Dr Rupy: We talk a lot about what to eat for our health. But what about the air we breathe at home? What if something growing silently behind your walls, under your floors, or even in your mattress could be affecting your energy, your brain, and even your immune system? Today, Dr Peter Cook, a leading expert at the MRC Centre for Medical Mycology, is going to guide us through what mould actually is, why we're seeing more of it in modern homes, and what a safe level of mould could be. Personally, I'm super interested in how home environments impact our health and the development of babies like my little boy. Together, we'll explore the practical steps you can take to prevent mould, reduce exposure, and make your home a genuinely healthier place to live, including whether there's any evidence for dehumidifiers and air purifiers in the home.
Dr Rupy: Dr Peter Cook, mould expert extraordinaire. We're going to be talking about something I really do not know much about, and that is mould. I wasn't taught that much about it at medical school. We were talking a little bit earlier about how this is sort of brushed over. I think about mould in the context of immunosuppressed patients. But let's bring it back to basics for our audience. What is mould?
Dr Peter Cook: Well, mould is, it's one of these terms that can mean different things based, so mould is like sort of that structure of fungus that's growing and in effect, and then it will sort of sporulate, you know, and then release these spores that can then go and infect and grow further. So effectively, mould is like a fungal growth, if that makes sense. When people say mould, it's actually a catch-all term that can refer to a few different things. But effectively, these are species of fungi that are abundant in our environment and they sort of can grow very rapidly, sporulate and release new spores. And so obviously they can, so yeah, so that's, I don't know if that's answered your question, but it's sort of, it's one of those sort of terms that can mean lots of different things, if that makes sense.
Dr Rupy: Stupid question from me. What, is mould the same as a mushroom?
Dr Peter Cook: Ah, that's a great question. So if you go back right to basics again, so there's sort of in the eukaryotes, there's, you know, as you know that, so there's sort of bacteria which are prokaryotes, they're separate. And then you've got plants, animals and fungi. So they're sort of major kingdoms. And so fungus is a huge kingdom and it can generate huge amounts of so many species. And so the mushrooms like fruits, it's sort of a fruiting, so that's certain types of funguses will generate things like mushrooms. Other funguses will sporulate from these like hyphal strands and then release more and more spores.
Dr Rupy: Okay. Is that what we're referring to now when we're talking about?
Dr Peter Cook: I think that's what commonly when people say mould, they don't necessarily mean the mushrooms that they eat in the super, that they get from the supermarket. They're thinking more the mould that you get growing in your bathroom.
Dr Rupy: Technically, they're from the same kingdom.
Dr Peter Cook: Well, exactly, yeah. But obviously the, the fungal, and this is where, you know, I'm not a mycologist, if that, I study fungi, but there's lots I don't know. The more you study, the more you don't know. And so yeah, but there's this huge variety and there's people that go mushroom hunting and it's sort of a huge community of people that are fascinated by fungi. You know, the medicinal benefits of it and things like that. So absolutely. I think when people are saying mould, they are more meaning the unwanted growth in their, in their homes, I think traditionally.
Dr Rupy: Yeah. So when we're specifically talking about domestic mould, what kind of moulds are we referring to? What, what are the sort of names?
Dr Peter Cook: Yeah, so, so in terms of species and sort of the major genera of funguses you're getting, so things like Aspergillus, which is primarily what we work on, things like Alternaria, Penicillium. I'll forget, Cladosporium. So when people say mould, they'll actually have a mixture of all of these different funguses present. And that's actually one of the complexities of it is that when people say they've got mould, that actually be a mixture of different species. Most of these moulds, and these moulds are around us all the time. I'm probably jumping ahead into one of your other questions, but they're sort of adapted to grow very well in soil. And of course, in the home environment, they love warm, moist sort of conditions. And so then that's why they're sort of particularly like homes, because homes are particularly warm and moist. So, but also it can vary. So different seasons, different sort of conditions in the house can actually, you could get mould that will look similar, but it's actually perhaps different species, you know, different types of mould.
Dr Rupy: So you can't determine the type of mould you have just by looking at it?
Dr Peter Cook: You can. So, but more, so there's sort of black mould, everyone sort of thinks of.
Dr Rupy: Yeah, because I'm looking at black mould at the moment.
Dr Peter Cook: But that will be a mixture of different funguses. And again, when people say black mould, there's, that can mean a different funguses. This is part of the complexity is that people don't really know very well, you know, people, there's not many studies out there where we go into people's homes and really define what is in the home.
Dr Rupy: Really?
Dr Peter Cook: It's incredible. I mean, there is some, but it's a really patchy.
Dr Rupy: Oh my gosh.
Dr Peter Cook: Patchy. In fact, I, I mean, so I should stress, I, I research in why does fungus cause disease. I'm not an epidemiologist, but I know, I collaborate with people that are and you know, they're trying to set up studies where more going into people's homes to work out what is there and how is that potentially correlating with making people unwell.
Dr Rupy: So, so in, and just to anchor the listener, you've got a number of different questions and you're trying to answer one of them. The first one is, you know, how does mould get into our house? Why are we seeing an increase in the exposure to mould? The second question which you're involved in is what are the mechanisms behind disease caused by mould? And then thereafter, I guess is, okay, well, how do we eradicate it? How do we create healthy environments where we can get to the root cause of why people are being affected?
