New research has found that air pollution—including car exhaust and smoke from burning wood—raises the risk of developing dementia.
The study looked at data from nearly 30 million people and was published in The Lancet Planetary Health.
Dementia, including Alzheimer’s disease, affects more than 57 million people worldwide and is expected to nearly triple by 2050. This study shows that long-term exposure to certain pollutants may play a bigger role in dementia than previously thought.
Researchers from the University of Cambridge reviewed 51 studies from around the world, including data from North America, Europe, Asia, and Australia. They found that three major types of air pollution were strongly linked to a higher risk of dementia:
– PM2.5: Tiny particles that can get deep into the lungs. These come from things like car exhaust, factories, power plants, and wood burning. For every 10 micrograms per cubic meter (μg/m³) of PM2.5, the risk of dementia increased by 17%.
– Nitrogen dioxide (NO2): A gas found in car exhaust and gas stoves. For every 10 μg/m³ of NO2, the risk of dementia increased by 3%.
– Soot: A black substance also found in PM2.5. For every 1 μg/m³ of soot, the risk of dementia increased by 13%.
In cities like London and Birmingham, the levels of these pollutants are high enough to be a real concern.
Experts believe air pollution may cause dementia through inflammation and oxidative stress—harmful processes that damage brain cells. These effects may start in the lungs and spread throughout the body, including to the brain.
The study’s authors say reducing air pollution could have wide-reaching health, social, and economic benefits. It would ease the pressure on families, caregivers, and health systems.
Although the research mostly involved white people in wealthier countries, the researchers say people in lower-income and marginalized communities often face worse air pollution. Future studies need to include more diverse populations, especially those who might benefit the most from cleaner air.
The researchers also found that air pollution may raise the risk of different types of dementia, including Alzheimer’s and vascular dementia (which is caused by poor blood flow to the brain). While the link to vascular dementia was stronger, there weren’t enough studies to prove this with high confidence.
The authors call for stronger pollution regulations and more action from urban planners, governments, and international agencies. “Preventing dementia is not just about healthcare,” said Dr. Christiaan Bredell. “It’s also about cleaner cities, better transportation, and protecting the environment.”
If you care about dementia, please read studies about People who take high blood pressure medications have lower dementia risk and findings of Early indicators of dementia: 5 behaviour changes to look for after age 50.
For more about dementia, please read studies about Common drug for constipation is linked to higher dementia risk and findings of Scientists find link between heartburn drugs and increased dementia risk.
The study is published in The Lancet Planetary Health.
Copyright © 2025 Knowridge Science Report. All rights reserved.
