The U.S. Navy Remediation Guide - Funny How the Navy Knows the Danger
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CHAPTER 13, SECTION 3
MOLD CLEANUP, REMEDIATION, AND CLEARANCE SAMPLING
IINTRODUCTION
The previous section stressed that prevention is the best policy: if
water does not get into the building, mold will not grow. However, if
you do find mold, it is crucial that you know how to safely and
effectively remove the contamination and to assess the project
success. Be prepared to review contract requirements, oversee the
remediation, or liaise with occupants about associated concerns.
This section is a compilation of the most widely practiced mold
remediation guidance, using the New York City Department of Health
Guidelines on Assessment and Remediation of Fungi in Indoor
Environments 1 as the foundation. Originally issued in 1993
specifically for Stachybotrys remediation, these guidelines were
expanded in 2000 to cover all mold remediation in indoor environments.
Information from the Environmental Protection Agency’s (EPA’s) Mold
Remediation and Schools and Commercial Buildings 2 and several other
documents is also incorporated.
“RULES” FOR RESPONSE AND REMEDIATION
1) Act Quickly. Rapid response and proper actions following water
damage are essential to significantly reduce or even prevent microbial
damage.
Ideally, response actions following water intrusion should begin
within 8 hours. Response within 24 hours will usually prevent mold
growth. If actions are not underway within 48 hours, chances are good
that mold will grow in or on water damaged materials and remediation
will be needed.
2) Locate and Fix Water Intrusion Source(s). This is essential to stop
additional water infiltration and damage. Make repairs before or
concurrent with removing water and drying the area.
Likely sources to check as water intrusion points include: the roof
(missing or damaged shingles/finish or flashing); loose or damaged
soffitts and gutters; chimneys; through-roof pipes or vents;
improperly sloped drains; improperly vented appliances, uncontrolled
humidity (i.e., moisture condenses on inside surfaces); improperly
installed vapor/moisture barriers or surface finishes (e.g., exterior
insulation and finish system [EIFS] or unsealed stucco); poorly fitted
or sealed windows; crawlspace, slab or other foundation material
(standing water or episodic incursion from rising water table);
heating and cooling system; visible signs of flooding or recurrent
water damage.
Revised 4/30/2008
3) Remove the Water and Protect Materials. Water can be removed from
hard surfaces by soaking it up or mopping. If large volumes of water
are in the building, it may be necessary to actively pump out standing
water and/or use wet vacuums. Other actions that may be helpful for
complete drying include:
a) Remove all wet carpet, rugs and padding.
b) Remove wall moldings (baseboard, decorative trim) to allow drainage
if water has entered the wall cavity.
c) Drill holes in the wallboard to facilitate drying inside the wall
cavities. Remove wet wallboard. This allows you to assess wall cavity
damage, determine when structural components are dry, and removes a
likely growth substrate for mold.
d) If built-in cabinets are wet, remove kick plates or drill holes for
drying.
e) Check for water in the ventilation ducts, pipe chases, crawl
spaces, basements, and attics.
Furnishings and other building contents that are not wet or damaged by
the water intrusion should be moved temporarily to a dry location. If
such items cannot be moved, protect them as much as possible, e.g., by
covering in plastic if water is still leaking into the area or by
elevating off the floor to remove from direct water contact.
If this is not possible, you might consider moving wet items to a
separate dry location. This can decrease dry time since you are not
trying to dry out the furniture and the room simultaneously.
4) Dry the Area. Control Humidity and Temperature. Once excess water
is removed, use fans/air moving devices to promote evaporation and
help drive off remaining moisture from furnishings and building
materials. This step, in turn, increases the amount of moisture in the
air, which must be removed by using dehumidifiers or by actively
exhausting air outside. Take care to ensure that partially dried areas
and/or those not initially damaged by water are stabilized as other
wet areas are being processed. Ideally, maintain relative humidity at
30-50%.
If weather permits, move wet furnishings outside to help with drying.
