Breathing polluted air might be doing more than harming your lungs—it could be quietly damaging your brain.

In one of the largest studies of its kind, researchers looked at data from almost 30 million people and found that long-term exposure to common air pollutants, like car exhaust and industrial fumes, is linked to a higher risk of dementia. These tiny particles in the air can travel deep into the body, and the study suggests they may contribute to memory loss and cognitive decline.

Dementia’s Global Toll and a Growing Crisis

A comprehensive review of nearly 30 million people’s health data has brought new attention to the connection between air pollution and a higher risk of developing dementia. This includes pollution from everyday sources such as vehicle exhaust.

Dementia, including Alzheimer’s disease, currently affects over 57 million people around the world. That number is projected to rise sharply, reaching an estimated 152.8 million cases by 2050. The consequences are far-reaching, placing a heavy burden on individuals, families, caregivers, and society as a whole.

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To better understand the connection, scientists from the Medical Research Council (MRC) Epidemiology Unit at the University of Cambridge conducted a large-scale review and meta-analysis, recently published in The Lancet Planetary Health. By combining and analyzing results from a wide range of studies, including those with conflicting outcomes, the researchers were able to draw more reliable conclusions about the link between pollution and dementia.

The final analysis included 51 studies and drew from data on over 29 million people, primarily from wealthier nations. Among these, 34 studies were part of the meta-analysis: 15 came from North America, 10 from Europe, seven from Asia, and two from Australia.

Three Dangerous Pollutants Implicated