IRA FLATOW: This is Science Friday. I’m Ira Flatow. In late summer, the skies in California, Oregon, and other West Coast states turned orange and, in some places, stayed like that for days due to the smoke and ash from wildfires. It is estimated that more than 8 million acres of land have been scorched this year. And wildfires are still blazing, nearly 40 still active out West.

And throughout this year’s wildfire season, you’ve been asking us to explain how the wildfires could impact your health. And now, two experts are here to do just that. Let me introduce them. Dr. Colleen Reid, assistant professor of geography at the University of Colorado in Boulder, welcome to Science Friday.

COLLEEN REID: Hi, Ira. Thanks for having me.

IRA FLATOW: Nice to have you. Dr. Chris Migliaccio, immunologist and research associate professor at the University of Montana in Missoula, welcome to Science Friday.

CHRIS MIGLIACCIO: Thanks for having me, too.

IRA FLATOW: Just a quick note. This segment was recorded in front of a live Zoom audience. You can find out about joining a future recording at sciencefriday.com/livestream. So let’s begin. I want to hear from both of you about how the wildfire season was in your respective states this year. Colleen, you go first.

COLLEEN REID: Sure, in Colorado this year, we had some of the largest wildfires we’ve ever had. We had the Cameron Peak fire, which is now the largest on record in Colorado, and actually a couple others that beat the largest beforehand. And some of them are still burning. And the fires are also a little later in the season than normal for Colorado.

IRA FLATOW: Wow. And Chris, what about in Montana?

CHRIS MIGLIACCIO: We actually had a relatively mild wildfire season. We had some small fires here and there. The worst of our smoke, actually, were from wildfires from Oregon, California, Idaho, and Washington. We got inundated with smoke from them, not so much from our own wildfires.

IRA FLATOW: We put out a call on our Science Friday VoxPop app during the height of the wildfires. And we asked you, our listeners, how you felt your health was being impacted, because you really were wondering about that. So here’s a message we got from Michael in Silverton, Oregon, back in September.

MICHAEL: Now that I’ve been close to a major fire event, been in hazardous smoke about 10 days with my family, I do have major concerns. I’ll be visiting my doctor because I’ve had immediate symptoms of asthma. And my spouse has had heart palpitations. My daughter’s too young to tell us what she’s experiencing, but she’s had a cough, too.

IRA FLATOW: Thank you. There’s a lot here, but let’s start with you, Chris. What do we know about how wildfires impact lungs?

CHRIS MIGLIACCIO: Yeah, so there are acute effects, especially when you get people– he mentioned asthma. And you have patients with asthma. Those are one of the first groups that are going to receive alerts that they should stay indoors once the levels start getting above what’s called 35 micrograms. It’s the particulates in the air. And so people with those types of lung issues, the particulates exacerbate it, and they start having an asthma attack, or their breathing is much more labored. And so yeah, those are the ones that are going to be most acutely affected, especially at the lower levels.

IRA FLATOW: Interesting. Colleen, do we know how wildfires affect the other parts of our bodies?

COLLEEN REID: Yeah, there’s some research that shows that in addition to impacting our respiratory health system, that there are some impacts on other systems of the body. So these particles that Chris was talking about. They get into the lungs, and they cause inflammation in the lungs. And sometimes, there’s enough inflammation that it can spill over and affect other systems, like the cardiovascular system.

The smallest particles can actually translocate into the bloodstream and then get found throughout the body. I’ve been part of one of a couple of studies that have documented that babies that gestate during wildfires can be born with lower birth weights than babies that gestate outside of these high-pollution events. And there’s a lot more health impacts that researchers want to study related to these higher-pollution events.

IRA FLATOW: And just peripherally, they can hurt your eyes, too, right? That just seems very obvious.

CHRIS MIGLIACCIO: Yeah, there’s a lot of those types of effects. You get the burning in the throat, because it’s going to damage some of the cilia as well as some of the immune cells of the lung as well. But you get that irritation to the eyes, other membranes that usually clear up when the smoke clears up. But sometimes, depending on the exposure, I’ve known—I myself, in a really bad fire season, I had a cough, a horrible cough that just lasted for two weeks after the fires.

IRA FLATOW: Well, is there any way to know if you had permanent lung damage? Can anyone tell that, a doctor?

CHRIS MIGLIACCIO: Well, in a recent study we did in fall in the 2017 wildfire season here, which was really bad here in the Missoula area, we studied a community just north of here. And we did find that the people in our cohort had alterations to their lung function that lasted at least two years after the fire. But we have no idea of knowing, because we actually had to put the study on hold because of the pandemic. So we were not able to go back up there to see how they are, if it’s improving, or if it’s still remaining low.

