Dr. Mariam Hanna: Hello, I'm Dr. Miriam Hanna, and this is the Allergist, a show that separates myth from medicine, deciphering allergies and understanding the immune system.

A thick blanket of smoke lay siege to my familiar hometown, covering every direction your eye could see. It lasted for days. Warnings came from the weather network seemingly daily to remind you that children, seniors, and those with underlying lung conditions needed to avoid staying outside for extended periods and take precautions for their respiratory health. An eerie orange glow filled the sky. This wasn't an ominous scene out of a movie. It was just last summer in Southern Ontario. At our asthma follow-ups, patients tell me their asthma was a bigger issue this spring. They needed their inhalers more. I've heard this same report dozens of times. It's winter currently, which for an allergist simply means one thing: Spring is around the corner. How should I counsel these families about this upcoming summer? Was this summer an anomaly or perhaps a new normal? Here to delve into this fascinating topic with me today is Dr. Byrne. Dr. Adam Byrne is an allergist and clinical immunologist with a master's in biochemistry. He has a busy community practice and also works at the Children's Hospital of Eastern Ontario in Ottawa. He is one of the clinical leads for the pediatric Severe Asthma Clinic at CHEO. Dr. Byrne is an active member in the CSACI and serves on several committees, including the National Residency Education Program meant to inspire residents across Canada about pursuing an exciting career in allergy and clinical immunology. Dr. Byrne is originally from St. John's, Newfoundland, although you really can't tell it from his accent, but he's passionate about many topics, including today's topic of climate change. Dr. Byrne, thank you so much for taking time out of your busy schedule to join us and welcome to the podcast.

Dr. Adam Byrne: Thanks so much. I will say if I get really going, my accent is going to show up. You're going to hear it pretty quick. Okay.

Dr. Mariam Hanna: We're going to try to make it happen today. Okay. So what I want to do with today's episode is actually break it down by disease as to how climate change can potentially impact some of the common conditions that we see in our office. Let's start with atopic dermatitis. How would climate change impact that?

Dr. Adam Byrne: Yeah, it's a great place to start. I mean, when you look at atopic dermatitis being like the first step on the atopic march, which is that progression where we see patients move from eczema to food allergies, to allergic rhinitis to asthma. When we look at the etiology of atopic dermatitis, it's because there's a barrier dysfunction, right? Our skin is supposed to look a little bit like a brick wall with our skin cells acting like the bricks, and then all the hydrophobic layers that act as a protection underneath it, acting as the mortar. And the problem with eczema is that mortar is not as effective as we'd like it to be. So things pass back and forth that shouldn't pass back and forth. And we also know anyone that's treated eczema before knows, or has eczema, knows that the environment is a big trigger for how your eczema flares, how well your eczema is controlled.

So ultraviolet radiation, toxins, allergens, temperature, humidity, they all have slightly different effects in everybody, but they all result in altered levels of control. As we get more atmospheric pollution, see changes in temperature, and changes in humidity, eczemas are going to start to be a lot harder to control. There's a neat, very small study where they took some people from Colorado, which has a low amount of what we call PM 2.5, particulate matter under 2.5 microns, and measured filaggrin, the gene most associated with eczema, and the breakdown products from filaggrin in their skin. Then they moved them to South Korea, which has a much higher PM 2.5 count, and at the exact same measurement, they found that their RIN levels in the same patients started to decrease shortly after arrival in this new city, largely due to the exposure to all the particulate matter they were seeing in this new city.

So, we are already seeing that this does cause some worsening of the biochemistry surrounding eczema. This is also known because particulate matter increases oxidative stress, leading to an increase in pro-inflammatory cytokines. You can measure increases in things like IL-6, IL-8, TSLP once you measure this in the skin of patients who are being exposed to particulate matter and other things as well. And of course, the other side of this too is that while eczema is bad, as we alluded to, it's the first step in a march, and so if we can't get good control of eczema, then all these other things that we tend to treat on a regular basis are going to start to get a lot worse.

Dr. Mariam Hanna: So let's march onto the next one then. My favourite, food allergy. How do you see climate change impacting food allergy?

Dr. Adam Byrne: There are a couple of different ways that this is going to happen. Right off the bat, we are aware that if your eczema is poorly controlled, you are more likely to develop food allergy. So, poor control of eczema is going to lead to increasing rates of allergy. We've had the concept of early introduction for foods for such a long time because the guidelines have changed over the past 10 to 15 years, which we're not going to get into because that's a whole other separate set of podcasts. But we've made these recommendations. I don't know about your clinic, but I haven't seen a tremendous decrease in the amount of peanut allergy that's walking in my door.

Dr. Mariam Hanna: Well, we still recommend them, Dr. Byrne, we still recommend them.

