Beware, The EPA Scale ERMI To Assess A Home For Mold Is Misleading!

How is the ERMI test from Envirobiomics a reliable solution for assessing mold in homes? Get accurate results with ERMI mold test kits with the experts at Sandium now!

Updated on Oct 23, 2023
5 min read
Beware, The EPA Scale ERMI To Assess A Home For Mold Is Misleading!

Don’t ever think that all research is for the advancement of science. Some research actually impedes progress and makes us go backward. Have you heard about the latest breakthrough on testing a home for mold with a single dust sample? It is based on DNA analysis of the concentrations of 36 species of mold. Sounds very scientific indeed. But is this test practical to test a home for mold? We say it is not.

As a result of a research project, EPA researchers devised a scale to assess a home for mold, called ERMI ©, for EPA Relative Moldiness Index. Then, the EPA patented their so-called “new technology,” and now the dust sample test along with the ERMI scale is touted as “the standard” for the field of mold testing.

Some background – The EPA Office of Research and Development (ORD), together with the Case Western Reserve University Medical School, conducted a five-year study in the Cleveland area on the effect of mold exposure on children. Their results show that the incidence of asthma in children in mold-remediated homes was extremely low compared to their previous “moldy” home environment. Wow! What a revelation, it took five years to find that out. They should simply have asked us (or you) and we could have told them and spared the taxpayers the cost of such a useless study. No real harm done here, except for 5 million dollars down the drain. Mind you, we are not disputing the obvious results. What is more alarming is that the test they developed for that particular study is now being touted as the latest breakthrough in testing homes for mold. Now, that is damaging! As seasoned mold inspectors we feel that this is going to hinder the progress in accurate assessing a home or building for mold.

Research biologist, Stephen Vesper from the US EPA / Office of Research and Development (ORD) / National Exposure Research Laboratory (NERL), recaps two studies as follows:
Susceptibility to Asthma Controlled by Modifying the Environment
In a just-completed, five-year study in Cleveland-area, water-damaged homes of asthmatics, EPA Office of Research and Development (ORD) researchers, in collaboration with Case Western Reserve University Medical School, established that specific molds were statistically more common in water-damaged homes. When the molds were removed from these homes, the children had a significant decrease in asthma symptoms and symptom days. The result was a statistically significant tenfold reduction in the use of medical interventions (ie, emergency room visits or hospital admissions) for children living in these homes.
In a just-completed study in Cincinnati, the relationship between mold concentrations and the development of wheeze and / or rhinitis in infants was tested. To measure exposure risk, EPA scientists developed the EPA relative moldiness index © or ERMI © based on the measurement of the concentration of 36 species of molds in floor dust samples by using EPA’s patented “Mold Technology.” The ERMI © values ​​were used to accurately predict the risk for infants developing respiratory illness.
By applying these findings and techniques, we should be able to reduce the asthma burden in the US, reduce the use of medical care, and save lives.

We will spare you the details, but in a nutshell here is how this new patented ERMI © testing works:
A mold inspector collects a dust sample using a cone-shaped HEPA filter trap by vacuuming a specific area of ​​a carpet (or tile or linoleum) in the living room and the main bedroom and the sample is sent to a lab for analysis. You can either combine the two locations or take separate samples, which doubles the cost of the analysis.

We recently had a telephone conversation with Dr. Vesper where he stated that all homes in the US have mold! We say he is mistaken. Unless there is a water or moisture problem causing mold to grow, mold does not grow inside a home, because it simply cannot grow without moisture! Dr. Vesper does not like to say that a home has a mold problem; he prefers to call it “mold burden” and that the range goes from low to high.

The sample is analyzed and the results compared to a national database of homes in the United States and an ERMI © score is derived. For example:

  • An ERMI © score of – 4 means that a given home (client) is in the 25% of homes in the US that have a “low mold burden”.
  • An ERMI © score of 0 means that a given home (client) has an “average mold burden”.
  • An ERMI © score of 5 or higher means that a given home (client) has a “high mold burden”.

So, let us say you plan to buy a two-story home where there is carpet upstairs in the bedrooms, and all rooms downstairs are tiled – living room, dining room and kitchen. A dust sample is collected upstairs in the master bedroom and the tiles in the living room are vacuumed. Results show an ERMI © score of “0”. So, we tell you that a score of “0” is average, and according to the EPA it’s an “average mold burden.” Will you be satisfied with that? Read on.

Although the results of the first project seemed clear (if you remove mold the wheezing symptoms go away) we question the validity of the dust test and the ERMI © scale. Let us look at the second project: “Relative Moldiness Index as Predictor of Childhood Respiratory Illness”. We find several flaws in that study.

If you were satisfied earlier knowing that your ERMI © score was average, that study reveals that a score of -4.29, yes “-4.29” can predict the incidence of illness. Holy smoke !! Americans are doomed if more than 75% of our homes have enough of a “mold burden” to make us sick! And, if this is true, what is the point of doing any testing at all?


