Study finds exposure to diesel exhaust can impair brain function within hours

A new neuroimaging study published in Environmental health discovered that our brain functions change when exposed to small amounts of diesel exhaust, a component of traffic-related air pollution. The results indicate that even small amounts of exposure to diesel exhaust cause negative changes in brain function. Research reveals the neural impact that traffic-related air pollution can have after limited exposure.

The adverse health effects caused by traffic-related air pollution, including respiratory and cardiovascular problems, are widely understood. Additionally, the negative impact on the central nervous system is newly recognized as an important health issue. Although the exact reasons for the harmful effects of traffic-related air pollution on the nervous system are unclear, early research suggests that the particles may be transmitted directly through the olfactory bulb or indirectly through inflammation.

These findings have serious implications, given that traffic-related air pollution is responsible for an estimated five million deaths worldwide each year, causing significant damage to both global health and productivity.

“For many decades, scientists believed the brain could be protected from the harmful effects of air pollution,” said study lead author Chris Carlsten, from the University of British Columbia. “This study, which is the first of its kind in the world, provides new evidence in support of a link between air pollution and cognition.”

To provide further evidence of the effects of traffic-related air pollution on body systems, the research team used a safe method of diesel exhaust dilution and studied brain changes at the using magnetic resonance imaging (MRI). Participants were exposed to diesel exhaust or filtered air after light exercise, which observed short-term effects on brain connectivity.

For the study, 25 healthy, non-smoking people between the ages of 19 and 49 were recruited. Recruitment was done through community posters, online notices and email notifications. The study was conducted in a double-blind, controlled crossover design at the Air Pollution Exposure Laboratory, located at Vancouver General Hospital, which is equipped with a state-of-the-art exposure cabin. technology that can mimic what it’s like to breathe in a variety of air pollutants.

Each participant was exposed to both filtered air and diesel exhaust at different times for comparison. Filtered air or diesel exhaust was present for 120 minutes during each exposure, with a particulate concentration of 300 μg/m3 or less. During the first 15 minutes of each hour, participants spent 15 minutes cycling at a slow to moderate speed. The study used a blinding method for participants and people collecting the MRI data. Thus, neither the participants nor the MRI technicians knew who had received diesel exhaust or filtered air. The MRI protocol used anatomical whole-brain MRI and functional MRI (fMRI) during a resting state, which lasted six minutes.

Results demonstrated that exposure to diesel exhaust resulted in decreased functional connectivity in the default mode network compared to filtered air. Previous studies have indicated that improved functional connectivity is related to physical activity, and the results of filtered air conditioning align with this finding. However, the same results were not seen for the diesel exhaust condition, indicating that the brain benefits of light exercise are not achievable in this condition.

“We know that impaired 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,” said Jodie Gawryluk, professor of psychology at the University of Victoria and responsible for the study. first author. “Although more research is needed to fully understand the functional impacts of these changes, it is possible that they alter people’s thinking or work capacity.”

Notably, changes in brain function were temporary, and participants’ connectivity returned to normal after exposure.

Nevertheless, these results are important for the well-being of the general public. These alterations in brain function are linked to decreased working memory, decreased work performance, and decreased work productivity. The study may help expand the knowledge base on direct evidence of neurocognitive effects caused by short-term exposure to traffic-related air pollution and should be considered a public health crisis. In addition, the results underscore the importance for individuals to limit their exposure to air pollution, including using public transport, reducing car use and wearing protective masks in areas. polluted.

“Air pollution is now recognized as the greatest environmental threat to human health and we are increasingly seeing the impacts on all major organ systems,” Carlsten said. “I expect we’ll see similar effects on the brain from exposure to other air pollutants, like smoke from wildfires. With the increasing incidence of neurocognitive disorders, this is an important consideration for public health officials and policy makers.

The study, “Brief Exposure to Diesel Exhaust Acutely Impairs Functional Brain Connectivity in Humans: A Randomized Controlled Crossover Study,” was authored by Jodie R. Gawryluk, Daniela J. Palombo, Jason Curran, Ashleigh Parker and Chris Carlsten.

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