ERMI Testing
ERMI Testing can help you understand the types and relative quantities of selected moulds found in settled dust within your property.
The Environmental Relative Mouldiness Index, or ERMI, is a DNA-based laboratory analysis. It examines dust collected from a home, workplace or commercial building.
The test looks for DNA from a defined group of mould species, then uses the results to calculate a relative mouldiness index.
At Air Quality Australia, we use ERMI Testing as part of a wider building investigation. We consider the laboratory data alongside your property’s moisture history, ventilation, construction and current conditions.
This approach gives you context, not just a number. It can help you understand possible mould concerns and determine whether further investigation is appropriate.
What Is ERMI Testing?
ERMI measures fungal DNA within the dust sample submitted to the laboratory.
DNA analysis can detect material from mould that may no longer be alive, so the result can reflect current conditions, previous contamination, or a combination of both. Settled dust can accumulate over time, which may provide a longer-term picture than a short air sample that only captures airborne particles during the sampling period.
However, the findings only represent the dust collected. Results can be influenced by:
- Where the sample was taken
- How much dust was collected
- The age of the dust
- Cleaning practices within the property
- Recent renovation or remediation work
- Movement of dust between different areas
- The property’s flooring and ventilation
- The laboratory’s collection and analysis method
Professional sampling and interpretation help reduce uncertainty and place the findings within the correct building context.
When May ERMI Testing Be Useful?
ERMI Testing may provide additional information when you’re investigating a building with a known or suspected history of moisture and mould. It may be considered when:
- The property has experienced flooding, roof leaks or plumbing failures
- You suspect hidden mould but can’t find an obvious source
- A musty odour continues after cleaning or repairs
- Previous occupants reported mould or moisture concerns
- You want to investigate the fungal profile found in settled dust
- Standard air sampling has provided limited information
- You’re assessing a property with a complex water-damage history
- Further data is needed to support a broader environmental investigation
ERMI isn’t automatically the right test for every property. In some situations, moisture mapping, direct surface sampling, air sampling or EMMA Testing may provide more useful information. We assess your concerns before recommending a testing method.
Why a Professional Building Assessment Matters
A laboratory result can’t tell you everything about a building.
An ERMI score doesn’t identify the exact location of hidden mould. It doesn’t explain why mould developed, or confirm whether the source remains active. That requires an assessment of the property itself.
Our Indoor Environmental Professionals may examine:
- Current and previous water intrusion
- Moisture levels within building materials
- Indoor temperature and relative humidity
- Ventilation and HVAC performance
- Airflow between rooms and concealed spaces
- Visible staining and suspected fungal growth
- Construction details and hidden cavities
- Previous repairs, cleaning or remediation
- Conditions around the sample location
We use these findings to interpret the laboratory data more carefully — helping you avoid making an expensive property or remediation decision based only on an ERMI number.
How Our ERMI Testing Process Works
We begin by discussing your property and concerns — asking about leaks, floods, musty odours, visible mould and previous building work, and considering what you need the assessment to achieve.
Our team then inspects the relevant areas and evaluates the building’s moisture conditions. If ERMI Testing is appropriate, we develop a sampling plan, and dust is collected from a selected area using the laboratory’s required method.
The sample is sent to an independent laboratory for qPCR analysis. When results are available, we review the identified mould species, reported quantities and calculated ERMI score, and compare this information with our inspection findings and the property’s history.
You receive a clear report explaining the results, their limitations and any recommended next steps.
Understanding Your ERMI Score
An ERMI score is a relative index. It should not be treated as a pass-or-fail result.
A higher score may indicate a greater relative presence of the selected water-damage-associated mould species in the submitted dust. A lower score may indicate a lower relative presence.
However, the score alone doesn’t show where the mould is located, whether it’s actively growing, or whether building occupants have experienced a particular exposure. Individual mould quantities may also provide useful information — two properties can receive similar scores while having different fungal profiles.
We explain the reported species, quantities and overall index in plain language, and discuss how the findings relate to the physical conditions observed within the building.
Important Limitations of ERMI Testing
The United States Environmental Protection Agency describes ERMI as a research tool. It has not been validated by the agency for routine non-research use.
For this reason, ERMI should not be used on its own to:
- Diagnose a health condition
- Declare a property safe or unsafe
- Locate the exact source of mould
- Replace a physical building inspection
- Confirm that remediation has succeeded
- Determine the complete exposure of an occupant
Air Quality Australia treats ERMI as one potential source of environmental information. Where it’s used, we interpret the findings alongside moisture data, building observations and other appropriate sampling methods — a balanced approach that helps you understand both the value and limitations of the test.
ERMI Testing Compared With EMMA Testing
ERMI and EMMA both analyse environmental material, but they look for different things.
ERMI Testing | EMMA Testing |
Analyses DNA from 36 selected mould species | Analyses selected mould DNA and mycotoxins |
Uses settled dust | Can use dust or other suitable environmental material |
Produces a relative mouldiness index | Does not produce an ERMI score |
Helps describe the selected fungal profile in dust | Helps investigate selected toxigenic moulds and mycotoxins |
Does not directly test for mycotoxins | Includes a laboratory mycotoxin panel |
ERMI may be considered when the main objective is to examine mould DNA within settled dust. EMMA Testing may be more suitable when the investigation specifically includes mycotoxins.
You don’t need to choose a test by yourself. We review your property and recommend the method most likely to provide useful answers.
Clear Advice About Your Next Step
Mould testing should help you make an informed decision. It shouldn’t leave you with a score you can’t interpret.
We explain what the laboratory found and how it may relate to your property. If further action is recommended, we provide practical guidance — this may include moisture control, targeted investigation, additional sampling or a professional remediation scope of works.
Our goal is to help you identify the underlying building issue and choose a proportionate response.
Book Your ERMI Assessment
If you’re concerned about hidden mould or previous water damage, speak with Air Quality Australia.
We’ll discuss your property and determine whether ERMI Testing is suitable. If another assessment would provide better information, we’ll explain why. You’ll receive professional guidance, independent laboratory analysis and recommendations based on the complete building investigation.