Robin Jade Conde

PODCAST: Mold testing standards and procedures (with Eric Larsen)

In this today’s episode, Reuben and  Tessa are joined by Eric Larsen to discuss mold testing and inspection. They cover topics such as national standards and credentials for mold inspection, the importance of certifications, the different types of mold tests, and the limitations of mold testing. They also touch on the value of air sampling, surface sampling, viable spore sampling, and ATP testing. Overall, the conversation provides insights into the various methods and considerations involved in mold testing and inspection. In this conversation, Eric and Tessa discuss the interpretation of mold test results. They highlight that not all mold inspectors interpret the results, it is recommended to look at reference samples and consider the conditions in the room to determine if it is related to indoor mold. They also discuss the lack of federal or state guidelines for elevated mold levels and the variation in what is considered elevated based on individual circumstances. The most concerning types of mold mentioned are Stachybotrys, Ketotium, and the Aspergillus Penicillium grouping. Eric shares some interesting mold investigation stories, and they emphasize the importance of finding a qualified professional to diagnose and resolve mold issues.


Mold testing and inspection do not have national standards or required credentials, but certifications can provide credibility and expertise.
Air sampling is a common and reliable method to determine mold exposure and can be used to compare indoor and outdoor air quality.
Surface sampling can provide additional information about the types of mold present and can be useful for targeted remediation.
Viable spore sampling and ATP testing are less common methods that offer a more detailed analysis of mold species and instant results, respectively.
Mold testing has limitations, and it is important to consider other signs and indicators of mold issues when interpreting test results. Not all mold inspectors interpret the results of mold tests, but it is recommended to consider reference samples and the conditions in the room to determine if it is related to indoor mold.
There are no federal or state guidelines for elevated mold levels, and what is considered elevated can vary based on individual circumstances.
The most concerning types of mold are Stachybotrys, Ketotium, and the Aspergillus
Penicillium grouping.
It is important to find a qualified professional to diagnose and resolve mold issues, and to be aware of potential conflicts of interest in the industry.


00:00 Introduction and Background
01:15 National Standards and Certifications
08:13 The Importance of Certifications
11:01 Quality and Variability in Mold Testing
14:26 The Role of Lab Technicians
22:30 Costs and Profit Margins in Mold Testing
26:34 Surface Sampling and Interpretation
30:37 Viable Spore Sampling and ATP Testing
31:05 Interpreting Mold Test Results
39:01 Understanding Elevated Mold Levels
44:49 The Most Concerning Types of Mold
48:20 Interesting Mold Investigation Stories
53:38 Finding a Qualified Professional for Mold Issues



The following is a transcription from an audio recording. Although the transcription is largely accurate, in some cases it may be slightly incomplete or contain minor inaccuracies due to inaudible passages or transcription errors.


Reuben Saltzman: Welcome to my house. Welcome to the Structure Talk podcast, a production of Structure Tech Home Inspections. My name is Reuben Saltzman. I’m your host alongside building science geek Tessa Murray. We help home inspectors up their game through education, and we help homeowners to be better stewards of their houses. We’ve been keeping it real on this podcast since 2019, and we are also the number one home inspection podcast in the world, according to my mom. Welcome back, Tessa. Great to see you. And Eric, we got Eric Larsen. In the studio. Eric, it’s like you never left [laughter]


Eric Larsen: That’s right.




RS: We had you on the last show and after we recorded that, Tessa and I said, we gotta get Eric back in ’cause there’s a lot more stuff that we’d like to go over with just Eric in the studio. We had Eric and Jayden on. Jayden was talking about his health care in our last, episode… But we had a bunch more follow-up questions. We thought we’re not gonna step all over Jayden’s story for this, but we’d like to get Eric on again. So we got Eric Larsen. On the show. Eric is a home inspector at Structure Tech and he’s also our lead mold technician. Is that the right title? Am I using the right title? Eric is that…


EL: Technician is a good title? Yeah, I like that.


RS: All right.


EL: Yeah. I think my designation technically says Certified Structural Mold Inspector.


RS: That’s even better. I like that.


EL: That is, technician is a good one. Yeah, I like that.




RS: Your version sounds a lot more official though. I like it. [laughter] All right, well go ahead Tessa.


Tessa Murray: Well, you know what, that’s a perfect segue actually. So I was gonna ask you, Eric, okay. Are there any sort of like national standards or credentials that are required to inspect or test for mold?


EL: No. No. And it might okay vary state by state to have some certain certifications, but in Minnesota here, there’s no designation that you have to have. There’s no certification, unlike radon or something of that where you, there’s a very strict testing process and a very strict certification process. Mold is kind of the wild west of all that.


TM: That… Yeah.


EL: Yeah. So you get a lot of different, realms of testers and certifications and there’s a lot of different level of quality of certifications out there too.


