Is Mold Testing a Scam?

TLDR About Mold In Your House

Mold is everywhere both inside and outside of your home. Mold tests that rely on air sampling are extremely ineffective, cause unnecessary fear, and could be considered nothing more than snake oil. The EPA has no standards or threshold limit values for airborne concentrations of mold or mold spores, and it is an absolute certainty that your house has detectable levels of mold spores inside the conditioned living space because we are constantly bringing in new mold spores on our clothes, pets, groceries, and some of us are even unknowingly hydrating colonies of mold every time we water our house plants.

Published scientific articles report that poor health outcomes resulting from “toxic black mold” lack well-substantiated supportive evidence, meaning that “toxic mold syndrome” is not real, or more accurately there is no evidence to support such a claim. Although the relationship between mold and human disease is inconclusive, mold isn’t great, and steps should be taken to limit mold growth in the house. Since mold thrives with the right amount of moisture when we look for signs of moisture, rot and decay caused by mold growth won’t be far away which means, mold is nothing more than a helpful indicator of a moisture issue that needs to be fixed.

I can already tell that I’ve made some divisive statements and that we have a lot to unpack, but I think I got this. First and foremost, I want to say that indoor air quality is very important which is why we made a video about ERV’s. Secondly, mold is real, the ability of a laboratory to identify unique species of mold is real, the need to identify the presence of mold in an industrial setting can be mission critical, but the efficacy of testing a non-sterile environment such as a home in the way that homes are currently tested is unproductive at best. That wraps up the TLDR, so let’s dive right in.

How to Identify the Presence of Mold

There are three main ways to inspect for mold. Physical Cues, Air Samples, and Swab Samples.

Inspecting for Physical Cues may include the use of all your senses and the use of some modern technology. Using your sense of sight to identify signs of moisture could include locating a stain, physical damage, a wet spot, or an active leak. Using your sense of hearing to locate moisture could allow you locate an active drip leak or running water. Using your sense of smell to identify moisture could include walking into a room that smells musty or different from other rooms in the house. Using your sense of touch to identify moisture could include touching a damp surface, or just feeling the increased levels of humidity on your skin. Using tools such as infrared cameras and moisture meters can confirm the presence of moisture, but the most important tool of all is your brain. Being able to understand how a house works and how moisture issues can occur is the most valuable skill that a home inspector has.

What you might have noticed is that I did not say to use your senses and tools to identify mold, I said use your senses and tools to identify moisture. Without moisture mold will not grow and since mold is all around us both in our indoor and outdoor air, the real problem isn’t the presence of mold, but instead the growth of mold. Before we discuss Air Samples and Swab Samples, lets learn a little more about the role mold plays in our natural world and how its growth can damage our homes.

So Much Mold Everywhere

Mold is a fungus and a natural part of the environment. Mold can be found anywhere that moisture and oxygen are present and mold’s role in nature is to break down organic matter such as the materials we use to build our homes. Mold spreads by using reproductive cells called spores. Spores can stay dormant and alive for years after being produced until they happen to land on a surface where the conditions are just right for growth. Spores travel by floating through the air and they can range between 2-10 microns which can be filtered out of the air in your home by using an ERV, so make sure you watch our video about ERVs and HRVs to learn more. Filtering your home’s air to remove mold spores is important because mold spores can be allergens even when they are dead.

There are potentially millions of species of mold on this planet, but here is a short list of 115 species worth mentioning. The overwhelming majority of mold spores live in harmony with humans, but there are always a few bad actors that can on rare occasions trigger allergies or asthma. Mold can also be categorized by its color and there can be White Mold, Yellow Mold, Green Mold, Orange Mold, Brown Mold, Pink Mold, and the dreaded and much feared Black Mold. There is no single type of mold referred to as Black Mold, there are many, but when people say Black Mold they are normally talking about Stachybotrys chartarum.

