March 16, 2022
The physical health effects of ozone pollution have been long documented, but a new study suggests it also may harm people's mental health.
Researchers found adolescents had an increased risk of depression if they lived in neighborhoods with higher levels of ozone pollution.
"I think our findings really speak to the importance of considering air pollution's impact on mental health in addition to physical health," said lead researcher Erika Manczak, a psychology professor at the University of Denver. "I believe state and federal air quality standards should be stricter, and we should have tighter regulations on industries that contribute to pollution."
Ozone, a gas molecule composed of three oxygen atoms, is one of the most dangerous types of air pollution in the United States. Ground-level ozone is regulated by the Environmental Protection Agency. It comes from pollution emitted from cars, power plants, industrial boilers, refineries and chemical plants, as well as paints, cleaners, solvents and even motorized lawn equipment.
Ozone attacks lung tissue by reacting chemically with it. Depending on the level of ozone exposure, it can cause coughing or a sore or scratchy throat, or inflame and damage the airways, leading to breathing difficulties.
Ozone exposure also can worsen lung diseases such as asthma, emphysema and chronic bronchitis. And these effects even can occur in healthy individuals – although the effects are often more serious in people with lung disease. Ozone exposure has been associated with increased school absences, medication use, hospital admissions and visits to doctors and emergency rooms.
Studies also have linked higher concentrations of ozone to deaths related to respiratory causes.
In the latest study, researchers analyzed four years of mental health data from 213 adolescents ages 9-13 living in the San Francisco Bay area. They compared that data with the air quality data for their home addresses.
The adolescents who lived in areas with higher ozone levels had a significant increase in depression symptoms over time. This was true even in areas where the ozone levels were relatively higher, but not as high as state or national limits.
"It was surprising that the average level of ozone was fairly low even in the communities with relatively higher ozone exposure," Manczak said. The study "really underscores the fact that even low levels of ozone exposure have potentially harmful effects."
The most common depression symptoms were chronic sadness or hopelessness, concentration problems, sleep disturbances and thoughts about suicide. The link between these symptoms and ozone level was not affected by the kids' sex, age, race, household income, parents' education level or the wealth of their neighborhoods.
The researchers emphasized that their findings are merely an association – not a direct cause-and-effect link. It is not clear how ozone may cause depression, but ozone and other types of air pollution have been found to increase levels of inflammation in the body, which has been linked to depression.
The researchers suggested adolescents may be particularly sensitive because they spend more time outdoors.
"Our findings and other studies suggest that even low levels of ozone exposure can pose potentially serious risks to both physical and mental health," Manczak said.