TM: Okay. So let’s dig into that a little bit more ’cause I find this so fascinating. I feel like mold is such a hot topic and there’s so many people out there that are concerned about mold and rightly so. It can create all sorts of health issues and problems, severe issues like what Jayden was sharing with us last week. So it kind of blows my mind that there’s not some sort of like, bar that’s been set [laughter] that someone who’s testing for mold or inspecting for mold, has to have some sort of certification for. So what if you are a consumer and you’re thinking about testing for mold, what would you recommend that consumer look for with a mold tester or inspection company?


EL: Yeah, if it… I mean the first thing is to look for a certification. Now there’s a lot of different ones and so if they list one, and you really wanna do your diligence, it would be worth looking into that certification. And when you do, looking for a certification that is essentially like accredited by a third party is kind of like the gold standard. So I have my certification through the American Council of Accredited Certifications, ACAC, and they use a third party board to essentially accredit their like certification exam. So you want that third party involved so that it’s not just like a company that’s like offering the course and then giving the test and slapping on like a certification because there are some of those too where you can probably take a course, two hours, three hour course and then, walk away with…


TM: Yeah. Whatever that company’s…


EL: Maybe an official looking certification that was actually not part of [0:04:44.8] ____.


RS: I mean we could self-certify our own home inspectors. We could say these are Structure Tech certified home inspectors [laughter] and what is that? It’s whatever we decide it’s going to be. But unless you go through a third party, and I mean I’ve learned a ton about that, serving on the board for the national home inspector. Well it’s, it’s called the Examination Board of Professional Home Inspectors. And we’ve got this national exam and it is a big stinking deal.


TM: It is a big deal. The National Home Inspector exam is kind of like the national exam to take if you want to be a licensed or certified home inspector. Right?


RS: Yeah. Yeah, exactly.


TM: Okay. So that’s a good tip, Eric. And like what are some of the kind of the big certifiers out there for mold education and mold certification for testing?


EL: Yeah. The one that I am aware of, because it’s the one I went through is the ACAC as I mentioned. Okay and there’s a company called Indoor Sciences that’s like a indoor air quality nonprofit, that is kind of the authority on teaching the preparatory exam. Or preparatory course to pass to help pass that exam. So that’s the and they have a lot of good indoor air quality resources and a lot of different indoor air quality related, educational content, that they help different professionals prepare for various licensing exams within all kinds of relative IEQ. So mold, mold remediation, industrial hygienists.


EL: Restoration work for flood or water damage and things like that. So, yeah, if you’re looking for a good, resource on just IEQ and/or air quality, they gather a lot of good research and publish a lot of good things on their website. But like I said, they have this preparatory class that’s probably, oh, maybe 40 to 60 hours of dictated content that you go through to help prepare and beyond not just to pass this exam through the ACAC, but also, it’s geared on just helping people go through the exam become well grounded on mold and stuff.


TM: So here’s another question for you. With those courses are they just kind of teaching you the basics of how to do conduct a mold test or the various mold testing that you can do and how to do that properly? And are they also offering training on kind of how to try and figure out how the mold got there in the first place and how to resolve it as well?


EL: It is all of that. Yeah, there’s different kind of like steps that you progress through, and learning about those things. So it just starts on understanding the basics of like fungi and like microbiology, essentially. And what are the differences between mold and bacteria and that kind of thing.


EL: And then from there, kind of, it evolves into talking about potential causes of mold growth. So you learn a lot about relative humidity and dew points, because that’s a big part of potential, creating wet surfaces and maybe more in homes that are in climates that a little bit more air conditioned dominant, but still relevant to our climate as well. So you learn about that.


EL: You learn about water management and how water moves at the exterior of the home and the course touches on that. And then it kind of gets into the different types of testing that you can do. So we can go into that in more detail later, like air sampling versus surface sampling versus viable spore sampling, non-viable spore sampling. There’s about maybe 10 different ways to test for mold roughly in that. And then from there, it kind of goes to how to interpret those test results, because there is a level of interpretation that comes with mold testing.


EL: It’s not cut and dry always. So we can talk about that a little bit more later too. And then lastly, kind of understanding the remediation process on a high level, not necessarily getting into the real details on that, but the class will prepare anyone to be able to understand what is the basic high level mold remediation process, how to inspect projects that have undergone mold remediation to determine if they were done according to a widely popular international standard that should be followed by mold mediators.


EL: And that’s kind of the last piece of the puzzle in that course. And then I guess the put that all together is that kind of summarizes how to best conduct a mold inspection is putting all these pieces together. It’s kind of understanding the situation, the client’s concerns, asking good questions that might lead into, uncovering information. And then, going through an inspection that is just using the proper tools and equipment to determine potential moisture-related concerns and then understanding how to perform the testing. And maybe helping the client with, how would the remediation process would work if there is an issue.


TM: That seems like all-encompassing training. But what’s interesting to me is that, I mean, that’s the training you got going through this specific organization. But since there’s no like national requirement, and there’s all these other different types of mold testing companies out there that offer their own credentialing, it’s very likely or possible that there’s people out there doing mold testing that haven’t been through that type of training or that thorough of training, right?