Mold Species Worth Mentioning
Absidia	Bipolaris	Malbranchea	Poria Incrassata
Acremonium	Botrytis	Memnoniella	Rhizopus
Acremonium strictum	Cephalosporium	Microascus	Rhizopus microsporus
Aleuria aurantia	Cercospora	Microsporum	Rhizopus oligosporus
Alternaria	Chaetomium	Mucor	Rhizopus oryzae
Alternaria alternata	Chaetomium globosum	Mucor amphibiorum	Rhizopus stolonifer
Arthrinium	Chrysosporium	Mucor hiemalis	Rhodotorula
Ascospores	Cladosporium	Mucor mucedo	Scedosporium
Aspergillus	Cladosporium cladosporioides	Mucor racemosus	Schizophyllum commune
Aspergillus carbonarius	Cladosporium herbarum	Myxomycetes	Scopulariopsis
Aspergillus clavatus	Cladosporium sphaerospermum	Neurospora crassa	Scopulariopsis brevicaulis
Aspergillus flavus	Claviceps purpurea	Nigrospora	Serpula lacrymans
Aspergillus fumigatus	Coelomycetes	Oidium	Smuts
Aspergillus nidulans	Cryptococcus	Paecilomyces	Sporothrix
Aspergillus niger	Curvularia	Paecilomyces variotii	Sporothrix schenckii
Aspergillus ochraceus	Drechslera	Penicillium	Stachybotrys
Aspergillus oryzae	Epicoccum	Penicillium brevicompactum	Stachybotrys chartarum
Aspergillus penicillioides	Epicoccum nigrum	Penicillium camemberti	Stemphylium
Aspergillus restrictus	Epidermophyton	Penicillium chrysogenum	Torula
Aspergillus sclerotiorum	Eurotium	Penicillium corylophilum	Trichoderma
Aspergillus sydowii	Eurotium chevalieri	Penicillium crustosum	Trichoderma viride
Aspergillus terreus	Eurotium repens	Penicillium digitatum	Trichophyton
Aspergillus unguis	Exserohilum	Penicillium echinulatum	Trichosporon
Aspergillus ustus	Fuligo septica	Penicillium purpurogenum	Ulocladium
Aspergillus versicolor	Fusarium	Penicillium roqueforti	Verticillium
Aureobasidium	Ganoderma	Periconia	Wallemia
Aureobasidium pullulans	Geotrichum	Peziza	Wallemia
Basidiospores	Graphium	Phoma	Wallemia sebi
Beauveria	Helminthosporium	Pithomyces	Zygomycetes

Will Mold Make Me Sick

Mold is the big bad wolf to so many people who are buying homes, but if mold was such a big issue, why doesn’t the EPA have any standards for mold detection? A 2003 study titled Indoor Mold, Toxigenic Fungi, and Stachybotrys Chartarum: Infectious Disease Perspective acknowledged that there are many papers suggesting a correlation between mold and human disease, but they all suffer from significant methodological flaws, making their findings inconclusive. As a result, there is no well-substantiated supportive evidence of serious illness due to mold exposure.

To put things more bluntly into perspective, a 2017 study titled Mold and Human Health: A Reality Check stated, and I quote; “previous reports of “toxic mold syndrome” or “toxic black mold” have been shown to be no more than media hype and mass hysteria, partly stemming from the misinterpreted concept of the “sick building syndrome.” There is no scientific evidence that exposure to visible black mold in apartments and buildings can lead to the vague and subjective symptoms of memory loss, inability to focus, fatigue, and headaches that were reported by people who erroneously believed that they were suffering from “mycotoxicosis.” Similarly, a causal relationship between cases of infant pulmonary hemorrhage and exposure to “black mold” has never been proven. Finally, there is no evidence of a link between autoimmune disease and mold exposure” end quote.

Basically, the real risk of mold in the home is not a risk to the occupants but a risk to the homes building materials and structure.

