Mold Testing Methods
ERMI and HERTSMI-2 are the two panels most often discussed in environmental medicine — here's what each actually measures.
ERMI
Developed by the EPA, ERMI (Environmental Relative Moldiness Index) compares levels of 36 mold species (26 associated with water damage, 10 more common/benign) using qPCR DNA analysis of a dust sample, producing a single index score.
HERTSMI-2
A simplified 5-species panel developed specifically as a faster, more clinically practical tool — commonly used to track whether a home's mold burden is improving, particularly after remediation.
Why we test on-site
Traditional ERMI/HERTSMI-2 testing means mailing a dust sample and waiting a week or more. We run the same underlying qPCR technology on-site with a portable device, giving you real, same-visit results — a real baseline before any changes, and fast re-testing after remediation or HVAC work to confirm it actually helped.
Frequently asked questions
ERMI (Environmental Relative Moldiness Index) scores 36 mold species and produces a research-grade moldiness index. HERTSMI-2 is a simplified 5-species panel developed to be a faster, more practical tool for tracking a home's mold burden over time — commonly used to decide if a home is ready to support CIRS recovery.
Both use qPCR (quantitative polymerase chain reaction) technology to identify mold species by DNA. The difference is turnaround: mail-in samples typically take a week or more, while on-site testing gives you results the same visit.
Yes — without a baseline, there's no way to know whether any changes (filtration upgrades, dehumidification, remediation) actually improved anything. Testing before and after is the only way to confirm real results.
Want to book an on-site assessment? See the full Mold & CIRS Support guide for what's included.
Why we standardized on qPCR for on-site work
After working across methods, we standardized on qPCR (quantitative polymerase chain reaction) for a practical reason: it delivers species-level identification with quantitative counts, which is the data format that actually drives decisions — and the format ERMI and HERTSMI-2 scoring descend from, so CIRS-literate physicians can use the results directly. Air sampling has its place but captures a moment; what's airborne during your sample window isn't the whole story of what's established in the building. Surface and dust-based qPCR reads the accumulated record. Same-visit results matter too: a household in the middle of health decisions shouldn't wait two weeks to learn whether the suspect room is the problem. We bring the method that answers the question being asked — which species, how much, and therefore what response — rather than the method that's merely easiest to sell.