A new study suggests that different kinds of air pollution may affect the brain and lungs in distinct ways, even after just one hour of exposure.
The Universities of Manchester and Birmingham were involved in the research in which volunteers were exposed to several common pollution sources such as diesel exhaust, woodsmoke, cooking fumes and particles created by cleaning-product chemicals, to examine how each affected thinking skills and breathing.
The trial involved 13 healthy adults over age 50 who had a family history of dementia, a group considered at risk for future neurodegenerative disease. Participants spent one hour breathing either clean air or one of four pollution mixtures inside a controlled exposure chamber. After a four hour break, the researchers looked for changes in memory, attention, reaction speed and lung function.
Perhaps surprisingly, it was found that those participants exposed to diesel exhaust and woodsmoke showed slightly faster reaction times on a simple psychomotor task compared with those exposed to clean air or cooking emissions.
Meanwhile, exposure to particles formed from limonene, a chemical commonly found in cleaning products and air fresheners, was linked to better performance on a basic working-memory task than cooking emissions.
Of course, the results were not consistently positive. Diesel exhaust also showed signs of potentially impairing more complex tasks which involved selective attention and decision-making. The researchers said the mixed pattern suggests that some pollutants may temporarily sharpen basic reaction speed while still disrupting higher-order cognitive processes.
The team also saw small but measurable changes in lung function. People who inhaled woodsmoke or particles linked to cleaning products showed slightly worse results on a common lung function test than when they breathed clean air. The changes were small and not considered harmful, but researchers said it was surprising to see any effect after only one hour of exposure and at relatively low pollution levels.
Scientists believe the differing effects may stem from the chemical composition of each pollution source rather than particle mass alone. Diesel exhaust and woodsmoke contained much higher levels of nitrogen oxides, gases that may temporarily increase blood flow through their relationship with nitric oxide, a known vasodilator. The authors suggested this could partly explain the faster reaction times observed in some tests.
Consortium lead, Gordon McFiggans, Professor of Atmospheric Sciences at the University of Manchester 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.’
The researchers warn that the study was small and not designed to determine long-term health effects however, the trial offers one of the first controlled comparisons of how multiple real-world pollution mixtures affect cognition and respiratory health in the same people.’
The team hopes future studies with larger groups will clarify how short-term pollution exposure affects the brain and whether repeated exposures contribute to dementia risk over time.
The full research can be read here.
Photo: Alla Eddine Taleb
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