EL: Sure, yeah.


TM: Okay. So it’s that much more important to know who you’re hiring.


RS: Actually a large number of people.


TM: Yeah. A large number of people.


RS: Yeah.


TM: That’s kind of scary.


RS: So we taking a swab or an air sample, getting lab results, sending lab results to the client, saying there there’s your mold test, like we’re done. Yeah. Not adding much value to anybody.


TM: Yeah, I think that’s the key takeaway is that there are, I mean, there’s a wide ray of quality when it comes to getting a mold test. You could have someone that just comes out, does the air sample, and sends you the results, no interpretation, no other information, just boom. Here’s what we found in the air versus something like what you just said, where you’re listening to their concerns, you’re looking at their house, you’re thinking about all the conditions, looking in the right places, trying to figure out how it got there.


TM: And what would be done to remediate it and fix it and giving, the client and the customer guidance on what to do to fix it and what the results mean. Like, that’s a very different scope.


EL: Yeah. Yeah. For sure.


TM: Okay. So can we dive into the different types of tests that are out there and kind of the pros and cons of each?


EL: Yeah. So we can start with the ones that we offer with our service and maybe what’s just most popular as well in the industry right now, which would be air sampling through aerosol cassettes using like a pump. So what this is, is drawing a known volume of air through a little slat on a round cassette that’s about maybe one inch tall and three inches in diameter. And in the middle of that cassette there’s a sticky microscopic slide that everything being pulled through that little slot it impacts against. And so any particles that are in the air essentially will stick to that. And by taking a known volume of air over that slide, you can be sure that you’re comparing sample to sample, like to like in terms of…


EL: ‘Cause if you ran a sample for 20 minutes versus five minutes and you don’t designate that, there’s going to be obviously more particles in the 20-minute sample.


TM: Sure.


EL: So you have to have a kind of an accurate amount of air moving over the slide. So then that slide is, we send them into a mold laboratory and there’s many mold laboratories across the country. There’s one locally here, there’s, we use one down in Florida, there’s many good lab, mold laboratories. They’ll pluck that slide out and look at it under like 600X magnification and give a kind of a breakdown of groupings of mold, kind of like sub species essentially or types of mold and the quantities that are found on that slide.


EL: And so that’s the basics of the test and then we take those results and kind of interpret them, which we can talk a little bit more about later based on the types of mold, the quantities and everything like that. So that’s air sampling and that’s what most people are using now at least in our market to sample for mold.


RS: Let me just ask Eric, when the lab is analyzing these results, it’s a human actually looking at these slides, right?


EL: Yeah. Yep. Yep. It’s a human and some labs read just 50% of the slide or 20% of the slide and they extrapolate that out. The lab that we use, they read 100% of the slide, which is nice then they give you the whole slide of what’s on there. So it can be a little bit more accurate, I guess, rather than just reading like a certain smaller percentage of the slide.


RS: Now, I know it’s a bit of a tangent, but I got to think that being this slide reader, working in a lab, doing this all day long, doesn’t that have to be one of the worst jobs imaginable? I don’t know just…


EL: I haven’t put too much thought about that. I mean, these are like trained microbiologists, so they’re people with, I’m sure, high levels of education training but yeah…


RS: Oh, that my point, you went to school, you got a degree, and now you’re doing this monotonous task all day long.


TM: You know what, different strokes for different folks, Reuben.


EL: There are some…


RS: That’s right, you’re right.


EL: I’ve heard of one lab that’s experimenting with AI to do this.


TM: Oh, wow. That makes sense.


EL: Like slide reading.


TM: Crazy. So these air samples…


RS: Can we teach a machine to do this?


TM: Yeah. So, do these air samples, mold tests, do they work in the winter, the summer, the spring, any time of year? Are there only certain times of year that you can do them?


EL: Yeah, they do work year round, they can be reliably used. So when we go to a house, we’ll take a sample outside of the home, like in the outdoor air, and then a couple samples inside the home. And the outdoor sample is used as a reference, because mold exists in outdoor environment, from decaying things, mushrooms, just naturally occurring phenomena. And so we take that sample outside to determine that if there are elevated levels inside the home, if they’re lower and similar to what’s outside, then we can attribute that maybe more to exterior air infiltration, maybe the windows were open for two days before we got there and didn’t know.


EL: So you always take a sample outside if possible to reference against, but when it’s a winter time, it’s too cold to sample outside, because if it’s below freezing, nothing’s going to stick to that slide. And when snow cover is on that knocks down a lot of the spores and there’s just not much activity. So then in that case, we’ll take kind of a reference inside the home and like an area of non-concern as an alternative reference. But mold levels though even inside a house and even hour to hour and day to day will naturally fluctuate. So you could go to a home and do some sampling at 8:00 AM in the morning in January. And then go back maybe two weeks later and go in the afternoon and you could get different results. They’re not going to wildly deviate necessarily. I don’t know.


