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Traffic pollution impairs human brain function within a few hours

A new study shows that common levels of traffic pollution can impair human brain function in just a matter of hours.

The study was the first to show in a controlled trial using functional magnetic resonance imaging (fMRI) that exposure to diesel exhaust disrupts the ability of different regions of the human brain to interact and communicate with each other.


Published in the journal Environmental Health, the findings show that just two hours of exposure to diesel exhaust leads to a decrease in functional brain connectivity — a measure of how the study provides the first evidence in humans, from a controlled experiment, of altered brain network connectivity caused by air pollution.

“For several decades, scientists have believed that the brain may be protected from the harmful effects of air pollution,” said senior study author Dr. Chris Carlstein, professor and chair of the Department of Respiratory Medicine and Canada Chair of Research in Occupational and Environmental Pulmonary Diseases at the University of British Columbia. It is the first of its kind in the world, providing new evidence supporting the relationship between air pollution and cognition.”

Measurement of brain activity before and after exposure to exhaust

For the study, researchers briefly exposed 25 healthy adults to diesel exhaust and filtered air at different times in a laboratory setting. Brain activity was measured before and after each exposure using functional magnetic resonance imaging (fMRI).

The researchers analyzed changes in the brain’s default mode network (DMN), a group of interconnected brain regions that play an important role in memory and internal thinking. Functional magnetic resonance imaging revealed that participants had reduced functional connectivity in diffuse areas of the DMN after exposure to diesel exhaust, compared to filtered air.

“We know that altered functional connectivity in the DMN has been associated with decreased cognitive performance and depressive symptoms, so it is concerning to see traffic pollution disrupting these same networks,” said Dr Judy Gorelock, a professor of psychology at the University of Victoria and first author of the study. Further research is required to fully understand the functional effects of these changes, as it is possible that they may impair people’s thinking or their ability to function.”

Take steps to protect yourself

Notably, the changes in the brain were temporary and the participants’ communication returned to normal after the exposure. Dr. Carlsten speculated that the effects could be long-lasting when the exposure is continuous.

He said people should pay attention to the air they breathe and take appropriate steps to reduce their exposure to potentially harmful air pollutants such as vehicle exhaust.

“People may want to think twice about the next time they are stuck in traffic with the windows open,” Dr. Carlsten said. “It’s important to make sure your car’s air filter works well, and if you’re walking or biking on a busy street, consider converting.” To a less busy road.”

While the current study only looked at the cognitive effects of pollution from traffic, Dr. Carlsten said other products of combustion are likely to be a concern.

“Air pollution is now recognized as the greatest environmental threat to human health, and we are increasingly seeing the effects across all major organ systems,” says Dr. Karlstein. “I expect that we will see similar effects on the brain from exposure to other air pollutants, such as smoke from wildfires, with increasing the incidence of neurocognitive disorders, this is an important consideration for public health officials and policy makers.”

The study was conducted at the University of British Columbia’s Air Pollution Exposure Laboratory, located at Vancouver General Hospital, which is equipped with a state-of-the-art exposure booth that can simulate what it’s like to breathe a variety of air pollutants.

In this study, which was carefully designed and approved for safety, the researchers used freshly generated exhaust that had been diluted and aged to reflect real-world conditions.



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