Acute air pollution exposure and risk of suicide completion

Abstract

Research into environmental factors associated with suicide has historically focused on meteorological variables. Recently, a heightened risk of suicide related to short-term exposure to airborne particulate matter was reported. Here, we examined the associations between short-term exposure to nitrogen dioxide, particulate matter, and sulfur dioxide and completed suicide in Salt Lake County, Utah (n = 1,546) from 2000 to 2010. We used a time-stratified case-crossover design to estimate adjusted odds ratios for the relationship between suicide and exposure to air pollutants on the day of the suicide and during the days preceding the suicide. We observed maximum heightened odds of suicide associated with interquartile-range increases in nitrogen dioxide during cumulative lag 3 (average of the 3 days preceding suicide; odds ratio (OR) = 1.20, 95% confidence interval (CI): 1.04, 1.39) and fine particulate matter (diameter ≤2.5 μm) on lag day 2 (day 2 before suicide; OR = 1.05, 95% CI: 1.01, 1.10). Following stratification by season, an increased suicide risk was associated with exposure to nitrogen dioxide during the spring/fall transition period (OR = 1.35, 95% CI: 1.09, 1.66) and fine particulate matter in the spring (OR = 1.28, 95% CI: 1.01, 1.61) during cumulative lag 3. Findings of positive associations between air pollution and suicide appear to be consistent across study locations with vastly different meteorological, geographical, and cultural characteristics.

Keywords: air pollution; case-crossover studies; environmental exposure; nitrogen dioxide; particulate matter; risk factors; suicide.

Figure 1.

Percent change in the odds of suicide associated with interquartile-range (IQR) increases in exposure to nitrogen dioxide (NO₂), particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀), particulate matter with an aerodynamic diameter ≤2.5 μm (PM_2.5), and sulfur dioxide (SO₂) on lag days (LDs) 0 (day of the suicide), 1, 2, and 3 (A) and during cumulative lags (CLs) 1, 2, and 3 (B), Salt Lake County, Utah, 2000–2010. The results were adjusted for average daily sunlight during the previous 3 days, daily mean temperature, daily mean temperature for the previous 3 days, mean dew point temperature, mean dew point temperature for the previous 3 days, daily mean air pressure, and daily mean air pressure for the previous 3 days.