EL: There’s not a lot of, I guess, great research that I’m aware of on how much fluctuation there can be within a home without other things changing. But things will it can be impacted by the humidity in the home, how many higher humidity might cause fewer spores to actually like sporulate or aerosolize. So conditions in the home, temperature, humidity, just natural fluctuation maybe how disturbed the carpet is or something like that. They can all affect how much mold is sampled in the air. So that’s just natural to get some variation. You would expect that if you took two samples that even one after the other sometimes.


RS: For some people, I’ve heard some people say, well, there’s no value in taking air samples because if you’ve got mold hidden inside the wall, that mold is not going to be in the air. And taking an air sample, if it comes up low, it’s going to give you the false sense of security when you could actually have a serious mold problem. What would you say to that, Eric?


EL: Yeah, I guess there is some truth to that. And there is some limitations to mold testing of course, because of that. But we use other tools to kind of identify if there might be other issues going on inside a wall, like using a moisture meter infrared camera to help see if there might be dampness in a wall, finished basement wall or something like that or if the home was built in the ’90s and has stucco then we’re usually recommending intrusive moisture testing for that and that could help uncover some of those issues. So usually there’s other signs that there might be an issue inside of the wall that’s sealed up, but we’re not in the capacity that we’re doing mold testing, which is mostly in real estate transactions.


EL: We’re not gonna find any value in trying to get permission to drill holes in walls to test inside of a wall cavity or anything like that. So, I suppose in technical terms that statement might be correct because if it is sealed inside the wall, it’s not gonna show up inside the room unless it’s really bad and then it might show up in inside. If there’s mold growing on like the backside of drywall and you can’t see it yet on the front side, that can still show up on an air sample for sure ’cause that mold can move through, the spores are small enough to move through spaces in that drywall or underneath the drywall, just little air gaps so.


RS: Okay. And so, if I’m summarizing your answer properly, Eric, making sure I understand what you’re saying. You’re saying that we’re not gonna go test the air in some room for no reason. If we’re doing an air sample in a room, it’s because we have reason to believe that that room has a problem and we’re already digging into something that we suspect. And doing the air sample is just one of many things we do to help figure out if there’s an issue.


EL: Yeah.


RS: Okay.


EL: Yeah, I mean we could go around and test every room in the house, but that would get very expensive for someone, and we’ve done that in a few cases for people who have extremely sensitive allergies or immunocompromised individuals, or somebody has a really high concern for mold we’ve tested a lot of different rooms in the house. But a typical client we were just… We’re not wasting that money and resources and everything on just randomly going and testing throughout the house. We’re going to those areas of highest concern especially where mold may have the chance of growing in areas that’s not visible to the eye.


RS: Yeah. And I got to say this too, while we’re talking about this and how much it costs. Mold is not a huge money maker for us. I mean, we do it, but the profit margins are pretty slim. The person making all the money is the labs. [laughter] Like we pay a boatload of money for every sample that we send off to a lab yeah. Thin margins, while it’s expensive, it’s expensive because it’s expensive, not because we’re jacking up the fees on it. I do got to qualify that. Sorry, back to you, right.


TM: Okay. So the air testing is kind of one of the most common tests that you’re doing for people and that you would recommend as a good indicator if you’re thinking that there’s a mold issue. And what other types of mold tests are there and which ones do you do?


EL: Yeah. And just a final note on that, air testing that’s a good way to determine exposure, breathing exposure that’s the most reliable way to do that. And so if somebody is like needing something for a doctor to say, hey, what are your exposure levels or something like that, that’s where air testing comes in. We usually take a sample, usually it’s in an area of the house where you’d be occupying it, not like in a crawl space where there’s very little access. We’re taking a sample where someone would be spending some time and usually in a relatively area of the room which would be considered like a breathing zone. So that’s just the last note on air testing.


EL: Yeah. So then we can also take surface samples if we see visible mold like growth on a surface drywall, block wall, we can take a couple different ways. We can take a surface sample of that. We can either take a swab and kind of dampen the swab and roll it over that staining and pick it up and put it in a tube or we can take a sticky piece of tape and adhere it to the drywall or the wood and lift off any spores that are on there. And the lab will analyze that as well and tell us what kinds of molds are present and the numbers of spores and everything else on that as well.


TM: So that would be more so like you know you’ve got mold, you can see mold, but you wanna know what type of mold you’re dealing with?


