Effect of short-term exposure to air pollutants on the risk of suicide mortality

Objective  To quantitatively evaluate the effect of short-term exposure to air pollutants on the risk of suicide mortality.

Methods  Based on the National Mortality Surveillance System, a total of 24 765 residents who died of suicide in Jiangsu Province from 2015 to 2020 were selected as the research subjects for the time-stratified case-crossover study. Air pollution data were extracted from the ChinaHighAirPollutants (CHAP) dataset. Meteorological data were obtained from the China Meteorological Administration Land Data Assimilation System (CLDAS-V2.0). The exposure levels of daily PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ on the case days and control days were estimated based on the residential address of participants. Conditional logistic regression models were used to analyze the exposure-response relationship between short-term exposure to air pollutants and suicide mortality.

Results  The mean concentrations of PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃ on the day of suicide deaths were 49.7 μg/m³, 84.5 μg/m³, 16.6 μg/m³, 34.5 μg/m³, 0.88 mg/m³, and 109.0 μg/m³, respectively, in Jiangsu Province from 2015 to 2020. The single-pollutant model result showed that PM_2.5, PM₁₀, NO₂, and O₃ exposure was associated with an increased risk of suicide mortality. For every 10 μg/m³ increase in exposure to PM_2.5, PM₁₀, NO₂, and O₃ on lag 0 day, the risk of suicide deaths increased by 0.79%95% confidence interval (CI): 0.12%-1.46%, 0.71% (95% CI: 0.25%-1.16%), 2.62% (95% CI: 1.09%-4.17%), and 0.51% (95% CI: 0.004%-1.02%), respectively. After adjustment for other air pollutants in the two-pollutant model, the association between NO₂ and suicide mortality remained stable, while the association of PM_2.5, PM₁₀, and O₃ with suicide mortality weakened or disappeared. No effect modification of gender, age, or season were found on the above associations, except that the association between PM_2.5 and suicide mortality was stronger in warm season than that in cold season.

Conclusion  Short-term exposure to air pollutants, especially NO₂, is associated with an increased risk of suicide mortality.