Air pollution linked to depressive symptoms in adolescents

Manczak, Miller, & Gotlib (2022) published “Census Tract Ambient Ozone Predicts Trajectories of Depressive Symptoms in Adolescents” in Developmental Psychology. Ozone, a gas produced when various pollutants from motor vehicle exhaust, power plants and other sources react to sunlight, has long been studied in relation to asthma and other respiratory disorders. Manczak et al. studied 213 9-13-year olds in the San Francisco Bay area over a four-year period. Their sample was 57% female, 53% racial/ethnic minority. They asked participants to self-report symptoms up to three times, then used their home addresses to examine air quality data based on Census tracts. 

Previous research had found associations between high levels of ozone and use of antidepressants by adults and that suicide and mental health visits to emergency rooms covary with seasonal ozone exposure. An APA release about the study notes that:

Adolescents who lived in areas with relatively higher ozone levels showed significant increases in depressive symptoms over time, even though the ozone levels in their neighborhoods didn’t exceed state or national air quality standards....

“It was surprising that the average level of ozone was fairly low even in the communities with relatively higher ozone exposure,” Manczak said. “This really underscores the fact that even low levels of ozone exposure have potentially harmful effects.”

In their study, Manczak et al. asked participants to complete the Children’s Depression Inventory (CDI), the Youth Self Report (YSR) of mental health symptoms, and the Traumatic Events Screening Inventory for Children. They used a composite measure of neighborhood disadvantage and collected data regarding family income and parental education.

One of their findings is that the average ozone levels were all below the National Air Quality Standard. Ozone was unrelated to symptoms at T1. However, as ozone increased from T1, depression measured by the CDS and the withdrawn/depressed subscale of the YSR increased significantly. There was no significant change in depression scores for children in low ozone Census tracts, but significant changes for those in average or above average ozone level tracts. Scores on the CDS and the withdrawn/depressed subscale were unrelated to sex, age at baseline, minority status, parental income, parental education, number of severe life stressors, and neighborhood disadvantage.

While the authors concede that the study is correlational and utilizes a relatively small sample, it may be important for practitioners who work with individuals who live in areas with higher ozone levels and it may be especially important for future research to look more carefully at seasonal variations in ozone levels as they relate to depression symptoms.