EL: Yeah. I don’t do a lot of surface sampling ’cause most people wanna know like how bad is this? More like rather is this mold or not? They’re not trying to prove it is or isn’t unless there’s like some sort of dispute that’s trying to be settled, but more often than not it’s taking that air sample in. If you wanna know how much is this impacting the air that I’m breathing, then that’s one way to do it. If you see something staining on area in that room, but sometimes following it up with that surface sample and [0:25:39.9] ____ that can provide some extra information, is it the same type of mold on the surface as what’s in the air. That can give you a little bit more information or just…


EL: Is it a water damage mold or is it a mold that grows more from like humidity? That can provide some information what’s on the surface. If it’s Cladosporium or something like that, that’s something that grows in more well-ventilated areas, like maybe in a like in a basement block wall or in like an attic or something like that. Versus like stachybotrys, which is a mold that grows in like very damp conditions, more advanced mold growth scenarios. Yeah, that surface sample can provide some extra information. Sometimes clients wanna pay the extra cost of analyzing that to get that extra information. But a lot of times I’ll just recommend in my reports, just regardless of what the air sample shows if there is some visible mold-like staining to remove it, clean it, whatever type of surface it’s growing on just that’s an actionable step to have that removed or cleaned regardless of what the air testing is showing.


TM: Okay.


EL: Sometimes if it looks like mold I can pretty confidently say it’s mold, but I won’t outrightly say it unless we take that test, surface test and have the lab confirm it. But you can still recommend cleaning of, cleaning or removal of that staining.


RS: Sure.


TM: Okay. Besides the actual like tape test or a swab test, is there other additional types of mold tests that are out there that are commonly done too?


EL: Yep. Yeah. The air sampling that we mentioned already is like non, it’s called non-viable air sampling. That means we’re taking spores in the air. Some of them might be viable and be able to regrow and some of them may not be able to regrow and those are non-viable but non-viable spores can still have health impacts. But there is a type of mold testing you can do called viable spore sampling where you essentially have to take a different type of sample. You have to keep the sample under refrigeration, like on… Ship it on ice essentially, and then the lab will culture it out and they’ll take it and they’ll actually take those spores and grow, essentially put them onto a media like a Petri dish and grow them out.


EL: And then they can tell you with a lot more accuracy what exact species of mold that is. ‘Cause what we’re getting in the air sampling is like a grouping of species, like there may be a hundred different subspecies within that genera of mold but then the viable sampling can take that and give it down to the exact species, which is not something we offer because it’s usually way more overkill than what most people need.


EL: But in commercial applications or if there’s various other parties involved that want to know that, there is that option for people to sample that way. So that’s viable spore sampling. Then there’s like the, we kind of talked a little bit about it last week with the ERMI testing, which is taking dust samples and seeing what types of molds are present in the dust. That’s an EPA developed method that’s still kind of under a trial basis according to the EPA who developed it, but it’s something that people are using out there and it’s something that even people can, I believe, collect on their own with the proper kits and things like that and send it in. And that can tell you historically what molds may have been present. Like it might show some mold type that may have been more prevalent like 50 or 60 years ago because of a water intrusion event or something, but it’s still hanging around in the dust.


EL: That can be useful too as part of a really thorough suite of testing and everything, but it’s not something we offer on that. And there are also a few people who do that around. Those are the main ones that kind of come to mind. There’s a couple other one-offs as well. And then there’s ways to sample for bacteria. Like if there’s been like a sewage backup in the home or something like that, there’s ways that you can swab or air test for bacteria that get into maybe like seeing if any harmful bacterias might be present.


TM: I wanted to dive into something you mentioned earlier about kind of interpreting the results. Is that something that all mold testers do or not? And what does that entail? What does that look like?


EL: Yeah. Yeah. I can’t answer this. I don’t believe that all mold inspectors or testers interpret the results or they may just interpret them very quick and dirty. If it hits a certain number, then they just give a blanket kind of recommendation. But what is kind of recommended is to look at that reference sample and think about the conditions in that room and everything or where that test was taken and interpret whether in your professional opinion, if you think that is related to an indoor mold related issue or is it something else that might be explained by…


EL: Exterior air or trapped spores coming in from the outside and then looking at the levels that are present. And this is where it, again, can kind of get a little bit dicey because there’s no federal or state guidelines as to what is considered elevated mold levels. And it again, can vary widely, what is elevated too, based on a person’s individual circumstance. What might be acceptable for one person might cause health concerns for another person.


EL: But there is some guidelines from the European Union that I believe most mold inspectors in our market use to kind of define what might be a little bit more elevated or abnormally high. There’s also some other research done by other seasoned mold professionals that kind of go into numbers that might constitute concern or be typical of a house with a mold-related issue on the inside. So we use all those things kind of combined together to give an interpretation.


EL: And sometimes our interpretation is just that we can’t say that this is completely clear or free, but we also can’t really call this clear and cut concerning or elevated. And so it kind of falls in that borderline middle where someone might want to do some more testing or just investigate a little bit further into the issue. And that sometimes is the recommendation. It’s not always, even with the thorough inspection that we’re doing and everything, it’s not always cut and dry with mold.


TM: It’s a big grey area, isn’t it, with mold. So when you get the results back, you’re looking at the species that are present and then the actual counts, like the spore count of it. And then when, if you’re doing air sampling, you’ll have an outdoor baseline reading that will tell you here’s what was present outdoors. And if you’ve got the same amount or less than that inside, then you probably don’t really have a mold issue at that time. If you’ve got elevated levels above that, then you might.