Dr Peter Cook: I think that's a really lovely summary. Yeah, absolutely. So you can't do everything, you know, but obviously the hope is by working together with other people answering these questions, we can understand the whole much more effectively.
Dr Rupy: Yeah. Let's try and answer that first question actually. Are we seeing an increase in the amount of mould in homes or is this an impossible question to answer?
Dr Peter Cook: No, no, no, it's, you know, we debate this. It's one of these questions that's very, without data, it's very hard. So people that study home exposure of, of things in the home that are pollutant, they generally don't look for fungi. When you, when you meet people who are, there's a lot of, there's a lot of interest in small particle pollution and things like that and wood burning stoves and things like that. But actually the particle sizes released are similar to fungal spores, but the, it's almost like this sort of, you know, the proverb of the elephant and everyone's looking at different parts of the elephant and you won't necessarily predict. So, so there is this sort of challenge of people have generally ignored fungi. And so, yes, almost certainly fungus has always been in our homes. It's just perhaps been ignored. And it's this classic question, I guess, is it's impossible to answer, but has it gone up? I suspect it probably has, because I remember when I was growing up, nobody talked about mould in the homes. But it was always there. And I think as sort of central heating has become more, you know, sort of more prevalent. And also home quality perhaps as well, there's a social, which again, I don't work on, but there's like, you know, if your housing stock is poor, then you're going to get more risk of getting mould infections and things like that.
Dr Rupy: With the caveat that we don't have as much data as we'd like to on whether mould exposure or mould prevalence is going up, let's take the argument that it is going up. How would we explain greater levels of mould in modern houses? The things that come to mind for me are, well, I've got my heating on the whole time. I'm not, I'm not in a cold house, you know?
Dr Peter Cook: Absolutely. So, so yeah, no, so again, this is, so yeah, they love warm and humid environments. And of course, in the winter, you are creating a warm, humid environment, which is perfect conditions for, for mould to, to, to thrive. If you are drying your clothes on radiators in the home without opening the window, which is completely understandable, you're trying to get your clothes dry, that is also creating, boosting up the humidity.
Dr Rupy: I've got a baby right now. So me and my wife had a, she had a child. I was just present. She always likes to remind me of that. 15 months ago.
Dr Peter Cook: Congratulations.
Dr Rupy: Thanks. The washing has gone through the roof, you know? And there's only so much our dryer can tolerate. So we, we are constantly putting stuff on dryers. And it's the middle of the winter as we're recording this right now. So none of the windows are open. I'm kind of worried.
Dr Peter Cook: So I think, I think, the first thing is people ask me a lot of this sort of questions and don't panic. It is, it's not to panic with these things. You know, we are seeing mould all the time. So, you know, you're walking out the door, you're seeing mould, you know, and there's so many other factors, not just in your home, you know, where do you work? What are you exposed to in your work? What kind of, you know, so for example, farmers are exposed to much, you know, so, so your occupation can also have massive implications on all these things. But there's also things like if you've got housing, you know, if you've got damp as well.
Dr Rupy: Yeah, damp, yeah.
Dr Peter Cook: You know, that also can, can, you know, sort of foster that. So it's, I guess it's not to panic, it's more to be aware of these factors so that if you have a problem, you try and correct it.
Dr Rupy: Are there particular building materials that are breeding grounds literally for mould? I'm thinking of cheap wood, plasterboard, certain wallpaper, paints.
Dr Peter Cook: I, well, there is anti-mould paint you can buy.
Dr Rupy: Okay.
Dr Peter Cook: Anecdotally, I've never tested it, so I can't, I can't say if it's effective or not, you know. My research doesn't really study the different materials, but this is not a new thing. So, you know, for example, a colleague of mine, he lives in a, in the countryside, and he was telling, we were chatting the other week and he was saying he's got this sort of, you know, he's tried all sorts to get rid of, you know, because he, you know, thatched cottage, that can also, so it's not necessarily just old versus new materials, this is just, you know, we live in, you know, and it's not just the UK, you know, most countries have moulds everywhere, you know, there's probably only a few areas in the world where there isn't mould. You know, these spores can go really high into the atmosphere and circulate around the globe, if that makes sense. So I wouldn't really worry too much about certain materials or not, it's more just about being, keeping on top of it if you, if you notice it trying to clean it. But we don't really know, and I guess this is the crux of your question is, you know, what is a safe level? We don't know. We, you know, so this is one of the key questions that we want to try and answer, you know, me and not just me, but the community of, if we could understand how and why they do this. And and it is almost certainly that some people are more susceptible than others. Why is that? We don't know. Is it that they've got other conditions? Absolutely. If you've got other conditions, that can almost lower your threshold, we think. But yeah, we, we need to do those studies and that's kind of what my group's trying to understand is that, you know, what is a safe level versus, you know, a level that's more concerning and needs addressing. So I think at the moment, the advice I would always urge people, which is similar to what people, you know, trying common sense, try and just reduce it as much as you can. If you can open windows occasionally, even though you've got a baby, I understand, and you're trying to keep it warm, but, you know, trying to keep a breeze through occasionally can be a good thing to do.
Dr Rupy: Yeah, because we, we live in a relatively old building, so I think it's already a little bit more exposed to mould than just where the, like the water collects outside and the stuff and the, the brick itself. There's so many different things that could potentially put us at risk of mould.
Dr Peter Cook: Exactly.