Do not use any building ventilation systems unless you have confirmed
that they are not damaged, contaminated, or electrically compromised
(wiring damage or electrical hazards).
There are two basic types of drying systems: open and closed. An open
or natural dehumidification system exchanges the moist air inside the
structure with dryer air from outside. For example, if outside
conditions are favorable (i.e., relative humidity less than about 40%
with moderate temperatures), opening windows and doors and
continuously ventilating the area with air movers, building exhaust
fans and/or ceiling fans will speed the drying process.
Page 2 of 18
A closed or mechanical system uses equipment to remove the evaporated
water from the remediation area. Be careful to ensure that the
dehumidification rate does not go below the evaporation rate or you
will slow drying time and may actually cause additional damage.
Controlling the temperature in the building will enhance both
evaporation and dehumidification efforts.
You should routinely check the temperature, relative humidity, and
material moisture to monitor drying progress. A moisture meter is
essential for determining the status of structural components and
furnishings.
5) Clean the area. Remove Mold if Required.
a) Once water is removed, assess remaining structural materials and
building contents to determine what can be saved. The general rule is
to remove all porous materials that were/are wet or damaged. Use a
mild detergent and water solution to clean non-porous materials.
b) If mold is visible or materials have been wet longer than 48 hours,
more extensive actions are needed to ensure that mold is completely
removed and unlikely to reappear. Mold removal plans must be approved
by the cognizant industrial hygiene, safety, and facilities personnel.
c) As a minimum, the plan should specify exactly what will be done
during remediation, how it will be accomplished, acceptable criteria
for reoccupancy, required sampling procedures and how to interpret
results. For example, include detailed removal procedures; protective
equipment for remediators; type of containments; contaminated material
disposal; special cleaning requirements (books, carpet): sampling
method(s) and interpretation criteria if sampling is required;
employee relocation requirements if needed; and risk communication
plan (e.g., meetings with employees, method and frequency of status
reports to employees and management, points of contact).
d) The cleanup and remediation guidance in this section applies only
when the contamination results from clean water intrusion, such as
broken water supply lines, roof or window leaks, or condensate from
high relative humidity. Cleanup of gray water (contains some
contamination, e.g., dishwasher or washing machine overflows; toilet
overflow (no feces)) or black water (unsanitary, pathogenic water
source, e.g., sewage; storm flooding) requires more extensive
procedures and protection because of the unsanitary conditions.
e) All procedures discussed in this section are minimum
recommendations for cleaning and/or decontaminating materials that
have been subjected to water damage, including building contents,
ventilation systems, and structural components. The investigative team
may recommend more stringent procedures based on actual conditions at
the site.
Page 3 of 18
f) Killing mold is not sufficient. Because residual biomass can still
elicit allergenic responses from sensitive individuals, mold must be
removed.
6) Ensure Personnel Protection and Communication.
a) Protect personnel, including occupants and cleanup/ remediation
personnel - A successful remediation means that all mold, spores, and
dusts are removed without exposing personnel or releasing any of the
contamination to other parts of the building or to the environment.
Protection is discussed in detail later in this section.
b) Communication - A critical component of the assessment phase is
open and honest communication and information exchange between the
investigators, managers, and occupants. This is even more important
during remediation. People need assurance that their work environment
is safe and that they are not exposed to the mold during cleaning or
removal procedures. Inform occupants of exactly what will occur during
remediation and what precautions are in place to protect them.
7) Follow up. After cleanup/ remediation is complete, revisit the area
periodically to ensure that leak repairs were effective, materials are
still dry, occupants have no complaints, and mold has not returned.