EL: Probably not, yeah.


TM: Okay. So you’re helping the homeowner understand that.


EL: And especially if you do a visual inspection, everything looks very clean, dry, there’s no areas of concern. You might get back a… I’ve seen a couple recently that right now outdoor molds are getting pretty high with all the rain that we’ve had and just all that. Activity that goes on in spring.


TM: In spring, springtime, the snow melts. Yeah, it’s the worst time of year for mold.


EL: Yeah, there’s a lot of mushroom related molds that are high. Cladosporium is really high outside. So there’s these molds that are coming in, sometimes 20,000 spores per cubic meter. That’s how they’re measured. And typically anything above 1000 inside could be considered something you want to pay attention to. CC 20,000 outside and then maybe it’s like 4,000 inside, but it’s the same type that it’s that Cladosporium or one of those outdoor molds. Then it becomes a little bit…


TM: That’s a grey area.


EL: More of that, is it, it probably is related to outdoor air and people have their windows open and we try to communicate with listing agents and clients to keep their houses closed up as possible 48 hours in advance with the testing to help mitigate that. But sometimes people have their windows open for hours at a time and spores can float in and they can get trapped in carpet, especially if there’s carpet in that area. And that can give you maybe that false high reading that is not actually showing an issue inside. But you don’t know for sure always, but you can say with pretty reasonable confidence that this is probably related to outdoor air. And I would usually recommend to a client in that case that they follow-up and see. Was there a lot of outdoor air communication from open windows and from people coming in and entering.


TM: Sure.


EL: For showing or something like that and they’re carrying spores in on their shoes or their clothes and stuff like that?


TM: Well, yeah, just like you said, the amount of air leakage between inside and outside could have an impact on that spore count. If it’s really high outside, and let’s say you’ve got a really old leaky house with a lot of air exchange happening, you’re going to get some of those mold spores inside inevitably.


EL: And that still could be still high spores inside, even though they’re outdoor spores, that could still be something that somebody would want to pay attention to because maybe people have allergies or just there’s more particles in the air. So then that comes down to the other. That would be a more advanced conversation of what do you do to seal up the house better? Can you install a HEPA filter on a furnace or install an air exchanger with a HEPA filter and really get into some advanced air quality, indoor air quality techniques there to help mitigate outdoor spore intrusion. But in terms of calling it an indoor mold-related issue, you’d be hard pressed to argue that without any sort of visual otherwise. Now, if you saw maybe.


EL: Maybe there was staining inside of sub slab duct work in that area, that can be related to that mold type Cladosporium sometimes. So then you’d be maybe couldn’t really say, this is definitely related to outdoor air duct.


TM: Yeah.


EL: So that’s why the interpretation gets a little more advanced and intricated in some ways.


TM: What are some the most common types of molds that are really bad like you don’t wanna see, that type of mold in your indoor environment?


EL: Yeah, well yeah, there’s usually just four types that pop up elevated indoors. The worst, for most people would be stachybotrys. That’s what people would commonly refer to as toxic black mold or black mold. So that tends to have the most wide ranging health effects for just about probably anybody in the general population if it’s elevated. So we pay attention to that a lot. Even if we see stachybotrys and it’s not super high, we still note that it’s potentially concerning because it means that there may have been either a previous mold related issue that may not have been properly cleaned up or there might be… There’s probably water damage at some point in the home. Probably because that mold doesn’t exist normally outdoors. Really it only can grow in indoor environments.


EL: So Stachybotrys is the one that we pay the most attention to or just that could be the most concerning for those reasons. Then Chaetomium which is what I believe was mentioned last week on the podcast, is the one that it was Jayden found in his house, and that’s the cousin to stachybotrys. So not as well researched maybe, but still does have, can have similar health impacts to stachybotrys and is a little bit more associated with water damage too. And then the most common one to find elevated indoors based on our experience is typically the Aspergillus penicillium grouping of molds. So that it’s a common, it doesn’t mean it’s not concerning, but it’s more common, probably the most common elevated indoor mold that Aspergillus penicillium. And it’s the culprit a lot of times with that is carpet, that’s one that thrives growing in carpet dust, the dust that trap in the carpet.


TM: All kinds of carpets?


EL: And there can be toxigenic…


TM: All kinds of carpets or certain carpets?


EL: Mostly basement carpets and I guess the shaggier, the potentially worse or the older the worse, or the carpet pad or the tack strips. So, yeah. And there are species within that grouping of molds that would be considered more toxigenic than others and that’s where getting down to that species level could inform that. But usually if there’s elevated mold and it’s clear enough, you just wanna put your money into remediating it rather than trying to test and figure out what exact species it is, so that’s the third one. And then you do see Cladosporium elevated sometimes as well, seeing more and more of it is in the last few years it seems like. Which is interesting. But that can be a mold that grows more in just well ventilated areas or just areas that, where humidity is the concern rather than moisture like a closed off room, in a basement storage room or ductwork, sub slab ductwork or maybe like an attic. So those are the typical four that would be worth paying attention to. Other ones you don’t see elevated inside very much, unless they’re coming from the outside.