But there are tests. As far as lung function, we do what’s called spirometry, and we can test people’s lung function. And we know where it should be, if they’re a healthy individual, where their lung function should be. These are the type of studies, though, that need to be done to see if there’s long-lasting effects or if there’s a cumulative effect. As people are getting exposed to fires routinely now almost every– as we call it up here in Montana, it’s fire season. We’ve got five seasons.

IRA FLATOW: Yeah, let’s go out to our audience again, to a question from Autumn from California about skies in wildfires. Go ahead, Autumn.

AUTUMN: Hi, there. Thank you. I was just wondering, when you see reddish-oranges or yellowish skies, do we need to worry about our health? What does that mean, and what can it tell us about the air quality?

IRA FLATOW: Yeah, good question. What do you say about that? I’ll put Coleen on the spot here. Go ahead.

COLLEEN REID: Yeah, what I understood of what happened those days in California was that there were particles really high in the atmosphere that were filtering the sunlight in a way that created that color. What matters for health is the particulate matter concentrations where people are breathing. And sometimes, there are smoke plumes that are aloft that are not affecting ground-level concentrations. But we’d have to go back and look at the actual data on those days to see what the concentrations were where you lived to understand what the risks were for health where you were.

IRA FLATOW: Now, we’ve heard a lot about particulate size, the actual size of the particles in this smoke. Colleen, what makes that so dangerous?

COLLEEN REID: Yeah, so what most of the time you get as the warnings for the air quality index is PM2.5. And that is for particles that are 2.5 microns or smaller. So a particle is any solid or liquid pollutant that’s so tiny that it stays suspended in the air. And PM2.5 is all particles that are 2.5 microns or smaller.

And actually, during wildfires, a lot of the particles are much smaller than that. There’s a lot that are more around PM1, so one micron or smaller. And the smaller they are, the deeper they get into the lungs. So they can get past the body’s natural defenses in the nasal cavity and in the trachea, and get down into the deep part of the lungs, into the alveoli. And then, as I said before, the smallest particles can actually cross into the bloodstream at the alveoli and therefore get throughout the body.

IRA FLATOW: When we think of a forest fire, we look at the trees. We look at the flames. But in these forest fires that we’ve been seeing, they’re wiping out whole communities, right? And that means they’re burning up plastics and tires and buildings, Colleen, and that must release a lot of stuff into the air.

COLLEEN REID: Right, and when we study the health impacts, we’re normally looking at PM2.5 because we have a lot of monitoring data on that, and we have ways to estimate what people are exposed to. There’s a lot of other aspects of the smoke that could be affecting health. A lot of gases are released. And there’s a lot of concern about the specific gases that are released when you burn man-made materials, like homes and cars and all of these things that have a lot of chemicals in them that are different than the chemicals that are released when you’re burning just vegetation. But at this point, we don’t have any information about whether the differences in the emissions affect health differently.

IRA FLATOW: Chris, clarify something for me, because we’ve heard for years about why living in polluted cities is bad for us. Are those pollutants not a direct comparison to wildfire smoke?

CHRIS MIGLIACCIO: That’s a great question, Ira. And as we’ve been talking, Colleen’s brought it up several times, and you asked about PM2.5. So historically, the reason the EPA puts guidelines based on PM2.5 levels is because we have a large amount of historical data on the effects of PM2.5. But that was all done, for the most part, on urban particulate matter, which is what you were talking about when you talked about pollution. In people who live in high-pollution areas, we know there’s a lot of adverse health effects, kids with higher levels of asthma and low birth weight and things like that.

PM2.5 just takes into account the size and not the chemistry of it. And the chemistry is going to be so different. And this is part of the difficult part of doing this type of research, is the chemistry is going to be different just between wildfires and urban pollution. And then you get into, like you’re talking about, manufactured fuels, like cars and homes, compared to—in our terrible wildfire season, 2017, here in Montana—it was almost completely vegetation. I think there might have been one home that got burned in the massive fires we had going. So the exposure there is going to be different.

And generally, when you’re talking about, and this is the other difficult part to compare the different exposures, is the urban studies. That’s a chronic, relatively low level, adverse level, but a low level compared to these wildfires where people get exposed to high levels of PM2.5. For example, in that 2017 season, this community was exposed, their daily average was 220 micrograms a day. But how does that relate to someone who’s exposed to this 40 micrograms daily living in a really polluted city? So it’s difficult in trying to understand acute versus long-lasting effects.

IRA FLATOW: I want to go back to your study that you mentioned earlier. What else did you learn about how this smoke event impacted the health of people who live there?

