A new study by researchers at the University of British Columbia and the University of Victoria has shown that common levels of traffic pollution can damage human brain function within hours.
The peer-reviewed results, published in the journal Environmental Healthshow that just two hours of exposure to diesel exhaust causes a reduction 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 pollution air.
“For many years, scientists thought that the brain could be protected from the harmful effects of air pollution,” said senior study author Dr. Chris Carlsten, professor and head of respiratory medicine and 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 link between air pollution and cognition.”
For the study, the researchers briefly exposed 25 healthy adults to diesel exhaust and filtered air at various 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 series of interconnected brain regions that play an important role in memory and internal thinking. The fMRI showed that participants had reduced functional connectivity in extensive regions of the DMN after exposure to diesel exhaust, compared to filtered air.
“We know that altered functional connectivity in the DMN is associated with reduced cognitive performance and symptoms of depression, so it is concerning to see traffic pollution affecting the same networks,” said Dr. Jodie Gawryluk, professor of psychology at the University of Victoria and first author of the study. “Although more research is needed to fully understand the functional impacts of these changes, they may affect people’s thinking or their ability to work.”
Taking steps to protect yourself
Notably, the changes in the brain were temporary and participants’ connectivity returned to normal after exposure. Dr. Carlsten said the effects could be long-term when there is continuous exposure. He said people should be mindful of the air they breathe and take appropriate measures to minimize their exposure to potentially harmful air pollutants such as car exhaust.
“People might want to think twice the next time they’re stuck in traffic with the windows rolled down,” said Dr Carlsten. “It’s important to make sure your car’s air filter is in good working order, and if you’re walking or cycling down a busy street, consider diverting to a less busy route.”
Although the current study only looked at the cognitive effects of traffic pollution, Dr. Carlsten that other products of combustion are likely to be a concern.
“Air pollution is now recognized as the biggest environmental threat to human health and we are seeing more and more impacts across all major organ systems,” says Dr. Carlsten. “I expect we will see similar effects on the brain from exposure to other air pollutants, such as forest fire smoke. With the increasing incidence of neurocognitive disorders, it is an important consideration for public health officials and policy makers. “
The study was conducted at UBC’s Air Pollution Exposure Laboratory, located at Vancouver General Hospital, which has a state-of-the-art exposure booth that can mimic what it’s like to breathe in different air pollutants. In this study, which was carefully designed and approved for safety, the researchers used freshly diluted and aged exhaust to represent real-world conditions.