Breathing In Fumes While Stuck in Gridlock May Be Ruining Your Brain, Study Finds

L.A.’s traffic is the 6th worst worldwide—plus, the city’s motorists lose 62 hours a year to gridlock

Stuck in traffic on the I-5 with no relief from the miles of gridlock in sight, your blood pressure spikes, your heart starts pumping faster, and you might just want to punch the roof of your vehicle. But that’s not why this quotidian L.A. situation is damaging your health, according to a new study. The real reason? Breathing in merely average levels of traffic pollution can compromise brain function in as little as two hours, a new study has revealed.

Fresh evidence showing a connection between air pollution and cognition has been discovered in the first controlled experiment indicating altered brain network connectivity from such environmental exposure. The results came in from researchers at the University of British Columbia and the University of Victoria in Canada and were published this week in Environmental Health. “For many decades, scientists thought the brain may be protected from the harmful effects of air pollution,” said Chris Carlsten, Canada Research Chair in occupational and environmental lung disease at UBC. The results revealed this week may prove this to be wrong.

For the study, 25 adults were exposed to diesel exhaust and filtered air at different intervals, while their brain activity was measured before and after each exposure—specifically, the researchers looked at their brains’ default mode network, a set of inter-connected regions that are key to memory and internal thought. Participants had decreased functional connectivity in widespread regions of the DMN after diesel exhaust exposure as compared to filtered air.

“We know that altered functional connectivity in the DMN has been associated with reduced cognitive performance and symptoms of depression, so it’s concerning to see traffic pollution interrupting these same networks,” said Dr. Jodie Gawryluk, a psychology professor at the University of Victoria and the study’s first author. “While more research is needed to fully understand the functional impacts of these changes, it’s possible that they may impair people’s thinking or ability to work.”

The study’s results are highly relevant to Californians, who make some of the world’s worst traffic snarls. A December 2021 study by transportation firm INRIX found that not only is L.A.’s traffic the 6th worst worldwide, but the city’s motorists lost 62 hours a year to gridlock. As for the I-5 South, INRIX’s 2021 Global Traffic Scorecard reported that it’s the most congested freeway nationwide.

But don’t panic. The neurological effects of diesel exhaust were found to be temporary, according to the study. The brain activity in each of the subjects who were exposed to diesel exhaust, rather than filtered air, reverted to normal. However, the study couldn’t account for the impact on the brains of people after sitting in gridlock several days per week for long periods.

Dr. Carlsten says that it’s best to minimize exposure to traffic pollution and adds that you can take steps to protect yourself.

“People may want to think twice the next time they’re stuck in traffic with the windows rolled down,” says Carlsten. “It’s important to ensure that your car’s air filter is in good working order, and if you’re walking or biking down a busy street, consider diverting to a less busy route.”

Stay on top of the latest in L.A. news, food, and culture. Sign up for our newsletters today.