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What Spore Counts Mean
Air sampling reports list spores per cubic meter, but the number alone does not define risk. Mold is everywhere, and normal indoor air often contains spores similar to outdoor air.
What Counts Cannot Tell You
Short term air samples cannot predict health effects for a specific person. Public health agencies emphasize that visual inspection and moisture investigation are more reliable than a single air test.
- No federal health threshold exists for mold spores
- Counts do not prove where mold is growing
- Short sampling windows miss daily variability
- Moisture sources are the real root cause
Indoor vs Outdoor Baselines
- Outdoor air is the baseline for comparison
- Indoor counts should be similar or lower than outdoors
- Different seasons can shift outdoor counts dramatically
- Weather and HVAC operation change results
Why Species Mix Matters
Common Outdoor Molds
- Cladosporium and other common genera appear on most reports
- See common indoor molds for examples
Water Damage Indicators
- Stachybotrys and Chaetomium often indicate chronic moisture
- Elevated indoor-only species suggest an indoor source
Context Factors
- 1
HVAC status
Running or off changes particle movement and counts.
- 2
Recent cleaning
Vacuuming and dusting can temporarily raise counts.
- 3
Sampling location
Samples near returns or windows can skew results.
Questions to Ask
- Was an outdoor control sample collected?
- How did you interpret the indoor to outdoor comparison?
- Were samples taken near visible damage or complaints?
- Does the report recommend next steps?