: [POST-BROADCAST CORRECTION August 8, 2025: A previous version of this story incorrectly said the name of expert featured in this piece from Columbia University as Brian Westervelt. In fact, his name is Daniel Westervelt.]
STEVE INSKEEP, HOST:
Some other news now. Canada is having its second-worst wildfire season on record, and this is affecting the United States. Just halfway through wildfire season, more than 4,000 fires have been recorded in Canada this year, with more igniting this week.
A MARTÍNEZ, HOST:
Yeah. And for people in the Midwest and Northeast especially, that means a lot of air quality alerts, often sent to their phones.
INSKEEP: So how does a Canadian fire diminish the air quality thousands of miles away? Daniel Westervelt helped us to answer that. He's a Columbia University professor and an expert in air quality and pollution.
DANIEL WESTERVELT: After you have this burning of this, like, vegetation, you get these very tiny, invisible-to-the-naked-eye particles.
MARTÍNEZ: Westervelt says these tiny little particles can float around in the air for up to two weeks.
WESTERVELT: And that gives them some time to go up higher into the atmosphere. So the higher you go into the atmosphere, the stronger the wind currents are and the easier it is to travel long distances.
INSKEEP: Now, there's some chance here which way the wind is blowing at a particular time helps determine which areas are most affected, of course. Years ago, he says, emissions from power plants or vehicles were bigger drivers of bad air quality. Now?
WESTERVELT: Wildfires now are pretty much the whole story when it comes to air quality problems in the U.S.
MARTÍNEZ: Dr. MeiLan Han is a pulmonologist and chief of pulmonary care at the University of Michigan. She says she's talking more and more about air quality.
MEILAN HAN: It's something I have to start counseling my patients about on a regular basis. And then, you know, as a scientist, we're seeing more and more researchers spending more time and effort into understanding this.
MARTÍNEZ: Han says these tiny particles can affect your lungs and enter the bloodstream, leading to conditions as serious as heart disease or stroke.
INSKEEP: Now, as wildfires become more common, you can prepare your home with a purifier on your HVAC system, or attach a furnace filter to a box fan.
MARTÍNEZ: Now, N95 and K95 masks also help. And living in LA, Steve, I always have one in my bag or car just in case a fire breaks out. Ultimately, Dr. Han says that people should take air quality alerts pretty seriously.
HAN: This is a new health hazard that we all have to come to grips with. And there are both short- and long-term consequences, so I think it really makes sense for everyone to educate themselves.
MARTÍNEZ: And set up those air quality alerts on your phone.
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