Traffic pollution is an ever-growing problem in increasingly busy and populous urban areas. Its effects on the human body have been well-documented, but one particular type of damage is often overlooked – the impact on brain function.
Researchers from the University of British Columbia (UBC) and the University of Victoria (UVic) have demonstrated in a recent study that normal amounts of traffic pollution can damage brain function within hours.
The peer-reviewed article published in the journal Environmental Health indicates that two hours of exposure to diesel exhaust reduces the functional connectivity of the brain. The study demonstrates for the first time in humans from a laboratory experiment that air pollution alters brain network connectivity (Gawryluk et al., 2023).
“For a long time, scientists thought that the brain might be protected from the harmful effects of air pollution,” said Dr. Chris Carlsten, the lead author of the study, also the head of respiratory medicine at UBC. “This is the first study of its kind in the world, and it shows that there is a link between air pollution and brain function.”
The Effects of Pollutants on The Brain
Pollutants from traffic have been found to have multiple adverse effects on the brain, including:
- Reduced mood and cognitive ability
- Decreased memory and concentration
- Risk of Alzheimer’s and Parkinson’s Disease
- Decline in thinking skills and learning
Previously, several researchers thought these effects could be particularly pronounced among children and the elderly, who are more vulnerable to these kinds of changes in their brain function.
To study the impact of traffic-related air pollution on the health of adults, the UBC researchers briefly exposed 25 healthy people to diesel exhaust and filtered air at various intervals during the study. Brain activity was assessed using functional magnetic resonance imaging before and after each treatment (fMRI).
The researchers looked at changes in the brain’s default mode network (DMN), which is a group of brain regions that work together and are important for memory and thinking. The fMRI showed that the participants’ functional connections in many parts of the DMN were weaker after breathing diesel exhaust than after breathing filtered air.
Dr. Jodie Gawryluk, the study’s first author, also a psychology professor at the UVic, 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 additional study is needed to understand the functional implications of these alterations completely, they may impede people’s thinking or capacity to work.
Taking Steps Reducing the Risk of Brain Damage
Remarkably, the changes in the brain were only temporary, and after the exposure, the participants’ brains went back to normal. Dr. Carlsten thought that the effects might last for a long time if the exposure is constant. He said that people should be aware of the air they breathe and do what they need to do to limit their exposure to dangerous air pollutants like vehicle exhausts.
“The next time people are stuck in traffic with their windows down, they might want to think twice,” said Dr. Carlsten. “It’s important to make sure your car’s air filter is in good shape, and if you’re walking or biking down a busy street, you might want to take a different path.”
To minimize the impact of traffic-related air pollution, individuals and governments can take steps to reduce their exposure to these harmful pollutants and protect their brain health. This includes:
- Encouraging the use of public transport, cycling, or walking
- Promoting the use of electric or hybrid vehicles
- Making sure that vehicles are well-maintained to reduce emissions
Even though the current study only looked at the cognitive effects of pollution from traffic, Dr. Carlsten said that other combustion products are probably also a problem.
Dr. Carlsten said air pollution is the biggest environmental danger to human health and is affecting all major organ systems. “Other air contaminants, such forest fire smoke, may have comparable brain effects. Public health and policymakers must acknowledge the rising prevalence of neurocognitive diseases.”
The study was done at UBC’s Air Pollution Exposure Laboratory at Vancouver General Hospital, which has a high-tech exposure booth that simulates breathing air contaminants.
The researchers employed freshly-generated exhaust that was diluted and aged to simulate real-world circumstances in this study, which was carefully planned and authorized for safety.
Traffic pollution has a clear and established impact on brain function and can impair cognitive, memory, and learning abilities. Reducing exposure to these pollutants is essential for maintaining healthy cognitive function, and this can be achieved through public transportation, alternative fuel sources, and effective air filtering.