Breathing diesel exhaust while sitting in traffic for just a couple of hours can affect brain function and cognition, a new study shows.
Traffic pollution has long been linked to memory problems, but long-term exposure was generally thought to pose the greatest risk.
Researchers in Canada have found that the damage causes measurable changes in just two hours.
Air pollution not only erodes neurological health, but also increases a person’s risk of death from all causes.
Diesel exhaust caused damage to neurological connectivity that specifically affected a region of the brain called the default mode network, which plays a role in people’s internal thoughts and memories.
in the new study published In the journal Environmental Health, researchers from the University of British Columbia and the University of Victoria exposed 25 people aged 19 to 49 to filtered air and diesel exhaust-contaminated air in a laboratory at different times for 120 minutes.
During that time, the study subjects rode a stationary bike with light effort for about 15 minutes to increase inhalation.
All subjects underwent MRI before and after each exposure to monitor brain activity at different stages.
They found that breathing diesel exhaust decreased functional connectivity, a measure of how brain regions interact and communicate with each other, compared to inhaling filtered air.
Dr Chris Carlsten, lead author of the study, said: “People may want to think twice the next time they’re stuck in traffic with their windows open.”
“It’s important to make sure your car’s air filter is working properly, and if you’re walking or biking down a busy street, consider detouring to a less traveled route.”
The researchers focused specifically on changes in the brain’s default mode network (DMN), a set of brain regions that are more active during passive tasks than tasks that demand focused external attention.
Damage to the DMN affects several areas of the brain, including the medial prefrontal cortex, posterior cingulate cortex, inferior parietal lobe, lateral temporal cortex, and hippocampal formation.
Activity in the DMN increases when we are awake and not engaged in any specific mental exercise.
We could be daydreaming, recalling memories, imagining the future, monitoring our surroundings, thinking about the intentions of others, etc.
Dr. Jodie Gawryluk, a psychologist at the University of Victoria and first author of the study. saying: “We know that impaired functional connectivity in the DMN has been associated with reduced cognitive performance and symptoms of depression, so it is concerning to see traffic pollution disrupt these very networks.”
“While more research is needed to fully understand the functional impacts of these changes, it is possible that they could affect people’s thinking or ability to work.”
The default mode network has a variety of features that could be hampered after hours of sitting in traffic on your commute home. The DMN is a center for self-reflection and shows activity during reflection on who we are, our personality traits and our feelings.
The DMN plays a role in our memory of the past. Its functionality is crucial to our ability to retain episodic memories, or detailed accounts of events that have happened during specific times in our lives.
The team’s findings offered a glimmer of hope: The neurological effects from exhaust exposure were short-lived. However, long-term exposure from commuting traffic will greatly exacerbate the health risks.
The study said: “Real-world exposures are often more persistent, particularly in regions of the world for which levels like the ones we use are not uncommon.”
“It is hypothesized that chronic exposure is indeed a series of short-term exposures (only one of which our participants were exposed to) that ultimately leads to cumulative deficits through a stress on allostatic load. But whether or not this applies to contamination in the neurocognitive realm, while a hypothesis, requires further study.
The fact that exposure to diesel exhaust can damage the brain is not in itself a new finding. In 2008, dutch researchers monitored 10 volunteers who were hooked up to an electroencephalogram (EEG) and exposed for 30 minutes to air in a laboratory contaminated with diesel fumes adjusted to levels typical of a busy city street.
At that time, the researchers saw that people’s brains displayed a stress response, indicative of a change in information processing in the cerebral cortex, which continued to increase even after the subjects had been removed from the fumes.