According to a new study, breathing in diesel exhaust while sitting in traffic for just a few hours can impair brain function and cognition.
Traffic pollution has long been linked to memory problems, but long-term exposure was widely 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 it also increases a person’s risk of death from any cause.
Diesel exhaust caused damage to neurological connectivity specifically affecting 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 between the ages of 19 and 49 to filtered air and air contaminated with diesel exhaust in a laboratory at different times for 120 minutes.
During this time, 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 breathing filtered air.
Dr Chris Carlsten, lead author of the study, said: “People might want to think twice the next time they’re stuck in traffic with the windows down.”
“It’s important to make sure your car’s air filter is in good working order, and if you’re walking or cycling on a busy street, consider diverting to a less busy route.”
The researchers specifically focused on changes to the brain’s Default Mode Network (DMN), a set of brain regions that are more active during passive tasks than tasks requiring focused external attention.
DMN damage 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 involved in any specific mental exercise.
We may be dreaming, remembering memories, envisioning the future, monitoring our surroundings, thinking about other people’s intentions, etc.
Dr Jodie Gawryluk, a psychologist at the University of Victoria and first author of the study, said: ‘We know that impaired functional connectivity in the DMN has been associated with reduced cognitive performance and symptoms of depression, it It is therefore worrying to see traffic pollution interrupting these same networks.’
“Although further research is needed to fully understand the functional impacts of these changes, it is possible that they alter people’s thinking or work capacity.”
The default mode network has a variety of functions that could be hampered after hours spent in traffic on your commute to work. The DMN is a hub for self-reflection and shows activity during rumination about 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 happened at specific times in our lives.
The team’s findings offered a glimmer of hope: the neurological effects caused by exposure to exhaust fumes were short-lived. However, long-term exposure from daily commutes in traffic will greatly aggravate health risks.
The study said: “Real-world exposures are often more persistent, particularly in areas of the world for which levels such as those we use are not uncommon.
“It is hypothesized that chronic exposure is indeed a series of short-term exposures (only one of which was exposed to our participants) that ultimately leads to accumulated deficits by stress on allostatic load…but whether or not this applies to pollution in the neurocognitive domain, while hypothetical, 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 followed 10 volunteers who were hooked up to an electroencephalograph (EEG) and exposed for 30 minutes to air in a lab polluted with diesel fumes adjusted to levels typical of a busy city street. .
Around this time, the researchers found that people’s brains displayed a stress response, indicating altered information processing in the cerebral cortex, which continued to increase even after the subjects were removed from the smoke.