JUANA SUMMERS, HOST:
Living around polluted air increases the risk of developing dementia. That is according to a new study. Alejandra Borunda with NPR's climate desk reports.
ALEJANDRA BORUNDA, BYLINE: About 20 years ago, a neuroscientist in Mexico City noticed that old dogs in the most air-polluted parts of the city were acting a lot like they had dementia. Emory University researcher Anke Huels was fascinated by that finding.
ANKE HUELS: They conduct an autopsy on dogs, or specifically looked at their brains...
BORUNDA: And inside, the researchers saw the characteristic signs of neurodegenerative disease.
HUELS: ...And found air pollution particles and nanoparticles in their brain, especially among the ones who had shown signs of neurodegeneration and Alzheimer's disease.
BORUNDA: The finding kicked off a whole new field of research, which asked, does air pollution contribute to dementia in humans, too? A new analysis in the medical journal The Lancet pulls together dozens of studies published recently, and it finds that for several types of pollution, the answer is yes. Clare Rogowski from the University of Cambridge led the study.
CLARE ROGOWSKI: Being exposed to certain levels of PM2.5 increases your risk of developing dementia by 8% over your lifetime.
BORUNDA: PM2.5 is one of the most common types of air pollution. It often comes from car exhaust or wildfire smoke or industrial pollution. The study also found that breathing in black carbon and nitrogen dioxide increased the chances of being diagnosed with dementia later. And Huels says other research is exploring exactly how pollution hurts the brain. She says it's a chain reaction. Tiny particles like black carbon...
HUELS: They are so small that when they enter your respiratory system, from there they can enter the alveoli of the lungs.
BORUNDA: Then the tiny particles can get into the blood.
HUELS: And once they are in your blood, they can cause systemic inflammation.
BORUNDA: And inflammation in the brain is linked to neurodegenerative disease. Rogowski says the new study results make a clear point.
ROGOWSKI: We can see that there would be a massive reward to decreasing our exposure to air pollution.
BORUNDA: She points to policy actions that reduce air pollution, like the congestion pricing New York City recently implemented to cut down on car and truck exhaust. Similar policies in London and Stockholm led to cleaner air. And Rogowski says the benefits of cleaner air aren't just for brains.
ROGOWSKI: We know asthma is associated with air pollution. We know cardiovascular things like heart disease are associated with air pollution.
BORUNDA: So, she says, less pollution means better health overall.
Alejandra Borunda, NPR News.
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