Dr. Adam Byrne: Absolutely. I wasn't saying to just ignore them. I think it's very helpful to do this, but the problem is that it's a multifactorial issue, and part of that factor may be the fact that climate change is not only affecting us, it's affecting our food. So let's take a look at peanut. There was a study done in 2016 where they took two different types of peanut, specifically, if you must know, the Virginia Jumbo and the Georgia Green Delicious. And what they did was, I like

Dr. Mariam Hanna: The trivial knowledge you submit to this podcast is great. It's just fantastic for that. Go ahead.

Dr. Adam Byrne: It's all I have really. So, they grew these peanuts over a period of two years in two different environments. They used the atmospheric or the ambient atmospheric carbon dioxide concentration, which keep in mind is already higher than it was a hundred years ago. And then in the other experimental group, they increased the carbon dioxide by about 250 micromoles. They grew them for two years and then measured the peanuts and found that the peanuts were bigger. The seed sizes are bigger, which is a big deal because most of the things that we're allergic to are actually the seed storage proteins. In fact, when you look at things like the Virginia Jumbo specifically, they actually had a significant increase in Ara h1, which is one of the proteins that we most associate with anaphylaxis. So, not only are our guidelines changing appropriately to prevent food allergies, but part of the problem is that the peanuts are changing as well to further compound this.

Part of what happens with climate change is that you're going to see a lot more fungal growth, and fungus can produce things like mycotoxins. There's a very specific mycotoxin called deoxynivalenol, and I did practice saying that before I got on the podcast. But if you actually expose mouse models to this particular mycotoxin while making them allergic to peanuts, the mycotoxin acts as an adjuvant, which, if anyone's familiar with vaccine science, knows that an adjuvant makes your immune system a lot more excited to see whatever's coming down the pipe. These mouse models ended up not only more significantly anaphylactic in terms of symptoms, but a lot of their biochemistry behind this got significantly worse as well. In fact, just being exposed to this mycotoxin increases rates of alarm secondary cytokines such as IL-33 and TSLP.

So, you're starting to see pro-inflammatory cascades just because climate change is resulting in a different presentation for a lot of these food allergy molecules, but it's also non-IgE mediated food allergies, right? You look at eosinophilic esophagitis, which, by the way, the barrier defect with eczema is very similar to the barrier defect you see in eosinophilic esophagitis. With that disruption of barrier that you see from particulate matter, there was a study in Utah where they looked at different patients who had eosinophilic esophagitis throughout the state, measured the particulate matter in the different areas of the state every day, and then looked at when they came to the emergency department. They found that when the particulate matter was higher, so when the air pollution was worse, patients with eosinophilic esophagitis were much more likely to present to the emergency department for complaints of food impactions, chest pains, or dysphagia compared to any other time of year. So, it's not just IgE mediated food allergy; it's the non-IgE mediated food allergy that's going to start to get worse as well.

IgE and non-IgE mediated food allergies getting worse, atopic dermatitis starting worse and earlier, now I have validation for the senior in the room saying my generation didn't have as many allergies as this generation does. Let's move on to allergic rhinitis. How do you see allergic rhinitis changing?

So, plant food is essentially sunlight and carbon dioxide. That's what it needs to grow. We know that in New Brunswick from 2006 to 2017, the grass pollen season increased by 24 days. In Ontario, the birch pollen season has increased by 60 days. That's two months of more birch pollen exposure for your pleasure. And then on top of that, in Saskatoon, cedar pollen has increased by over 80 days. So right off the bat, the fact that these plants are being pushed to produce their pollen more is resulting in prolonged seasons, and it's not just that they're producing pollens for longer periods of time, they're also producing them in new locations. Europe now has a lot of ragweed allergy, which may surprise some people because ragweed isn't supposed to be in Europe. But because of species migration secondary to climate change, a lot more people are getting sick from ragweed.

We're also seeing this in North America, so a lot of the trees that cause us to be allergic, things like birch and oak, are pushing away the less allergic trees such as pine and fir trees. And then one of the things that's also come up is that not only are the pollen particles being made in higher amounts, they're also, just like our friend the peanut, a lot more allergenic than we used to see them. So we're starting to see a lot more prolonged allergy seasons. The pollens we're seeing are more allergenic, and that combination is leading people to be a little bit more sensitized to their pollen. So smaller amounts of the pollen are leading to worsening symptoms. So again, "worst allergy season ever" might not be an exaggeration for that patient. Everybody's favourite other side of the allergic rhinitis coin is non-allergic rhinitis, which every allergist absolutely loves. Nothing more to see than patients with chronic rhinitis symptoms and not a whole lot we can do to help them out because the allergy really what allergist are you talking about here? This is the most aggravating condition. I still think you have allergies. I can't show you that we're not going to irritate your nose.

