Ozone exposure may be linked to depression in adolescents, study finds

Exposure to ozone from air pollution may be connected to a rise in depression among adolescents, a new study has found.

The study, published in the journal Developmental Psychology on Monday, is the first to link ozone levels to the development of depression in adolescents over time.

These depressive symptoms may manifest as persistent feelings of sadness or hopelessness, difficulties concentrating, disturbances in sleep or thoughts about suicide, the authors wrote, while noting their findings are preliminary and more research is required to establish cause.

“Our findings really speak to the importance of considering air pollution’s impact on mental health in addition to physical health,” lead researcher Erika Manczak, an assistant professor of psychology at the University of Denver, said in a statement.

Scientists had previously linked higher ozone levels with physical illnesses, such as asthma, respiratory viruses and premature death resulting from respiratory ailments, the authors noted. But the association between depression and exposure to ozone — a gas produced when pollutants from vehicular exhaust and power plants react with sunlight — has been little explored.

To determine the connection, Manczak and two Stanford researchers analyzed data from a previous study about early life stress that included 213 adolescent participants in the San Francisco Bay Area. The participants — who self-reported depressive and other psychopathology symptoms over four years — ranged in age from nine to 13, with 57 percent of them female and 53 percent from minority backgrounds, according to the study.

Using this existing data on mental health, the scientists cross-referenced the results with census information about their home addresses and corresponding air quality data from the California Environmental Protection Agency, according to the study.

Those adolescents who lived in areas with relatively higher ozone concentrations demonstrated significant increases in depressive symptoms over time, even though the ozone levels in their areas did not surpass state or national air quality standards, the authors found.

The findings, according to the study, were not influenced by other factors like sex, age, race, household income, parental education or socioeconomic traits of the neighborhoods.

“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.”

The authors suggested that one possible reason for the association between heightened ozone exposure and depressive symptoms is the fact that ozone and other air pollutants can contribute to inflammation in the body. Inflammation, they explained, has previously been linked to the onset and development of depression.

In addition, the authors stated, adolescents may be particularly sensitive when compared to individuals in other age groups because they tend to spend more time outdoors.

While the authors concluded that there is a link between ozone exposure and depressive symptoms in adolescents, they acknowledged that the findings are correlational only, and therefore do not prove that ozone levels cause an increase in such conditions. Their sample size was also relatively small and from just one area of the U.S., while other components of air pollution could have also played a role, they added.

Still, the authors emphasized that their research has helped in “identifying a novel potential contributor to mental health in youth.”

The scientists recommended that communities consider ways they might be able to reduce their children’s exposure to ozone, such as holding youth sports events inside when air pollution is high and investing in renewable energy sources. They also stressed that because air pollution disproportionately impacts marginalized communities, ozone levels could be exacerbating health disparities.

“State and federal air quality standards should be stricter, and we should have tighter regulations on industries that contribute to pollution,” Manczak said. “Our findings and other studies suggest that even low levels of ozone exposure can pose potentially serious risks to both physical and mental health.”