Environment/Climate Change
Longitudinal association between air pollution and suicide mortality among Canadian adults: An analysis of the 2006 CanCHEC cohort Brian Steele* Brian Steele Shelby Yamamoto Ambikaipakan Senthilselvan Roman Pabayo
Background. Long-term exposure to air pollution is associated with morbidity and mortality, including respiratory, cardiovascular, and oncologic outcomes. However, limited research has evaluated the association between long-term pollutant exposure and psychiatric outcomes. This study aimed to estimate the longitudinal association between air pollution exposure and deaths from suicide among Canadian adults in an administrative cohort.
Methods. Urban respondents in the 2006 Canadian Census Health and Environment Cohorts with residential mobility (postal code) data were followed from July 1 2006 to June 30 2017. Outcome data were obtained from the Canadian Vital Statistics – Death database. Individual- and area-level socioeconomic covariates were assigned at baseline using the 2006 Census. Particulate matter (PM2.5) and ozone obtained from the Canadian Urban Environmental Health Research Consortium were assigned at the postal code level and modeled as time-varying lagged exposures using restricted cubic splines. Analyses were conducted using extended Cox proportional hazard models with cluster-robust standard errors. Baseline hazards were stratified by age, sex, and income adequacy.
Results. Among the analytic sample of 1,588,340 Canadians, 104,450 deaths (6.6% of sample) were observed during follow-up, 2,790 of which were suicides (0.2%). In adjusted models, an IQR-range increase in PM2.5 exposure (2.73 µg/m3) was significantly associated with increased relative hazards of suicide (aHR: 1.27, 95% CI: 1.08 – 1.51). Coefficient plots show non-linear but positive associations between PM2.5 and suicide. Results were inconsistent for ozone.
Conclusion. Long-term PM2.5 exposure was associated with increased relative hazards of suicide mortality over time. Though limited by selection and information biases, these findings contribute some of the first evidence suggesting that suicide is one of the many conditions associated with long-term air pollution exposure.