TM: So that’s helpful to hear you explain that. You have extensive knowledge not only knowing what’s typical, but you know what might cause that mold where you might see it and potentially maybe even do you understand some of the symptoms that go along with these different types of mold too?


EL: Just on a very high level Yeah like stachybotrys that and then maybe chaetomium, that can be it can be some, and I think Jayden was experiencing some of this, some of the brain effects, headaches, that kind of thing, nasal. A lot of it just comes down to congestion, maybe breathing issues, that kind of thing as well. Sinus type of stuff. But yeah the stachybotrys can have the more maybe harmful long-term consequences. And I’m not a doctor qualified to talk about this, but that would be from more prolonged exposure to high levels, so.


TM: So, before we run out of time, I wanted to ask you, I’m sure you have seen a lot of interesting situations out in the field while you’re doing these mold investigations. So what are a couple that stick out to you?


EL: Yeah, so one I got a call for was in a condo like a 20 floor condo in Edina, where the person was seeing a little bit of black staining start to grow at the bottom of their closet. That was like abutting up against a bathroom. And the area had been… Again, it reminded me of the situation we talked about last week with that experience that he had where he saw a little bit of staining in the closet, behind the clothes. It was very similar, come to realize that did some testing. That wall was wet. I could see some anomalies in the ceiling above the bathroom with like an infrared camera. The testing showed high levels of stachybotrys among some other molds in this case. And so this was like a definite clear recommendation for mold remediation. I went back out to the property a couple weeks later, like when there was in the middle of the remediation process, and come to find out there had been like a leaking pipe in the unit above that. And these floors in between the condos were concrete.


EL: And so the water was finding its way to run down like a pipe chase way behind that closet. And then it was saturating the concrete that the whole unit was built on. And so it was starting to essentially saturate that concrete, wick up the walls in the surrounding bedroom. And so when I was there, they had flood cut up two, three feet, like around the entire bedroom, not just that little closet area, but when they started digging into it it was like this has been wet for a while. And there was carpet in there. It will all be tearing out. So that was a very interesting one, just from that little leak. And the concrete is unforgiving because it doesn’t show up on the ceiling as quickly, but it finds its way down and eventually had its water finds its way as you know into the smallest of places. And then… So that was a…


TM: I’m sure was the homeowner really sick?


EL: Yeah, it was actually a landlord tenant situation and so the tenant was getting sick and they were starting to… They basically had to move out of the units from what I understood.


TM: Wow.


EL: Yeah. Yeah. And then there’s a lot of them but there, another one that comes to mind is, there was actually I was doing the mold test for an inspection that Reuben was helping out Melin with, and it was a basement of a finished basement. And they came to find out the shower was leaking at the enclosure. Basically it had been improperly installed, wraparound shower enclosure that had been, I believe it was caulked in the wrong areas essentially. And so it didn’t have the weep holes to drain out. And so the water was making its way kind of onto the carpet and the carpet tack strips on the adjacent wall. And that one also had high stachybotrys. When carpet gets wet, if it’s not dried out within 48 hours properly, that’s long enough for mold growth to start in carpet. It’s very, again, very unforgiving sometimes. And then with carpet mold can really find an ample food source because there’s so much dust trapped in carpet. And that’s why I say kind of the shaggier, the older, the potentially more dust that’s trapped in there. And so with that, just carpet getting wet, day after day and…


TM: Gross.


EL: From showering from… And then in other areas of that basement there was also some staining of the tack strips along the exterior, maybe from exterior water intrusion. So that one had a whole suite of all those aspergillus, chaetomium.


TM: It was a Petri dish down there in that bag.


RS: Yeah, I remember that one.


TM: Gross. How’d you feel afterwards? Do you guys feel any health effects when you’re spending a lot of time in a house that’s really moldy? You don’t, Ruben?


RS: Never.


EL: I can sometimes, but then sometimes I think I trick myself into it too, like where I just feel like I know it’s there, but then… So then it’s almost like a placebo effect. [laughter]


TM: Yeah.


RS: I was just staying at a hotel in San Diego and I looked up above my bed, the wallpaper was peeling just a little bit and I just kind of put my finger up there and I kind of pulled it back and I mean, it easily came back several inches and everything behind there was just solid black. Oh, not solid black. I mean, it’s moldy black, it’s…


TM: Oh man.


RS: Solid black might have been an adhesive, but this is like, I mean, it is so moldy. And then I noticed it in the bathroom too, and it’s like, so there’s mold everywhere in this room and I just kind of shrugged and went, eh, and I felt no ill effects. I mean, I saw it on the first day I was there, I spent two nights there and nothing. It didn’t affect me in the least, at least not that I know of. Maybe I was cloudy thinking, but maybe I had a cloudy head. I don’t know. I felt fine.


