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Mold Dust Tests – ERMI Testing

by Amanda Demsky
ERMI mold dust test

Mold is a common health problem plaguing many homes across the globe, irrespective of financial status or location. A homeowner or renter who suspects mold can quickly become overwhelmed and stressed about where to start and what to do. So, what should you do when you think you have mold in your home? Mold is a serious issue, and safely detecting mold and the types of mold is often the first step in determining the best course of action. This is why it’s beneficial to use the Environmental Relative Moldiness Index (ERMI) method of testing mold.

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What is an ERMI test?

One of the easiest, least invasive, and relatively inexpensive ways to test for mold is through a test called Environmental Relative Moldiness Index (ERMI). This type of test samples the dust in your home for the presence of mold. This dust specimen is examined utilizing mold-specific quantitative polymerase chain reaction (MSQPCR), a method that evaluates mold species, and is then compared to a national database to reveal your home’s relative moldiness index (RMI).

What does that mean for those of us who don’t speak scientific snobberism? In short, this test uses the analysis of settled dust in homes and buildings to determine the concentrations of the DNA of the different species of molds that are present. The makers of the ERMI mold testing method have assembled a database of different molds–36 to be exact–that they refer to when defining and scoring a home or building’s mold population. The results are then compared to a thousand or more homes in the U.S. Environmental Protection Agency’s (EPA) national database, which allows current–and potential–home and business owners to evaluate the moldiness of their buildings in comparison to other similar structures throughout the United States. They also differentiate between which molds are caused by water damage (WDB) and which molds aren’t. This can be very helpful for homeowners because it takes out the guesswork and enables them to know what their next step should be in mold remediation. Unlike some mold kits and methods, the ERMI method identifies precisely what molds are in the building and measures their quantity with a purported 100% reliability.

How do you collect a mold sample for the ERMI?

Most mold testing kits are dependent on air samples. While this can be helpful in many cases, it is not the ideal method for obtaining samples. The ERMI, however, relies on the dust from carpets. Carpet dust acts as a reservoir for mold spores. There is no Hoover or Bissel on earth that can fully eliminate even a month’s-worth of embedded microscopic mold spores from carpet fibers, which is why carpet dust is a greater representation of mold levels over time versus short-term air samples.

Below are only brief, generalized instructions for carpet dust sampling. The EMLab P&K website explains their ERMI mold sampling method in greater detail, if needed.

  • Dust samples are collected by vacuuming approximately 2 square meters (or 21 square feet) in the living room and 2 square meters (or 21 square feet) in a bedroom for 5 minutes each with a Mitest™ or DustChek™ sampler-fitted vacuum directly adjacent to the sofa or bed, respectively.
  • Ship the dusted cassettes to the laboratory (EMSL Analytics, EMLab P&K, EnviroBiomics, Inc., Mycometrics) for overnight delivery. (If the samples are stored before analysis, precautions should be taken so additional mold growth in the sample is avoided.)

What is a safe ERMI score?

After receiving an ERMI test from a qualified mold inspector laboratory, it is time to evaluate the results. The ERMI Safe Life website explains the nuances of ERMI scoring most succinctly:

“The ERMI score is the difference between Group 1 (bad) and Group 2 (good) molds. ERMI scores range between -10 (really good) and +20 (really bad.) Most people with Chronic Inflammatory Response Syndrome (CIRS) cannot tolerate an ERMI score above +2 without becoming ill. However, there are many individuals who have been very ill and are extremely sensitive. They often need an ERMI score as low as -1 to continue recovery. You will need to listen to your body because an ERMI score that is safe for most people, may not be safe for you. You will need to learn what ERMI score is safe for you.”       

Note: A great suggestion is to share the documentation with a health provider to better understand one’s health issues in correlation with their home’s ERMI mold score. In nearly 100% of all cases, a doctor is unable to even diagnose mold sickness without a reliable mold test from a reliable mold-testing laboratory.

How much does an ERMI test cost?

