Moderate levels of traffic pollution have the potential to damage human brain function in just a few hours, a study has found. The study found that exposure to diesel exhaust for just two hours reduced functional connectivity in the brain.
Researchers from the University of British Columbia and the University of Victoria in Canada used functional magnetic resonance imaging (fMRI) to measure how brain activity changed before and after exposure to diesel exhaust and filtered air in 25 healthy adults.
What the research team looked at was changes in the brain’s default mode network (DMN). The DMN is an area of the brain that becomes active when you are drowsy or daydreaming. It is a network of neurons that spreads over the medial prefrontal cortex, posterior cingulate cortex, and parietal cortex, and plays an important role in memory and insight by connecting each area with each other.
In this study, functional connectivity was reduced in a broad area of the DMN after exposure to diesel exhaust compared to filtered air.
“Since changes in functional connectivity in the DMN are known to be associated with cognitive decline and depressive symptoms, it is concerning that traffic pollution disrupts these same networks,” said the researchers. “We need further work to fully understand the functional impact of these changes. A lot of research is needed, but it has the potential to damage people’s thinking and work ability.”
The brain changes were temporary and brain connections returned to normal after exposure, the researchers speculated, and that these effects could be prolonged where exposure continued.
Although the study only looked at the cognitive effects of traffic, the researchers said other products of combustion could also be a problem.
“Air pollution is now recognized as the greatest environmental threat to human health, and we are increasingly seeing effects on all major organ systems,” said the researchers. A similar impact is expected,” he added.
The results of this study were published in the journal ‘Environmental Health’ under the title of ‘Brief diesel exhaust exposure acutely impairs functional brain connectivity in humans: a randomized controlled crossover study’.
