What The ERMI Test Really Means

The US Environmental Protection Authority developed ERMI to provide a straightforward, objective, sensitive and standardized way to assess mold and indoor air quality investigations.

Based on widely published data from EPA researchers and the 2006 HUD American Healthy Home Survey, the test has been developed as a tool to evaluate the potential risk of indoor mold growth and associated health effects to occupants.

In order to most effectively use this tool, the ERMI obtained needs to be compared to a national database. Indices were determined using this method for 1,096 homes across the U.S. as part of the 2006 HUD American Healthy Home Survey. Individual indices, ranked from lowest to highest were used to create a national Relative Moldiness Index (RMI) Scale.

In initial studies by the USEPA, the concentrations of different mold species in “moldy homes” (homes with visible mold growth or a history of water damage) and “reference homes” (homes with no visible mold) were compared. Based on those results, mold species were selected and grouped into those with higher concentrations in moldy homes (group 1) and those with lower concentrations (group 2). To calculate the ERMI the individual concentrations of the mold species detected are log-transformed and the sum of group 2 logs is subtracted from the sum of group 1 logs. Here is an example of an ERMI report from Envirobiomics Lab: 

To assist in the interpretation of the ERMI score this table can be used:

However, when looking at the ERMI lab results it is also important to look at the species detected. If counts are abnormally high, it may be assumed the building has a source of mold contamination.the potential to harm health. However, do not discount low counts either, the presence of certain mold species can indicate a problem as well as they may have the potential to produce mycotoxins.

See below the health risks associated with certain mycotoxins:

There are certain clinical labs you can use to see if the mycotoxins are being absorbed in your body. Different labs test for different mycotoxins and depending on the mold species you have, it’s important to know where to go next. Based on the  ‘ERMI Test’ table,’ we’ve simplified your lab search using your spore count results. Below are three labs, the mycotoxins they test for, and then matched to the ERMI test:

It is important to note that the ERMI sample does NOT indicate the source of the mold contamination in the building. Rather, it is used to understand if there is potential source areas that exist in the building. A further investigation and strategic testing will still need to be performed to identify the location of the mold problem. For more information about the ERMI sample or to book an appointment for a thorough inspection feel free to call us at any time!

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