What Is A Conflict Of Interest When Testing For Mold

When a mold inspection company is also the mold remediation company the mold inspector is incentivized to find a mold issue so they can charge for mold remediation. This is called a conflict of interest. Let’s say hypothetically that we identified a small mold issue during one of our inspections, and 3 weeks ago a local mold inspection and remediation company took and processed an “onsite air sample” to detect mold and told our client that the small isolated patch of “toxic black mold” in her ventilated attic space caused by seasonal condensation was so severe that if she wanted to keep herself and her family safe, she would need to pack whatever she can as quickly as she can, leave the house immediately, get a hotel for the next 3 days, and oh yeah… don’t forget, pay $12,000 to the mold inspection and remediation company that uses fear to make money.

Let’s also say hypothetically that she called around and found a company that took great care of her for a quarter of the price that wasn’t concerned about the mold at all because they know about the lack of health risks posed by mold.

I am not saying that all conflicts of interest are a bad thing, sometimes it is an unavoidable fact of life, but it is very important to arm yourself with knowledge before making a decision spurred on by emotion. Some mold inspectors use tools like infrared cameras, moisture meters, and humidity detectors to manipulate the emotions of a person who is already in a vulnerable position, but thankfully there are also those who use their tools and knowledge to educate their customers.

Foundations Needed to Talk About Air Sample Testing

On that topic of education, I think it is finally time to lay the foundation we need to start talking about air sampling to detect mold.

Tight Houses

Some houses allow more air to pass through them than other houses and this can be measured using a blower door to test the air tightness of a house. The average American home has a blower door score of 7 ACH50 which means 7 air exchanges with the outdoor air every hour at 50 pascals. Houses that meet or exceed the Passive House standard must have a blower door score at or below 0.6 ACH50 or 0.6 air exchanges with the outdoor air every hour at 50 pascals.

Mechanical Ventilation

Modern tight houses have Energy Recovery Ventilators or ERVs that can filter particles much smaller than mold spores out of the air. These ERVs will exchange the indoor air with fresh filtered air no less than 8.5 times per day if not significantly more times than that. This can effectively filter out all airborne particulate in the home.

Movement of Air

Particles in air don’t always move the way you would expect. If you place a helium balloon in your car the balloon will move to the front of the car as you accelerate and move to the rear of the car as you brake which is opposite of how anything heavier than air would act. What this means is that the forces acting on particles suspended in the air such as mold spores will affect the movement of these particles through the air in ways that would be challenging for even a supercomputer to process.

Sample Type

There are two types of air sampling methods that are commonly used. One is called Culturable Sampling which pumps a known volume of air onto petri dish covered with a nutrient media. The petri dish will then be transported to a laboratory and incubated to see if anything grows. This type of test only identifies living mold spores that are strong enough to survive and grow on the petri dish after the collection process, it does not detect non-viable mold spores which are just as capable of causing allergies. The most common sample type is Spore Trap Sampling which pumps a known volume of air onto a greased slide which will catch viable and non-viable spores, pollen, and other types of particulates.

Sample Size

These air samples on average pass 75 liters of air across the collection media. The size of an average American home is 2,400 sqft and contains approximately 550,000 liters of air. A mold air sample is calibrated to pump no more and no less than 75 liters which is the size of my wife’s camping backpack, and this makes it easy to understand the size of a sample vs the amount of air in a home.

Sample Location

Samples can be taken in wall cavities, small rooms, large rooms, or even outdoors. Air movement or the lack there of can affect the validity of a sample. In a wall cavity tightly packed insulation may not allow air to move freely which could result in a low detection result whereas an outdoor sample could draw from a breeze that moved mold a great distance and just so happened to be sucked into the sampler.

Reduced Sample Size in Practice

When a sampler is calibrated to draw 15 liters of air per minute to average 75 liters of air passed through the device during a 5-minute test, what this equates to in the laboratory is that a plastic bag filled with 75 liters of air can be emptied in 5 minutes. In the real world many of these devices are operated with less than 6 inches of space between the inlet and outlet of the sampler. Vortices around the device are created that interact with the suspended mold spores in ways that we are challenged to understand, but in practice the sample area is significantly smaller than my wife’s 75 liter camping backpack.

