Air pollution could be increasing the risk of dementia, according to a major analysis of research involving nearly 30 million people.
Scientists found that tiny particles from car exhaust and industrial sources may play a key role in the development of dementia, including Alzheimer’s disease and vascular dementia.
Dementia affects over 57 million people worldwide, and this number is expected to reach nearly 153 million by 2050. While some high-income countries like those in Europe and North America show signs of decreasing dementia rates, the global outlook remains concerning.
The new study, published in The Lancet Planetary Health, was led by researchers at the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge. They reviewed 51 studies involving over 29 million people and conducted a detailed analysis of 34 studies from around the world, including North America, Europe, Asia, and Australia.
They found clear links between exposure to air pollution and increased risk of dementia. The three main pollutants associated with this risk were:
PM2.5: These are tiny particles 2.5 microns or smaller, which can be inhaled deeply into the lungs. They are produced by vehicles, power plants, factories, wood-burning stoves, and construction sites.
Nitrogen dioxide (NO2): A harmful gas mainly produced by burning fossil fuels, especially from diesel vehicles and industrial processes.
Soot: A type of fine black carbon particle from car exhaust and wood burning that can enter the lungs and affect the heart and brain.
For every 10 micrograms per cubic meter of PM2.5, the risk of developing dementia increased by 17%. For NO2, the risk went up by 3% for the same level of exposure. For soot, every 1 microgram increase raised the risk by 13%.
The study suggests that long-term exposure to air pollution may harm the brain by triggering inflammation and oxidative stress. These processes are known to damage brain cells and play a role in dementia.
Importantly, the researchers highlight that most of the people in these studies were white and from wealthy countries. Yet, people in poorer or marginalized communities are often more exposed to pollution. This means they could be at even higher risk and deserve more attention in future studies.
The study also found that air pollution may be more strongly linked to vascular dementia, which is caused by problems with blood flow in the brain. However, more research is needed to confirm this.
Experts say reducing air pollution could have wide health benefits. Stricter environmental policies, better city planning, and cleaner transport could all help lower the risk of dementia and ease the burden on families and health systems.
Preventing dementia is not just a health issue—it’s an environmental and social one too. Everyone has a role to play, from governments to city planners to individuals making daily transport choices.
If you care about dementia, please read studies about a simple solution to fight dementia and big causes of memory loss, dementia you need to know.
For more health information, please read studies that people who take high blood pressure medications have lower dementia risk and early indicators of dementia: 5 behaviour changes to look for after age 50.
The study is published in The Lancet Planetary Health.
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