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volume of airflow removed from the enclosure should replace the volume of the
container at every 5 to 15 minutes. Airflow volume must be relatively high for
large enclosures, enclosures with awkward shapes, enclosures with multiple
openings, and operations employing several workers in the enclosure.
Airlocks are mechanisms on doors and curtains that control the air
flow patterns in the doorways. Direct the patterns through doorways so that air
flows toward the inside of the enclosure. Use vestibules, double doors, or double
curtains to prevent air movement through the doorways. To use a vestibule, a
worker enters a chamber by opening the door or curtain and then closing the
entry before opening the exit door or curtain.
Check the airflow between adjacent rooms using smoke tubes or
other visual tests to ensure the flow patterns draw air toward the work area.
As a general rule, if the containment has been constructed properly
and openings have been sealed, the polyethylene sheeting should billow inwards
on all surfaces. If it flutters or billows outward, negative pressure has not been
established or has been lost, and you must find and correct the problem before
continuing the remediation activities.
Heating, Ventilating, and Air Conditioning (HVAC) Systems.
Heavy mold growth on ceiling tiles may impact HVAC systems if the space above
the ceiling is used as a return air plenum. In this situation, construct the
containment from the floor to the ceiling deck and replace the filters in the air-
handling units servicing the area once remediation is finished.
Prior to work beginning, secure HVAC systems servicing the
contaminated area; lock and tag-out in accordance with the Command's Energy
Control (Lockout/Tagout) Program.
Coordinate technical assistance in identifying remediation
procedures for contaminated HVAC systems with the local Industrial Hygienist
and/or Safety and Health professional and mechanical engineers.
USE OF BIOCIDES AND DISINFECTANTS. The use of a biocide,
such as chlorine bleach, is not recommended during mold remediation. Mold
remediation removes the mold to prevent human exposure and damage to
building materials and furnishings. It is necessary to clean up mold
contamination, not just to kill it. Dead mold is still allergenic, and some dead
molds are potentially toxic.
In most cases, it is not possible or desirable to sterilize an area; a
background level of mold spores will remain in the air (roughly equivalent to or
lower than the level in outside air). These spores will not grow if the moisture
problem has been resolved.