“Our work shows that short-term exposure to air pollution can significantly impact upon several dimensions of cognition,” says coauthor Francis Pope, PhD, an environmental scientist and professor at the University of Birmingham in England.
“In particular, it shows that selective attention is affected, which can diminish an individual’s ability to concentrate on everyday tasks. It could also make it more difficult to avoid distractions, meaning that our ability to perform tasks effectively will be reduced,” says Dr. Pope.
Exposure to Air Pollution Harms Decision-Making Ability
Investigators aimed to find out whether short-term exposure to air pollution affects brain function and whether breathing through the nose or mouth plays a role in how or how much it affects different types of brain functions.
A total of 26 adults participated in four different conditions. They were exposed to either clean air or high levels of pollution for one hour, with some participants wearing a nose clip to restrict nasal breathing.
Before and four hours after exposure, participants completed four cognitive tests measuring skills like working memory, attention, emotion recognition, and reaction time.
Researchers found that selective attention and emotion recognition were negatively affected by air pollution — regardless of whether subjects breathed normally or only through their mouths.
Selective attention helps decision-making and goal-directed behavior, such as prioritizing items on your shopping list in the supermarket, while ignoring other products and resisting impulse buys, according to the authors.
Socio-emotional cognition involves detecting and interpreting emotions in oneself and others, and helps guide socially acceptable behavior.
The pollution exposure didn’t affect working memory or reaction time.
Why does pollution affect some types of brain function? “The exact mechanisms linking air pollution to cognition are not fully understood, but the working hypothesis is that air pollution leads to inflammation, which has been linked in other studies to reduced cognitive performance,” says Pope.
Mouth Breathing Won’t Protect Your Brain From Harmful Fumes
The method of inhalation — through the nose or through the mouth — did not seem to affect the results, suggesting that the lung-brain pathway, rather than the nasal pathway, might be responsible for the cognitive effects, according to the authors.
That finding corroborates studies on the long-term effects of air pollution, says Anthony Wexler, PhD, a researcher and professor at UC Davis in California. Dr. Wexler was not involved in this current study.
“There’s other literature that talks about the particles that get into our brain through the olfactory bulb, but this study didn’t see that, and my research team didn’t see that either in our research,” he says. The olfactory bulb is the first part of the brain that receives information about what’s been inhaled through the nose.
That suggests that trying to avoid the effects of air pollution through mouth breathing won’t make much if any difference, says Wexler.
Because the study is short-term, it was able to look at the effects in humans rather than lab rats; that’s a strength of the research.
“Performing a long-term study that examined the cognitive impact of this kind of pollution on humans would not only be unethical, but it would also likely be prohibitively expensive,” says Wexler.
Poor Air Quality Could Hinder Innovation and Worker Productivity
“The implications of the paper are quite profound. Improved air quality will not only improve your physical health, which is well known — it will also help lead to better educational outcomes and workplace productivity,” says Pope.
Reduced productivity impacts economic growth, further highlighting the urgent need for stricter air quality regulations and public health measures to combat the harmful effects of pollution on brain health, particularly in highly polluted urban areas, he says.