Identification of Mold Spores

Some air and swab samples can be processed by laboratories to do more than just identify the number of spores and species trapped in a sample. Some laboratories can identify enzymes, cell wall components, and even sequence the DNA of the mold found in your home. This is all very exciting and fascinating science for clean rooms and forensic investigators, but for a living breathing home with pets, children, and dirty clothes, it might just be best to take a quote directly from the EPA; “Sampling is unnecessary.”  

Air Sample Testing for Mold

Now that we have a solid foundation, we are finally ready to discuss air sampling to detect mold. Let’s say we are going to sample two houses and each house will have 3 samples take or 225 liters of air passed through a detection media. House Mold has a severe mold problem in the corner of a large room and House No-Mold does not have a mold problem. House Mold is a tight house with an amazing ERV ventilation system that filters no less than 4,675,000 liters of air per day which is 8.5 filtered air exchanges per day that are capable of filtering out 99% of every mold spore that passes through the filter each time the air passes through the filter. We might as well say the filter has a 100% mold spore capture rate. Because of the number of filtered air exchanges taking place in House Mold our 3 samples will represent approximately 0.000048% of the house’s air. To help you understand how insignificant that number is; imagine that you hurt yourself and had to go to the doctor. I am 5’10” tall and if a doctor looked me up and down to see where I hurt myself this would be the equivalent of the doctor only looking at a human hair’s thickness of my body and then telling me my diagnosis. In this example the lack of mold found in the air samples would result in House Mold being given a clean bill of health even though the house had an active moisture issue and was being eaten alive by mold.

Conversely, House No-Mold is not a tight house, and it doesn’t have an ERV to filter the air. Two days before the air sample was taken a heavy rain saturated the ground and as the naturally occurring mold continued to eat leaves, grass clippings, and other organic matter as it also started to release millions of spores into the air. These spores entered the home because the house is not a tight home and every time a bathroom fan, kitchen hood vent, gas water heater, or clothes dryer exhausted air, new air from the outside had to make up for the air that was exhausted effectively filling House No-Mold with mold spores and allergens. The sun came out and dried up all the rain and on the day of the air sample the outside mold spore levels, which is used as a control value, were very low and the indoor mold spore levels were very high. This resulted in House No-Mold being torn apart, poked, and prodded at great expense to look for the mold issue that never existed.

This is just one example of the infinite ways in which testing a house for mold using an air sample can be misinterpreted. The main reason you can’t check if a building complies with federal mold standards is because there are no mold or mold spore limits set by the Environmental Protection Agency or any other federal agency, and if you do find visible mold growth the EPA states that sampling the mold is unnecessary, and that remediation would be the next best step.

Air Sampling for Mold vs Air Sampling for Radon

Now before anyone calls into question sampling the indoor air of a house for radon, lets quickly explain the difference. First the EPA and the World Health Organization have strict radon action levels set to protect homeowners from radon whereas federal guidelines for mold or mold spore limits do not exist. Secondly mold spores are released from a localized source such as under a dripping sink where concentrations of mold spores will change as you move closer or further away from the source, whereas radon is being uniformly released from under the earth’s surface and into your home passing through any material with ease since radon is more than 350 times smaller than a mold spore thus making the passive detection of radon in the home possible without requiring any air exchanges to detect radon.

Should I Get A Mold Inspection

If you’re still debating whether you should get a mold inspection, I want to make it clear that if you want a mold inspection you should get a mold inspection. However, my belief and the reason why Two Moose Home Inspections doesn’t offer mold inspections is because I don’t see the value, but again, if you want a mold inspection then you should get one.