Dr Rupy: And I guess to, without answering the question of how much is a bad level of mould, how do we even measure mould exposure in a room? So in this room.
Dr Peter Cook: Well, that's a great, no, no, no, that's a great question, you know, and so you can buy kits, you know, there's things where they're, you can put a, a plate and you just sort of put it on your windowsill.
Dr Rupy: Just a normal dinner plate?
Dr Peter Cook: Oh, sorry, I should have said. My apologies. A sort of a culture dish plate.
Dr Rupy: Okay.
Dr Peter Cook: Like a plastic dish and you can, and you can do this in the home and then you, you literally are just relying on it falling on the plate. That's, that's one way. Um, there are air samplers that you can get as well, it will actively profile the air, you know, because obviously, but you know, again, where you put this in the room, the type of day, the time of, you know, the time of year. So, you know, for example, I think a lot of, you know, there are forecasts of and people project the sort of, you know, the extent of the fungal, you know, like when's it most prevalent in the environment and it, you know, it's mainly in the spring and the autumn if you go outside, you know, you get this sort of massive spikes of.
Dr Rupy: Spring and the autumn, really?
Dr Peter Cook: Yeah, so that's in terms of the outside exposure.
Dr Rupy: Oh, oh, sorry, yeah.
Dr Peter Cook: So in terms of the home, if that makes sense. So that's the other thing you've got to remember that it's not, it's also outside. So it's like, it's not just in your home, if that makes sense. But yeah, no, so it's one of these, there's loads, there are ways you can measure it, absolutely. Trying to work out though what it means to help you is one of the challenges, right? So it's that question of because we don't know how much can be there. The other challenge to answer your question actually as well is that trying to identify them can be quite challenging, you know, you don't, there are these different types. Yeah, you can, normally you have to use like a microscope to sort of really screen. Obviously the most effective thing is if you sequence their DNA. And there are researchers, again, my team sort of collaborate with these kinds of people, but they sort of go in and go to people's homes and try and, the most effective way is to sequence the sort of, you know, the swapping the walls and sequence it. But that's quite a sort of research intensive thing that wouldn't be sort of available to the, the general public.
Dr Rupy: Yeah, yeah.
Dr Peter Cook: But those are the sorts of studies that we need to do to really sort of address your question really.
Dr Rupy: So with the plate, that will give you an idea of the different types of mould that you might be exposed to. Again, with the caveat of, depends where you put the plate, you're putting it by the window, you're putting it by the aircon, you're putting it in the corner.
Dr Peter Cook: Exactly.
Dr Rupy: So with the plate, that will tell you what's there in terms of.
Dr Peter Cook: But getting amounts is very, I think that's the.
Dr Rupy: Getting amounts is different. So, so in terms of like these air samplers.
Dr Peter Cook: Yes.
Dr Rupy: In terms of measuring, I don't know, per cubic metre, like how many spores there are in.
Dr Peter Cook: Yeah, so, so, no, it's, it's, I'm only smiling because, um, I was debating this with my team the other week about, you know, where's the data that shows how many spores we breathe in? Most of it is, it's sort of, it's really patchy. And so, you know, we, we always say that we breathe in thousands of spores a day, but that's very crude estimates. And of course, some people could breathe in much more and some people much less. And these are, lots of it's from like mathematical modelling and trying to work out in a cubic metre of how much, how many spores there were. And then they sort of projected. So yeah, so we, yeah, so that, but you can, it is a fascinating question that you can kind of go down.
Dr Rupy: So in terms of a range and how we would actually measure that, let's assuming like you're in a completely sterile environment. Are we looking at the number of spores per cubic metre? Is that a good measure?
Dr Peter Cook: Yeah, yeah, I, yeah, roughly. I mean, again, it's more, it's just a really hard thing to actually measure because of course, you know, so for example, if you hypothetically think about you've got a room, you've got a really dense patch of mould on one side of the room, what's the level of exposure on the, on the far side of the room? So, and obviously wherever you put the equipment, you know, these are the kinds of questions that we don't really have a great handle on.
Dr Rupy: Yeah, I guess to answer this question, it's, it's difficult, right? It's really challenging, which is perhaps one of the reasons why there isn't much data out there. Because you need to go into people's homes, you know, you need a lot of buy-in from them. You need to, you know, get a lot of different, you know, to get enough statistical sample size. So it's a really challenging question to, and you also need to do it over a long period of time to try and normalise seasonal differences versus, what about in the summer, you know, your great point about, you know, I've got heating on at the moment because it's the winter at the moment. But in the summer, how does that affect? And of course, when you do the study, could really alter that.
Dr Rupy: Yeah, yeah, yeah.
Dr Peter Cook: And so these are the kinds of questions that we need to address. It is unfortunately one of the challenges of working on mould is that you spend a lot of time going, I don't know. But that's why we need to find out.
Dr Rupy: Yeah, yeah. And so is there any range in a cubic metre that you're like, that's just stupidly high. That is like, you know, I would be worried if I like, I would do something about it myself if there was a way to sample anything that showed a number of spores per metre cubic.
Dr Peter Cook: So no, no, no, I'm, I'm not judging the question. It's just generally there is no such, we don't know. And of course, because it could be relative. That's the other challenge, right? So if I, if you said, oh, you know, it's this number of spores per cubic metre, for example, then, but if you're immunosuppressed, then your risk is way lower.
Dr Rupy: Yeah.
