Reviewed by the Nampa Mold Experts inspection teamUpdated How we write and check these pages
Short answer: ERMI measures DNA from 36 mold species in settled dust and produces a score; HERTSMI-2 uses five water-damage-associated species. They reflect longer-term buildup, not a single moment. They don't locate the moisture source, and they aren't a standard for judging whether a home is safe. We pair them with an inspection so the result leads somewhere.
What ERMI and HERTSMI-2 measure
- ERMI (Environmental Relative Moldiness Index) was developed by EPA researchers for research use. It compares 26 water-damage-associated species with 10 common outdoor species, using a lab method called quantitative PCR, and produces a single score.
- HERTSMI-2 uses five species strongly associated with water-damaged buildings and produces a simpler score. Some physicians use it to help judge whether a home is suitable for a sensitive patient.
Both rely on dust collected in a defined way, usually by vacuuming specific areas into a special filter cassette, or with a cloth swab of undisturbed surfaces.
What these tests can't do
- EPA has said ERMI was developed as a research tool and isn't validated for routine use by the public to judge a home.
- They don't tell you where the mold is or what's causing it.
- Dust can include old contamination from past problems that are already fixed, or spores carried in from elsewhere.
- Scores need context: the house, its history and what an inspection shows.
That's why we don't sell dust tests on their own. Booking ERMI Testing in Nampa, ID with us includes a moisture inspection, so a high score comes with a likely source and a plan.
When a dust test makes sense
- Your physician has requested an ERMI or HERTSMI-2 for a specific patient
- You're deciding whether a home is suitable for a mold-sensitive household member, with your doctor's guidance
- You want a longer-term picture alongside air samples
- After remediation, when your doctor wants to compare before and after
For most other questions, such as a musty smell, a home purchase or a leak, an inspection with air samples is more useful. See types of mold tests.
Cost of ERMI and HERTSMI-2 testing
ERMI testing with professional dust collection typically runs $300–$600; HERTSMI-2 typically runs $150–$300. Lab fees vary by lab and turnaround, and DNA analysis often takes longer than spore trap results. Adding a dust test to an inspection is common. Your exact price is confirmed before the visit. See price ranges.
For families with health concerns, see mold testing for families. Questions about dust testing for a specific patient are best discussed with the ordering physician.
ERMI Testing Nampa, ID: questions
Which is better, ERMI or HERTSMI-2?
Neither is better in general. Use whichever your physician requests. HERTSMI-2 is narrower and often cheaper; ERMI reports more species.
Can I collect the dust myself?
Mail-in kits exist. Professional collection follows a consistent method and comes with an inspection that explains the result. If your doctor is fine with a home kit, it can be a lower-cost option.
What ERMI score is bad?
Scores are interpreted on ranges from the research data, and physicians who use them often have their own thresholds. A score on its own doesn't tell you what to fix; the inspection does. Every ERMI Testing Nampa, ID report we write includes that context.
Is ERMI Testing in Nampa, ID required for my doctor's program?
Some physician-led programs ask for it. Bring their instructions when you book so we collect the sample the way they want.