But look at who the non-allergic rhinitis patients, what do they complain about? Oh, it's seasonal change when there's no particular season trigger because their testing is negative, it's changes in pressure, it's changes in humidity. It's particulate matter like cigarette smoke or perfumes. "I can't walk through department store X because every time I go through my nose starts to leak," and these are all legitimate symptoms. I don't mean to be making fun of that, it's just we're very limited in what we could do to help these people. It's going to get worse though because all of these things we just complained about, we've also discussed are escalating during climate change.

You're going to give me solutions at the end of this episode, but let's move on to asthma and then we'll come up with solutions.

So asthma, love it. It's a lot of fun to treat, but it's going to get worse. Some of the things we've talked about are going to be direct impacts, right? We talked about the barrier function. We talked about it with eczema. We talked about it with eosinophilic esophagitis. That same type of barrier exists in the lungs. So right off the bat, it's going to be disrupted by a lot of the air pollutants that we often see. And in fact, we know this. We know that air pollution, the oxidative stress, actually, if you want to get really scientific about it, there is one study that showed that it actually modifies through DNA methylation, the production of FoxP3 in T regulatory cells. T regulatory cells are really important. They stop allergies from being just out of control. But if this is modified by air pollution, then you are much more likely to be diagnosed with asthma by the age of seven, and your asthma is much more likely to be more severe.

So already right off the bat, air pollution is making things worse for younger children. And then there's the lovely but somewhat dramatized, but accurate story you told right at the beginning of all the forest fires. I mean, how many of us had patients that were super well controlled and steady on their asthma, and then because they got exposed to forest fire smoke hundreds of kilometers away, they ended up needing more of their rescue medication, having to go to the emergency department, needing oral steroids, being admitted to the hospital. Other things that could trigger asthma include mold. When you look at Hurricane Katrina, one of the theorized severe events secondary to climate change, if you measured mold in the homes of New Orleans the year after Hurricane Katrina, it was way higher than usual and went back down to normal afterward. But mold can be a real common trigger for asthma.

And then there is a really fascinating concept. We're talking about extreme weather events of what we call thunderstorm asthma. So thunderstorm asthma, in the first 20 to 30 minutes of a thunderstorm, you get a lot of winds, you got a lot of rain. Patients with pollen allergies and asthma are very susceptible during that time. What can happen is that the actual pressure, the osmotic pressure, and the wind cause grass pollen high up in the air to fracture, and these grass allergens are now extremely tiny, very ultrafine, and they can work their way further down into your lungs than usual. Is this a big deal? Not often, but in Melbourne, Australia, in 2016, they had a, pun intended, perfect storm where they had high winds, high grass pollen counts, and they had a really terrible thunderstorm. And what happened in that particular instance was that patients who, in some cases, didn't even know they had asthma, ended up going to the emergency department, their GP for further treatment, it affected up to 10,000 patients, and 10 deaths are directly related to this thunderstorm asthma event that occurred. We're going to start seeing these extreme weather events a lot more often.

Dr. Mariam Hanna: Let's move to what we can actually do about climate change within the realms of our practice. We are all practicing allergists and clinical immunologists, seeing patients in our office every single day. We recognize climate change and its potential impact on many of the diseases that we see. So what now? What are we going to do about it?

I'd like to say, like I said to a lot of my patients, "Oh, if I had that pill, you'll get so much better and things will go away and you never have to worry about this again." And I cannot do that. My good feeling message is a little bit muted today. There is a lot that you can do. First off, I encourage everybody to read more about this stuff. You're going to start seeing this in your clinic. It's going to start affecting your day-to-day events. You should know what's coming at home, in your clinic. Monitor your carbon footprint. Now, I'm not saying you should go live in a mud hut, don't get me wrong. I enjoy my creature comforts as well, but if there are certain things that you can do to reduce your reliance on fossil fuels, you can walk to the store instead of drive to it, maybe you do it that day.

The biggest real issue from a lot of this perspective is that we need to use our position as physicians to advocate for change because as much as I'd love to say that individuals can make a difference because everybody loves a good story like that, as I mentioned before, this is going to be a societal-wide change that needs to be enacted, and you're going to need a lot of support from large agencies. So use the knowledge that you've learned to advocate. When a political candidate, because we do have elections that will come up in the next year or two, when someone comes to your door and says, "Vote for me," ask them about climate change. And if their answer is, "Oh, we have a plan," ask them what the plan is and then analyze it. Does it make sense? This is something that we need to factor in.

And not only their change for climate change, we are going to need a lot more funding for healthcare. But you look at all of these events making all of these chronic conditions that we have significantly worse. We learned in the past five years, our healthcare system is not necessarily equipped to deal with a societal-wide crisis. Can you imagine if we had COVID during bad climate change issues, we're going to be in a lot of trouble. So I think that we need to stop reacting and be a little bit more proactive in how we push for this because it is coming, it's going to be here, and so we just need to make sure that we're prepared.

