New research reveals that just an hour of exposure to common indoor and outdoor air pollutants can trigger changes in people’s lung function and brain activity.

A new study involving scientists from the National Centre for Atmospheric Science (NCAS), has shown that short‑term exposure to everyday air pollution can alter how our lungs and brains function – highlighting why the type of pollution matters as much as how much of it we breathe.

Air pollution is already known to increase the risk of heart and lung disease, and growing evidence links long‑term exposure to higher dementia risk. But, most air quality regulations focus on the total amount of particulate matter in the air. This new research shows that pollution from different sources can have distinct and sometimes contrasting effects, even when levels are the same.

In a carefully controlled clinical study, 15 healthy volunteers were exposed on separate occasions to clean air and to pollution mixtures commonly found in daily life. The volunteers were aged over 50 and had first relatives with dementia. The pollutants they were exposed to included diesel exhaust, woodsmoke, cooking emissions, and a citrus‑scented aerosol formed from limonene – a chemical widely used in cleaning products.

Each exposure lasted just 60 minutes. Researchers assessed participants’ lung function and a range of cognitive processes, including attention, memory, and reaction speed, both before exposure and four hours afterwards.

NCAS scientists at the University of Manchester and the University of York played a central role in designing and running the experiments at the NCAS‑supported Manchester Aerosol Chamber, where the exposures took place, as well as in characterising the different gas and particle pollution emissions to which volunteers were exposed.

The study found that lung function was most affected by exposure to limonene‑derived aerosols and woodsmoke, even after just a 60‑minute exposure. Although the changes were small, detecting them over such a short period surprised researchers and suggests the respiratory system may be particularly sensitive to certain pollution sources.

Brain responses also varied depending on the type of air pollution. Exposure to diesel exhaust and woodsmoke was associated with faster processing speed, while limonene‑derived aerosols enhanced working memory compared with cooking emissions. In contrast, diesel exhaust showed signs of impairing higher‑level executive function (the mental skills we rely on to plan, focus, and make decisions).

“Even though all the pollution mixtures contained similar levels, we didn’t see a single, uniform response. Each source produced its own pattern of short‑term changes in the lungs and the brain. This tells us that the composition of pollution really matters,” says Dr Aristeidis Voliotis.

The researchers highlight the importance of what is known as the lung–brain axis: the close biological connection between respiratory inflammation and brain function. Pollution can affect the brain directly, when particles or chemicals enter the bloodstream or nervous system, or indirectly through inflammation in the lungs.

By safely exposing the same people to different real‑world pollution mixtures, the team were able to detect differences that would be missed if they had only looked at overall pollution levels. This approach opens new doors for understanding how air pollution contributes to neurological disease.

“The effects of air pollution on human health are an inherently multidisciplinary problem, and it was especially insightful to work in a truly multidisciplinary environment with researchers from the clinical, social, biomedical, and atmospheric science domains. Bringing together these different perspectives challenged us to rethink our methods and ultimately develop an approach that was both effective and broadly applicable, opening new avenues for future research in the area,” explains Dr Aristeidis Voliotis.

With populations ageing and cities becoming more densely populated, understanding how pollution affects people’s health is increasingly urgent. The researchers suggest that their findings strengthen the case for pollution‑specific guidance, more refined air quality regulation, and better protection for vulnerable groups.