Types of Mold Tests Explained
Different tests answer different questions. Choosing the right one saves money and gives you results you can act on.
Air sampling (spore trap)
A pump pulls a measured volume of air through a cassette. A lab counts and identifies spores. Inspectors compare indoor samples to an outdoor control sample — elevated or unusual indoor types suggest a hidden source.
Best for: suspected hidden mold, musty odors, after water damage, clearance testing.
Surface sampling (swab or tape lift)
Collects material from a visible spot to identify the mold genus. It confirms what a stain is, but not how much is in the air.
Best for: identifying a visible growth.
Bulk sampling
A piece of material (drywall, carpet, insulation) is removed and analyzed. Used when a material's condition is in question.
Dust testing (ERMI / HERTSMI-2)
DNA-based (qPCR) analysis of settled dust for specific mold species. ERMI was developed for EPA research; the EPA cautions it isn't validated for routine home use, but some clinicians and inspectors use it as a screening tool.
Moisture mapping and thermal imaging
Not mold tests on their own, but moisture meters and infrared cameras find the wet areas where mold grows. Good inspections always include moisture assessment.
Which test do I need?
- I see mold: usually no test needed — fix the moisture and clean or remove it.
- I smell mold but can't see it: inspection plus air sampling.
- After a flood or leak: inspection with moisture mapping.
- Buying a home: inspection, with air samples if there are signs of moisture.
- After remediation: clearance air testing.