A new study has found that spending just one hour breathing in polluted air can alter the way your brain and lungs function. Air pollution, particularly particulate matter (PM), has been linked to numerous diseases, including asthma and several forms of cancer.
Study Methodology
In this research, healthy adults were exposed for 60 minutes to five different air types: clean air, limonene SOA (a citrus fragrance commonly used in cleaning products), diesel exhaust, woodsmoke, and cooking emissions. After an hour, the volunteers had a four-hour break before researchers tested their lung function, working memory, attention, emotion processing, psychomotor control, and motor function.
Respiratory and Cognitive Impacts
The greatest respiratory impact was seen among people exposed to limonene, followed by woodsmoke, diesel exhaust, and cooking emissions. Regarding cognition, diesel exhaust showed the strongest signs of impairing executive function, which is responsible for planning, focused attention, and emotional regulation. This may be due to nitrogen oxides altering blood flow to the brain.
Though participants were only exposed to pollutants for an hour, the researchers warned that repeated exposure could lead to permanent cognitive issues and health risks such as cancer.
Expert Commentary
Dr Thomas Faherty, lead study author and post-doctoral researcher at the University of Birmingham in the UK, stated: "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."
Particulate Matter and Health Risks
Particulate matter consists of microscopic particles from sources like car exhaust, power plants, wildfires, and fuel burning. These particles can penetrate deep into lung tissue and enter the bloodstream, causing inflammation, constricting blood vessels, raising blood pressure, promoting artery-narrowing plaque, and triggering oxidative stress that damages cells, mitochondria, and DNA.
Past research has tied fine particulate matter (PM2.5) to dementia. A February study found that for every small increase in PM2.5, Alzheimer's disease risk rose by nearly nine percent. Experts estimate about 150 million Americans are regularly exposed to environmental pollution.
Study Details
In the new study from the University of Birmingham, researchers recruited 15 healthy adults over age 50 without dementia but with a family history of the disease. The average participant age was 60, and 62 percent were men. All were white. Participants were unaware of the order of exposure to the five conditions and were asked to identify which they experienced with a confidence rating.
The team found limonene aerosol exposure reduced lung function by 3.4 percent, followed by woodsmoke exposure at 2.6 percent. Diesel exhaust exposure led to small reductions in executive function, measurable through tasks like copying shapes and word recall.
Gordon McFiggans, study author and professor of atmospheric sciences at the University of Manchester, noted: "Even though the pollution mixtures were adjusted to contain similar levels of particulate matter, 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."
The team emphasized that more research is needed on long-term effects of exposure to different types of particulate matter, which could help drive legislation and other measures to protect vulnerable populations.
