What it is
Ascospores aren't a single mold species - they're the spore type produced by a large group of fungi called Ascomycetes. A high count in an air sample suggests there's an active mold source somewhere, even if you can't see it.
Where it grows
Air samples - Ascospores are very common in outdoor and indoor air. High indoor counts compared to outdoor often indicate hidden growth.
Health impact
Common allergen. Symptoms vary by the specific species producing the spores.
This species does not typically produce mycotoxins, though it can still cause allergic reactions and respiratory irritation.
Property risk
A high Ascospore count in an indoor air sample is a flag for hidden water damage. Often the trigger for a more thorough wall-cavity or attic investigation.
When to test
If you see what looks like ascospores in your home - or if a lab report flagged it in your air samples - testing the affected area against an outdoor baseline is the most useful next step. The decision about remediation depends on:
- How much is present (spore count per cubic meter, or visible square footage)
- What's beneath it (porous materials like drywall and insulation usually need removal; hard surfaces can often be cleaned)
- Whether the moisture source is identifiable and fixable
Our approach
For confirmed indoor ascospores colonies, our process is the same as for any mold species: identify and stop the moisture source, contain the work area, remove what's compromised, HEPA-filter and HEPA-vacuum the surrounding area, dry everything, and verify with a post-remediation clearance test against the outdoor baseline.