Air Pollution and Emergency Department Visits for Mental Disorders among Youth

Although exposure to ambient air pollution has been linked to mental health problems, little is known about its potential effects on youth. This study investigates the association between short-term exposure to air pollutants and emergency department (ED) visits for mental health disorders. The National Ambulatory Care Reporting System database was used to retrieve ED visits for young individuals aged 8-24 years in Toronto, Canada. Daily average concentrations of nitrogen dioxide (NO₂), fine particulate matter (PM_2.5), and daily maximum 8 h ozone (O₃) were calculated using measurement data from seven fixed stations. A case-crossover (CC) design was implemented to estimate the associations between ED visits and air pollution concentrations. Mental health ED visits were identified using International Classification of Diseases 10th Revision (ICD-10) codes, with seven categories considered. Models incorporating air pollutants and ambient temperature (with lags of 0-5 days) using a time-stratified CC technique were applied. Multivariable regression was performed by sex, three age groups, and seven types of mental health disorders to calculate relative risk (RR). The RRs were reported for one interquartile range (IQR) change in the air pollutant concentrations. Between April 2004 and December 2015 (4292 days), there were 83,985 ED visits for mental-health related problems in the target population. Several exposures to air pollutants were shown to have associations with ED visits for mental health including same day exposure to fine particulate matter (IQR = 6.03 μg/m³, RR = 1.01 (95% confidence interval: 1.00-1.02), RR = 1.02 (1.00-1.03)) for all and female-only patients, respectively. One-day lagged exposure was also associated with ED visits for PM_2.5 (RR = 1.02 (1.01-1.03)), for nitrogen dioxide (IQR = 9.1 ppb, RR = 1.02 (1.00-1.04)), and ozone (IQR = 16.0 ppb, RR = 1.06 (1.01-1.10)) for males. In this study, urban air pollution concentration-mainly fine particulate matter and nitrogen dioxide-is associated with an increased risk for ED visits for adolescents and young adults with diagnosed mental health disorders.