🧠 The real risk of pollution on our brain

Air pollution doesn't just affect our lungs. Invisible particles circulate in our daily environment and appear capable of reaching our brain. This silent threat could play a role in the development of neurodegenerative diseases like dementia or Alzheimer's disease.


Previous studies had already highlighted this danger. In this article we already discussed the impact of air quality on our mental health. In this one, we mentioned a link between pollution and cognitive performance. Recently, researchers examined a vast dataset from tens of millions of people worldwide. Their objective: to determine the real impact of air quality on cognitive disorders through a meta-analysis. The results, published in The Lancet Planetary Health, provide concerning but essential insights for public health.

Pollution and dementia: a confirmed link

This meta-analysis, led by the University of Cambridge, compiled 51 studies representing nearly 29 million participants. The analysis identifies three major pollutants associated with an increased risk of dementia: fine particles (PM2.5), nitrogen dioxide (NO2), and soot.

Each substance increases the risk in measurable ways:
- For every 10 µg/m³ of PM2.5, the risk of developing dementia increases by 17%
- Each 10 µg/m³ increment of nitrogen dioxide increases the risk by 3%
- Finally, the risk increases by 13% for every 1 µg/m³ of soot

These values illustrate the significant impact of prolonged daily exposure. The pollutants mainly come from road traffic, industrial plants, and domestic combustion. They penetrate deep into the lungs, enter the bloodstream, and reach the brain, where they can trigger harmful mechanisms.

Brain mechanisms and biological effects

Pollution appears to promote dementia through brain inflammation and oxidative stress. These processes damage cells, proteins, and DNA, weakening cognitive function.

Particles can also travel via the olfactory nerve, creating a direct effect on the brain. Pollution thus acts locally while causing reactions throughout the body, disrupting natural defenses and facilitating the accumulation of proteins associated with Alzheimer's.

Despite these observations, pollution alone does not explain the onset of dementia. Age, genetics, cardiovascular health, education, and physical activity also contribute to the overall risk. Environmental exposure is therefore part of a combination of factors.