What it is
Aspergillus is one of the most common indoor molds in the world. There are over 180 species, several of which colonize the inside of buildings readily. Many are visible as powdery green, yellow, or black patches.
Where it grows
Walls, insulation, HVAC ductwork, dust, food, and decaying organic material. Often spreads via the HVAC system once a colony establishes - a problem in one room quickly becomes a whole-house issue.
Health impact
Triggers allergies and asthma. Some species (Aspergillus fumigatus most notably) can cause infections in immunocompromised individuals. Most healthy adults experience irritation rather than infection.
This species produces mycotoxins. That matters because mycotoxins can affect indoor air quality even after visible mold is gone - they ride on dust particles and require thorough removal, not just surface cleaning.
Property risk
Spreads quickly. Can contaminate HVAC systems and re-deposit spores across the home. Frequent companion species to Penicillium in water-damaged homes.
When to test
If you see what looks like aspergillus 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 aspergillus 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.