I Got a Mold Inspection Report. What Do These Numbers Mean?

Answer: A mold air report is an indoor-to-outdoor comparison plus species list, not a pass/fail lab grade. There is no single official “safe” spores/m³ number used by EPA or IICRC. What matters: is indoor total well above the outdoor baseline taken the same day, and are water-indicator genera (Stachybotrys, Chaetomium) present indoors when they are absent or rare outdoors?

Pair this page with elevated spore counts. Do not merge the slugs.

How to read the sheet

• Ratio first. Indoor several times outdoor, same-day samples, points to an indoor source — even if the absolute number looks modest.
• Species second. Cladosporium at outdoor-like levels is common. Elevated Aspergillus/Penicillium indoors is a moisture flag. Stachybotrys or Chaetomium indoors at any meaningful count is a wet-cellulose flag, not a color nickname.
• Air ≠ location. A cassette does not say which wall. Moisture mapping and openings find the source.

Houston outdoor baselines in warm months are often higher than dry climates. That is why the outdoor sample on the same ticket matters more than a national rumor threshold.

IICRC S520 describes post-remediation verification. Clearance should be independent of the remediator when the file calls for it.

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