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Which is Better, the ERMI or the EMMA?

by Catherine

The Pros and Cons of Using ERMI and EMMA Tests to Assess Mold Exposure Risk Inside a Home

(Note: This article was originally posted on Sinusitis Wellness. I have added some additional content for this post.)

It is likely that you are reading this article because you are exploring options for testing for mold in your home or perhaps in a home that you are intending to purchase or rent. Maybe you are looking to test because you know that you are mold sensitive and want to be careful, or maybe you want to test because someone in the home is experiencing health symptoms, and you suspect mold to be the causative factor. Whatever the reason, I realize that making heads or tails of testing options that assess the potential health risk that a home may pose is difficult, to put it mildly. And, while no single testing method is perfect, and nothing beats professional, extensive visual and mechanical inspections, I am a fan of not guessing when it comes to mold and mycotoxins. Thus, in this article, I am going to attempt to simplify, explain, and compare two of the most popular, analysis-based testing options for mold, the Environmental Relative Moldiness Index (ERMI), and the Environmental Mold and Mycotoxin Assessment (EMMA).

Before I get into the details of the ERMI and the EMMA, I think it is important to lay out the basics of why these two tests have risen in popularity in mold-aware circles. The main reason, in my opinion, is that both tests are designed to assess mold exposure risk from a HUMAN HEALTH perspective. But why should we care about our indoor mold exposure levels in the first place?

All Homes Have Mold . . . Obviously

Yes. All homes have mold. Outdoor mold enters constantly, and we carry mold in on our clothing, shoes, bags, pets, and on and on. But when mold actively begins growing on building materials or belongings and alters the biome of an indoor environment, something very dangerous can happen: the fungal load of the home will continue to increases exponentially (which means mold exposure is also increasing) and mycotoxins can become present in the occupants’ breathing air and living spaces. The toxic potential of some molds and their ability to produce these mycotoxins is why I assert to anyone listening, that you need to be concerned about mold levels in your home. You also need to know whether or not the molds present in your home are pathogenic (capable of causing disease) or toxigenic, producing mycotoxins which may have many deleterious effects on the human body, including being known to cause some cancers.

What Are Mycotoxins?

Mycotoxins are well-documented for their toxic effects on the human cell. Mycotoxin exposure causes problems in normal cell function and is associated with a wide variety of clinical symptoms and diseases. The World Health Organization (WHO) 2011 publication entitled “Mycotoxins. Children’s Health and the Environment” defines mycotoxins as follows:

  • A toxin is a naturally produced poison.
  • A mycotoxin is a natural byproduct produced by fungi (mold) that evokes a toxic response when introduced in low concentrations to Vertebrates (humans), by a natural route—inhalation, ingestion, or skin contact/absorption.

Thus far, we know, based on scientific study, exposure to mycotoxins produced by the following molds can cause health symptoms:

The one thing I cannot fully discuss here, in terms of mycotoxins, is what level of mycotoxins is an acceptable level for your home. That is because there is no established acceptable level. Yes, you heard me correctly. Even though inhalational exposure to mycotoxins is known to cause illness, disease, and cancer, there are no established parameters for what “safe” exposure levels are or should be. That is why you need to be your own advocate and to be aware of any health symptoms that seem to occur because of exposure to your home or any other indoor environments. YOU are the only one who can safeguard and protect your health when it comes to mold.

Indoor Mold/Fungal Burden

Quantifying a home’s mold or fungal burden is important, because the higher the burden, the higher the need for extensive remediation beyond single-area containment and removal of the mold source. In other words, the indoor fungal burden determines whether the mold issue is a small leak and simple fix or is systemic and distributed throughout the home requiring extensive deep cleaning to properly remediate. To date, the testing methods commonly employed for mold burden determination are Spore Count analysis (in some shape or form—you can read my in-depth discussion of that type of testing HERE), the ERMI (Environmental Relative Moldiness Index), and the EMMA (Environmental Mold and Mycotoxin Assessment).

Spore Trap Testing Limitations

Spore counts are used to give an indication of the mold spore count inside the home compared to outside of the home. The reasoning goes that the comparison will show if the fungal burden inside the home is indicative of normal fungal ecology (in other words, just a microcosm of the mold in the air outside of the home) or is indicative of water damage and indoor contamination (the molds that are appearing are different and/or are present in higher numbers than what is present outside of the home). It is very obviously an imperfect method, as are all testing methods, and is subject to errors due to factors such as the wind outside, number of occupants inside the home, indoor air movement, and humidity levels, to name a few. And, while spore counts can give a good indication of problematic areas or rooms where the mold source might be for further investigation, when not done in a very targeted and precise manner by a knowledgeable professional, they have little meaning. Additionally, if the spore count does not also tell which molds are present and whether there are mycotoxins present, it is not really a good indicator of the “health hazard” of the home. Thus, you could spend thousands on it and really have no conclusive answers or a clear path as to how to properly remediate. Ugh.

