Short exposure to air pollutants impacts lung and brain

Common indoor and outdoor air pollutants can alter both brain and respiratory function after only one hour of exposure according to new research.

The findings in NPJ Clean Air published by a team of researchers including Dr Thomas Faherty from the University of Birmingham reveal that different pollutant sources produce varied health effects even at identical concentrations in the air. The new study offers key insights into how air pollution impacts brain health and may contribute to dementia risk.

Air pollution can influence the brain either directly, when harmful particles enter the brain, or indirectly, through inflammation in the lungs which then impacts the brain. Neurological diseases have been increasing for decades and there is now a greater appreciation that long term exposure to elevated levels of air pollution are associated in dementia risk. Air quality is often measured by the total amount of particulate matter but this new study demonstrates that the source of the pollution matters as much as the quantity.

In a double‑blind study involving 15 healthy volunteers, participants were exposed to clean air, limonene SOA (a citrus fragrance commonly used in cleaning products), diesel exhaust, woodsmoke and cooking emissions. After 60 minutes of exposure, and a four-hour break, researchers assessed respiratory function alongside working memory, selective attention, socio‑emotional processing, psychomotor speed and motor control.

Respiratory responses showed limonene had the greatest impact on lung function, followed by woodsmoke, diesel exhaust and finally cooking emissions.

Cognitive function has mixed impact from pollutant sources

Cognitive function was also found to be significantly influenced by pollutant source. Diesel exhaust and woodsmoke improved processing speed; limonene‑derived secondary organic aerosol enhanced working memory compared to cooking emissions; and diesel exhaust showed signs of impairing executive function. The team suggests that the presence of nitrogen oxides (NO_X), known vasodilators, may alter blood flow to the brain and contribute to these mixed cognitive effects.

Dr Thomas Faherty of the University of Birmingham said: “This unique clinical study highlighted the importance of the lung–brain axis in brain responses to air pollution. Safely exposing the same individuals to multiple real‑world pollution mixtures allowed us to detect differences between pollutants, demonstrating the value of this approach for further pollution-dementia research.”

Consortium lead, Professor Gordon McFiggans from Manchester University said: “Even though the pollution mixtures were adjusted to contain similar levels of particulate matter, which is how we currently measure air pollution, we didn’t see a single, uniform response.

“Instead, each pollution source produced its own pattern of short‑term changes in the lungs and the brain. This tells us that the body doesn’t respond to all air pollution in the same way, the source and composition of the pollution really matter.”