Air pollution is a known risk factor for certain mental health problems in adults, but a new study also links high rates of air pollution to poorer psychiatric health in children and adolescents.

To investigate this link, researchers from Umeå University in Sweden examined what is known as “register-based” data. All medications given to Swedish people are registered, and in this case, researchers zeroed in on individuals under age 18 from Stockholm, Västra Götaland, Skåne and Västerbotten. They then looked at this information in connection with the Swedish National Register, which logs air pollution.

Due to the socioeconomic range in these regions, researchers first had to control for factors that might affect the outcome, including variety in wealth and ethnicity.

Researchers found that air pollution levels do seem to impact adolescent and childhood psychiatric diagnoses, but they couldn’t directly measure rates of mental illness.

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