Dr Peter Cook: So, or sorry, your risk is way higher with a small, with a lower amount of exposure.
Dr Rupy: You got, you got what I meant.
Dr Peter Cook: So that's one of the challenges of really answering this question is that it, it almost certainly will vary depending on the individual and also it's not just the amount, it's how much you are. Does that make sense? So what I mean, so, so it's not just the amount of spores you breathe in on one instant, it's are you breathing it in the same amount tomorrow?
Dr Rupy: Ah, okay.
Dr Peter Cook: What about the day after? What about the day after that? Does it go up or does it, you know, it's that classic, this is one of the challenges of working on, I guess, and also, I should just add, people who potentially develop these responses to fungi, there might be other factors going on as well, you know, so that might also be, these things are multifactorial. There's never just one thing. I think fungi are a crucial factor of often been ignored, but, you know, pollution is another factor, right? You know, if you're living in a, in a city versus a sort of countryside, you might have differences in mould, but there'll be other factors as well. So it's a really tricky question to untangle. So I'm not being evasive, it's just we generally don't know. And these are the kinds of questions that we really should, it would be great, you know, if I was to come back in the future and answer those kinds of questions with research. But that, yeah, that's why, it's one of the challenges of the field, which is sort of attracted me to work on this question.
Dr Rupy: It's, it's fascinating because this is essentially an, what I'm asking you is, in a, in a roundabout way is how much exposure do I need to, you know, be exposed to in order for there to be ill effects or harm. But then also, the additional question is my susceptibility as well, which can determine whether a small amount of exposure is going to lead to harm or I'm actually pretty resilient and, you know, you're going to have to really whack some mould over my head, you know?
Dr Peter Cook: No, no, it's, it's funny because, you know, when I, I, I think we were chatting earlier about, you know, people, you know, I, I didn't, my research history trajectory, so to speak, I didn't start working on mould. It's something that I became really interested in. I always studied, I started my research career starting the immune system and then fell into fungi, if that makes sense, because I thought it was such a fascinating question. And I go to conferences regularly now and present to other scientists and, and regularly people come up to me and said, I've been meaning to deal with that mould patch for ages. I think people think about the home exposure, which is absolutely sensible, but things like composting, right? If you compost a lot and you're in the garden a lot, you will be exposed to a much higher level of certain of these kinds of funguses than you will be otherwise. And if you know, so if you're, if you're doing lots of gardening work, of course, you're tilling the soil. Obviously, how the whole concept of composting is that these moulds are really good at breaking matter down, right? So you'll, so, so it's that thing of everyone obsess about the home and rightly so, but what, what also where you work. So I remember, it's, it's anecdotal, so, but I remember a colleague of mine told me about one of their colleagues that he sort of developed sort of allergies and asthma over time. And he retired and they moved the filing cabinet away from the office and there was this big mould patch that they never realised was there. So it could be that, you know, it needs such a long period of exposure to really drive that as well. So these are really deceptively simple questions to try, but really complicated to actually untangle.
Dr Rupy: Yeah.
Dr Peter Cook: Because it's like, you know, if you're exposed to a high level of spores, but it's, as you were saying, whack around the head with them, that might not be a massive problem compared to somebody exposed to a low amount, but all the time.
Dr Rupy: All the time. Yeah, yeah.
Dr Peter Cook: And that, and there's no way, unfortunately, well, that's one of the things we're trying to address is could we actually try and understand this?
Dr Rupy: Yeah. Let's bring it back to a question you are more likely to answer. So what, what size are we talking about with mould?
Dr Peter Cook: So, very, it's small as in, you need a microscope to, you know, so, so for example, the particular matter that people really worry about in pollution is the PM 2.5. I don't know if you know much about pollution.
Dr Rupy: No, tell me about PM.
Dr Peter Cook: So pollution that people worry about is like car fumes and all the, diesel, etc, is, it's a PM stands for particular matter. And if it's under 2.5 microns, there's sort of PM 10, which is 10 microns. So the 2.5 microns is what people are more concerned about, you know, even things like tires, you know, like the rubber on car tires, that actually creates particular matter that we're breathing in. Spores, depending on the, on the sort of type of spores, but things like Aspergillus that we work on, they're about, they're right in that two microns, two to three micron range.
Dr Rupy: Oh, okay.
Dr Peter Cook: So you would need a microscope to see that. Some of the spores can be larger, we're talking 40 microns, right? But they're still, you know, so for people who don't talk those kinds of units very often, you know, your cells are, you know, 10, tens of microns big. So some of the spores can be larger than the cells that we have, if that makes sense. But some of them will be way smaller.
Dr Rupy: Wow.
Dr Peter Cook: So there's, so that's actually a really interesting aspect of the biology of why some spores might be driving different kinds of response just because of their size.
Dr Rupy: Just from the size, yeah.
Dr Peter Cook: Because it would drive different responses as you breathe it in or get it on your skin or something.
Dr Rupy: Are there a particular type, like the ones that you mentioned earlier, like Penicillium, Aspergillus, Cladosporium.
Dr Peter Cook: Cladosporium.
Dr Rupy: Cladosporium, sorry. Yeah, yeah, there'll be a quiz at the end. Are there particular ones out of those that are, tend to be smaller or?
