What an ERMI report measures
One ERMI score cannot show where mold came from, whether it is alive, what you breathed in, or why you feel unwell. Keep the full species report and the sampling method. Compare them with leaks, damp materials, musty smells, recent cleaning or building work, and an inspection.
Sample
The test reads settled dust
Dust can contain DNA from old or current mold, outdoor air, pets, building work, and rooms mixed into one sample. Cleaning also changes what the sample contains.
Panel
It measures 36 selected species
The method uses 26 Group 1 species associated with water-damaged homes and 10 Group 2 species commonly found indoors from outdoor sources.
Formula
Two totals become one score
The formula subtracts the Group 2 total from the Group 1 total. Different mixes of mold can give the same score.
Limit
DNA is not an exposure dose
The report does not show whether the mold is alive, actively growing, airborne, inhaled, or responsible for symptoms.
A low score can miss a room, hidden cavity, recent leak, or material that was not represented in the dust. A high score cannot prove current exposure, illness, or the need to leave. The building still needs moisture evidence and inspection.
Save this test
Save the report with the sample map
Keep the score, mold results, collection method, rooms, leaks, repairs, and inspection findings together.
If you repeat the test, name the question first and use the same lab, device, rooms, and collection method.
Who should avoid inspection or cleanup
ERMI measures dust from a building, not a person. The score has no special range for age, sex, or pregnancy. Age and health matter when choosing who can safely inspect or clean a damaged area.
Infants and children
Notice which rooms the child uses and when symptoms happen. A child's wheeze, asthma, allergy, tiredness, or trouble focusing needs its own medical review during the building check.
Teenagers and adults
The same dust score applies at every age. Notice where and when symptoms happen, because home, school, and work spaces may differ.
Women, pregnancy, and postpartum
There is no pregnancy ERMI cutoff. Use qualified help if cleanup could disturb a large area, sewage, or a heating and cooling system. Discuss health concerns before doing the work yourself.
Men
There is no male ERMI range. Keep the building findings and any medical review as separate records.
Older adults and people with health concerns
Lung disease, a weak immune system, mobility limits, or other health problems may make inspection and cleanup less safe. Ask a health professional before starting cleanup if you have health concerns.
How to collect a dust sample you can explain later
Decide what building question the sample should answer. If you already see mold, smell a lasting musty odor, or find an active leak, fix the moisture problem instead of waiting for an ERMI score.
Read the lab's instructions before you clean or collect dust. The original research method vacuumed 2 square meters in bedrooms and 2 square meters in living rooms. Results from cloths, wipes, vacuum bags, single rooms, and mixed rooms may not be comparable.
Write down each room and surface you sample. Also record the area or collection time, dust age, last cleaning, leaks, floods, building or HVAC work, open windows, pets, and moved furniture.
Use a device the lab accepts. Keep the sample dry and label it exactly. Keep each building's dust separate and skip sampling visible mold, unless the instructions say otherwise.
Name the place and question
Write down the building, room, and reason for testing, such as a leak, odor, symptoms in one place, a home purchase, or a check after repairs.
Map the sample
Record the rooms, surfaces, floor area, collection time, device, dust age, and recent cleaning. A mixed sample can hide which room added a high count.
Keep the full report
Save the score, Group 1 and Group 2 totals, all 36 mold results, units, detection limits, sampling method, lab, and report date.
Inspect moisture and damage
Look for leaks, stains, damp materials, condensation, musty smells, hidden wet spaces, and mold in the heating or cooling system. Get qualified help if the source is unclear or the job is large.
Act on the source, not the score
Stop the water, dry wet materials, and safely clean or remove damaged material. Base the work on the moisture and damage you find. The score alone isn't enough.
How to understand an ERMI score and species report
Start with how and where the dust was collected. Then read each mold result, the two group totals, and the final score. Compare the report with leaks, damp materials, musty smells, and an inspection.
Lower relative score
Lower position on the original US research scale
The dust ranked lower than more homes in the original group of 1,096 US homes. A lower rank does not show that every room is dry or free of hidden mold.
Unclear or method-mismatched result
Middle position or a score that conflicts with the building evidence
Check how and where the dust was collected. Review the mold counts, dust age, cleaning, outdoor air, leaks, smells, and inspection. ERMI has no proven medical borderline range.
Higher relative score
Above 5 was the highest quartile in the original 1,096-home US scale
The dust had more mold DNA than the lower three quarters of the original research homes. This rank is not a measure of your exposure or health.
Above 5 means the top research quarter, not unsafe
The original scale ranked dust from 1,096 US homes. Values above 5 fell in the highest quarter of that housing sample. The study did not create a health dose, a safe-home certificate, a CIRS cutoff, or a rule for moving back after remediation.
