For this research, scientists looked at the effects of traffic fumes on 25 healthy adults. They studied brain scans before and after exposure and found that traffic fumes had immediate effects on the brain, decreasing connectivity between brain networks and overall cognitive function.

While the effects of pollution on humans have long been studied, this study is the first to look specifically at its acute effects on brain activity.

Chris Carlsten, M.D., a senior author of the study, said in a statement, “For many decades, scientists thought the brain may be protected from the harmful effects of air pollution. This study, which is the first of its kind in the world, provides fresh evidence supporting a connection between air pollution and cognition.”

One significant limitation of the study was that it compared filtered air with air contaminated with diesel fuel, and diesel vehicles are less common than gasoline in vehicles on American roads and highways. Additional studies that include more types of traffic fumes will help us understand the global implication of these findings.

It will also be interesting to see what long-term studies find in addition to these acute, adverse effects.

The latest findings regarding cognitive decline are another reason to avoid breathing polluted air whenever possible (and push your local legislatures to help incentivize the transition to EVs). Seeking cleaner air is easier said than done, especially for racial minorities and lower-income groups that bear the brunt of air pollution in the U.S.2

“Air pollution is now recognized as the largest environmental threat to human health, and we are increasingly seeing the impacts across all major organ systems,” says Carlsten. “I expect we would see similar impacts on the brain from exposure to other air pollutants, like forest fire smoke. With the increasing incidence of neurocognitive disorders, it’s an important consideration for public health officials and policymakers.”

These findings collectively represent a growing public health crisis that will require collective action to tackle. As cleaner energy, vehicle, and home power options are discussed as green and sustainable options, positive health outcomes should be considered as part of the equation.