When levels of air pollution are high and the streets are choked full of smog, hospitals see a surge in kids suffering from mental health issues. 

Researchers have found that days of high air pollution are followed by spikes in psychiatric problems being reported among children. Paired with this, they found that kids living in disadvantaged neighborhoods were more susceptible to the effects of air pollution, such as depression and suicidal thoughts, compared to children living in more privileged areas.

Reporting in the journal Environmental Health Perspectives, researchers from Cincinnati Children's Hospital Medical Center first studied levels of fine particulate matter (PM2.5), tiny specks of pollutants small enough to pass through the lung tissue into the bloodstream, in the outdoor air across Hamilton County in Cincinnati. This was then compared to the number of pediatric psychiatric emergency department visits collected in Cincinnati for conditions including anxiety, schizophrenia, depression, bipolar disorder, suicidality, and more. 

The link was clear: If there was a period of especially heavy pollutions in the city, the hospital would see more children with acute mental health complaints within the next one to two days. Furthermore, the spike in mental health admissions was especially pronounced among children living in high poverty neighborhoods. 

“This study is the first to show an association between daily outdoor air pollution levels and increased symptoms of psychiatric disorders, like anxiety and suicidality, in children," study author Cole Brokamp, PhD, a researcher with the division of Biostatistics and Epidemiology at Cincinnati Children's hospital, said in a statement.

"More research is needed to confirm these findings, but it could lead to new prevention strategies for children experiencing symptoms related to a psychiatric disorder. The fact that children living in high poverty neighborhoods experienced greater health effects of air pollution could mean that pollutant and neighborhood stressors can have synergistic effects on psychiatric symptom severity and frequency."

This research is just one of many recent studies to identify this link. One study from this year, also by Cincinnati Children's researchers, was even able to pinpoint a possible relationship between exposure to air pollution, metabolic disturbances in the brain, and generalized anxiety symptoms. As per their findings, people who were recently exposed to high pollution had higher concentrations of myoinositol in the brain – a marker of the brain's neuroinflammatory response to traffic-related pollution. Another piece of research from 2018 found that air pollution had a negative effect on the test scores of children.

Further work is needed before scientists can fully understand the whole relationship between air pollution and the mind, but an increasingly large mountain of evidence is showing that the effects of gas-guzzling cars and fossil fuels on human health are far-reaching.