The ERMI or Environmental Relative Moldiness Index is a DNA-based test used to identify mold species found in homes. Based on Mold Specific Quantitative Polymerase Chain Reaction or MSQPCR for short, we can now identify and quantify molds in a quick, accurate, and reproducible way. This PCR analysis enables the detection of non-viable mold as well as viable mold which is important since even non-viable mold can contribute to health problems. Traditional air sampling takes just a snapshot of the mold conditions found inside your home at any given moment and can be affected by many factors. The US Environmental Protection Agency in conjunction with the Department of Housing and Urban Development used this DNA-based test to conduct the American Healthy Homes Survey in 1096 homes across the United States. These results were then analyzed to develop the ERMI which describes the mold burden present in a home.

This test results in the identification of 36 different mold species which are divided into two categories. The first category or Group 1 is composed of 26 different mold species that are commonly found in water-damaged buildings. The second category or Group 2 is composed of 10 different mold species that are commonly found in all homes across the country and are not related to a history of water intrusion. After these two groups are calculated, Group 1 is then subtracted from Group 2 to give you your ERMI score. Ideally, the score should be less than 2. However, it is also important to look at the individual species of mold identified and their quantities when evaluating your test results.  The standard deviation is a maximum of +/-3. This value is then graphed from lowest to highest with the scale ranging from -10 up to 20. The graph is divided into quarters with each quarter increasing the chances that you have a mold problem. ERMI Figure 1-page-0If your score is -4 to -10 and you fall in the lowest quartile, you have the least likelihood of having a mold problem, whereas if your score is over 5 and you fall in the highest quartile, there is a high likelihood that you have a mold problem as this represents the greatest mold burden. This graph gives you the relative moldiness of your home compared to other homes across the US. The ERMI is not a health index but rather a mold index that is a helpful tool for you to identify whether your home, work, school, or other environment may be contributing to your illness.


Dr. Shoemaker has tried to correlate the ERMI test to its effects on health by way of his HERTSMI-2 score. Although he makes no guarantee as to whether or not you will be adversely affected based on this score, it might be another helpful tool for you to consider when evaluating your home, school, or work environment. He considers any score over 15 as too high to be safe, a score of 11-15 as borderline with the building needing to be treated, and a score of less than 11 as probably being safe. Please keep in mind that we are all individuals and some people will be more sensitive than others. To calculate your HERTSMI-2 score based on your ERMI test results, please see the example below.

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The ERMI can be done quickly and easily by taking a sample of dust from your home and sending it in to the lab. The test is easy enough for homeowners to do themselves without the need to hire a professional and costs less than $300. Complete instructions for performing the test are included with the test kit.  For further information regarding the ERMI or to order your test kit, please visit


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