At Two Moose Home Inspections we don’t inspect for mold, but we do inspect for moisture. We use our knowledge of building science, our senses, our infrared cameras, and our moisture meters to detect sources of moisture, and if we happen to come across something that looks like mold, we will take a picture and note it in the report. The EPA states that sampling the mold to identify the type of mold is unnecessary since stopping the source of moisture and cleaning up the mold are the next steps. Without moisture mold can’t grow, and that is why we look for moisture.

Even when there are no signs of moisture it’s almost a guarantee that water vapor trapped between two layers of drywall or trapped behind a vapor barrier will have not only resulted in benign mold growth but also gone completely unnoticed until the building materials are removed and replaced which normally happens during a remodel. The term “Mold Inspection” can be so misleading to the consumer because mold exists everywhere in our world, and there is no way to guarantee that a small colony of mold isn’t growing in between the concrete basement foundation wall and the finished basement drywall, because there is always a chance mold could be hiding.

Mold Remediation

If mold is found in your house, it is important to determine if there is an active moisture issue. If there is an active moisture issue, then the first step is to stop the source of the moisture. Once the moisture has been stopped the area should be allowed to dry and then the area should be cleaned.

Most houses have mold issues that are visible to the homeowner such as mold on the shower curtain, shower tile grout, or on the ceiling above the shower. These are all indications of poor ventilation and moisture evacuation. These mold issues are even classified as “black mold” because of their color, but homeowners rarely seem concerned about mold in this part of their home. When it comes to the need for mold remediation, it almost seems like a personal preference.

But when you do choose to remove mold, it is highly recommended that a mold remediation company is hired to remove any visible mold since they can use the proper cleaners, but remediation is pointless unless you stop the moisture. Many homeowners mistakenly think bleach is a good way to remove mold, but bleach is 90% water and when the bleach is used on porous surfaces, the chlorine content of the bleach dries up immediately leaving behind water that can help the mold grow and spread even more.

Goldilocks Zone for Mold Growth

You might remember the story of Goldilocks and The Three Bears. Goldilocks was an uninvited interloper much like mold, she ate the bear’s porridges, sat in the bear’s chairs, and slept in the bear’s beds. To grow big and strong mold needs an amount of moisture that is just right, not too much and not too little. This is called the Goldilocks Zone and it might only exist for mold during certain times of the year or at certain distances away from an active water source.

One of the most common places that we see mold in our area is on the north facing side of an attic. This happens because the roof on the south facing side of the attic is being heated by direct sunlight during the day, and the roof on the north facing side of the attic gets no direct sunlight and normally has a huge pile of freezing cold snow resting on top of it. As the attic heats up during the day condensation forms on the cold surface similarly to how condensation forms on the side of an ice cold beverage on a hot day. When this happens, mold begins to grow on that side of the attic. The two cures for this type of an issue are to first increase the attic’s ventilation to help keep the attic cooler thus lowing the dew point or secondly removing the snow from the north facing roof to allow all the surface temperatures in the attic to equalize more evenly.

During the spring runoff season all the snow on the ground begins to melt and saturates the soils around the house. Houses that would normally have a dry crawlspace may have a damp or even wet crawlspaces during the spring and it is possible this elevation in crawlspace humidity may be enough to cause mold growth. Ideally the drainage around the house would be robust enough to handle any influx of soil saturation, but if not, proper ventilation, dehumidification, or the use of a sump pump may be necessary to properly control moisture in the crawlspace.  

Conclusion

In a perfect world, mold should never be allowed to grow in your home, but since mold is already hidden in every nook and cranny of your house since the day of its construction, it is important to understand that finding mold isn’t the end of the world, but instead mold is nothing more than a helpful indicator of a moisture issue that needs to be fixed. Mold testing and remediation has its place in this world, but never let someone scare you into buying any service for you home without first learning the facts and understanding the risks. If at the end of the day you decide that you want to use an air sample tester to arbitrarily measure the amount of mold in your home, just remember to take the results with a grain of salt and think rationally about their meaning.

I hope you learned something today, If you have any questions or if you would like to schedule a home inspection, please visit Two Moose Home Inspections .com, have a wonderful day.