The research, conducted by scientists from King’s College London, was published in JAMA Psychiatry on Wednesday.
The findings could explain why teenagers who grow up in urban areas have a higher risk of psychosis, according to a release about the study.
Though researchers were able to find a connection, they did not prove air pollution was the cause of psychotic experiences, according to Dr. Joanne Newbury, from the Institute of Psychiatry, Psychology & Neuroscience, the lead author of the study.
“We found that adolescent psychotic experiences were more common in urban areas,” Newbury said in the release. “While the study could not show pollutants caused adolescents to have psychotic experiences, our findings suggest that air pollution could be a contributing factor in the link between city living and psychotic experiences.”
A psychotic experience can include hearing voices and extreme paranoia. These experiences tend to be more common in teenagers than adults, according to the release, but teens who report those experiences are more likely to develop psychotic disorders or other mental health problems.
Researchers used information from the E-Risk study, which includes data from 2,232 children born in England and Wales.
Scientists used hourly estimates of air pollution from locations where the teens spent a majority of their time when they were 17, in order to calculate their exposure to air pollution. They also used private interviews about their psychotic experiences when they turned 18.
Even accounting for risk factors for psychosis, researchers found psychotic experiences were “significantly more common” for teens who had the highest exposure to air pollution, made up of nitrogen dioxide, nitrogen oxide, and tiny particulate matter.
“Children and young people are most vulnerable to the health impacts of air pollution owing to the juvenility of the brain and respiratory system,” Professor Frank Kelly, of Environmental Health at King’s College London, the co-author of the study, said.
“Given that 70 percent of the world’s population will live in cities by 2050, uncovering the mechanisms linking the urban environment to psychosis should be an urgent health priority,” Kelly added.