Study reveals alarming impact of even brief exposure to air pollution on our brains

Air pollution can impair cognitive functions like interpreting emotions, focusing on tasks and engaging appropriately in social situations

Even brief exposure to air pollution can affect our brain’s ability to make decisions and focus on work, a new study has found.

While the respiratory and cardiovascular impacts of air pollution are well documented, the study found that even short-term exposure to high levels of air pollution can impair cognitive functions needed for daily activities.

These functions include interpreting emotions, focusing on tasks and engaging appropriately in social situations, according to the study published in Nature Communications on Thursday.

"Our study provides compelling evidence that even short-term exposure to particulate matter can have immediate negative effects on brain functions essential for daily activities such as doing the weekly supermarket shop," said Dr Thomas Faherty, a researcher at the University of Birmingham who co-authored the study.

The researchers exposed participants to either high levels of air pollution, simulated using candle smoke, or to clean air. They assessed cognitive performance both before exposure and four hours afterwards, focusing on tasks that measured working memory, selective attention, emotion recognition, psychomotor speed, and sustained attention.

While working memory remained unaffected, selective attention and emotion recognition showed significant declines after exposure to polluted air.

These impairments occurred regardless of whether participants breathed through their mouths or noses, suggesting that inhalation route had little impact on the cognitive effects.

"Poor air quality undermines intellectual development and worker productivity, with significant societal and economic implications in a high-tech world reliant on cognitive excellence," said professor Francis Pope, another co-author of the study from the University of Birmingham.

"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."

The researchers believe that inflammation triggered by exposure to particulate matter, which is found in all polluted urban areas, may be responsible for these cognitive deficits.

Our brains are just as vulnerable to environmental toxins as our lungs, and it's time public health policies reflect that reality.

Dr Thomas Faherty, study co-author from the University of Birmingham

This could explain why some brain functions, like working memory, appear more resilient to short-term pollution exposure while others, such as attention and emotion recognition, are more vulnerable.

Selective attention is key for decision-making and goal-oriented behaviour – like navigating a grocery store, focusing on a shopping list while ignoring distractions. Emotion recognition helps individuals interpret social cues, guiding appropriate responses in interpersonal interactions.

"This study shows the importance of understanding the impacts of air pollution on cognitive function and the need to study the influences of different sources of pollution on brain health, particularly in vulnerable older members of society,” said professor Gordon McFiggans from the University of Manchester.

Globally, air pollution is the leading environmental risk factor for human health, linked to premature mortality and a range of diseases.

PM2.5, the fine particulate matter most harmful to health, was associated with 4.2 million deaths in 2015 alone, according to the World Health Organization.

The WHO recommends that 24-hour PM2.5 exposure limits should not exceed 15 micrograms per cubic metre, with an annual limit of 5 micrograms per cubic meter. However, more polluted cities like Delhi have seen levels go up to 249 micrograms per cubic metre.

The researchers say there’s a need for further studies to explore how different pollution sources affect cognitive functions, particularly in vulnerable populations such as children and older adults.

They are also calling for investigations into protective measures that could reduce these effects and protect people living in polluted cities.

"Air pollution is not just a respiratory or cardiovascular issue; it's a cognitive one," said Dr Faherty.

"Our brains are just as vulnerable to environmental toxins as our lungs, and it's time public health policies reflect that reality."