A multidecade study of young adults living in the United Kingdom has found higher rates of mental illness symptoms among those exposed to higher levels of traffic-related air pollutants, particularly nitrogen oxides, during childhood and adolescence.

Previous studies have identified a link between air pollution and the risk of specific mental disorders, including depression and anxiety, but this study looked at changes in mental health that span all forms of disorder and psychological distress associated with exposure to traffic-related air pollutants.

The findings reveal that the greater an individual’s exposure to nitrogen oxides across childhood and adolescence, the more likely they are to show any signs of mental illness at the transition to adulthood, at age 18, when most symptoms of mental illness have emerged or begin to emerge.

The link between air pollution exposure and young adult mental illness symptoms is modest, according to the study’s first-author Aaron Reuben, a graduate student in clinical psychology at Duke University. But “because harmful exposures are so widespread around the world, outdoor air pollutants could be a significant contributor to the global burden of psychiatric disease,” he says.

The World Health Organization (WHO) currently estimates that 9 out of 10 people worldwide are exposed to high levels of outdoor air pollutants, which are emitted during fossil fuel combustion in cars, trucks, and powerplants, and by many manufacturing, waste-disposal, and industrial processes.

In this study, air pollution, a neurotoxicant, was found to be a weaker risk factor for mental illness than other better-known risks, such as family history of mental illness, but was of equal strength to other neurotoxicants known to harm mental health, particularly childhood exposure to lead.

Read the full article about air pollution for kids from Duke University at Futurity.