odds ratio [OR] = 1.05, 95% confidence interval [CI]: 1.01, 1.10; per 5 °C increase on lag 0–3 days). The associations were stronger in the warm season (March 22 to September 21), with ORs and 95% CIs ranging from 1.08 (1.02, 1.15) to 1.20 (1.10, 1.30) per 5 °C increase depending on the lag periods. We observed synergistic interactions between WBGTmax and PM2.5 and NO2 in the warm season, associated with higher odds of suicide. The associations of WBGTmax with suicide were most pronounced at high NO2 levels. Conclusions: We found evidence of synergistic interactions between WBGTmax and PM2.5 and NO2 on suicide in the warm season, emphasizing the need for considering the combined effects of heat stress and air pollution in suicide prevention strategies.
