Just two hours’ exposure to traffic pollution can impair brain function, according to new research which provides ‘fresh evidence’ of the link between air pollution and cognition.

The Canadian study saw 25 adults exposed to diesel exhaust in a laboratory setting, with their brain activity measured before and after each exposure.

Researchers analysed areas of the brain involved with memory and internal thought, looking to see what changes occurred in the brain’s default mode network (DMN).

The research team found that after being exposed to diesel exhaust, participants had reduced functional connectivity in various regions of the DMN.

Senior study author Dr Chris Carlsten, professor and head of respiratory medicine at the University of British Columbia, 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.”

First author Dr Jodie Gawryluk, a psychology professor at the University of Victoria, added: “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.”

While the research team said the changes to brain function were temporary, they considered whether the effects may be longer lasting is the exposure is greater.

They urged people to consider the air they breathe and take steps to protect themselves, including keeping car windows closed when stuck in traffic and if walking, opting for a route where there is less traffic. The team also suggested that people check their car’s air filters.

Dr Carlsten said: “Air pollution is now recognised as the largest environmental threat to human health and we are increasingly seeing the impacts across all major organ systems.

“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.”

Read the study in the journal Environmental Health.

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