Podcast Transcript
Yes, you can have a mold problem without smelling it, and there are a bunch of reasons for that. Number one is it could be dormant. Mold produces those microbial gases—think of them as digestive gases, the same way we produce gases when we digest. Incidentally, those are not our gases; those are also microbial VOCs. We are really not digesting; we’re ambulatory composters if you really think about it.
It’s not dissimilar in the sense that mold is digesting your building. It doesn’t have a stomach or a digestive tract; it does this externally. As it breaks down stable components like drywall paper into nutrition, it releases byproducts, some of which are gases. That’s what we pick up as the musty smell.
Hello everyone, and welcome to your indoor air podcast brought to you by Change the Air Foundation. My name is Kendra Seymour, and today we’re going to be talking about that moldy smell—what it is, what it might mean for your home and your health.
The technical term you may have heard for this is microbial volatile organic compounds, or MVOCs for short. To help us understand what our nose knows, our guest today is Jason Earl. Thank you, Jason, for being here.
It’s a pleasure to be here. Thank you for having me.
Now, if you don’t know Jason yet, he is a man on a mission—an adoring father of two boys in diapers, an incurable entrepreneur, and an indoor air quality crusader. He’s the founder and CEO of Got Mold and the creator of the Got Mold Test Kit. The realization that his moldy childhood home was the underlying cause of his extreme allergies and asthma led him into the healthy home business in 2002, leaving behind a successful career on Wall Street.
Over the last two decades, Jason has personally performed countless sick-building investigations, solving many medical mysteries along the way and helping thousands of families recover their health and peace of mind. He has been featured on Good Morning America, Extreme Makeover: Home Edition, The Dr. Oz Show, Entrepreneur, Wired, and more.
I’m so excited that you’re here. I know you and I have had some really interesting conversations around MVOCs, so I’m excited to dig in and help our listeners learn a little bit more about what might be going on in their home.
Let’s start with an orienting question that might seem simple but is where a lot of people begin. If you smell mold in your home, it’s an indicator that something is going on. But if I can’t smell mold in my home, do I have a problem?
Very good question, and also, thank you so much for having me. It’s a pleasure to have this conversation in public because we’ve had so many interesting conversations, and I wish we had pressed record for those as well.
Yes, you can have a mold problem without smelling it. There are a bunch of reasons for that. Number one is it could be dormant. Mold produces those microbial gases—think of them as digestive gases, the same way we produce gases when we digest. Incidentally, those are not our gases; they are also microbial VOCs.
We are really not digesting—we’re ambulatory composters if you think about it. Mold is digesting your building externally, releasing those gases into the air as it breaks down stable components like drywall paper into nutrition. It then releases byproducts, some of which are gases, and that’s what we pick up as the musty smell.
Now, if it’s dormant, those metabolic processes stop. That doesn’t mean you don’t have a mold problem; it just means it’s not actively producing these things.
The other thing is sometimes the pathway to you isn’t clear. Air has to get to you for an odor to reach you. Depending on how the building is built, ventilation, and many different variables, sometimes you can have active mold growth producing MVOCs, and they’re simply not reaching your olfactory senses.
I’m glad you brought up the dormant state because sometimes people say, “I only notice a smell after a big storm” or “only during a certain season.” That’s because it’s going in and out of the feeding cycle.
Before we unpack what an MVOC is, let’s clarify something. Sometimes people don’t understand the difference between a mycotoxin and an MVOC. Without getting too deep, can you quickly explain the distinction?
Yes. This is a field of rabbit holes, but for simplicity, when talking about mold, we have three big buckets.
The first is spores—those hardy reproductive capsules that multiply. We pick those up in spore traps and dust tests.
The second bucket, which is commonly discussed but often poorly understood, is mycotoxins. These get all the headlines. About 100 or so molds produce these compounds, and even so, they don’t always produce them. Mycotoxins are not necessarily a great marker for the presence of mold growth.
The third bucket, often overlooked but most abundant, is the musty odor—these microbial VOCs. We are familiar with VOCs in man-made contexts, like the smell of new houses, cars, or gasoline. Microbes also produce VOCs. Because they are gases, they are volatile and evaporate into the air.
Unlike spores and mycotoxins, MVOCs penetrate walls readily. Mycotoxins and spores do not because they are physical matter. When mold releases MVOCs, they spread, which is why you smell them even if the mold isn’t in the same room.
To summarize, MVOCs—the musty odor—are gases produced as mold digests building materials. All molds produce MVOCs, while not all molds produce mycotoxins, which are particles, not gases.
If MVOCs are always produced, is there always a noticeable odor?
Not necessarily. The variance in odor comes from what mold is eating. Different building materials produce different smells. The life cycle, temperature, and other factors also influence MVOC production.
Some microbial VOCs come from bacteria, not just mold. Actinomycetes, for example, thrive in damp buildings and produce an earthy scent like wet soil. There’s a blend of different microbial gases, and the combination determines the specific musty smell.
Also, odors can come from building materials breaking down. Hydrolysis, caused by temperature and humidity, can release VOCs from materials. Mold also has the ability to methylate compounds, altering their chemistry. For example, a historical case of arsenic-containing wallpaper revealed that mold was converting arsenic into a toxic gas, causing sickness.
This is all fascinating, but let’s pivot to health effects. What do we know about how MVOCs impact health?
Typical mold-related symptoms include cognitive issues—headaches, nausea, dizziness, fatigue, difficulty concentrating, and brain fog. These are also symptoms of VOC exposure.
Recent research points to the trigeminal nerve as a key player. It detects chemical irritants below our odor threshold and sends distress signals. This nerve responds to pungent VOCs, including MVOCs. Once irritated, it can trigger cytokine storms, causing inflammation and worsening conditions like autoimmune disorders.
This also explains why people who have had mold exposures often become chemically sensitive. Toxicant-induced loss of tolerance (TILT) is when smaller and smaller chemical exposures cause bigger and bigger reactions. This is why people with mold sensitivities often struggle with perfumes, cleaning products, and other chemicals.
To wrap up, if someone smells mold, what should they do? Should they test for MVOCs?
If you smell mold, you have a mold problem. Testing for MVOCs has mixed reliability. Your best course of action is to find the moisture source. A good indoor environmental professional (IEP) will conduct a thorough moisture assessment to locate the issue.
Thank you, Jason, for this wealth of information. If people want to connect with you, how can they do that?
We created a welcome page at gotmold.com/change theair, where you can download our free eBook full of checklists and FAQs. You can also find us on Instagram, where we take live questions.
Thank you so much for having me!
