Mycotoxin Testing for a Home: ERMI and HERTSMI-2
Mycotoxin testing for a home checks house dust and surfaces for mold, not your body. The common home versions are the ERMI and HERTSMI-2 dust tests, which score how moldy a building is. As a test-specific band, a HERTSMI-2 score under 11 usually reads as safe, 11 to 15 as borderline, and over 15 as a danger level for a sensitive home.
What mycotoxin testing tells you about a home
This page is about testing a building, not a person. If you have health concerns, talk to a physician. For a home, the goal is simple. You want to know if mold has grown from a moisture problem, and how much. Dust tests answer that better than most methods.
House dust settles over weeks. It traps a record of the mold that has been in the space. A lab reads that dust with DNA analysis and scores it. That is why a dust test gives a steadier read than an air grab, which only samples one moment. To see the wider set of options, read our .
ERMI vs HERTSMI-2 vs surface tests
Three home tests come up most often. They differ in how much they cover and what they cost. Here is the plain version.
| Test | What it checks | Sample | Best for |
|---|---|---|---|
| ERMI | 36 mold species by DNA, combined into one moldiness score | Settled house dust, mailed to a lab | The fullest whole-home read |
| HERTSMI-2 | Five water-damage molds, scored into safety bands | Settled house dust, mailed to a lab | A shorter, cheaper re-check |
| Surface swab or tape | The mold growing on one spot | A swab or tape lift you mail in | Confirming a single stain |
Prices and lab terms change, so check each listing. A dust test runs roughly $150 to $300, and a surface swab often costs less.
What the HERTSMI-2 score bands mean
HERTSMI-2 is a short dust test built from five common water-damage molds. The lab turns the result into a single number. These are test-specific bands for the building, not a health reading.
Under 11: usually read as safe. The home shows a low level of these water-damage molds.
11 to 15: borderline. This range calls for a closer look. You check for hidden moisture, run a visual scan, and often re-test after cleanup.
Over 15: a danger level for a sensitive home. It points to an active or recent water problem that needs a real cleanup, not just a wipe.
One caution applies to ERMI too. The single score can hide a high reading of one nasty mold. Always look at the species list, not just the total. For background on the dust method, see our black mold guide.
How to collect a dust sample
The sample makes or breaks the result. Follow the kit steps exactly. Most dust kits ask for dust that has settled for a week or more, so do not clean the area first.
You usually wipe a set area of floor or a high shelf with the supplied cloth. You seal it, fill in the room, and mail it back. Wear gloves and an N95 mask while you sample, since stirring dust can send spores into the air. A quick way to pick the right room is to scan for suspect spots first with our mold identification app.
What to do if the score is high
A high score means the home needs cleanup and a moisture fix, in that order. Find the water source first. A leak, a damp basement, or a wet HVAC coil will feed new mold no matter how well you scrub.
For small areas, clean hard surfaces with a mold-rated cleaner and let them dry fully. Wear an N95 mask, gloves, and eye protection while you work. Bag porous items that stayed wet, like soaked drywall or carpet, since those rarely come clean. For product picks, read our guide to . For a large or hidden problem, hire a remediation pro and re-test the dust after the work is done.
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Get Early AccessFrequently Asked Questions
What is mycotoxin testing for a home?
For a home, mycotoxin testing usually means a dust test that measures mold DNA in the house. The two common versions are the ERMI test and the HERTSMI-2 test. You collect settled dust, mail it to a lab, and get a score that reflects how moldy the home is. These are environmental tests about the building, not tests of a person.
What is an ERMI test?
ERMI stands for the Environmental Relative Moldiness Index. It is a dust test that uses DNA analysis to detect 36 mold species in a home. The lab combines the results into a single moldiness score. It was first built as a research tool, so the number needs context, and the individual species matter as much as the total.
What do the HERTSMI-2 scores mean?
HERTSMI-2 is a shorter dust test that looks at five water-damage molds. As a test-specific band, a score under 11 is usually read as safe, 11 to 15 as borderline that needs more checking, and over 15 as a danger level for a sensitive home. The bands describe the building, not any person's health.
Is a mycotoxin test for a home the same as an air test?
No. A dust test collects settled dust that builds up over weeks, so it captures a steadier picture. An air test grabs whatever floats past during a short window, and heavy spores that fall to the floor can be missed. Many people run a dust test for the whole-home read and use a surface swab to check one specific spot.