ERMI & Mycotoxin Testing
These are the most requested—and most misunderstood—tools in environmental diagnostics. We offer both. That's exactly why you deserve a straight answer about what they measure, what they can't tell you, and when they're worth doing.
What ERMI Actually Is
ERMI—the Environmental Relative Moldiness Index—is a DNA-based analysis of settled house dust. Using a method called mold-specific quantitative PCR (MSQPCR), the laboratory quantifies 36 mold species in a dust sample: 26 species associated with water-damaged buildings and 10 common outdoor-derived types. The relationship between the two groups produces a single index score.
ERMI was developed by the U.S. EPA as a research tool for large population studies, and EPA's position remains that it is not validated for routine clearance or pass/fail evaluation of individual homes. That caveat is printed on responsible lab reports, and we say it plainly rather than burying it: an ERMI score is evidence, not a verdict.
Why use it at all, then? Because dust is a historical record. Air sampling captures a snapshot of what's airborne during one visit; dust accumulates what has been in the environment over months. For sensitized occupants, intermittent problems, or homes with suspected past contamination, that longer memory—especially the species-level detail beneath the score—can be genuinely informative when read by someone who understands its limits.
Snapshot vs. archive
When ERMI Helps—and When It Misleads
Appropriate Uses
- As a screening layer when occupants are highly sensitive and a broader picture of historical mold burden is wanted
- When intermittent or past contamination is suspected that a same-day air sample might miss
- To complement—never replace—on-site inspection, moisture mapping, and targeted air or cavity sampling
- When a physician managing a patient's care has requested environmental context on the home
- For before-and-after comparison in homes undergoing major remediation, interpreted with appropriate caution
Misuses We Caution Against
- As a stand-alone pass/fail verdict on whether a home is "safe"
- As a substitute for finding the moisture source—an index score locates nothing
- As a real-time measure of what you're breathing today (dust reflects accumulation over months or years)
- As a reason for panic or drastic decisions without a building investigation to confirm and locate an actual source
Mycotoxin Testing: Environmental vs. Clinical
Mycotoxins are chemical byproducts that certain molds—including Stachybotrys, some Aspergillus species, and Chaetomium—can produce under particular growth conditions. They are not alive, they are not spores, and they can persist in dust and on materials after the mold that produced them is dead. That persistence is why a building's history matters even after visible growth is removed.
Environmental mycotoxin testing analyzes dust or material samples for specific toxin families (trichothecenes, aflatoxins, ochratoxin, and others). It can add weight to an investigation when toxigenic species have been identified, when sensitized occupants aren't improving after standard remediation, or when documentation needs demand it. Like ERMI, it lacks established health-based thresholds—results support a picture; they don't settle it alone.
Clinical testing—urine or blood mycotoxin panels—is a medical matter between you and your physician, and we do not interpret it. What we provide is the other half of that conversation: objective documentation of whether your building contains the moisture conditions and fungal reservoirs that could plausibly explain an exposure.
Health decisions belong with your physician
How We Use These Tools Responsibly
Advanced testing is never our starting point—it's a layer we add when the question calls for it. Every ERMI or mycotoxin sample we collect sits on top of a full on-site investigation: moisture mapping, visual assessment, and targeted sampling. That's the difference between a number in a vacuum and evidence in context. If a test won't change the answer or the protocol, we'll tell you not to buy it.
See What Every Investigation IncludesFrequently Asked Questions
What is a "good" or "bad" ERMI score?
ERMI produces a numeric index from the difference between two groups of species: 26 associated with water-damaged buildings and 10 common outdoor types. Higher scores suggest a greater relative burden of water-damage-associated molds in the dust. But EPA has not validated any threshold as a health-based standard, and scores are sensitive to how and where dust was collected. We treat the score—and especially the individual species data behind it—as investigative context, not a grade.
What is HERTSMI-2?
HERTSMI-2 is a simplified scoring method derived from ERMI data, using five of the water-damage-associated species. It was popularized within the mold-illness clinical community as a screening tool for whether a building may be suitable for sensitized individuals. Like ERMI, it is not a validated regulatory standard—we can compute and interpret it from ERMI lab data for clients whose physicians work with it.
My doctor ordered a urine mycotoxin test. Does that tell us about my house?
Not directly. Clinical specimen testing is a medical question that belongs with your physician, and the relationship between urinary mycotoxin findings and a specific building is scientifically complex—diet and prior exposures can contribute. What we can do is the environmental half: determine whether your home actually has the moisture conditions and fungal reservoirs that could plausibly account for an exposure, and document it objectively.
If these tools have so many caveats, why offer them at all?
Because in the right hands and the right situations they add real information—historical burden, hidden reservoirs, species-level context that spore traps can't provide. The caveats are an argument against misusing them as verdicts, not against using them as evidence. Our value is knowing which tool answers which question, and being candid about what each result can and cannot support.
Wondering Whether Advanced Testing Fits Your Case?
Tell us what's happening in your home and we'll recommend the tools that actually answer your question—and skip the ones that don't.