Dr Peter Cook: Yeah, yeah, yeah. So, so Aspergillus is the one that we work on mainly because that's not because the others aren't important, we think they are, but we work on Aspergillus because that's one of the most clinically sort of associated, you know, in the clinic of clear sensitisation to Aspergillus is a key feature. But yeah, so, so, so, so Cladosporium, Penicillium, they're sort of similar sizes and then Alternaria is a bit larger, but there's, there's other funguses as well that can cause, um, allergy, but those are the major ones that people focus on.
Dr Rupy: Those four. Yeah.
Dr Peter Cook: Yeah.
Dr Rupy: How many are there? It was a stupid question again, like how many are we talking, you know, hundreds, thousands?
Dr Peter Cook: Well, no, so, that's a, well, it's one of these things, the more you look, the more you find out, right? But, um, there's, there's sort of, you know, a few more species of fungus that are associated with causing allergy. You know, so there's this sort of fungal mix that people can be screened with to see if they're sensitised to, to fungus. Um, but there's obviously thousands and thousands of other types of fungus. Whether they're, why they're causing allergy and the other ones aren't, that's a great question, right? And that's actually one of the questions that we try to think about is, you know, what is it, what makes one of those four funguses that you talked about particularly more allergenic than all the other funguses we see?
Dr Rupy: Let's talk a little bit more about the mechanisms. So is it the fact that they're so small and can be readily ingested that make them inherently harmful? Are they triggering the immune system in some way or is there some, I'll let you talk through the mechanisms.
Dr Peter Cook: No, no, no, it's, so, so, so this is very much in my wheelhouse, so to speak. So the spores themselves are beautiful and fascinating, you know, so they are, they're these sort of very small molecule, but they are, they can grow incredibly quickly. So within 12 to 24 hours, they can form these long hyphal strands. So these are, they are primed and ready to go. But actually, when we breathe them in, they're kind of coated in this layer that masks a lot of danger signals that would normally activate our immune response. But if they get the chance to grow, then they can, they can go nuts and that. So we know that the immune system, so this is again what I study, we know that cells of the immune system are really good at clearing these, but how our immune systems work in health to clear them without causing any sign of disease, we don't really understand that very well. As in most people study this sort of really sort of diseased situation and then, you know, when there's a disruption, they're not cleared, then the spores can, can drive these response. So, so yeah, so these are really difficult questions to model because you're right, they're really small, so they get quite deep into our airways. And so that we think causes, most of, we have sort of cells in our body called macrophages and these are sort of, they're called macrophage because it's, so they're sort of very good at sort of eating things and they're kind of constantly maintaining and clearing out surfactant and all the stuff that our lungs produce to help sort of us breathe. Macrophages are in the airway clearing all this surfactant up. We think those are the cells that are really responsible for clearing a lot of these spores, but why they suddenly stop, say if somebody's sort of getting this development of a response, is that that's kind of the switch we're interested in is why is it that these cells suddenly stop doing that along with other cell types coming in and what is the sort of controls of that? You know, how is that regulated?
Dr Rupy: I didn't realise they stopped and that was the cause of the.
Dr Peter Cook: Well, that's, that's our hypothesis, right? So, so some people would argue that the spores themselves are not driving disease, they are just, they are, so if you've already got some other condition, the spores will come in and then make it worse.
Dr Rupy: So it's the immune system that is leading to the symptoms of disease rather than the spore infection itself.
Dr Peter Cook: Well, exactly, yeah. So what we think is going on, and again, proving this in humans is, is challenging, but with models that we have in the lab and things, we think that absolutely, we think mostly the spores are cleared with us quite effectively, immune system fairly silently. And there's something happens that makes them make it, that triggers other cell types to come in and make that immune response worse and that underpins a lot of the disease. So, so like, like asthma and lots of these allergy conditions, it's all immune cell mediated. And it's inappropriate, right? So you don't want to be responding to fungus.
Dr Rupy: Totally, yeah.
Dr Peter Cook: You don't want to, and you know, another sort of classic asthma related allergen is house dust mite. So, you know, your immune system reacting to that is completely unhelpful. But why it triggers that in the first place, considering we're all exposed to it is, is one of those sort of big questions that we're trying to, trying to answer. And of course, the other thing is the fungus is doing something as well. So it's not just the host, right? So what we've found is that the fungus, even though it's being cleared, it's still growing ever so slightly as we breathe it in, which is this weird thought, isn't it? That, so it's actually exposing factors that can drive this response. So the fungus is having a role to play here as well, if that makes sense.
Dr Rupy: I'm in front of some mould. I breathe in these spores. The initial immune response is activated. Then, talk us through the secondary responses at what level.
Dr Peter Cook: Yeah, yeah, no, no, absolutely. So, I mean, this is, um, you know, so all pathogens that we recognise, they have antigens, that's what the immune system recognises. And so, um, we call the antigens on, on things that don't cause us harm, but trigger these responses, allergens. So that's one of these, so apologies if I slip into these kinds of terms.
Dr Rupy: That's good to clarify.
Dr Peter Cook: So the allergens are present. And then what happens is, you know, there's a cascade of different immune cells coming and they activate cells that secrete these certain secretory factors called cytokines. And these cytokines that mediate a lot of the immune response. And it's these cytokines that cause all the features that you're associated with like things like asthma or allergies. So they'll cause like your airway hypersensitivity and make you cough. All these cytokines are, are sort of triggering responses on epithelial cells, all the cells of our, in our lungs, which will cause, you know, overproduction of mucus. So, you know, if you've got an asthmatic, they're much more likely to make mucus. They struggle to breathe because literally the immune response is causing the airways to shrink. And this is all caused by something that we're all seeing and it's completely harmless to some of us, yet some people have this exaggerated response.
