Aspergillus/Penicillium count explained

Many microscopy reports group Aspergillus and Penicillium-like spores because they can be difficult to distinguish by spore morphology alone.

Why the grouping matters

These molds are common in the environment, so finding some spores does not automatically identify an indoor source. Interpretation depends heavily on the indoor/outdoor pattern and the moisture inspection.

When the pattern becomes more interesting

A strong indoor elevation relative to outdoors, especially in a room with moisture damage or musty odor, can support further investigation. Identification to a more specific level may require a different analytical method.

Do not diagnose a building from one line item

Look at all sample locations, outdoor control, other spore types, detection limits, sample volume, and the inspector's notes.