Beware! The EPA mold scale ERMI© is misleading

Charles and Danielle Dobbs

EERMI testingRMI testing, developed by the EPA to test a home for mold is, in our opinion, totally meaningless, flawed, and impractical.  This post is actually a paper we published several years ago, and we thought the information would interest our readers.  The post is in two-parts.  The first part, Is ERMI Testing Reliable to Test a Home For Mold, explains how the ERMI test was developed.  In the second part, we point out the flaws of ERMI testing.

ERMI testing involves 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’s 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 accurately assessing a home or building for mold.

Research biologist, Stephen Vesper from the U.S. 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 (i.e., 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.

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.

EPA relative moldiness index

A few years ago, we 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.
As an 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 obvious (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” (see below) 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?

relative moldiness values

In Part 2, “Is ERMI Testing Reliable To Test A Home For Mold?“we point out six (6) flaws about ERMI testing and our reasons we believe this testing is meaningless, flawed, and impractical.

ABOUT THE AUTHORS: Charles and Danielle Dobbs are professional mold assessors, expert witnesses, authors of several books on mold.  Feel free to contact us for questions pertaining to this article.

Lin, K. T., Shoemaker, R.C. Inside Indoor Air Quality: Environmental Relative Moldiness Index (ERMI©). Filtration News May/June 2007: 32-36.

PRWEB. EPA Relative Mold Index (ERMI©) – A Powerful New Standardized Investigation Tool for Screening Homes for Mold Contamination. 2/2007.

Vesper. S.J., McKinstry C., Haughland R.A., Iossifova Y., Lemasters G., Levin L., Khurana Hershey, G.K., Villareal M., Bernstein D.L., Lockey J., Reponen T. Relative Moldiness Index as Predictor of Childhood Respiratory Illness.  Journal of Exposure Science and Environmental Epidemology 2007: 88-94.

Written by Charles & Danielle Dobbs – Professional mold assessors, expert witnesses, authors of several books on mold, and mold education bloggers

Charles & Danielle Dobbs - Professional mold assessors, expert witnesses, authors of several books on mold, and mold education bloggers