An example of where spore count analysis falls short would be with the identification of aspergillus. Aspergillus is the most common indoor mold. Indoor Environmental Professionals report discovering Aspergillus/Penicillium-Like Mold in 90% of homes tested. As you saw in the chart above, Aspergillus/Penicillium-like molds make up 6 out of the 9 mycotoxin-producing molds. Common lab samples for spore trap testing don’t identify these spores to the individual genus. Thus, from a health standpoint, you really don’t know what you are dealing with. . . until, as I said before, you do more testing. That’s where the ERMI and EMMA can come in.

ERMI (Environmental Relative Moldiness Index)

In short, the ERMI was created by the U.S. Environmental Protection Agency, Office of Research and Development to assess the water damage history of a home by analyzing dust for the presence of 36 different mold species. DNA from mold in the dust is then analyzed using a mold-specific quantitative polymerase chain reaction (MSQPCR) that quantifies the mold spores present to the species level. Dust is used for the analysis, because dust build-up around a home, such as the dust that builds in carpets or on top of the refrigerator, can be the perfect reservoir for mold (both new and old) and can give a wonderful picture of the mold levels in that home over time. The dust specimen for an ERMI can be collected via vacuum canister or Swiffer cloth.

The 36 mold species included on the ERMI are divided into two groups: Group I consists of 26 mold species most-commonly found in water-damaged homes, and Group II consists of 10 mold species that are considered outdoor molds—which is not something I totally agree with but will discuss more later. The results are then compared to the ERMI, an index or scale, which was developed for use in the U.S. to estimate the relative moldiness of a home. By comparing the counts of the two groups, an ERMI score is then determined which can be low to high—from -10 to 20. There are a lot of variables, but, in short, an ERMI score of three or more can be too much for mold-sensitive individuals.

(Note: The Health Effects Roster of Type-Specific Formers of Mycotoxins and Inflammagens – 2nd Version or HERTSMI-2 is another test very similar to the ERMI but less expensive and only tests a dust sample for 5 molds deemed most likely to cause health issues. The HERTSMI-2 scale is as follows: less than 11 is safe, 11 to 15 is borderline, and above 15 is dangerous. The HERSTMI-2 can be calculated from both the ERMI and EMMA test results.)

Pros and Cons of the ERMI

(Note: This is all based on my opinion. I am NOT an Indoor Environmental Professional (IEP), so please defer to a trusted IEP before making any decisions on the safety or remediation needs of your home.) 


  • The MSQPCR technology precise, and if a mold species is present in the sample, it is found and identified.


  • People like the idea that one test can determine the “moldiness” of a home or building.


  • The EPA continues to develop the testing; thus, it should become even more useful over time.


  • Gives a good picture of the history of a home, in terms of water damage and mold issues, so it is a good tool when looking for a safe home to purchase or rent.


  • Can use it to calculate the HERSTMI-2, which was designed specifically for the health assessment of indoor environments.


  • Tests for 36 different types of mold.


  • Because it was developed by the EPA it holds importance in legal cases where mold exposure is on the table.


  • Some environmental professionals report finding little to no correlation between the ERMI results and actual mold found on site. In other words, it is showing both historical and current mold species. Thus, there could be some mold species present in the sample that may not be a current problem in the home.


  • The cost (several hundred dollars). If remediation is needed additional testing will need to be done to pinpoint the source and cause of the mold problem, so things get expensive quickly.


  • The sample collection method is inconsistent and poorly defined, making accuracy an issue. For example, it was developed by the EPA using the vacuum canister method, but most specimens are now are collected using the cloth method.


  • Dust is taken from multiple sites, so results tell nothing about mold source location or severity.


  • Results are based on a scoring system rather than a sample analysis. Sample analysis is really where the power of the ERMI lies. Thus, to get the most out of it, non-professionals will need to pay or hire a qualified IEP to interpret the results to truly diagnose a home. For example, when an ERMI score is low, but Stachybotrys is present. Stachybotrys produces highly toxic macrocyclic trichothecenes. Because of the low ERMI, the occupant could feel that the home is safe and continue to live there and get sick from the hazardous mycotoxins. Additionally, and this is where the Group I and II distinction comes in that I don’t totally agree with, there low ERMI scores where Mucor and Rhizopus are detected. While considered outdoor molds, if present indoors and stirred up, both can cause a serious illness in immunocompromised individuals.