Improper sample selection of “moldy” and “non-moldy” homes
First, the homes were classified as either “moldy” or “non-moldy” based on the following criteria. The paper states:

“A” moldy home “(MH) had at least one of the following: water damage history, visible mold / water damage, or moldy odor. A” non-moldy “home (NMH) had none of these.”

Any experienced mold inspector knows that a visual home inspection is not enough to assess a home for mold, and we cannot rely on our nose to establish whether a mold problem is present. We must also collect air samples. By taking several air samples we can find out 1) how many spores are in the air in a particular room and 2) the species (genera) that are present and their respective amounts of spores. That tells us right away whether there is a mold problem and where.

We certainly cannot rely on a “nose test” because an air test may indicate a mold problem even though neither the occupants nor us could detect a “moldy odor”. Alternatively, on several occasions we have been called to homes because the occupants smelled an odor that they attributed to mold. Our tests revealed normal levels of mold spores, but volatile organic compounds (VOCs) found in new building materials, such as cabinetry or carpet were the culprits, and produced the odor.

We conclude that the samples in that study were improperly selected. Assessing the air quality with air tests would have established scientifically beforehand whether homes had a mold problem or not. Also, the study does not say whether the visual inspections were conducted by “home inspectors” or “mold inspectors.” It only says that the onsite visits were performed by a “trained two-person teams.”


If Plan A does not work, go to plan B

“The Wilcoxon test performed on the mold concentrations for homes grouped by the inspection process into NMH versus MH showed that no species was significantly different in concentration between these two groups of homes.”
.. homes were reclassified into “more moldy homes” (MMHs) and “less moldy homes” (LMHs).

It is not proper to choose different groups half way through the study and massage the data with statistics to come up with something meaningful simply because the two original groups, non-moldy homes and moldy homes, did not work out.


The ERMI © scale seemed to have been derived solely with less moldy and more moldy homes.
Referring to the y-coordinate of ERMI © scale “Percent of Homes in the US”, are we to believe that the data representing homes in the US came only from “less moldy homes” and “more moldy homes”? If so, this scale is not representative of homes in the US and is flawed if the “no moldy homes” have been totally omitted.


Improper control of variables of homes with smokers and non-smokers. The researchers state:

“. major mold / water damage was observed through home inspection and survey in only 5% of the homes, yet 19.6% of the infants developed wheezing and 49% developed rhinitis at age one. Therefore, most cases of illness were not predictable.” on the basis of a home inspection. These predictions could have been complicated by other exposures, such as smokers living in the home. ”

Indeed, it has long been recognized that children are affected by cigarette smoke. This variable should have been taken into account by selecting only homes with non-smokers.

The researchers added:

“.. an immediate and obvious improvement to predicting risk of respiratory illness would be to include additional information to the RMI in the predictive model like smoking in the home, pets, dust mites, or other indicators that could be taken from the home survey . Adding these factors to the logistic model might improve the prediction of illness even more. ”

Why did they think of that prior to conducting this $ 5 million study?


The study was biased – The introduction of the research paper indicates that a parallel study of air tests was conducted but the body of the paper hardly mentioned the comparative results. It states:

“A parallel study did not find any associations between the total mold spores count and rhinitis or allergen sensitization. However several associations emerged when mold species were identified.” “However, the methods used in that study are very time consuming and not highly standardized.”

We certainly agree that individual species (or genus) (not the total spore count) should be taken into account as well as their individual amounts of spores and their ratios to be compared to levels found in an outside sample. In addition, the research paper fails to say that air tests are both qualifying (identification of genera) and quantifying (amount of spores).

Researchers made a biased judgment by saying that collecting air tests are “very time consuming and not highly standardized”. We disagree – air test results can be obtained immediately in a lab if you live near a laboratory or as little as one day if the samples are sent overnight to a laboratory. It takes a minimum of five to ten days to get the result from an ERMI © test dust sample. It certainly would have been nice if researchers could have also included the results of air samples as comparison. And, what do the researchers mean by ‘highly standardized? “They talk about standardization when their research is flawed!


Questionable molds found in both moldy and non-moldy homes
Table 1 found in “Relative Moldiness Index as Predictor of Childhood Respiratory Illness” shows Stachybotrys and Chaetomium mold to be present in both “Moldy homes” and “Non-moldy homes”.

We have recapped the information to show the average of mold concentrations for Stachybotrys and Chaetomium as follow:

Stachybotrys: Moldy homes: 3.3; Non-moldy homes 2.3

Chaetomium: Moldy homes: 2.9; Non-moldy homes 2.0

It is known that Stachybotrys mold grows in a wet environment and Chaetomium mold is grows on, among other things, drywall that is wet or has been wet! Both types of mold are often found together in a home with mold problem. How can the researchers explain this?