Dr Rupy: So, would you, would you agree that what we're seeing when this happens is essentially a pro-inflammatory response?
Dr Peter Cook: Yeah, so, so it's, it's sort of what we would refer to as inappropriate.
Dr Rupy: Inappropriate.
Dr Peter Cook: So it's or, or if I was going to be precise, if I, you know, so I should try to be, hypersensitivity. So that's kind of the, you know, so it's a type of a hypersensitive response. So autoimmunity, for example, is also a hypersensitivity response, right? You're reacting against yourself. Whereas hypersensitivity in the context of allergy is so you're reacting against something that is actually harmless. Now, actually, fungus is kind of this interesting thing. It's not harmless because if you don't get rid of it, it will actually, it can cause really serious disease. So if you're immunocompromised, the fungus can invade your tissue. So, so it's one of these sort of, as ever when we come up with classifications, there's always these grey areas, right, where things don't quite fit. So in the context of fungus, as what we think is going on is as a healthy person is continually clearing this fungus regularly, because we're breathing it in all the time, for whatever reason, and that's what we're trying to understand what those signals are, it's triggering a response that can, that can be inappropriate and then that drives this pro-inflammatory response.
Dr Rupy: Got you. Does that make sense?
Dr Peter Cook: Yeah. And these steroid treatments, you know, so people who go on treatment for things, that's not curing, it's just dampening down this inflammation.
Dr Rupy: Totally, yeah. So we're treating the symptoms, not the root cause in this respect.
Dr Peter Cook: Correct.
Dr Rupy: What about direct impact of the mycotoxins themselves? So are they.
Dr Peter Cook: Ah, well, this is a different, this is a different thing.
Dr Rupy: Okay.
Dr Peter Cook: No, no, no, so this is, lots of people obviously are interested in this. So, so obviously fungus are, are commensals as well. So, so we, we breathe in fungus, but we also ingest fungus, if that makes sense. You know, obviously, everyone thinks about the negative side of fungus, but obviously without fungus, you couldn't make bread and things like this, right? So it's great stuff. So we have, we have resident fungus in our gut. The fungus to create these sort of mycotoxins, these are these sort of secondary metabolites. You really need to have the fungus sort of growing. And in our lungs, they're not in there long enough to sort of generate sort of toxins, so to speak. I think what people normally worry about is things like, if you get sort of contamination of crops and things like that, and that can then lead to higher levels of these secondary metabolites and then that is been linked to.
Dr Rupy: That's directly toxic.
Dr Peter Cook: Yeah, okay. But I think in the context of your question of mould that we're breathing in, that's kind of a separate thing, if that makes sense. Now, of course, the, the complexity of this is that, you know, obviously once a, if you're immunosuppressed or some kind of impairment and the fungus is actively growing, so these fungus can, you know, literally invade a lung if, if in the right conditions, then of course those secondary toxins can also cause disease. So I think the mycotoxin side of things is more people are worried about ingesting food with mycotoxin.
Dr Rupy: With mycotoxin in it. Yeah.
Dr Peter Cook: Really where mycotoxin, you know, is when they're sort of, you know, the, it's gone bad within storage.
Dr Rupy: I know it's a big issue within, um, certain crops, commodity crops, grain, wheat, coffee.
Dr Peter Cook: It's because of the storage.
Dr Rupy: Yeah, yeah.
Dr Peter Cook: So it's not, it's not necessarily, it's not an issue at harvesting and stuff like that.
Dr Rupy: No, no.
Dr Peter Cook: It's more just when they store it, there's a risk of, because the spores are everywhere, that they grow and contaminate and then spoil the crop and they don't realise.
Dr Rupy: Yeah, yeah, yeah, absolutely. Um, let's, let's start hypothesising about the susceptibility. I'm really intrigued by this because it is a very, again, another difficult question to answer about what is it about someone's genetic makeup, environment, you know, lifestyle that leads them to be more susceptible to the same patch of mould that is being, you know, breathed in by other people around them.
Dr Peter Cook: Yeah, yeah, you know. Sure. Well, so, so I think there is certainly a genetic element, you know, so again, um, you know, you meet people where, you know, that they've got asthma, their mum had asthma, their grandma had asthma. So there are certain genetic associations with, with you're more predisposed to getting asthma, absolutely. But I think if you actually go to these studies where, and this is not fungal specific, I should stress at this point, this is more, um, in the context of just asthma globally. And, you know, asthma is a great, it's a great example of really that's, it's an umbrella term for probably lots of different conditions that will, does that make sense? So you can have two different asthmatics, but they actually have quite different kinds of response but the same symptoms. It's one of the inherent challenges of it. And so effectively in an asthma context, most, you know, it's about 50% is thought to be genetic and then the other half is, is environmental. Now that's very hand-wavy, but that's because it's, it's not like the, the sort of genetic studies of, they've resolved some key factors, but there's no sort of smoking gun of, this is the key thing that we could target, we could cure asthma. It's, it's more complicated than that. Partly because this is a chronic condition and we're all exposed to different things in our environment all the time. And that's actually one of the major, also major factors. Obviously, risk factors, you know, if you have, if you're more sedentary, if you're, you know, overweight, if you're spending, you know, a lot of time, if you're in environments where you're exposed to much higher levels, all of those things are risk factors. But there's also things like pollution as well. Um, so if you're, and all these things, I think are connected. You know, so if you overlay incidence of hypersensitivity to pollution, I think you get a very good correlation. And also the other interesting thing about, and there's some things we don't completely understand, you know, the rate of hypersensitivity of asthma is going up.
