Air pollution has been tied to Alzheimer’s disease. Here’s what you need to know

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Exposure to air pollution is making Alzheimer’s disease patients’ cognitive decline even worse, Pennsylvania researchers warned Monday, following a study.

Living in areas with high levels of pollution from wildfire smoke, car exhaust, and factories is linked to an increased amount of toxic proteins in the brain that are believed to trigger the most common form of dementia and progress the disease.

Patients who lived in areas with higher amounts of the particulate matter for even just one year had more severe accumulation of those proteins than those with less exposure. They also experienced faster memory loss, impaired judgment, and more difficulty with personal care.

“This study shows that air pollution doesn’t just increase the risk of dementia — it actually makes Alzheimer’s disease worse,” Dr. Edward Lee, co-director of the University of Pennsylvania School of Medicine’s Institute on Aging, explained in a statement.

To reach these conclusions, Lee and his team studied the brains of more than 600 people who had died with Alzheimer’s. The brains were sourced from the Penn Medicine Brain Bank. Researchers noted they could not account for factors such as second-hand smoke and if patients had worked with potentially dangerous chemicals.

Smoke from wildfires fills the skies over Arizona’s Grand Canyon last July. Air pollution from wildfires and other sources across the US has been found to make Alzheimer’s disease worse, researchers said Monday (Getty Images)

A growing body of research on PM2.5

The findings build on years of research showing similar negative impacts to brain health. Traffic pollution was linked to signs of Alzheimer’s disease in brain tissue in an Emory University study last year and wildfire smoke has been tied to an increased risk of dementia.

Last week, Johns Hopkins Medicine researchers announced a potential link between air pollution and an increased risk for Lewy body dementia, which is a progressive neurodegenerative brain disorder and the second most common form of dementia after Alzheimer’s.

These and other studies have also cited the formation of toxic protein in the brain and hallmarks of Alzheimer’s disease following exposure to PM2.5 air pollution.

PM2.5 is a form of particulate matter — a mixture of many chemicals — that is emitted from gasoline, oil, diesel, wood, agricultures, landfills, construction, wildfires, and volcanoes. The particles each have a diameter about 30 times smaller than that of a human hair, according to the Environmental Protection Agency. People can also be exposed through water sources, and the particles can travel for hundreds of thousands of miles.

When inhaled, the particles can get into the lungs and bloodstream, resulting in premature death, acute bronchitis, and cardiovascular conditions. These threats disproportionately impact children, infants, people with asthma, and older adults with chronic heart or lung disease.

A television crew is shrouded in the smoke from a wildfire last April in Forked River, New Jersey. Areas regularly affected by fires and near factories are at greater risk of the negative health effects of particulate matter (Getty Images)

Air pollution and Alzheimer’s threats are both growing

Even with air pollution across the country at its lowest levels in decades, nearly half of Americans are exposed to dangerous levels, according to the American Lung Association.

But some people are more affected than others, including wildfire-riddled areas of California and the West, areas near highways, and residents who live around factories. By 2030, air pollution from artificial intelligence data centers could result in as many as 1,300 early deaths each year, according to Caltech researchers. Climate change fueled by greenhouse gas emissions is also making wildfires more frequent and severe.

Right now, 91,000 premature deaths are linked to air pollution from oil and gas, according to a recent study from researchers in the U.S. and U.K. About 135,000 air pollution deaths occur in the U.S. each year.

There are fewer deaths from Alzheimer’s disease, for now. Last year, the number of Americans who died from Alzheimer’s disease reached more than 119,000, and it continues to climb. In 2022, it was the sixth-leading cause of death among individuals aged 65 and older, according to the Alzheimer’s Association. And for the first time, the number of people living with Alzheimer’s is more than seven million. That number is expected to jump to 13 million by 2050.

Air pollution could make a “big impact” on the risk for developing Alzheimer’s disease, Lee said. To reduce exposure, people can do workouts indoors, make sure they have air cleaners and good filters in their homes, wear tight-fitting N95 masks or respirators, and strictly follow air quality alerts.

“It underscores the value of environmental justice efforts that focus on reducing air pollution to improve public health,” he said.