If we poked around further into the study we would, no doubt, find other flaws. The study does look impressive with all kinds of statistical analyzes, but if you read it carefully there are many holes. With statistics all kinds of things can be derived, but massaging the data is not proper. By removing the group of “Non-moldy homes” (NMHs) and then using two groups “More moldy homes” (MMHs) and “Less moldy homes” (LMHs), researchers found something to report. At a score of -4.29 they found a correlation between the incidence of illness in a home with (enough) mold between the “less moldy” and the “more moldy homes.” Give us a break !!! There is no doubt that this study will impress many people because it is based on DNA analysis and many people will accept it at face value and not read it carefully. With all its bells and whistles, we say that ERMI © dust sample testing is flawed.

Until a better tool comes along we will continue to use the traditional method of collecting air samples in different parts of the home with an outside control, and collecting surface samples if mold-like substance is visible. Air samples are not perfect, and things can always be improved but, in our opinion, they give us a better picture than one or two dust samples that are supposed to be representative of the entire home. ERMI © testing does not tell us precisely if and where a mold problem exists. Air tests can. If you had a score of 5 or 10 that would tell you that there is a serious mold problem somewhere (pardon me “high mold burden”). But, we would have to go back to the house and guess what. . . we would have to collect air samples to find the location of the problem. So, why not collect air samples in the first place? Besides, spore trap analysis is very fast, and you could get the same day results if you wanted to, while dust sample analysis takes five to 10 days. Clients do not have money to waste on some fancy DNA testing that does not tell them whether a mold problem exists in their house and if so, the location of mold contamination.

Researchers are in their ivory tower and do not have a clue of real situations or budgetary concerns of the average homeowner. Clients want to know three things from a mold inspector:

  1. Do I have a mold problem?
  2. If so where is it?
  3. How do I get rid of it ??

This ERMI © scale was designed for a specific study. In our opinion the application of the ERMI © test should not be extrapolated and touted as the “latest technology” to evaluate a home or building for mold, especially because the study was questionable in the first place. Several US laboratories now perform this analysis, and novice and unaware mold inspectors started performing the test for clients. ERMI © testing appears “scientific” because it involves DNA analysis, and thus it sounds impressive for the majority of people. It can identify the species of mold, such as “Aspergillus penicillioides” or “Cladosporium cladosporioides”, or “Cladosporium herbarum” while an air test identifies the genus “Penicillium / Aspergillus”, or “Cladosporium.” We say that knowing the genus of mold is usually sufficient to assess a home for mold, knowing the species does not really add anything to the testing.

The EPA would have you believe that all homes have a mold problem. A prominent laboratory (not the one we use) states the following in their ERMI © report:

“Mold accumulates in homes over time and can be found in carpet dust and other accumulation sites.”

This is misleading – mold does not accumulate in homes over time. This would mean that older homes have more mold than newer ones. This is not true. During the Florida hurricanes of 2004 we found that most of the mold problems came from homes less than 5 years old. We won’t go into detail here as why this was the case.

Mold is found everywhere on earth and the amount of mold spores fluctuates day by day according to the weather and geographical location. However, if a greater amount of mold spores is found inside a home and / or if the genera are different than the outside it means that a source of mold is growing inside.

It is worth repeating – mold is the result of a water or moisture problem. Mold grows when three things are present – a surface to grow on, organic food, and water. Water being the only thing we can control. Without a source of moisture mold cannot grow. Period!

Dr. Shoemaker, MD who treats patients who have been exposed to mold thinks highly of the ERMI © testing, but he warns: “No sampling can replace the skill of the experience mold inspector in investigating mold problems.” What Dr. Shoemaker does not know is that the best mold inspector could miss a mold problem by performing only a visual mold inspection. It is essential to collect air samples in different parts of a home. Then the laboratory results will tell us the amount of mold spores per cubic meter and the genera compared to spores found in an outside sample. With this information we get a picture of what is going on and where. Like air testing, the ERMI © test is a tool to detect a mold problem, but the dust test gives less practical information than the traditional air tests. The score representing the “mold burden” is too vague. If the ERMI © score is elevated, it does not tell the client the location of the problem. Consequently more testing would be required, specifically air tests in various rooms, which would increase the overall cost of testing for the client.

The subject of mold is not well understood and this is why we wrote a book on mold: MOLD MATTERS – Solutions and Prevention, to educate home and building owners about mold from A-to-Z and to teach mold prevention. Much research is needed especially on the effects of mold on health. Since mold affects people differently, there are many people who are not taken seriously when they complain of various symptoms after being exposed to a moldy environment. Research on the effect of mold on health is long overdue and more research should be done in this area.

If researchers come up with better testing that give us more information than air testing in terms of pin-pointing the location of a hidden mold problem (that wall, rather than the other three), and quick turn around analysis, we will jump on it . In the meantime, we feel that the so-called “new technology” of ERMI © testing makes us go backward. It gives us less practical information, it is too vague, and it ends up being more costly to homeowners than air tests. Finally, because the meaning of the ERMI © score is vague, it has the potential of implicating mold inspectors in lawsuits. When mold inspectors get sued because it is found later that a serious mold problem was developing at the time of ERMI © testing, researchers will be far away in their ivory towers and mold inspectors will be by themselves fighting lawsuits against them.

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