Significant association between increased risk of emergency department visits for psychiatric disorders and air pollutants in South Korea

Background The association between air pollutants and psychiatric disorders has been investigated in many countries. However, results for the association between air pollutants and emergency room (ER) visits for psychiatric disorders are inconsistent. Further, systematic large-scale studies relating to the same are lacking, especially in South Korea. Objective We aimed to investigate the acute and short-term cumulative effect of air pollutants on ER visits for psychiatric disorders in South Korea. Methods The data on nitrogen dioxide (NO 2 ) and particulate matter (PM 2.5 and PM 10 ) and ER visits due to nine representative psychiatric disorders were collected from eight major cities in South Korea for three years. We estimated the relative risk (RR) at lag 0 and a cumulative 11-day RR by increasing a 10-unit for PM and 0.01-unit for NO 2 using the Distributed Lag Nonlinear Model. Results During the study period, a total of 79,092 ER visits for psychiatric disorders were identified and tested for association with NO 2 , PM 2.5 , and PM 10 . The RR at lag 0 of depression per 0.01-unit increase in NO 2 was the highest (3.127; 95% confidence interval [CI] 2.933 to 3.332) among the psychiatric disorders. The RRs at lag 0 of anxiety disorders per 10-unit increase in PM 2.5 (1.709; 95% CI 1.424 to 2.053) and PM 10 (2.168; 95% CI 1.957 to 2.403) were the highest among the psychiatric disorders. Significance Air pollutants increased ER visits for psychiatric disorders with the highest RR of depression due to NO 2 and anxiety disorder due to PM 2.5 and PM 10 . These results contribute evidence to the positive association between ambient exposure to air pollution and aggravation of psychiatric disorders, indicating air pollution may be a modifiable risk factor in mental health management. Impact statement We investigated the effect of air pollution on emergency room visits caused by major psychiatric disorders in prominent cities in South Korea. Using the Distributed Lag Nonlinear Model, an advanced analysis method, we calculated the acute effect and short-term cumulative effect. Air pollutants increased ER visits for psychiatric disorders with the highest relative risk of depression due to NO 2 and anxiety disorder due to PM 2.5 and PM 10 . These results reveal an association between ambient exposure to air pollution and aggravation of psychiatric disorders and suggest that air pollution may be a modifiable risk factor in mental health management.