  • ERMI does not test for the presence of mycotoxins. In scientific literature thus far, mycotoxins are the number one indicator of potential health hazards in the home. Mycotoxins are also what doctors are measuring in a patient’s urine or blood when testing for mold toxicity and mold illness. Without specific information about mycotoxins in the home, it may be hard to tie the patient’s illness to the indoor environment.

EMMA (Environmental Mold and Mycotoxin Assessment)

EMMA uses dust from the home’s furnace/air handler filter to detect the presence of 10 toxigenic or pathogenic mold spores and assesses the mycotoxin levels in that dust. RealTime Labs developed the test based on their knowledge of and years of experience testing for 15 of the mycotoxins known to be dangerous to human health AND known to be the toxic byproducts of molds commonly found in water-damaged homes.

Knowing if, to what extent, and to which specific mycotoxins the occupants are being exposed to can inform BOTH remediation and medical treatment. This is because exposure to mycotoxins is the most well-documented and studied piece of the mold/health puzzle (in both animals and humans) thus far, so, in my opinion, it only makes sense to test the environment for them. (RealTime also offers a mycotoxin ONLY test that is less expensive.) Thus, an EMMA test, at a cost like ERMI, gives an indication of the actual health hazard of the home better than other tests currently being used.

The EMMA uses a quantitative PCR (qPCR) procedure for the detection of ten known pathogenic fungal species in the dust specimens. EMMA includes six analyses that were designed and used by the EPA and four analyses that were previously developed by Real Time Labs for mycotoxin-specific testing. The qPCR method used detects fungal DNA to the species level. The data generated for each specimen is plotted against a standard curve to calculate the amount of fungal DNA present in the specimen (nanograms of DNA per milliliter of dust). Controls are included to verify that the DNA extraction procedure was successful and accurate. For the mycotoxin assessment portion, testing is done using competitive enzyme-linked immunosorbent assay (ELISA), a sensitive, specific method for detection, using antibodies prepared against the mycotoxins to indicate their presence in the sample. Each analysis is specific for the mycotoxin identified and does not cross-react with any other mycotoxins in the same sample. In other words, it will only identify mycotoxins that are present and will not yield a false-positive result.

EMMA is based on finding clinically significant links between the molds in the home and the mycotoxins present in both the home and the occupants, so it takes into account intricacies in reporting the data, like filamentous fungi (like Aspergillus sp. or Penicillium sp.), which are branching and difficult to conduct actual spore counts on. The EMMA shows results as DNA ng/ml of fluid, rather than spores/mg of dust or spores/ml of solution, like the ERMI. This allows for more precise reporting of how much fungal DNA is present in the sample. The reasoning goes, that once you know the detectable levels in your home and body, you can implement protocols to remove exposure and bring those levels down to where they are undetectable. Then, when you achieve test results that show undetectable mold and mycotoxin levels in the home (and the body, of course), you know that remediation or treatment has been successful. This way of designing environmental testing, in theory, should make it easier for the occupant to monitor the health of the home and to quickly identify when an issue occurs or to associate a spike in health symptoms with similar spikes in the fungal load of their home.

Pros and Cons of the EMMA

(Note: This is all based on my opinion. I am NOT an Indoor Environmental Professional (IEP), so please defer to a trusted IEP before making any decisions on the safety or remediation needs of your home.) 


  • Only environmental test that tests specifically for the presence of mycotoxins.


  • Developed for clinical significance. Molds are not included that do have clinical research or known health significance.


  • Well-defined sample size and testing parameters.


  • Answers the two most-critical questions when deciding on remediation: Are the organisms found in the home toxigenic and/or pathogenic? What, if any mycotoxins are being produced and are present in the home?


  • Easy-to-read results. Not based on a score. Any presence on the test is significant.


  • Can be used to complement and compare with mycotoxin urine testing. In other words, what you are doing to assess your body complements what you are doing to assess your home.


  • Shows the current fungal burden of the home.


  • Can be used to calculate the HERSTMI-2.


  • Tests for the presence of Candida Auris, an emerging multidrug-resistant yeast causing invasive health care associated infection with high mortality.


  • Not as well-known or utilized by IEPs as the ERMI.


  • Does not pinpoint the mold source.


  • Does not include as many molds as the ERMI.


  • Can be expensive.

So, Which is Better?

There is obviously more than one way to skin a cat or to test for mold, as it were, but gathering as much data as possible that has significance when it comes to your health is the name of the game. Mold often cannot be seen or smelled, so both the ERMI and EMMA can be used to find the problems that more traditional means of inspection can easily miss. And, despite what many people tell you, it is not always either/or, because if what you are after is the most data possible, so that you can fully remediate and make your home safe a combination of testing might actually be your best and wisest bet.

