Short-term air pollution exposure and exacerbation of psychosis: A case-crossover study in the capital city of South Korea

There is a growing concern that air pollution exacerbates mental disorders. However, studies assessing the relationship between short-term exposure to ambient air pollution and acute exacerbation of psychotic symptoms in psychiatric disorders are limited. This study aims to examine the association between short-term air pollution exposure and acute exacerbation of psychosis in diverse psychiatric disorders. We analyzed 15,917 patients with psychosis (schizophrenia and related disorders and mood disorders with psychotic features) who visited Emergency Departments (EDs) in Seoul, South Korea, between 2008 and 2016. We estimated short-term exposures to particles <2.5 mu m (PM2.5), particles <10 mu m (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and carbon monoxide (CO). We employed a conditional logistic regression with a time-stratified case-crossover design to compare the levels of ambient air pollution on ED visit days with those on control days. Results show that the risk of ED visits for psychosis was significantly associated with interquartile range increases in PM2.5 (Odds Ratio [OR] = 1.028; 95% Confidence Interval [CI]: 1.006, 1.049), PM10 (OR = 1.022; 95% CI: 1.003, 1.040), NO2 (OR = 1.037; 95% CI: 1.007, 1.068), and SO2 (OR = 1.030; 95% CI: 1.003, 1.058) in the best-fitting lags. Exposure to the highest quartile of air pollutants generally showed a higher risk for psychosis. The associations were higher among male patients, those with schizophrenia and related disorders, and in the cold season. This study provides new evidence that short-term exposure to elevated levels of air pollutants may increase the risk of acute exacerbation of psychosis. These findings could contribute to the development of policies for reducing air pollution levels and the presentation of psychoses. Further studies are warranted to elucidate our findings and explore the underlying mechanisms.