Daily changes in ambient air pollution concentrations and temperature and suicide mortality in Canada: Findings from a national time-stratified case-crossover study

• Published in: Environmental research 2023-04, Vol.223, p.115477-115477, Article 115477
• Main Authors: Villeneuve, Paul J., Huynh, David, Lavigne, Éric, Colman, Ian, Anisman, Hymie, Peters, Cheryl, Rodríguez-Villamizar, Laura A.
• Format: Article
• Language: English
• Subjects: Air Pollutants - analysis; Air Pollutants - toxicity; air Pollution; Air Pollution - adverse effects; Air Pollution - analysis; Canada; Canada - epidemiology; Case-crossover; Cross-Over Studies; Environmental Exposure - adverse effects; Environmental Exposure - analysis; Female; Humans; Mortality; Nitrogen Dioxide - analysis; Ozone - analysis; Particulate Matter - analysis; Suicide; Temperature
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2023.115477

Worldwide, approximately 1900 people die by suicide daily. Daily elevations in air pollution and temperature have previously been linked to a higher risk of death from suicide. To date, there have been relatively few studies of air pollution and suicide, particularly at a national level. National analyses play an important role in shaping health policy to mitigate against adverse health outcomes. We used a time-stratified case-crossover study design to investigate the influence of short-term (i.e., day to day) interquartile range (IQR) increases in air pollutants (nitrogen dioxide [NO2], ozone [O3], and fine particulate matter [PM2.5]) and temperature on suicide mortality in Canada between 2002 and 2015. For air pollution models, odds ratios (ORs) derived from conditional logistic regression models were adjusted for average daily temperature, and holidays. For temperature models, ORs were adjusted for holidays. Stratified analyses were undertaken by suicide type (non-violent and violent), sex, age, and season. Analyses are based on 50,800 suicide deaths. Overall, temperature effects were stronger than those for air pollution. A same day IQR increase in temperature (9.6 °C) was associated with a 10.1% increase (95% confidence interval (CI): 9.0%–11.2%) of death from suicide. For 3-day average increase of O3 (IQR = 14.1 ppb), PM2.5 (IQR = 5.6 μg/m3) and NO2 (IQR = 9.7 ppb) the corresponding risks were 4.7% (95% CI: 3.9, 5.6), 3.4% (95% CI: 3.0, 3.8), and 2.0% (95% CI: 1.1, 2.8), respectively. All pollutants showed stronger associations with suicide during the warmer season (April–September). Stratified analyses revealed stronger associations for both temperature and air pollution in women. Daily increases in air pollution and temperature were found to increase the risk of death from suicide. Females, particularly during warmer season, were most vulnerable to these exposures. Policy decisions related to air pollution and climate change should consider effects on mental health. •Daily increases in NO2, PM2.5 and O3 were associated with higher suicide mortality.•Those associations were strongest in women and during the warmer season.•A same day increase in temperature was associated with the highest risk of suicide.•Higher levels of PM2.5 and O3 may amplify the temperature-suicide association.