Guides · Updated September 21, 2026
The Short Answer
ERMI, the Environmental Relative Moldiness Index, analyzes settled household dust with a DNA-based method to estimate mold contamination. The EPA describes it as a research tool developed by EPA scientists, and states that it has been peer reviewed for research purposes but has not been validated for non-research purposes. Mold Shark runs ERMI or HERTSMI when a clinician asks for it or a home has a long history of water problems, and always alongside an inspection, never instead of one.
What ERMI Measures
An air sample is a snapshot of one moment. Dust accumulates over weeks and months, so it carries a longer history. ERMI and the shorter HERTSMI panel use qPCR, a DNA-based method, to detect mold species in a settled dust sample and combine the results into a score.
What The EPA Says
The EPA's own description is short. ERMI is a research tool developed by EPA scientists for estimating mold contamination. It has been peer reviewed for research purposes but has not been validated for non-research purposes.
In plain terms, the agency that created the index does not present it as a routine test for deciding whether a home has a mold problem.
Why People Still Order It
Most requests come from people working with a clinician who has asked for it as part of their own evaluation. Others have a home with years of water problems and want the longer view that dust provides. Those are reasonable uses, as long as the result is read for what it is.
Mold Shark collects the sample and the laboratory reports it. We do not interpret what a result means for anyone's health.
What A Score Cannot Tell You
A score does not say where the moisture is, which wall is wet or what has to be repaired. Two homes with the same score can have completely different problems. That is why a dust panel is ordered alongside a full inspection: the inspection finds the cause, and the panel adds history.
Questions To Ask Before Paying For One
Three questions settle whether it is worth ordering:
- 01Who asked for it, and what will they do with the result?
- 02Has the building been inspected for moisture, or would this be the only test?
- 03Would a different result change what you do next?
