Living in an area with high air pollution increases the chance of suffering from a major mental illness or depression, scientists have discovered.
In the biggest study ever looking into a link between emissions and neuropsychiatric disorders, researchers compared 151 million health insurance records with pollution statistics across the US.
The team from the University of Chicago then verified their findings using data from health registers covering 1.4 million people in Denmark.
Americans living in the most highly polluted areas were at 27pc increased risk of being diagnosed with bipolar disorder, while incidents of major depression rose by 6pc.
Likewise, Danes who were exposed to high emissions before the age of 10 were 50pc more likely to suffer major depression in adulthood, and at more than double the risk of schizophrenia and personality disorders.
British scientists said the results suggested that improving air quality might offer an opportunity to prevent mental illness.
Dr Atik Khan, a study author and computational biologist, said: "These neurological and psychiatric diseases - so costly in both financial and social terms - appear linked to the physical environment."
The research was published in the journal 'PLOS Biology'.