Traffic pollution can impair brain function in just two hours

Traffic pollution can impair human brain function after few hours of exposure, a study has shown.

Just two hours of exposure to common levels of traffic pollution can cause a decrease in the brain's functional connectivity, researchers at two Canadian universities found.

The study by teams at the University of British Columbia and University of Victoria, published the study in the Environmental Health journal, gives the first evidence of altered brain activity induced by air pollution in humans.

Senior study author Dr Chris Carlsten, an environmental lung disease specialist, said: “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.”

Researchers briefly exposed 25 healthy adults to diesel exhaust and filtered air in a laboratory setting. Brain activity was measured before and after each exposure using functional magnetic resonance imaging.

Changes seen in the brain’s default mode network (DMN) — a set of interconnected brain regions used for memory and internal thought — showed participants had decreased functional connectivity in widespread regions of the network after exposure to diesel exhaust, compared with filtered air.

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The changes were found to be temporary, with participants' brains returning to normal after the exposure.

But Dr Carlsten said the effects could be long-lasting with longer exposure.

He warned drivers to take steps to limit their exposure to traffic pollution.

“People may want to think twice the next time they're stuck in traffic with the windows rolled down,” said Dr 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.”

Study author Dr Jodie Gawryluk, a psychology professor at the University of Victoria, said: “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.

“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.”