At Bald Eagle Inspection Services, we are occasionally asked about DNA-based mold testing, sometimes referred to as PCR, ERMI, or HERTSMI testing. While we can perform these tests upon request, it’s important for our clients to understand what they are, how they came about, and why they are generally less reliable than our standard controlled testing methods.
What Are DNA-Based Mold Tests?
DNA-based mold testing uses a technology called Polymerase Chain Reaction (PCR) to detect mold DNA in dust samples. These methods became well known under names like ERMI (Environmental Relative Moldiness Index) and HERTSMI-2. Unlike traditional air sampling, which measures airborne spores at the time of testing, PCR testing looks for mold DNA in settled dust, essentially providing a “historical snapshot” of what has been present in the home over time.
Where These Tests Came From
These tests were originally developed for the U.S. Department of Housing and Urban Development (HUD) as a carpet fiber analysis tool for research purposes. They were not designed for routine private-sector inspections or for determining current airborne mold exposure. Because the tests lack formal accreditation under standards such as ISO/IEC 17025, there is no independent oversight to ensure consistency, accuracy, or repeatability.
Why They’re Often Unreliable
The main limitation with DNA-based testing is the lack of standardized collection methods. Many commercial kits provide swabs, cloths, or vacuum attachments but offer little to no direction on:
- How much surface area to collect from
- Whether the surface should be cleaned or untouched
- How much pressure to use during collection
Without these controls, two samples taken from the same location can produce completely different results depending on the technique, the collector, and even the lab performing the analysis. This makes results harder to interpret with confidence.
Why Surface Samples Are Less Relevant for Health Risk
Surface sampling, including most DNA-based methods, measures what is sitting on a surface, not what is in the air. While it can be useful for certain investigative purposes, surface contamination does not generally affect our health the same way as airborne contamination does.
- Airborne mold can be inhaled directly, entering the respiratory system and posing a more immediate health concern.
- Surfaces can be dirty while the air is clean, or surfaces can be spotless while the air contains high mold spore levels.
- Because of this, airborne mold is always considered a higher priority when evaluating potential health impacts.
Why Bald Eagle Inspection Services Uses Controlled Methods
When assessing mold concerns, it’s important to focus on how mold actually impacts health, most often through the air we breathe. Our preferred method, air quality testing, is fully controlled:
- Same calibrated equipment and media every time
- Same collection volume and duration
- Accredited laboratory analysis for consistent, defensible results
We also provide controlled historical-type testing using composite or swab samples, which can be taken from multiple locations in a home to identify spores that have been present over time. These methods follow strict protocols to ensure reliability.
Cost and Accuracy Considerations
While we can perform DNA-based PCR, ERMI, or HERTSMI tests upon request, they are generally more expensive and less accurate than controlled air quality testing. In most cases, our standard methods provide a clearer, more actionable picture of mold exposure and contamination.
Bald Eagle Inspection Services, LLC is a leading Mold Assessment company that provides services in Upstate New York and beyond.