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Long-term exposure to air pollution may cause your brain to age more quickly and put you at higher risk for a stroke, a new study suggests.

Exposure to higher levels of air pollution may be linked to lower total cerebral brain volume, according to a study published in the May issue of Stroke, which analyzed health data from nearly 1,000 men and women over 60 who did not have dementia and had not had a stroke.

Total cerebral brain volume naturally decreases as humans age, resulting in declines in ability to learn new things and retrieve information, but the researchers found that air pollution exposure may be linked to premature brain aging and higher risks for certain brain strokes.

The findings add new knowledge to the impact of air pollution on the structure of the brain, a link that has remained largely unclear in research.

Specifically, a 2 microgram per square meter increase in PM2.5 (particulate matter in the air that is less than 2.5 micrometers wide) was associated with a 0.32% lower total cerebral brain volume, the study said. To put that in context, brain volume decreases at about 0.5% per year after age 40, and PM2.5 levels can vary widely across the world. For example, the PM2.5 in Beijing is about 175 micrograms per square meter, while the PM2.5 in New York City is about 30 micrograms per square meter.

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