Bioaerosol containment and protection

LATHAM, NY - The term "professional judgment" crops up frequently in US Environmental Protection Agency-published guidelines on mold remediation. That seems to underscore the importance of training and certification - however, the EPA has yet to regulate or standardize threshold limit for airborne mold contaminants.

Biocides The EPA writes, "The use of a biocide, such as chlorine bleach, is not recommended as a routine practice during mold remediation, although there may be instances where professional judgment may indicate its use (for example, when immune-compromised individuals are present.)"

The EPA says mold will not grow if the moisture problem in the building has been resolved. In most cases, the EPA says, it is not possible nor desirable to sterilize an area, that mold spores will remain in the air at or below outside air levels.

Schools: Remember that, in some states, only registered pesticide applicators may apply biocides. Fungicides developed for outside use - hexachlorobenzene, organiomercurials, pentachlorophenol, phthalimides, and dithiocarbamates - are not appropriate for indoor use.

The Institute of Inspection, Cleaning & Restoration Certification (IICRC) S500 Standard and Reference Guide for Professional Water Damage Restoration (1999) and the American Conference of Governmental Industrial Hygienists ("Bioaerosols: Assessment and Control, 1999) set guidelines based on total surface area for containment and protection in mold remediation.

The EPA offers information from this work. If the total area affected is less than 10 square feet (minimum), N-95 respirator, gloves and goggles should be used. For areas affected from 10 to 100 square feet (limited or full) and 100 square feet and up, guidelines suggest using professional judgment for personal protection. Gloves, N-95 respirator or half-face respirator with HEPA filter, disposable overalls, goggles/eye protection are listed for limited; gloves, disposable full body clothing, head gear, foot coverings, full-face respirator with HEPA filter are recommended for full.

Guidelines suggest containment is not required for less than 10 square feet. For limited area, use polyethylene sheeting ceiling to floor around affected area with a slit entry and covering flap; maintain area under negative pressure with HEPA filtered fan unit. Block supply and return air vents within containment area.

For areas of full exposure, two layers of fire retardant polyethylene sheeting, with one airlock chamber, is required. Maintain area under negative pressure with HEPA filtered fan exhausted outside of building. Block supply and return air vents within containment area.

Mold can generally be removed from nonporous surfaces by wiping of scrubbing with water or water and detergent. Porous materials present more of a problem. Discarding them may be the most expedient solution. Seal them double-bagged in 6-mil polyethylene sheeting.

It’s important to remove it; painting over mold can result in peeling. Mold can also result in structure damage; it feeds on wet wood. A roof leak can result in eventual weakening of floors and walls through biological activity. The US Environmental Protection Agency suggests consulting a structural engineer where mold structural damage is suspected.

Mold and mold spores may stick to the surface of tanks, hoses and attachments of wet vacs used in remediation efforts. Thoroughly clean and dry after use.

Wet vaccums should not be used to vacuum porous materials such as gypsum board. The EPA suggests using wet vacs only when materials are still wet; otherwise, spores may be spread.

Source: US Environmental Protection Agency