Recently, metered dose inhalers have come under everybody's eye and lens as something that's potentially worsening our climate. Can we get your 2 cents on how much of an impact this is and what we should be doing with our patients with metered dose inhalers for their asthma?

Metered dose inhalers are super convenient, especially for patients who don't have the ability to take deep breaths in like children or patients who already have significantly impaired lung function. The reason they're really good is because greenhouse gases push the medicine into your lungs. And so the more we've learned about the impact of this, I mean, it's not a huge amount. MDIs are proposed to be responsible for about 0.03% of all greenhouse gas production. But if you're looking to reduce somewhere, I mean, every little bit helps. I think the way I looked at one MDI puffer, if you use 200 doses from an MDI puffer, that's the equivalent of driving your car, your gas-powered car, 290 kilometers. So I'm not saying you should switch everybody off your MDI puffers, but if a patient's not particularly well controlled, they're entering a new stage of life, their age changes, so you have more options available, we should definitely be considering whether they should stick with an MDI or is there a dry powder inhaler or a turbo inhaler or other form of us to give this asthma medication so that we can do our little part to try to help make everybody's environment a little bit better along down the road.

Dr. Mariam Hanna: I think that's a good way of framing it, but I will emphasize the 0.03% that you mentioned. It's a fraction closer to zero than 1%, right?

Dr. Adam Byrne: Fraction.

Dr. Mariam Hanna: Exactly. It may not be ideal to puffer shame your patient for which puffer they're going to take, right?

Dr. Adam Byrne: Oh, a hundred percent. Keeping their asthma under control is going to be much more important than saving that fractional amount of greenhouse gas that goes out, especially when there are huge offenders that are operating unchecked, and that's really what needs to be fixed.

Dr. Mariam Hanna: Yeah, I saw this analogy recently that compared the amount of carbon footprint from a metered dose inhaler versus eating a hamburger, and eating a hamburger, because of all of the resources that are used to create the hamburger, was about a hundred times more. If not,

Dr. Adam Byrne: I do like my hamburgers, and see, this is part of the problem. Listen, I was as guilty as everybody else. I love my creature comforts, right?

Dr. Mariam Hanna: I intentionally chose a hamburger.

Dr. Adam Byrne: You know me very well. So I'm sitting here in my very comfortable office. I have heat. I'm relaxing. I am very lucky to be able to live the life I live, but I'm also very aware that I live the life I live because of fossil fuels. And at some point in time, we have to say we need a shift. And part of that shift means advocating for the governments to make the right decisions. There was a great decision where it's like, "Hey, we want to get rid of gas-powered cars by 2035," or whatever the actual number was. Super, but what are you doing to support that? We don't have the infrastructure right now to do that. Are you providing, for example, convenience stores or rest stops with the necessary battery chargers in order to be able to make this a viable proposition? Otherwise, it's going to fail. So having grandiose suggestions without backing it up with evidence and the actual finances to make this change, it's empty air, which we talked a lot about today.

Dr. Mariam Hanna: I'm going to say that that's an empowering note for us to wrap up on. So, alright, time to wrap up and ask today's allergist, Dr. Adam Byrne, for his top three key messages to impart to patients and physicians on today's topic, climate change. Dr. Byrne, over to you.

Dr. Adam Byrne: So climate change is real. Don't let anyone tell you otherwise. And it's going to be a major burden on the health of individuals and society for years to come. The second tip, make sure that your patients know about the effects of climate change, both from an advocacy perspective, but also to make sure that they're well controlled on their therapies and are actually taking their medications like they're supposed to. Review action plans every time they come in. And then just my last tip is educate yourself about the differences that you could make as an individual and how you can advocate for greater change throughout society, how this is going to be prevented from becoming much worse than it could be.

Dr. Mariam Hanna: Thank you, Dr. Byrne, for joining us on today's episode of The Allergist.

Dr. Adam Byrne: Well, thank you so much for having me. What a great time.

Dr. Mariam Hanna: This podcast is produced by the Canadian Society of Allergy and Clinical Immunology. The Allergist is produced for CSACI by Podcraft Productions. The views expressed by our guests are theirs alone and do not necessarily reflect the views of the Canadian Society. This podcast is not intended to provide any individual medical advice. To our listeners, please visit www.csaci.ca for show notes and any pertinent links from today's conversation. The "Find an Allergist" app on the website is a useful tool to locate an allergist in your area. If you like the show, please give us a five-star rating and leave a comment wherever you download your podcasts and share it with your networks, because today we hope that this has been an adjuvant to spark conversations about climate change. Thank you for listening. Sincerely, The Allergist.