Mold Growth Conditions
Risk by temperature, RH, and time.
Example
You enter
- Relative humidity (percent) 80
- Temperature (°F) 75
- Hours of elevated humidity 60
You get
- Risk high
- Threshold RH growth (%) 60
- Threshold RH high (%) 70
- Typical germination hours 24
Checked against published worked examples from: EPA / IICRC S520-2024 mold-risk practice.
Details, formula, and sources
Formula or tableMold-growth conditions: temperature 40-100 °F, RH ≥ 60-70% sustained, organic substrate, time ≥ 24-48 hours. EPA / IICRC S520-2024 thresholds.
Source and editionEPA 402-K-01-001 (Mold Remediation in Schools and Commercial Buildings) + IICRC S520-2024 (Standard for Professional Mold Remediation) by name.
Free accessEPA 402-K-01-001 free at epa.gov/mold. IICRC S520-2024 licensed.
What governsEstimate. AHJ and licensed professional govern.
API field namesrh_percent, temperature_F, hours_elevated, risk, threshold_rh_growth_percent, threshold_rh_high_percent, typical_germination_hours