Breathing polluted air over long periods could increase your chances of developing dementia, according to a large new study.
Researchers analyzed data from nearly 30 million people and found strong links between exposure to air pollution and the risk of developing diseases like Alzheimer’s.
Dementia affects more than 57 million people globally, and that number is expected to triple by 2050.
While some countries have seen a slight drop in dementia rates, the overall global trend is still climbing.
Scientists are trying to understand what increases someone’s risk of developing dementia—and now, outdoor air pollution is emerging as a key factor.
The study, led by researchers from the University of Cambridge’s Medical Research Council (MRC) Epidemiology Unit, reviewed 51 studies from around the world.
The team looked at different types of air pollution, including tiny particles called PM2.5, nitrogen dioxide (NO2), and soot.
These pollutants mostly come from sources like car exhaust, burning fossil fuels, power plants, and even wood stoves.
They found that for every increase of 10 micrograms per cubic meter (μg/m³) of PM2.5 in the air, a person’s risk of developing dementia went up by 17%. PM2.5 particles are so small that they can be inhaled deep into the lungs and even enter the bloodstream.
Nitrogen dioxide, a common byproduct of diesel vehicles and gas appliances, was linked to a 3% increase in dementia risk for every 10 μg/m³. Soot, which is a component of PM2.5, was also tied to a higher risk.
Although the exact reasons air pollution may cause dementia aren’t fully understood, researchers believe it involves brain inflammation and oxidative stress—harmful processes that can damage brain cells and lead to memory problems over time.
Polluted air can reach the brain directly or travel through the body after entering the lungs, triggering widespread damage.
The researchers emphasized that these findings are important for public health and policymaking. Cutting air pollution, they say, would not only improve respiratory and heart health but could also reduce the risk of dementia, easing the burden on families, caregivers, and health systems.
They also noted that most of the studies reviewed included people from high-income countries, primarily white populations.
Since lower-income and marginalized communities are often more exposed to air pollution, future research should focus on these groups to better understand the full impact and ensure fair solutions.
The findings suggest that tackling dementia isn’t just a job for doctors—it also requires smarter urban planning, stricter environmental laws, and cleaner transportation systems. Keeping the air clean might just help keep our minds clearer too.
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