Dr Rupy: Going up, yeah, yeah.
Dr Peter Cook: And why that is, I don't think people have great.
Dr Rupy: No.
Dr Peter Cook: There's, there's again, there's no, there's loads of theories.
Dr Rupy: For me, what makes most sense is that there's, it's multifactorial. And I think diet clearly has an implication. If you're more, if you're exercising more regularly, that clearly, you know, if you're, if you're not exercising, and of course, you know, if your diet's worse and you're not exercising so much, then you're going to become more overweight. And we know that if you're overweight, your immune system changes as well. So all these, but also, you know, how well are you sleeping? We already know people have shown that, you know, if you sleep poorly, that can impact your immune system. And that would that, so, you know, and of course, we're all living busy, complicated lives. So trying to understand all these factors is really challenging. And I think what, but what I would propose, I guess, is we're trying to look at, you know, what is that fungal side of the equation? How is that driving that? But you can't ignore the other factors. So again, you know, people say, you know, you could be in a household of people and only one person develops a response to fungi and the others don't. Why is that, right? And so that's, that can be genetics has a part to play in understanding that almost certainly, but all these other factors are probably contributing as well.
Dr Rupy: What I'm hearing is susceptibility is a mix of genetic predisposition, although we're, we're largely focused on, on, you know, asthma. But in terms of, if you have other illnesses, if your diet is poor, if your liver health is poor, if you're in a high environmental pollutant area where your body is essentially trying to detoxify as much as possible, and you add the added stress of mould exposure, you're more likely to have symptoms potentially.
Dr Peter Cook: Yeah, I, I think, it's very hand-wavy, but that would be, that's kind of what I would, that's sort of our thinking.
Dr Rupy: Let's talk a little bit more about the other conditions. I think anecdotally, you hear a lot of stories, um, particularly post-COVID of chronic fatigue being associated with mould exposure and, you know, once people sort the mould out, we'll talk about in a second. Um, you know, again, anecdotally, their symptoms improve, their, um, you know, the brain fog, all the symptoms that we would associate with chronic fatigue, although that is a very broad sort of umbrella term for what I believe is a whole host of different conditions. Um, so all these things do seem to add up for certain people. And I think mould is, again, as an underappreciated research field, and something that, you know, as doctors, we, we don't really talk about mould other than outside the context of asthma or immunosuppressed patients. It's, it's probably a blind spot.
Dr Peter Cook: Absolutely. So I should, you know, and, and it's fantastic if people have recognised mould might be making it worse and they've corrected that, that's fantastic. You know, that's really great to hear. Um, I guess, again, from a scientific perspective, proving that, as you said, is really, is really difficult. Um, but and the, the data is just not there to be able to give concrete advice. But I think it's again, if we can, if all of us can reduce mould exposure in the home, that probably won't be a bad thing.
Dr Rupy: Yeah.
Dr Peter Cook: But somebody who's improved that, they could have changed other things in their life without even realising, you know, like that's the, the challenge, isn't it? As you know, with when you sort of people do interventions, it's really challenging to work out, well, is that the only thing you changed or is there other things you changed in by doing that change? And I think, yeah, this idea of sort of the envirome, you know, what we breathe in and how that affects our health, I think we're only really, really sort of tipping, sort of scratching the surface or, you know, tip of the iceberg really in understanding how what we breathe in the environment is impacting us more broadly and our health is, yeah, I think really a fascinating question.
Dr Rupy: Yeah.
Dr Peter Cook: Um, but yeah, it's, it's one of these things that you could talk, it's very difficult to give concrete sort of, sort of evidence. But it's things like, you know, like people who have, I think I mentioned earlier, sort of, you know, log burning stoves in their home, which people say, you know, but then you're exposed to a huge amount of particular. So even if you've pulled up, covered up the mould patch, but then you put a log burner in your home.
Dr Rupy: Yeah.
Dr Peter Cook: So there's all these sort of, does that make sense?
Dr Rupy: Yeah, it's, you can't standardise for your exposure, you know, in the home, whether you could be using an air freshener, you could be using, exposing yourself to a whole bunch of other household chemical products, you know, um.
Dr Rupy: Let's talk some strategy about reducing mould exposure, which I think you would agree is a pragmatic strategy for everyone, I would say.
Dr Peter Cook: Sure. Yeah, yeah, yeah.
Dr Rupy: So if we're trying to reduce our exposure, what should we do?
Dr Peter Cook: Well, the first thing is, for example, if there's a root cause of it, trying to fix that issue would be ideal. So, for example, if there's a damp patch and you've got a leaky roof, maybe try and fix, if you can, and that's not always easy, you know, but that's sort of one of the sort of, I know that sounds very basic, but really that is, you know, if you can, if you can make your environment slightly less favourable, that's way better. And then I guess the other, the other strategy is, I think we chatted earlier before about, you know, trying to circulate air in the house. That's a great one as well, you know, because they do like, you know, sort of if you've got windows open, that can create a circulation of airflow, that can be helpful. Difficult, of course, in the winter months if you're trying to save and not have your heating bill too much. So one of those, that's part of it. Also just trying to clean it really early on. So if you notice it building up, trying to remove it before it gets too bad because then it makes it much harder to get rid of.
