Show Notes

We got lots of questions on our recent episode about air, exercise, and wildfires, so here is a short, deeper dive into the topic. We gave Howard the episode off, so I have a special guest, Christopher T. Migliaccio, a Research Assistant Professor in Immunology at the University of Montana. His main research interest is how environmental particulates in the respiratory system affect pulmonary immunology, and he is doing ongoing work on the effect of wildfires on pulmonary function.  


  • Lung immunology and the role of macrophages
  • The medium-term health effects of multi-day exposure to smoke, based on a cohort study of Montana’s 2017 wildfires
  • Consequences of particulate for lung infections, from influenza to coronavirus 



“Crossing the Chasm” by Kevin MacLeod ( licensed under Creative Commons: By Attribution 3.0

Disclaimers apply (at the end of the episode).

About The Show

Paul Kedrosky is a frequently injured athlete and a venture capitalist. Howard Luks is a top sports orthopedic surgeon. Smart, candid, and experienced analysis, ideas and tips about health, fitness, and longevity from two athletes and sports orthopedic surgeon—and guests.

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Paul: [00:00:00] Hey, I’m back. We got thinking about this topic more, wildfires and exercise, smoke, air quality. And we got more questions. And we realized, well, there was  more to say. It just had to be by someone who knew more about the relationship between smoky air and exercise than we did. So, I found someone. 

Chris: [00:00:18] My name is Chris Migliaccio.

Paul: [00:00:21] Not to put too fine a point on it, but this turns out to be one of Chris’s main research interests.

Chris: [00:00:26] I’m at the University of Montana and the Center for Environmental Health Sciences.  I’m an immunologist by training. I also have a Pharm. D. degree.

Paul: [00:00:34] You can see why Chris might have a great perspective on  effects of wildfire smoke on lung function.

Chris: [00:00:41] My research, pretty much just focused on the effects of environmental exposures on respiratory immunity and function. And so lately it has focused on, the effects of wildfire smoke.

Paul: [00:00:55] Like many people — okay, okay, me — living around wildfires got Chris interested in the consequences of living around wildfires. 

Chris: [00:01:02] They always joke that you’ve got, five seasons up here in Western Montana, Northern Rockies: you’ve got fall winter, spring, summer, and fire.  You can almost expect every summer or every other summer, we’re going to get hit with a lot of smoke, and no one had been doing any research on that. So I partnered with a colleague of mine and, who’s an atmospheric chemist and we started in the basement of one of these buildings, kind of jury rigging our own type of exposure chamber.

Paul: [00:01:34] So from your research, how does this effect happen on macrophages?

Chris: [00:01:39] You’ve got macrophages in pretty much almost every tissue of the body. They are the frontline innate immune cell that then, will, is part of that, signaling to mount an adaptive response. And so in the air space you’ve got the alveolar macrophages and they deal with any foreign substance, particles, things that you breathe in, which is basically every breath you take. And for the most part, they’re able to deal with it.. For people without allergies and things like that, every breath we take is not a massive immune response to foreign particles and the macrophages, the general one on that. and what we. The macrophages have no problem –they can clear it out. either they destroy these particles because they phagocytose and break it all down or they just gobble them up and you go back up the mucociliary escalator into the GI tract and that’s getting rid of that way.

Paul: [00:02:33] So this isn’t Guangzhou or Northern India. This is California and Montana. We’re not talking about industrial pollution. We’re talking about wood smoke from wildfires and it turns out it’s different.

Chris: [00:02:45] And so we said, let’s see if there’s any issues with, with exposure to wood smoke. CBecause we have no idea, all studies historically on PM 2.5, which is referred to as the respirable fraction, that those particles, that small are what get down into the airspaces and cause most of the problems.

And so I was, collaborating with a colleague over at Montana state in Bozeman who had infectious models in mice. And we said, let’s see if it affects strep pneumonia model. When we saw an increase in deposition of the strep pneumonia, following an acute high level exposure. And we saw that it affected some functions of the macrophages. You don’t get really much inflammation from the smoke, but we saw that because the macrophages take up the particles, it affected some functions, including one function that is part of, stimulating the adaptive immune system and T cells.

Paul: [00:03:45] The obvious question now is, does it matter how much you get? How long you’re breathing it? Does that change how bad it gets? Does that change how long the effects last? 

Chris: [00:03:55] Yeah,  those are the interesting questions. And again, this is all really new areas of research as we’re, more and more people are recognizing as we’re getting more and more wildfires, the seasons are lasting longer. The fires are becoming more intense. That we’re seeing these exposures. The assumption is most of the studies are based on, or the thought on PM 2.5 is particle deposition. So there should be a dose- response to that. Yeah, but none of that’s been done.

 Paul: [00:04:26] So Chris and his colleagues took a different approach. They tracked some people over time who had recently been exposed for a while to dense, nasty wood smoke. And , well, they saw what happened. Spoiler. It’s not great news.  

