Study: 2 hour exposure to traffic pollution impairs brain function

A study showed that even short exposure to traffic pollution has adverse effects on the brain.

Bad effects of traffic

Effect of traffic pollution on the human brain

According to a new study by researchers at the University of British Columbia (UBC) and the University of Victoria, a two-hour exposure to diesel exhaust decreases the brain’s functional connectivity, which is the measure of how different areas of the brain interact and communicate with each other.

The study also provides the first evidence of humans changing brain function due to air pollution.

For many decades, scientists thought the brain may be protected from the harmful effects of air pollution,” said senior study author Dr. Chris Carlsten, professor and head of respiratory medicine and the Canada Research Chair in occupational and environmental lung disease at UBC. “This study, which is the first of its kind in the world, provides fresh evidence supporting a connection between air pollution and cognition.

In the conduct of the study, researchers briefly exposed 25 healthy adults to diesel exhaust and filtered air at different times in a laboratory setting.

This was conducted at UBC’s Air Pollution Exposure Laboratory, located at Vancouver General Hospital, which is equipped with an exposure booth that can mimic what it is like to breathe a variety of air pollutants. The researchers also used freshly-generated exhaust that was diluted and aged to reflect real-world conditions.

The brain activity was measured before and after each exposure using functional magnetic resonance imaging or fMRI.

Changes in the brain’s default mode network (DMN), which is a set of interconnected brain regions that are vital for memory and internal thought, were analyzed.

The fMRI showed that the participants’ functional connectivity in widespread regions of the DMN decreased following exposure to diesel exhaust.

“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.

Gawryluk added that while further study is still needed, it is possible that they may impair people’s thinking or ability to work.

Still, the brain connectivity returned to normal following brief exposure.

Carlsten, however, said people should think twice before rolling down their car windows while they are stuck in traffic as effects could be long-lasting where exposure is continuous.

“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,” Carlsten added.

Aside from traffic pollution, other products of combustion may also be a concern, he warned.

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,” Carlsten said. “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, Carlsten added.

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Source: University of British Columbia