CHRIS MIGLIACCIO: Yeah, so we found the effects on lung function. And what we also found there is an increase in the immediate flu season. So the fire ended in September. That season, 2017, 2018, there was an increase in people diagnosed with flu in our cohort. And there was a subsequent study that found that, yes, there is an increase in flu.

So the idea is that these types of exposures adversely affect our respiratory immunity, make us more susceptible to, well, bacterial and viral, but respiratory infections. And that’s a huge concern any fire season, but especially this coming season now with areas like where Colleen’s from, where they had massive fires, California and all of those. There’s a strong chance that these people who were exposed are going to be at increased risk for infections.

IRA FLATOW: Just a reminder that I’m Ira Flatow, and this is Science Friday from WNYC Studios. In case you’re just joining us, we’re talking with Colleen Reid and Chris Migliaccio about the health effects of the wildfires that are burning out West. And we see that there are lots of health effects. And we’re dealing, of course, with a respiratory pandemic right now. Do we have any idea how COVID would intersect with the wildfire health issues?

CHRIS MIGLIACCIO: Well, I mean, there are people that are looking at that right now. This was a huge concern at a wildfire smoke symposium we had just this past March. And it’s a huge concern. We’re not sure. We suppose that there’s going to be an increased incidence in viral infections and higher susceptibility. I mean, you’ve got the fire seasons in some communities plus flu and the pandemic. It’s a real big concern.

IRA FLATOW: Yeah, we’ve had listeners who are asking about what they can do, what actions they can take. For example, we had a question coming in from Hal in Cottage Grove, Oregon.

HAL: During the weeks when the air quality was so bad, we limited our activities outside to the morning. And we wore repurposed COVID masks to keep out the ash. Also, I ordered a HEPA filter to tape onto my box fan that would clean the air.

IRA FLATOW: Colleen, was that a good idea? I mean, what can people who live out West and deal with wildfire smoke year after year do to protect themselves?

COLLEEN REID: Well, regarding the HEPA filter, that’s a really great idea. The one intervention that we have really good evidence for is that HEPA filters can decrease air pollution inside homes. We know that the air pollution from wildfires can leak inside, depending on how tight the home is. And HEPA filters can do a good job. And there’s been more and more people using these, getting a really good air filter connected to a box fan that you can put in your window. And therefore, as it pulls in the air, it can go through the filter and filter out some of those particles.

Regarding the masks, the masks that we’re wearing to protect others from potential COVID-19 exposures is, basically, you’re wearing it so that you’re protecting others from yourself. If you were to have the virus, wearing a cloth mask or a surgical mask can stop the virus that you breathe out to get to others. But it doesn’t do such a good job of protecting you from what you’re breathing in. It blocks a little bit, but not a lot of the air pollution from outside.

The N95 masks and the KN95 masks, those will protect the wearer from what they’re breathing in. And so one other thing I always want to say about those is that there are some of those N95 masks that also have a valve on them that makes it easier to breathe with one on. And those are actually not good for protecting others from COVID. If you were to be an asymptomatic carrier, it will just exhaust whatever you’re breathing straight out. So an important thing to note is if you’re trying to both protect everyone from COVID and yourself from the wildfire smoke, get one without one of those valves.

IRA FLATOW: And one last question to you, Chris. Is there anything we can learn from history? Has history told us anything about how we deal with smoke and fire events? I’m thinking of Pompeii, even, or the 9/11 smoke that hung around for weeks. Is there anything we can learn from that?

CHRIS MIGLIACCIO: Probably the biggest thing is that, with anything, there’s probably some adverse effects. Just in my research and things that I’ve read, I think that our body can handle some exposures. You’re going camping. You’re by the campfire. Smoke gets in your face. That’s annoying. But I think, for the most part, a healthy person, their body can handle those types of exposures. Something that is overwhelming, like these wildfires, like the smoke and ash from 9/11, those types of things overwhelm the system.

And that’s where you start to get these adverse effects, some which we’re still learning about. So you want to protect yourself if you’re going to be– if something like that’s going to happen. And I think the previous one that you just played is what we tell people to do all the time, is with these wildfires, especially if you’ve got some conditions, create a safe space in your home with a HEPA filter or something. Have a room that’s got this thing running constantly. It really helps people with asthma or other types of respiratory issues. That’s the best you can do.

IRA FLATOW: Very good information for us, and something I think we’ll all take to heart. I want to thank both of you for taking time to be with us today, Dr. Colleen Reid, assistant professor of geography, University of Colorado in Boulder, Dr. Chris Migliaccio, immunologist and research associate professor, University of Montana in Missoula.

COLLEEN REID: Thanks.

CHRIS MIGLIACCIO: Thank you very much.

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