Chris: [00:04:39] So  in 2017,  there were a couple of huge fires here in the Missoula area. One of which was in Seeley Lake, Montana. And  we just published a paper on that this year on a couple of years study, where we followed a group of people in there. And we found that there is a decrease in lung function, but it was delayed. Like we tested them right after the fires, fourty-nine days in high levels of wildfire smoke. And a year later when we went back, their lung function was actually significantly decreased and it stayed decreased with a slight uptick two years out. and that wasn’t what we expected at all.

Paul: [00:05:19] And that’s not all they found. In an eerie parallel to coronavirus, it turns out that it had other effects.

Chris: [00:05:26] And in addition, we found, and this was not in the paper, but we did a survey to see if there was maybe some alteration to the subsequent flu season. And at least with our surveys,  had what looked like a significant increase in the number of people who were diagnosed with the flu that first season.

 So that was, the smoke cleared mid September, and then they were looking, late fall winter through the flu season and  three to six months after there was an increase in flu cases in the area.  That’s a huge concern.

Paul: [00:06:02] So is inhaling all these small particles reducing the population of macrophages, changing the composition? What do you think’s going on here?

Chris: [00:06:11] So it’s not necessarily a reduced population. What our hypothesis is they’re affecting certain populations where they’re, decreasing the effectiveness or skewing. Because at any given time, the idea is that there is, a mix of populations. And in certain pathologies, there’s going to be a shift to a more prominent population.

You’ve got a shift in macrophages from what’s called an M1 or inflammatory because you want an immune response against the growing tumor that then shifts to what’s called a TAM, a tumor associated macrophage. And those are the ones they shift their, activity. And they start suppressing immune and promoting not only the growth of the tumor through blocking of the immune response, but also, promoting things like angiogenesis so it can grow.  What we have found is that it looks like they’re not deleting them cause we don’t see any death. We hypothesize that it’s shifting the, the environment such that it’s macrophage subsets that, are not efficient at fighting  the respiratory infections are being promoted . In fact, we’re doing current work on that and trying to figure it out.  

Paul: [00:07:26] Skewed macrophage populations ,and possibly a declining ability to fight off some lung infections … well that sounds uniquely badly timed right now, given coronavirus. And, unsurprisingly, Chris and his colleagues are thinking about that .

Chris: [00:07:40] We know just in general, that exposure to chronic air pollution puts people susceptible to a lot of respiratory issues and diseases. I was at a virtual conference in the spring —  a wildfire symposium — and that was a huge point of discussion. We know there’s going to be a wildfire season later this summer. And  it’s already was worried how this is going to affect the flu season, but now you got flu, now you’ve got these massive wildfires and the pandemic: how bad is this going to be?  It definitely is a huge concern that people are going to be a lot more susceptible following things like this.  

Paul: [00:08:14] So has your work changed your own life? I don’t know if you’re a biker or a runner, but are you less likely to bike, less likely to run, if AQI is high or there’s a lot of particulate or even modest particulate .

Chris: [00:08:26] Yeah, I do. I, I avoid as much as I can.  We know that exercise is beneficial; we know that breathing smoke is not. At what level  are the benefits still outweighing, the, adverse effects. And at what point does that switch? can we say, you could do 30 minutes of moderate exercise at this level,but not at this level, and still get the benefits of it.

Paul: [00:08:51] But it’s hard to  think about this stuff. Even when it has to do with members of your own family

Chris: [00:08:56] It’s funny, my daughters do, high school sports and the, administrators and coaches are like, they look at the numbers and as soon as it hits 150, they’re not supposed to be able to practice outdoors. So they go indoors and they run really hard and an enclosed gym. And I’m like the PM levels are pretty much just as high in hermetically, sealed gym, they’re still going to be exposed to that. When they tell you to go inside, the whole point is you’re decreasing your activities.

Paul: [00:09:27] To circle back closer to the beginning , they’re still following that group of people in Seeley Lake who were exposed to those 2017 fires. They clearly have lessons for all of us exposed to wildfire smoke, trying to get outside, trying to exercise, just trying to live a normal life.

Chris: [00:09:46] They were just exposed to unprecedented levels: fourty-nine straight days with a daily average of over 220 micrograms per cubic meter, which is  crazy.

Paul: [00:09:58] But this is 2020, the age of coronavirus. And nothing’s easy, even researching stuff that might have to do with coronavirus.

Chris: [00:10:06] We were supposed to go back this past spring and we do lung function testing as well as some others, but we had to scrap that because of the pandemic. Asking my staff scientist to do spirometry on, people during a pandemic, it just wasn’t safe. So, we’re in a holding pattern right now. But anything we could find, especially if the lung function can hopefully return to normal, or if we find out this is the new normal.

Paul: [00:10:29] Well, we’ll end on that. Another new normal, like we needed one. I hope you found it interesting, useful ,or something in between. Thanks to Chris for doing this.

 Thanks for listening.

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About the author:

Paul Kedrosky & Howard Luks

Paul Kedrosky & Howard Luks

Paul Kedrosky is a frequently injured athlete and a venture capitalist. Howard Luks is a top sports orthopedic surgeon. Smart, candid, and experienced analysis, ideas and tips about health, fitness, and longevity from two athletes and sports orthopedic surgeon—and guests.