TM: Wow.


RS: I don’t think I get affected.


EL: No, that’s the thing about it, like sometimes I’ll go into a house, and one partner is like just having all these health effects and then the other one is completely fine and couldn’t tell anything’s going on. And so yeah, just it affects people so individually and I think going back to last week too, there’s different ways that you can kind of test yourself to see if you are sensitive to mold or allergic to different types of mold. There’s like different in prick tests and things like that, or the blood tests that he was talking about. So that’s all interesting stuff, but…


TM: Wow. Well, I’m sure we could go on and on and you’ve got a lot of stories, but for sake of time, I think we should probably wrap this up. So thank you so much Eric for sharing all this information. It’s been really interesting. It’s hard to believe that something that’s such a big problem and causes so many health issues with people, there is no like national standard for how to test for it or no national standard that says this is dangerous or this is safe. And so you’re kind of just at the mercy of your own research and hopefully finding a qualified professional that has experience and is ethical to help you diagnose and resolve any mold issues that you might have. And it is a huge moneymaking industry. So as a consumer you have to be conscious of that and navigating that, it’s a challenge.


EL: Yeah. And just a final note on that, if you are a consumer, conflict of interest is another thing to watch out for in the industry because there are companies that are set up to remediate mold and they may be good remediators and use the proper certifications and everything, but they also test. And so then you have to ask yourself like, well, if they’re testing and doing the remediation, there is a conflict of interest even if they’re doing it according to all the standards. And if they’re trained properly and certified properly, there’s still that conflict of interest that they could be pushing you towards remediation. And then, once remediation is done, it’s always a good idea to post check that work with a post remediation verification test. And that should also be conducted by a third party. So that the mold mediator should never be essentially checking their own work with a test. That’s also a conflict of interest. So, always think about that, just line of third party and who’s involved and who’s doing the testing, who’s doing the remediation.


TM: Yeah, that’s a good point.


EL: Make sure there’s some separation.


TM: The last thing I just wanna add to this, and this is a pretty bold statement, but this is my personal opinion, I don’t think I’ve ever seen a house that doesn’t have mold in it. I don’t know. Would you say you’ve ever been in a house that doesn’t have mold in it?


EL: Well, technically, unless it’s a hospital clean room, every home is gonna have at least some, it could be very small amount, but at least some background mold, normal indoor fungal ecology we call it. And that’s just from that, even if it’s a well sealed up house, they’re still gonna find its way in. Spores are still gonna come in on people. And so yeah, there’s no such thing as, unless, again, it’s designed that way in a sterile environment in a hospital or some other manufacturing facility, there’s gonna be something in the air.


TM: I think it’s just, it’s helping. Yeah.


EL: Yeah. So I don’t know if that’s what you were referring to.


TM: I think it’s just helping if people understand, to have realistic expectations that if you’re gonna get a mold test, you’re probably gonna find mold [laughter] There’s gonna be a positive result. It’s just a matter of how sensitive are you to it or your family and is it creating any negative health impacts and if so, what to do about it?


RS: And is it unusual?


EL: Yeah.


TM: Right. Is it unusual?


RS: Yeah, we can do mold testing and say, yeah, you got mold, it’s about the same as what the outdoor levels are. And it’s like, okay, you just shrug, you go, okay. While you have mold, you don’t have mold. And I’m sure that Eric, you find that on a lot of cases, right?


TM: Yeah.


EL: Yeah, yeah. Exactly. It’s like, yeah, you could say every house has mold, but is it concerning, is it related to something going on in the indoor environment, indoor source. Yeah. That’s where the intricacy comes at.


TM: And you need someone who knows what they’re doing to interpret the results and help you understand it. Yeah.


EL: Yeah. Yeah. That’s why if you get one of those at home, like tests, mold tests and you just set a Petri dish out for a couple days, something’s gonna land in there and find a suitable environment to grow. And then you’re gonna have, all of a sudden you’re gonna have a colony of mold spores, like in that Petri dish. So, of course, that could give people a false sense of, oh, my house has dangerous mold in it. ‘Cause there’s all this mold growing in a Petri dish, but it’s just, there could just be a random spore floated in from the outside and then found this really suitable Petri dish environment to grow in and started to grow. So that’s a side topic, but it is, that there are tests like that that can mislead as well I guess. Yeah.


TM: Misleading people.


RS: Yeah.


TM: For sure.


EL: Yeah.


TM: Well, thanks again for coming on and sharing Eric. And if anyone’s listening and you’ve got thoughts or questions about this podcast, please send them too Ruben.


RS: Podcast at, I thought you were gonna say it this time, Tess. So I was waiting for you.


TM: I’m not stepping on your toes this time. You [laughter], this is your jam.


RS: I was hoping you would. Okay. It’s


TM: Perfect.


RS: All right, thanks everyone.


TM: Thanks for listening.


RS: Thanks Eric. Great day on. Take care.


EL: Yeah, thank you.


TM: Until next time.