Dr. Cohen: New study links breathing wildfire smoke to dementia

Aug 21, 2023, 11:45 AM | Updated: Aug 29, 2023, 8:05 am

wildfire smoke dementia...

Smoke in Seattle shrouds the skyline on August 20, 2023. (Photo: Bill Kaczaraba/

(Photo: Bill Kaczaraba/

The smoke in Seattle skies could be detrimental to your long-term health, according to Dr. Gordon Cohen, talking on “Seattle’s Morning News,” especially for dementia.

Cohen, citing a study published in the Journal of the American Medical Association, said people in areas of the U.S. with high levels of air pollution have a greater risk of developing dementia.

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“The study is interesting because it’s really the first time that they have been able on a national level to find that people who lived in areas of the country with higher concentrations of particle pollution were at greater risk of developing dementia than those who didn’t live in similar areas,” Cohen said.

The study looked at 27,857 people between 1998 and 2016. They found that about 15% (4,105) developed dementia during the study period. All of them lived in those areas of the U.S. with higher concentrations of particle pollution.

This particle pollution is a mix of solid and liquid droplets that float in the air and can come in the form of dirt, dust, smoke, and pollen. Cohen said it is not clear why the particulate contamination causes an increase in dementia.

“This is an observational study,” Cohen explained. “There are a couple of possibilities for the dementia link. One is that there is, in fact, a direct attack, so to speak of these particles on our brain, it can either cause cell death of our neurons that are connected to our nose. And that could result in dementia. It’s also possible that particle pollution is modifying the inflammatory proteins that act on the brain.”

“So it’s possible that it’s having a direct effect. But it’s also possible that there’s an indirect effect,” Cohen continued. “We do know that exposure to particle pollution can cause heart conditions and blood vessel problems. And these are both also known to be a risk for Alzheimer’s disease and other forms of dementia.”

Cohen said masks, the type we wore during the pandemic, can help and that, “for example, when there’s smoke in the air from these wildfires because it will filter out most of this particulate matter.”

He also said that air quality monitors can assist in figuring out whether you are at risk.

“If you buy an air quality monitor, it measures PM2.5 levels, so it’s something that you can look at,” Cohen said. “But particulate matter can also come from things like coal and natural gas-fired plants, cars, agriculture, unpaved roads, and construction sites. But what’s really important for us here today is wildfires. And, in this particular study, the link to dementia was most robust in areas where pollution from agriculture and wildfires was the greatest.”

PM2.5, or particulate matter 2.5, refers to tiny particles or droplets in the air that are 2.5 microns or less in width. The largest PM2.5 particles are about 30 times smaller than a human hair.

PM2.5 can penetrate deeply into the lung, irritate and corrode the alveolar wall, and consequently impair lung function. High levels of PM2.5 are bad for our health. Most studies indicate PM2.5 at or below 12 μg/m3 is considered healthy with little to no risk from exposure. If the level goes to or above 35 μg/m3 during a 24-hour period, the air is considered unhealthy and can cause issues for people with existing breathing issues such as asthma.

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“You couldn’t make a decision about where you live relative to busy streets, do you live under an airplane flight path or something like that,” Cohen said. “But you know, here we are in Seattle, in the skies are filled with smoke that’s been blown over from Spokane, or at times, it’s being blown down from Canada or whatever, and we don’t even have our own local forest fires, that particular matter is being blown into our environment? So you can be proactive and wear a mask, and, you know, stay inside and use air purifiers, HEPA purifiers are designed to filter the air like that. And so that’s something that you can do that will make a real difference.”

Listen to “Seattle’s Morning News” with Dave Ross and Colleen O’Brien weekday mornings from 5-9 a.m. on KIRO Newsradio, 97.3 FM. Subscribe to the podcast here.

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