See research details
Keep the EPA status, formula, sampling method, geography, health research, and building action as separate questions.
An ERMI kit isn't EPA approved for deciding whether a home is safe, whether cleanup succeeded, or whether a person is ill.
Keep the two group sums and individual species counts. A single score can rise because Group 1 increased, Group 2 decreased, or both changed.
Use the number to describe relative mold DNA in that dust sample, not to diagnose illness, set a re-entry date, or decide that everyone must leave.
You can't compare scores without the device, rooms, sampled area or time, dust age, recent cleaning, and laboratory method.
Record country, climate, building type, season, and comparison population. The US quartiles aren't universal building or health standards.
A list of species or DNA fragments does not show whether those organisms were growing, active, airborne, or responsible for a person's symptoms.
What you can do about dampness and mold now
Focus on the building. Stop the water, dry wet materials, photograph the damage, and clean safely. Get qualified help when the source is hidden or the job is too large.
Act on visible water and mold now
Fix the leak or moisture source. EPA says wet materials often avoid mold if they dry within 24 to 48 hours. Do not wait for a test while water is still coming in.
Make a room-by-room moisture record
Photograph stains, condensation, warped material, leaks, musty areas, and humidity readings. Note dates, weather, plumbing events, roof or window problems, and whether symptoms change away from the space.
Clean within the job you can safely handle
EPA says the person living there can clean many areas under about 10 square feet if they follow its guidance. Get professional help for larger areas, major water damage, sewage, possible HVAC mold, or health concerns.
If you retest, repeat the method
Use the same lab, device, rooms, area or collection time, and dust-age rules. Save the repair and cleaning details so you can compare the two samples.
One ERMI or HERTSMI-2 score isn't enough for costly building or medical decisions. Find the moisture and damage before moving, discarding belongings, opening walls, fogging, using ozone or mold-killing chemicals, or starting treatment. Severe trouble breathing, chest pain, fainting, sudden confusion, or a serious allergic reaction needs urgent medical help.
What to save from an ERMI report
Keep these together
- Full ERMI score, Group 1 sum, Group 2 sum, every species result, units, detection limits, laboratory, and report date
- Collection device, rooms, surfaces, sampled area or time, dust age, last cleaning, and whether samples were pooled
- Leaks, flooding, odor, staining, condensation, humidity, renovation, HVAC, pets, open windows, and outdoor context
- Inspection findings, moisture readings, photographs, source location, damaged materials, and contractor scope
- Repairs, drying, cleanup, items removed, repeat method, repeat question, and symptom location or timing kept as a separate record
Question for the visit
“What moisture source or damaged material does the building evidence identify, and what decision would change because of this dust report?”
Sources for ERMI Mold Dust Test
Current July 2026 research-tool status and non-research validation limit.
Current public recommendation against ERMI use outside research.
Dust and DNA method, research-only status, and inspection priority.
No health-based indoor mold standards, sampling limits, visual and odor inspection, and remediation priorities.
Moisture control, 24 to 48 hour drying, prevention, and homeowner guidance.
Cleanup scale, HVAC, contaminated water, contractor, and health-concern boundaries.
Original 1,096-home US ERMI development, vacuum sampling, 36 species, and relative scale.
112-home repeatability, room correlation, time comparison, and vacuum-bag method differences.
144 Finnish homes, visible-mold association, moisture-damage mismatch, and geographic limits.
Moisture-driven fungal function and limits of species presence as a health indicator.
Current method history, formula, original scale, quartiles, and research applications.
Risk of public cleanup decisions based on a tool developed only for research.
See each claim's sources
limitation
EPA describes ERMI as a peer-reviewed research tool that has not been validated or recommended for non-research home use.procedure
The original ERMI study measured 36 mold species by quantitative PCR in standardized floor dust from 1,096 representative US homes.range
The original unitless US research scale ran from about -10 to 20, with values above 5 in the highest quartile; these are relative housing ranks, not health thresholds.interpretation
Room, time, dust, and collection method affect comparability, and vacuum-bag values can differ from standardized floor-dust values.limitation
The US index did not transfer perfectly to 144 Finnish homes, where species distributions differed and ERMI associated with some visible mold findings but not moisture damage.context
A 2024 experimental house-dust study found moisture influenced fungal gene expression more strongly than species presence and noted inconsistent health associations for species-based measurements.safety
EPA and NIOSH prioritize moisture correction, prompt drying, visual inspection, musty odor, and qualified remediation over routine mold sampling.