Dr Rupy: How do you remove it?
Dr Peter Cook: Just like with sort of cleaning products. It's, it's a sort of no, it's just, you know, you can, and also, I guess, stopping build up of water and condensation. That's another key thing, right? So.
Dr Rupy: Do you have to physically remove it or use, if you, I've heard if you use a chemical or a bleach, that's one of the worst things you could do because it could break down the spore size and make it even more likely for you to breathe it in.
Dr Peter Cook: Um, again, it's one of these things that I don't think there's any evidence that I'm aware of. It's possible that that could be the case. Um, I think it's just, again, it's like, you know, but those, I think what's more of an issue is sometimes those products themselves can be quite harmful.
Dr Rupy: Yeah.
Dr Peter Cook: In the first place, right? And so what's worse, the chemicals or the mould in the first place, you know, it's that sort of challenge. So I think it's, it's, I think if you can get it rid of it before it's got really bad, that's sort of obviously one of the key things. Obviously, you might have to resort to things like that, but then if you do use it, maybe keep the windows open and don't go in that room for a little while till all of that, does that make sense?
Dr Rupy: Yeah, yeah, yeah.
Dr Peter Cook: So I know this is sort of common sense sort of stuff.
Dr Rupy: No, but it's a simple stuff. I mean, like, you know, I think a lot of people, particularly in a, but I should say we all get, like, so for example, it's not like my wife laughs at me because it's, she says, you know, I go and talk about mould and then I come home and we have the same things. And we have two kids, so we are, you know, they're a bit older than yours, but I know exactly what you're referring to with, you know, so again, we have the same challenges of how do you keep on top of it and trying to minimise it. So it's just that sort of, you know, trying to make sure that there's, you're keeping on top of it with the, from a cleaning strategy if you, so for example, bathrooms are normally, you know, classic place of where it stores up. But maybe sort of, you know, trying to, to get rid of it more regularly rather than let it really build up and then try and remove it would be much more effective.
Dr Rupy: What's your opinion on dehumidifiers to try and reduce?
Dr Peter Cook: So I get asked this a lot. Um, I think it can absolutely help because it will reduce the moisture. But of course, it depends where the moisture is as well, right? So if the moisture is in the wall, that, but absolutely, it could help. Again, I, there's anecdotal evidence that some people say it does and other people say it hasn't helped at all. Um, but the, in theory, the theory of it would be sound, but yeah, there is, it could be one strategy. If you have a particular problem, I know when I was renting a long time ago, we put one in, it made no difference.
Dr Rupy: Yeah.
Dr Peter Cook: So I think it's, it's down to that sort of personal experience.
Dr Rupy: Air purifiers.
Dr Peter Cook: Again, they absolutely, they might be able to help, but of course, if you go outside, you're going to be exposed. If you open the window, then potentially. So I don't know how, say if you had bad, I don't know if those studies have really been done, that if you put it into a mouldy, into a mouldy room, if you said if there was a massive mould patch here and you put one over there, would it really reduce it? Would it be able to cope? I don't know.
Dr Rupy: Yeah.
Dr Peter Cook: You know, so I think you'd have to check.
Dr Rupy: I wonder if, if you had a decent air purifier that reduced the particular matter in your room and you, you're working in an enclosed room for a long period of time, like you're working on your laptop or whatever, or even, you know, rooms that you spend a lot of time in, like your living room where you're watching TV, that kind of stuff, it kind of makes sense in my mind.
Dr Peter Cook: It would make sense. I guess the proof is in the pudding. And so it's really, I'm not aware of people who've actually done studies on that. Um, but absolutely, in theory, there is some logic to it. But I don't know, and again, it goes back to what we said right at the start, which is that for certain people, it probably wouldn't make any difference because they're probably got quite a high threshold.
Dr Rupy: Yeah.
Dr Peter Cook: And we don't really understand why that person would have a higher threshold than somebody else, but for somebody else, maybe it could help.
Dr Rupy: This has been great. I mean, like, I, I appreciate the nuance and the fact that we're keeping it strictly around the evidence base, but there's enough like, you know, wiggle room where we can talk about some hand-wavy stuff as well. I think it's important because people, it's my background as a scientist, I just can't help but.
Dr Rupy: But a lot of people are investing a lot of money and time and energy into removing mould from their home, but also thinking about it as the root cause of symptoms as well for people who are perhaps suffering with chronic fatigue or raised inflammation or they're just trying to optimise their homes. And I think that personally, I think that's a pragmatic decision. We've had mould in, in my home. I've got a young child and so I'm constantly thinking about, you know, just trying to optimise his environment as much as possible, looking at even electricity exposure as well as like particular matter and all the rest of it. So as well as maintaining a healthy diet. So I think, you know, we, and we do get asked questions about mould quite a bit. So I'm glad that we've, we've had a conversation with you about it.
Dr Peter Cook: Epic. Well, thank you so much, Peter. That was, uh, an education for me and I'm sure, uh, we're going to get loads more questions about mould as well, but we will direct them to your university email address. Well, yeah, absolutely. No, it's all right. We won't do that. There'll be thousands of emails. Thank you. I really appreciate it, Peter. That's great.
