Updated September 2026
ERMI mold testing in Newark, NJ collects settled dust from a room, usually by vacuuming a measured floor area or wiping a surface that has not been cleaned for months, and sends it to a lab for DNA analysis of 36 mold species. The result is a score, often reported with HERTSMI-2, that reflects the home's mold history rather than a single afternoon.
What ERMI measures and why it differs
ERMI stands for Environmental Relative Moldiness Index. It was developed as a research tool to compare homes by the mold DNA in their dust: species associated with water damage count against the score, and common outdoor species count in its favor.
That makes it useful for a history question, such as whether a house has had a mold problem over time, and less useful for finding where the mold is. For location, we use an inspection and moisture mapping.
Mail-in ERMI kits versus professional collection
Mail-in ERMI kits use the same lab method. The difference is in how carefully the dust is collected.
A mail-in kit works if
- You follow the collection area exactly
- The room has not been cleaned recently
- You only want the score
Professional collection adds
- Room choice based on an inspection
- A documented chain of custody
- An explanation tied to your house
What decides the cost of ERMI testing
ERMI pricing depends mostly on the lab fee, which varies by lab and turnaround. We quote the lab cost before collecting. These factors decide the total:
- Number of samplesEach room sampled is analyzed separately.
- Lab and turnaroundFaster results cost more.
- Score setERMI with HERTSMI-2 may be one report.
- Paired inspectionCollection during an inspection saves a visit.
- Access timingPre-move-in sampling needs coordination.
- Report detailExplanations for a doctor or landlord.
ERMI, HERTSMI-2 or air sampling?
Each test answers a different question.
| ERMI | HERTSMI-2 | Air sampling | |
|---|---|---|---|
| Sample | Settled dust | Same dust sample | Air, indoors and out |
| Shows | 36 species over time | 5 water-damage groups | Spores at one moment |
| Suits | Home history | Water-damage focus | Active sources, clearance |
| Finds location | No | No | Sometimes, by room |
Settled dust sampling
Dust is collected from a measured area of carpet with a vacuum and filter cassette, or wiped from a flat surface that has not been cleaned for some time, such as the top of a door frame or a high shelf. The collection area and method follow the lab's instructions exactly, because the score depends on it. We avoid rooms that were just cleaned or recently renovated, and we note the room, surface and conditions on the chain of custody form sent with the sample.
HERTSMI-2 scoring
HERTSMI-2 uses the same lab data as ERMI but scores only five mold groups most associated with water-damaged buildings. Many labs report both. The two scores can disagree, because ERMI subtracts the outdoor species while HERTSMI-2 ignores them. We walk you through both numbers and what they suggest about the house. Neither score tells you where the mold is, so a high result is followed by an inspection to find the source, not by guesswork or by tearing into walls at random.
ERMI versus air sampling
Air samples show spore levels in the air at one moment, compared with outdoors. ERMI shows which species have settled in the house over months. Air sampling is better for clearance after removal and for finding whether a hidden source is active now. ERMI is better for a long-term picture, such as when someone is sensitive and wants to know the history of a home before moving in. They answer different questions, and we recommend whichever one fits yours, or both when the question needs both.
How ERMI sampling works
Define the question
History of the house, or a specific room?
Pick the room
Usually a bedroom or main living area.
Check the surface
Not recently cleaned or vacuumed.
Collect dust
Measured area, lab method followed.
Chain of custody
Logged and sent to the lab.
Receive scores
ERMI and HERTSMI-2 when reported.
Explain results
What they suggest and what to do next.
Moving into a Newark rental
About 77 percent of Newark dwellings are rentals, so a lot of people moving here move into a unit someone else lived in. For a sensitive household choosing between Newark apartments, ERMI on settled dust can show whether a unit has had water damage mold over time, which a quick walkthrough cannot. We sample before move-in where the landlord allows access, since cleaning for a new tenant changes the dust.
ERMI questions
Lower scores mean fewer water-damage species relative to common ones. The lab report gives ranges, and we explain where yours falls.
No. It reflects the whole sample. An inspection finds the location.
It answers a different question: history rather than what is in the air right now.
No. Cleaning removes the dust that the test needs.
Air and surface clearance testing suits that better, because old dust may still carry DNA from before.