National Center for Healthy Housing
Healthy Rebuilding Demonstration

Protocol for Mold Cleanup

A national panel of experts convened to develop the cleanup protocols based on scientific research and best practice. The final protocols included debris removal, cleaning, HEPA vacuuming, treatment of wall cavities with a borate solution, and moisture removal.

See Recommended Procedure for Mold Cleanup for detailed description of procedure.

Sampling Collection and Analysis Procedures

Baseline samples were collected for culturable mold and total mold spores using Petri dishes and low- and high-flow sampling pumps, respectively. Samples were also taken during the remediation process and immediately following the clean up procedures.

The team used a low-flow pump to sample indoor air at 2.5 liters per minute for 20 minutes. Airborne particles were collected onto polyvinyl chloride (PVC) filters.  The filter cassettes were returned to ColumbiaUniversity for mold analysis.  To each filter, 5 ml of pyrogen-free water with 0.05% Tween 20 added as a surfactant to remove the mold spores.  The samples were incubated (in orbital shaker) at 25^oC for 1 hour. Aliquots of 100 µl were spread-plated onto two different culture media (Dichloran-glycerol agar and Malt extract agar) and incubated at two different temperatures: 25^oC  and 37^oC .  Findings are presented in the units of colony forming units per cubic meter of air (CFU/m³).

Results

The samples indicated that mold levels were 100 times outdoor levels during remediation work. Home #1, which underwent a less extensive cleaning procedure and was not allowed to dry completely, continued to be a host for mold at elevated levels (>10,000 CFU/m3)   Following revised protocols effectively reduced mold levels in Home #2 to very low levels post-treatment. The cost of this decontamination process after all possessions and furnishings are removed from the home is between $3.40 to $4.10 per square foot of floor area or $4,400 for an average 1,200 foot home.

Conclusions

The drying process and cleaning of all surfaces in a home, including upper walls and ceilings, is critical to the success of mold clean-up. The findings also highlight the importance of appropriate personal protection equipment for homeowners and workers during possession removal and during mold remediation and support the idea that successful mold remediation procedures in moderately damaged homes can be performed in a cost-effective way.