Why ERMI Mold Tests Are Not a Substitute for a Licensed Mold Assessment

When it comes to evaluating indoor air quality and mold risk in a home, two approaches are often discussed: ERMI (Environmental Relative Moldiness Index) testing and licensed mold assessments performed by trained professionals. While ERMI testing can provide interesting data, it is not a substitute for a comprehensive on-site evaluation.

Here’s why a licensed mold assessment remains the most reliable way to determine the current condition of a home’s air quality:

1. ERMI Tests Measure Dust, Not Air Quality

ERMI testing relies on collecting dust samples and analyzing them in a lab for mold DNA. While this can identify species that have been present in the past, it doesn’t reflect the real-time condition of the air your clients are breathing today. A licensed mold assessor, on the other hand, evaluates current airborne mold levels through direct sampling and environmental measurements.

2. No Context for Source or Cause

An ERMI score may indicate the presence of certain mold species, but it doesn’t explain where the mold is coming from or why it’s there. Licensed inspectors can trace the problem back to a leaking pipe, poor ventilation, or foundation moisture — giving homeowners actionable solutions. Without this context, ERMI results can be misleading.

3. Lack of Industry Recognition for Decision-Making

While ERMI was originally developed for research purposes, it was never intended for real estate transactions or diagnostic use. In contrast, licensed mold assessments follow state regulations, established standards of practice, and are legally recognized for disclosure and remediation planning.

4. Potential for Misinterpretation

ERMI scores compare a home’s mold burden to national averages, but this doesn’t always mean a home has a current problem. A high score may simply reflect historic water damage, not an active issue. A professional mold assessor uses multiple data points — air samples, moisture readings, visual inspection — to provide accurate, present-day results that buyers and sellers can act on.

5. Actionable Recommendations Come from Professionals

Perhaps the most important difference: an ERMI report only delivers a lab result. It doesn’t include recommendations for fixing issues, verifying remediation, or protecting occupants. Licensed mold professionals provide detailed reports with findings, interpretations, and solutions — the information that truly matters to real estate clients.

✅ The Bottom Line

ERMI testing may serve as a research tool or supplemental data point, but it does not reflect the current air quality conditions in a home. For buyers, sellers, and homeowners who need clear, actionable answers, a licensed mold assessment remains the gold standard. It not only identifies problems but also provides the context and guidance needed to protect property value and occupant health.

ERMI Test vs. Licensed Mold Assessment

Feature	ERMI Test	Licensed Mold Assessment
What It Measures	Mold DNA in settled dust (historic exposure)	Current airborne mold levels, visible conditions, and moisture sources
Accuracy for Current Air Quality	❌ Limited – reflects past contamination, not real-time air quality	✅ High – measures what occupants are breathing now
Source Identification	❌ Does not identify the cause or location of mold	✅ Traces mold to leaks, ventilation issues, or hidden water damage
Actionable Results	❌ Lab score only, no recommendations	✅ Detailed report with findings, interpretation, and remediation guidance
Regulatory Recognition	❌ Research tool, not recognized for real estate or legal use	✅ State-regulated and widely accepted in real estate transactions
Best Use Case	Supplemental data or screening tool	Primary evaluation for health, safety, and property decisions