I love hearing from you. If you have questions or comments, please write to me below or email me at catherine@moldfreeliving.com.
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Janelle February 22, 2021 - 2:02 am

Hi Catherine,

Your blog is incredibly useful for my husband and me. THANK YOU for taking the time to put all this together. We “accidentally” stumbled up on the fact that we have mold present in our blood while doing a live blood cell analysis at our integrated medicine clinic. Also, found out I have EBV (often triggered by mold). After a lot of thinking back and investigating we realized it was from our water damaged apartment we lived in for 2 years, but moved out of last July. We are in the process of trying to get the mold out of our bodies. Also, currently waiting for mycotoxin UA results.

I have a question for you…we were not aware of this mold problem at the time we moved out and moved ALL of our stuff with us (possible cross-contamination). We don’t own many things, but as for our couch, wood dining table and ottoman, is there anyway to test JUST these items? I am specifically worried about the couch, it sat right under where the mold problem was. I’ve read about the EMMA and ERMI tests, but it sounds like they test the air circulating in the house, rather than a specific porous object, like a couch. Any suggestions?

Catherine February 26, 2021 - 2:28 am

You could do one of the Immunolytics tap tests on those items. One test per item. It would be the cheapest way to get an idea of potential contamination. You can also do tape lifts or source samples, but you would need a professional to do those. Additionally, are you reacting to those items? Your body will likely be the first to tell you if something is just not okay for you.

Janelle February 27, 2021 - 1:02 am

Thanks a ton, that is helpful. I went with the My Mold Detective to test the air for spores and just ordered Immunolytics kit as well so I can test some of my furniture.

I just got my mycotoxin UA results, I am off the charts for ochratoxin a. I feel like when I sit on the couch there isn’t anything extremely obvious, but maybe since my ochratoxin a count is already so high it might be hard to tell… two days ago I took a whole 24 hour period away from the couch, then sat on it yesterday for less than an hour and today noticed my left kidney feels funny. I do know ochratoxin a targets the kidney, but it’s hard to tell if the pain today is directly related to sitting on the couch yesterday.

I see the EMMA test includes ochratoxin a, but if I am worried about these specific mycotoxins being in/on our furniture from our last apartment (no way to confirm this though) do you think EMMA testing would still be useful? Do you know, if there were ochratoxin a mycotoxins in the couch, would they be in the air at this point and get picked up by this test? I noticed it says, “EMMA uses dust from the home’s furnace/air handler filter to detect the presence of 10 toxigenic or pathogenic mold spores and assesses the mycotoxin levels in that dust.” Our situation is unique in the sense that we are living in a mother-in-law basement/ apartment and my in-laws occupy the upper two stories. The whole three story house is about 5,000 sq ft (our basement area is roughly 1,200 sq ft and is pretty much closed off from the rest of the house, at least closed off from free flowing air from the upper two levels). Do you think if there was ochratoxin a present in our area it would get picked up in the home’s furnace/ air handler filter? The furnace is downstairs with us, in a closet with slatted doors, so I guess it probably would? Maybe I should of gone straight for the EMMA instead of My Mold Detective? I know you are not a professional mold tester, just curious to know if you have any thoughts on it.

Catherine March 10, 2021 - 5:41 am

I am not a fan of the My Mold Dectective– it is not powerful enough to give you an accurate read. It won’t give you any more info than the gravity plates from Immunolytics. The EMMA or the Environmental Mycotoxin test can both be used on household dust as well. You don’t have to use a filter. I think if you are going to do it on your own, you are wanting to know what the load is (aka how many colony forming units you have) in the air and on your things, and what your exposure risk is aka what are the mycotoxin levels. You could also do an ERMI instead–that will not tell you mycotoxins, but will tell you if you are being exposed to water-damage indicator molds which are toxin producing. I hope that makes sense. AT the end of the day, if the couch makes you feel unwell, I would get rid of it. It is not worth it to keep it if it negatively affects your health. My two cents.

Patricia Thames February 7, 2021 - 8:35 pm

I really need help I am close to death either by the mold or myself, I am so sick. Please if I could just talk to you, I live near the Atlanta area.

Catherine February 10, 2021 - 9:57 pm

Hi, Patricia, I am just a blogger–not a doctor or health practitioner. I really think you need to see someone trained to treat mold toxicity. Dr. Dennis is in the Atlanta area if your issues are sinus related. Dr. Susan Tanner also sees patients in her Atlanta office a few days per week–she is an environmental medical doctor. Dr. Ou is also in Atlanta and treats mold toxicity.


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