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| The purpose of containment
during remediation activities is to limit release of mold into
the air and surroundings, in order to minimize the exposure of
remediators and building occupants to mold. Mold and moldy debris
should not be allowed to spread to areas in the building beyond
the contaminated site.
The two types of containment recommended
in Table 2 are limited and full. The larger the area of moldy
material, the greater the possibility of human exposure and the
greater the need for containment. In general, the size of the
area helps determine the level of containment. However, a heavy
growth of mold in a relatively small area could release more spores
than a lighter growth of mold in a relatively large area. Choice
of containment should be based on professional judgment.10
The primary object of containment should be to prevent occupant
and remediator exposure to mold. |
Containment Tips |
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Always
maintain the containment area under negative pressure.
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Exhaust
fans to outdoors and ensure that adequate makeup
air is provided.
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If the
containment is working, the polyethylene sheeting
should billow inwards on all surfaces. If it flutters
or billows outward, containment has been lost, and
you should find and correct the problem before continuing
your remediation activities.
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Limited
Containment
Limited containment is generally
recommended for areas involving between 10 and 100 square feet (ft2)
of mold contamination. The enclosure around the moldy area should consist
of a single layer of 6-mil, fire-retardant polyethylene sheeting. The
containment should have a slit entry and covering flap on the outside
of the containment area. For small areas, the polyethylene sheeting
can be affixed to floors and ceilings with duct tape. For larger areas,
a steel or wooden stud frame can be erected and polyethylene sheeting
attached to it. All supply and air vents, doors, chases, and risers
within the containment area must be sealed with polyethylene sheeting
to minimize the migration of contaminants to other parts of the building.
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 case, containment
should be installed from the floor to the ceiling deck, and the filters
in the air handling units serving the affected area may have to be replaced
once remediation is finished.
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The containment area must be maintained under negative pressure
relative to surrounding areas. This will ensure that contaminated
air does not flow into adjacent areas. This can be done with a HEPA-filtered
fan unit exhausted outside of the building. For small, easily contained
areas, an exhaust fan ducted to the outdoors can also be
used. The surfaces of all objects removed from the containment area
should be remediated/cleaned prior to removal. The remediation guidelines
outlined in Table
2 can be implemented when the containment is completely sealed
and is under negative pressure relative to the surrounding area. |
| Containment
Area |
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[Click
on image for larger picture]
Photo 8: Full containment on large job |
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Full
Containment
Full containment is recommended for the
cleanup of mold-contaminated surface areas greater than 100 ft2
or in any situation in which it appears likely that the occupant space
would be further contaminated without full containment. Double layers
of polyethylene should be used to create a barrier between the moldy
area and other parts of the building. A decontamination chamber or airlock
should be constructed for entry into and exit from the remediation area.
The entryways to the airlock from the outside and from the airlock to
the main containment area should consist of a slit entry with covering
flaps on the outside surface of each slit entry. The chamber should
be large enough to hold a waste container and allow a person to put
on and remove PPE. All contaminated PPE, except respirators, should
be placed in a sealed bag while in this chamber. Respirators should
be worn until remediators are outside the decontamination chamber. PPE
must be worn throughout the final stages of HEPA vacuuming and damp-wiping
of the contained area. PPE must also be worn during HEPA vacuum filter
changes or cleanup of the HEPA vacuum.
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10
For example, a remediator may decide that a small area that is extensively
contaminated and has the potential to distribute mold to occupied areas
during cleanup should have full containment, whereas a large wall surface
that is lightly contaminated and easily cleaned would require only limited
containment. |