To bleach, or not to bleach: that is the question! Once a recommended remedy for mold remediation by both the Occupational Health and Safety Administration as well as The Environmental Protection Agency has now become a thing of the past.
Spore?Tech Mold Investigations, LLC, a mold testing firm and laboratory in Louisville, KY challenged this myth by going to the source. This is what they found. Will chlorine bleach kill mold or not?yes or no? The answer is yes, but with a caveat. That answer comes from The Clorox Company, Oakland CA, manufacturer and distributor of Ultra Clorox? Regular Bleach. The company's correspondence to Spore?Tech Mold Investigations, LLC stated that their Tech Center studies supported by independent laboratories show that ".3/4 cup of Clorox liquid bleach per gallon of water will be effective on hard, non-porous surfaces against. Aspergillus niger and Trichophyton mentagrophytes (Athlete's Foot Fungus)". Whether or not chlorine bleach kills other molds and fungi (such as stachybotris or chaetomium), the company did not say. The "hard, non-porous surfaces" part of the sentence is a caveat. Mold remediation involves the need to disinfect wood and wood-based building materials, all of which are porous materials. Thus, chlorine bleach should not be used in mold remediation as confirmed by OSHA's and EPA's updated recommendations and suggested guidelines. The use of bleach as a mold disinfectant is best left to kitchen and bathroom countertops, tubs and shower glass, etc.
The goal to remediating mold is not to simply "KILL" the mold, but to actually "REMOVE" the mold from the affected area. Accepted guidelines and standards have been set by agencies such as the Occupational Health and Safety Administration, The Environmental Protection Agency, and The Institute of Inspection, Cleaning, and Restoration. Following is an example of a basic mold remediation protocol.
Prep and Removal
Containment barriers are to be established prior to any work being started. The area(s) will be contained with a barrier of no less than 4mil plastic and will be in place not only for containment of Microbial growth and Bacterial contaminants, but also for dust suppression methods for mediation of debris throughout the home and HVAC system (if needed).
Additionally, the containment area will be placed under negative air conditions to further contain microbial growth and dust. Air scrubbers will be in use during the remediation process and up to twelve (12) hours prior to any post remediation testing.
Any drywall and/or plaster showing signs of water staining and/or mold growth will be removed to a minimum distance of one foot (1') past the last visible signs of microbial growth and/or water damage. Drywall on adjoining walls will be removed to a distance of no less than one foot (1') past the last visible signs of microbial growth and/or water damage (unless deemed salvageable by the project manager). Dust suppression methods will be used to control the dispersion of drywall dusts (negative air / air scrubbers) All cabinets and/or vanities that show signs of water damage and/or microbial activity will be removed and discarded if not deemed salvageable as part of the remediation process. Any affected tile that is on top of a subfloor will be removed to expose subfloor and subfloor will then be remediated, cleaned, and treated.
Wood framing (studs, sole plates, trusses and web members) will be treated with an abrasive method (Sanding, Soda Blasting, Dry Ice Blasting or Wire brushed) and then thoroughly cleaned with a HEPA vacuum, damp wiped, the HEPA vacuumed again. Any wood components that have been rotted through will be removed and replaced, rather than cleaned. All wood components will be treated with an anti-microbial / anti-bacterial agent. (Approved by industry standards). For a list of EPA approved agents, please refer to their web site at http://www.epa.gov/.
All insulation, if any, in the affected area will be removed and new insulation should be installed as part of the build back process.
Cleanup Practices
In addition, all remaining smooth surfaces within the containment areas (and any other areas if necessary) will be wiped with an antimicrobial agent and all other surfaces HEPA vacuumed (then repeated) to aid in removal of residual debris containing hazardous particulates (Note: Hazardous is not limited to bacterial but also includes the dusts from uncontained work environments). It is recommended, but not required that the ductwork in the home should be flushed (cleaned) of all residue and all inlet outlet vents should be cleaned (unless determined to be contaminated through thorough mold testing).
All debris within the work area will be contained in contractor grade (no less than 4 mil) plastic bags and properly disposed of.
Rebuild and Post Test
At completion of remediation work, it is recommended that a post-remediation visual assessment be conducted to ensure complete remediation of contaminated building materials. This should be performed by a third party entity and prior to any build back activities. This should consist of a visual inspection of all remediated areas, crevices and wall cavities. (where applicable)
After satisfactory completion of the visual assessment we recommend that air samples are taken to judge the effectiveness of the cleanup activities. Release criteria for post-remediation mold sampling should be judged using Air-O-Cell (or similar) spore trap samples inside the building (amount as applicable) and one outdoor sample (as the baseline/control sample). The average of the outdoor sample collected will be used to compare to the indoor samples.
Results from samples collected following any remediation activities should be analyzed by one who is qualified to interpret the test data in order to accurately deem a remediation project complete or not complete.
Conclusion.
Laundry bleach is not an effective mold killing agent for porous building materials and NOT EFFECTIVE in the mold remediation process. OSHA is the first federal agency to announce a departure from the use of chlorine bleach in mold remediation. It is our opinion that in time, other federal, state and other public safety agencies will follow OSHA's lead and the evidence from independent studies being conducted by industry leaders nation wide. The public should be aware, however, that a chlorine bleach solution IS an effective sanitizing product that kills mold on hard non porous surfaces and neutralizes indoor mold allergens that trigger allergies when used correctly.
