MINNEAPOLIS (WCCO) — Researchers have found that breathing dirty air, even just for a day, can cause people to become more aggressive and violent.

That’s according to the findings by a research team comprised of the University of Minnesota School of Public Health and Colorado State University.

Researchers studied the association between daily violent and non-violent crimes and short-term increases in air pollution across 301 counties in 34 states during a 14-year period.

One of their main findings: increases in daily air pollution levels raised the risk of violent criminal behavior, such as assaults. Also, the risk of violent behavior increased even at low pollution concentrations that are usually considered safe for people to breathe. And the findings were consistent across a diverse range of community types.

“While our study cannot identify the exact processes that link air pollution and violent behavior, we believe that exposure to air pollution has immediate effects on the brain, which results in behavioral changes,” said study lead author and U of M Assistant Professor Jesse Berman.

Researchers say the effects of air pollution may increase the impulsivity of people and escalate what is known as the “fight or flight” stress response. Meaning, everyday minor conflicts have a higher risk of becoming a more serious, physical altercations.

On the other hand, air pollution did not increase the risk of non-violent crime.

Daily pollution levels were determined based on the amount of fine particulate matter, including diesel and exhaust chemicals, as well as ozone in the air.

The findings were recently published in the journal Epidemiology.