ROB SCHMITZ, HOST:
Breathing wildfire smoke can increase the risk of developing dementia. That's the headline from a study published this week in the journal JAMA Neurology. And as climate change intensifies wildfires, the smoke they emit is becoming a bigger problem, especially in states like California. Joan Casey led the study. She's an environmental epidemiologist and a professor at the University of Washington School of Public Health. Good morning.
JOAN CASEY: Good morning.
SCHMITZ: So what exactly did you find? I mean, how does wildfire smoke affect the body?
CASEY: Wildfire smoke is this mixture of gases and particles, the most important particle being PM2.5 - or particles less than 2.5 micrometers in diameter. They can get into the lungs. From there, they can move into the bloodstream. They can cause inflammation and oxidative stress and DNA damage in the body...
SCHMITZ: Wow.
CASEY: ...And down the road, potentially dementia.
SCHMITZ: So how do the risks of wildfire smoke then compare to those of, let's say, just normal air pollution caused by factories and car exhaust?
CASEY: In our study, we saw a much stronger relationship between long-term exposure to wildfire PM2.5 than other sources of PM2.5. And when I think about it, there's a few reasons that might be the case. The sources of PM2.5 from wildfires are organic material burning in forests. It's shown to cause more inflammation in the human body, and wildfire PM2.5 has more ultrafine particles. And those tiny particles can move from the nose directly into the brain, potentially damaging brain cells and resulting in dementia.
It's also important to think about how we're exposed to wildfire smoke. Most days, people are walking around, they're not exposed to wildfire smoke at all. And then there are a few days a year, maybe more now that climate change is intensifying, where people are exposed to really high levels. And so it could be that big bolus of exposure that's resulting in dementia developing.
SCHMITZ: And how strong are these links between wildfire smoke exposure and links to dementia?
CASEY: We found that for a one microgram per meter cubed three-year average increase in wildfire PM2.5, there was an 18% increase in the risk of folks developing dementia.
SCHMITZ: That seems pretty high.
CASEY: I would have to agree.
SCHMITZ: So what can people who live in areas where wildfires are becoming common do to protect themselves?
CASEY: I tell people to check the air quality index where they live. They can go to airnow.gov and look at the AQI. The number older adults or people with conditions want to look for is 101. If you see an AQI over 101, reduce outdoor activities, wear a face mask, something like an N95 or KN95. And try to stay inside, shut the windows, run an air filtration system if you're able to. For everyone else, that number is 151. And at that time, you'd want to take some of those same behavior changes.
SCHMITZ: That's Joan Casey. She is an environmental epidemiologist and professor at the University of Washington School of Public Health. Thanks, Joan.
CASEY: You're welcome.
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