Air pollution has long been linked to breathing problems, heart disease, and reduced quality of life. But scientists are now increasingly worried about another possible danger that may be even harder to detect: damage to the brain.
A new study from researchers in the United Kingdom has found that common air pollutants can change both brain function and lung function within only a few hours of exposure. The findings suggest that even short periods of breathing polluted air may quickly influence how the brain works.
The research was published in the journal npj Clean Air and was carried out by a team of scientists from several U.K. institutions, including the University of Birmingham.
For many years, experts have known that polluted air can irritate the lungs and increase the risk of asthma, chronic lung disease, strokes, and heart attacks. More recently, researchers have started to connect long-term exposure to air pollution with neurological diseases such as dementia.
Dementia is a growing global health problem, especially as populations age. Millions of people worldwide are living with memory loss and cognitive decline, and scientists are trying to better understand the environmental factors that may contribute to these diseases.
One important theory is called the “lung-brain axis.” This idea suggests that the lungs and brain are closely connected. Polluted air may harm the brain directly when very small particles travel into the bloodstream and eventually reach brain tissue.
Pollution may also affect the brain indirectly by causing inflammation in the lungs, which then triggers harmful changes throughout the body.
The researchers behind the new study wanted to better understand whether different pollution sources affect the body in different ways.
Most current air quality measurements focus mainly on the amount of tiny particles floating in the air, known as particulate matter. However, the scientists suspected that the type of pollution itself may matter just as much as the total amount.
To investigate this, the researchers conducted a carefully controlled clinical study involving 15 healthy volunteers.
In what is known as a double-blind study, neither the participants nor the researchers directly interacting with them knew which pollutant exposure was being tested at a given time. This helps reduce bias and improves scientific accuracy.
The volunteers were exposed to several different types of real-world air pollution. These included clean air, diesel exhaust, woodsmoke, cooking emissions, and limonene secondary organic aerosol.
Limonene is a citrus-smelling chemical commonly found in cleaning products, air fresheners, and scented household items. When limonene mixes with other chemicals in indoor air, it can form tiny particles known as secondary organic aerosols.
Each participant was exposed to the pollutants for 60 minutes. Four hours later, the researchers tested their breathing and several aspects of brain function.
The scientists measured working memory, attention, emotional processing, movement speed, and motor control.
The results showed that different pollutants affected the body in different ways, even though all pollution mixtures were adjusted to contain similar levels of particulate matter.
Limonene-related pollution had the strongest effect on lung function. Woodsmoke and diesel exhaust also affected breathing, while cooking emissions had the smallest respiratory impact.
The brain effects were more complicated and somewhat surprising.
Diesel exhaust and woodsmoke appeared to improve processing speed in some tasks. Limonene-related pollution improved working memory compared with cooking emissions. However, diesel exhaust also showed signs of harming executive function, which is the brain’s ability to plan, focus, and make decisions.
The researchers believe nitrogen oxides, often called NOX, may partly explain these mixed results. These chemicals are commonly found in vehicle pollution and can change blood flow in the brain. Changes in blood flow may temporarily alter mental performance in different ways.
Professor Gordon McFiggans explained that although the pollution mixtures contained similar amounts of particulate matter, the body did not react to them in the same way. Each pollution source created its own unique pattern of effects in both the lungs and the brain.
Lead researcher Thomas Faherty from the University of Birmingham said the study highlights the importance of understanding how the lungs and brain interact when people breathe polluted air.
One especially concerning finding was how quickly the effects appeared. Detectable changes were seen after only one hour of exposure.
The researchers warn that if such changes can occur so rapidly, repeated or long-term exposure over many years may have much larger consequences for brain health.
This may be especially important for people living in cities, where traffic pollution, cooking emissions, and indoor air pollutants are part of daily life.
The study also raises questions about current air quality regulations. Since different pollution sources appear to affect the body differently, measuring only total particulate matter may not fully capture the real health risks.
The scientists say future public health strategies may need to focus more carefully on the exact sources and chemical makeup of air pollution rather than only measuring particle levels.
The findings may also help doctors better understand why some people are more vulnerable to neurological diseases such as dementia.
Overall, the study provides important new evidence that the air people breathe every day may influence brain health much faster than previously understood.
If you care about brain health, please read studies about how the Mediterranean diet could protect your brain health, and blueberry supplements may prevent cognitive decline.
For more health information, please see recent studies about antioxidants that could help reduce dementia risk, and Coconut oil could help improve cognitive function in Alzheimer’s.
Source: University of Birmingham.