In general, the ERMI test sampling kits, including the laboratory services, cost around $300 or less. (If additional parts are needed for dust collection, the DustChek™, for example, is an additional cost of $6.50.)

If a simpler collection method is preferred, Mycometrics ERMI mold test is the least complicated because it uses a Swiffer-type AccuCloth Kit for only $290. Mycometrics also offers an affordable HERTSMI test option for $155, using the same easy collection method.

As for the ease of finding an ERMI test Amazon might offer, the only one listed on the site is an ERMI mold test that is currently (as of 4/16/2019) unavailable. Pricing information is also not available on Amazon at this time, though it may be beneficial to check at a later date.


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The Environmental Relative Moldiness Index (ERMI) method of testing and indexing mold is quickly becoming the more superior method available on the common market. It’s built a groundbreaking reputation among mycologists, victims of mold, health providers, and even property owners over the years. Because ERMI’s automated analysis provides for rapid, reproducible results that can be accurately interpreted, patients, prospective home-buyers, industrial hygienists, and mold remediators have a lot to look forward to in the future. The promise shown in the level of ERMI test reliability is quite astounding.

If you have used an ERMI mold testing kit, please share your experience in the comments below. Your personal experience is highly valuable to other readers who are battling mold problems.

For more information regarding mold, mold prevention, and mold solutions, please check out the rest of MoldBlogger.com.

Article by Amanda Demsky from the Moldblogger team.

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Dee April 24, 2019 - 5:21 am

My partner &I moved into a unit in March of this year. I have truly been sick,nose bleeds,headaches,&crazy stress.I alerted the owner.Nothing has been done .I have did too successful test that both reveal black mold .If anyone could please tell me how to go about reporting this ,I truly would appreciate and advice .Thanks…Dee

will October 18, 2019 - 2:05 pm

Im feeling a lot of confusion around the amounts of ERMI tests and how much the prices differ. The lab fee at EMSL is only $165. https://www.moldtesting.com/ermi-mold-sampling Do you know why the lab fees vary so much? And why wouldn’t everyone get the cheapest one if they ERMI is all testing the same 36 spores?
Thanks so much for your input!!!

Kat May 5, 2020 - 6:06 am

I have mycotoxins in my system and need to avoid recontamination. I’m trying to figure out which test to do for mold testing of dust, especially in the basement. I contacted ERMI and was informed they no longer analyze the swifer. We had the air quality test which was normal (air samples inside the house were almost identical to the outside air). There is no water damage or visible mold in the house.

Any recommendations on which test to do and whether there’s any advantage to hiring a mold professional vs. taking the sample ourselves?

Kat May 5, 2020 - 6:07 am

EMSL no longer analyzes swifer test.

Gayle Halversen November 4, 2020 - 3:29 pm

Please tell me how to order an ERMI accudust kit. Thanks, I need one right away. Can you test multiple rooms with this test method? I need to test my bedroom, bathroom and kitchen.

Frederick B Coor December 29, 2020 - 12:54 pm

WHo can I call to talk to about my particular issues?

Frederick B Coor December 29, 2020 - 12:55 pm

Do you have a toll free number?

John McMillen April 29, 2021 - 9:53 am

I recently ran across a website that has a calculator and offers a bit of insight on your ERMI results and thought I’d pass it along: https://www.explainmyermi.com

Dan November 1, 2021 - 3:45 am

If you get your ERMI results back and need some help understanding what they mean, you might want to try “Explain my ERMI” https://explainmyermi.com It’s an online tool that gives you instant analysis of your ERMI results. It rates your results into one of 4 groups which gives you a general rating of how bad your ERMI score is. The actual report breaks down each of the molds into their colonizer group based on how much moisture is required for growth, and tells you exactly how elevated each mold is above the baseline ERMI index – which I found helpful to see how much each mold was actually elevated. They also have a list of mycotoxins for each of the molds and give you some ideas of where each of the molds might be found. Oh, and there’s a built in HERTSMI calculator too.


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