Wallemia sebi
The dry-tolerant dust dweller
What it tells you about the building
Wallemia is among the most xerotolerant fungi known, growing at humidity levels too low for most molds. Elevated Wallemia in dust suggests a persistently elevated background humidity rather than a discrete leak — a whole-environment signal.
Why it matters in assessments
Wallemia sebi is a component of dust-index panels and its elevation is a useful humidity fingerprint. For sensitized occupants it also matters as a mattress and textile dust resident, concentrating in exactly the items with the most contact hours.
What remediation requires
Humidity control is the fix: hold 35–50% RH, ventilate storage areas, and launder or clean the textile reservoirs where it concentrates. There is no wall to open — the environment itself is the substrate.
Small, compact brown colonies, rarely dramatic — usually detected by lab analysis rather than by eye.
- House dust and mattress dust
- Stored textiles and upholstered furniture
- Slightly humid closets and storage
- Agricultural and food environments
State editions
Where this species shows up depends on where local climate and housing stock meet its moisture requirement. Read the local picture:
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