Post-remediation air quality testing (clearance testing) confirms mold spore counts returned to safe levels. Learn what tests are used, what results mean, and when re-occupancy is safe.
Post-remediation verification (PRV) — also called clearance testing — is performed by an independent industrial hygienist or environmental consultant after mold remediation is complete and before reconstruction begins. The same company that performed remediation should not conduct its own clearance testing.
Standard clearance testing uses air sampling (spore trap cassettes analyzed by an accredited lab) to compare indoor spore counts to outdoor control samples. Acceptable clearance: indoor counts at or below outdoor levels for the same species, and no Stachybotrys or other atypical species detected. Results typically take 24–72 hours.
Additional IAQ testing after water damage may include: volatile organic compound (VOC) testing for musty odor compounds, ERMI (Environmental Relative Moldiness Index) dust sampling for comprehensive species identification, and particulate matter testing if occupants have HVAC-related complaints. Clearance testing costs $200–$600; comprehensive IAQ panel: $400–$1,200.
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