Should I Conduct ERMI Sampling?

Mar 16, 2022

There is a growing concern of mold affecting indoor air quality in properties. Many clients ask about the Environmental Relative Moldiness Index (ERMI) testing for their properties. Often, clients learn about ERMI through blogs or medical professionals which market it as a cutting edge mold sampling procedure to discover fungal contamination on properties. In this blog, we discuss the basics of ERMI and if it should be used to test mold on your property. What is ERMI and Its Benefits?

What is the ERMI?

The ERMI was a survey conducted by Environmental Protection Agency (EPA) scientists for estimating mold contamination. The initial survey was conducted at over 1,000 homes to evaluate mold concentrations by using dust sampling methods. The results were then correlated with 36 types of mold species. The initial survey created a level of ERMI score based on the results of mold species of each type.

How it’s done?

The method involves templating carpet flooring in one square meter in the living room and the bedroom of the property. After collection is complete, the sample was analyzed using PCR (polymerase chain reaction), a form of DNA testing.

What’s the benefit?

The benefit of ERMI vs traditional air sampling is it goes down to the species level while air sampling only goes down to the genus. This is beneficial as it may determine species present in the home which are mycotoxin producers. The other benefit is that ERMI can show historic mold events in the home by sampling dust over air.

Any downsides?

On the other hand, the EPA states that the ERMI should not be used in routine home inspections as it is not a validated test. Sampling in areas that were not included in the initial survey will also generate results that can’t be compared to the original survey.

The typical Indoor Science Approach to Mold Inspections

Mold inspections can range in complexity and size however there are a few essentials that should be performed during an assessment. First, we recommend conducting a moisture evaluation of the property. This can be accomplished by using thermal imaging in conjunction with a moisture meter. This allows the inspector to determine possible moisture sources that may be causing fungal growth or find areas of hidden dampness. The second phase of an assessment is sampling. This can be conducted by collecting air samples for mold. Air samples can show which types of mold are in the air and their concentrations. Another form of sampling that can be used during an assessment is surface sampling. This involves direct sampling of visible fungal growth to determine its type.


While EPA has not validated the ERMI method, we do offer it to clients who request as it may be useful to medical professionals. Please reach out to professional mold inspectors such as Indoor Science to determine the proper approach to evaluate your property.