CLEANING AND REMEDIATION PROCEDURES
1) General Considerations
a) In most cases, at least some kind of cleaning will be required
following water infiltration. Even with quick response actions, the
area will have to be dried out and surfaces wiped down to prevent mold
growth. If mold is visible, it must be completely removed. This can be
as simple as washing and (high efficiency particulate air (HEPA)
vacuuming, or as complex as demolition and reconstruction.
b) Successful cleaning requires an understanding of the location of
contamination and the reason why fungal growth initially occurred. The
more extensive the moisture damage, the more likely it is that you
need to look for hidden mold colonization. Thus it may be necessary to
open and inspect representative structural components (i.e.,
destructive investigation) to estimate the extent of mold growth and
determine the best remediation approach.
c) When writing or reviewing a cleaning and remediation plan, think
about the following issues. While the plan should be written by the
facility, public works, or the contractor, it should be coordinated
with and reviewed by IH, safety, occupational medicine, and other
appropriate members of the investigative team.
i) Type of Occupant – Use more conservative guidelines for cleaning
mold in high risk populations, such as health care facilities or child
care centers.
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ii) Building Structure - Residential buildings generally have more
wood (framing) than commercial buildings. Commercial building may have
steel support structures that are less likely to support mold growth
and are usually easier to clean if they become contaminated.
iii) Building Use - Special protocols are needed to clean mold in
libraries or museums where discarding contaminated contents may not be
an option.
iv) Extent of contamination – Small areas of visible mold growth can
be cleaned quickly and easily. At the other extreme, buildings with
extensive contamination may need to be demolished down to the
structural framing for successful remediation.
v) Potential health effects - Are occupants reporting symptoms? Are
there confirmed diagnoses from a physician (vs. self-reported
diagnosis)?
vi) Potential for personnel exposure – Define the exposure pathway to
ensure remediation addressees the complete process.
vii)Remediation risks - Consider the potential for spreading
contamination and possible health impacts to occupants and
remediators.
viii) Remediation costs - Can the area be cleaned successfully? What
are the costs for remediation vs. relocating employees to another
site?
ix) Building plans – Is the contaminated building already scheduled
for demolition or extensive renovation?
2) Cleaning Guide Based on Type of Material. In general, the success
and ease of cleaning building materials is based on their porosity.
a) Non-porous - Materials that do not absorb moisture and will dry
quickly, such as metal, glass, hard plastic, tile. These materials can
usually be salvaged by thoroughly cleaning with a mild detergent
solution. If visibly contaminated, materials should also be HEPA
vacuumed before returning to service. Ensure that ALL surfaces of the
object(s) are clean.
b) Semi-porous – Materials like wood, concrete, linoleum and vinyl
floor covering, vinyl wall covering, hardboard furniture, painted
drywall or plaster. These will absorb moisture if exposed to water for
a long time. If semi-porous materials are very wet, it is best to
discard them. Otherwise, they can be dried thoroughly and cleaned the
same as non-porous materials.
c) Porous – Because porous materials readily absorb and retain water,
they should almost always be discarded. Examples include carpet,
padding, mattresses, stuffed furniture,
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wicker, fabrics, wallboard, insulation, and ceiling tiles. You can
usually save linens, drapes, and clothes after thorough washing or
professional dry-cleaning.
i) Damp wiping and vacuuming will not work because you cannot clean
the air spaces and channels that are an inherent part of the structure
of porous materials. For example, damp wiping gypsum wall board will
remove vegetative colonies and mold components on the surface but will
not remove colonies or spores that have infiltrated the “nooks and
crannies” within and throughout the wallboard. This is why if you wash
mold off a wall but take no further action, the mold will usually
reappear in a week or so.
ii) The exception to discarding porous materials is when dealing with
items that have historic or high monetary value, are irreplaceable, or
have sentimental or other inherent value (i.e., furniture, books, art,
carpets). Such articles may be cleaned, but it requires special
procedures and hiring a specialist is usually the best option. This is
very expensive and may not be successful.
d) Following is general guidance for cleaning groups of material that
are damaged by clean water and/or have visible mold growth. Check
material dryness with a moisture meter. For floors and structural
components, a meter with drivable pins is best so that the probes can
penetrate to the center of the material.
i) Papers and Books - Consider photocopying important documents and
discarding the originals. You may be able to freeze or freeze dry
paper items.
ii) Ceiling tiles & insulation - Discard.
iii) Upholstery & drapes, including upholstered furniture - May
require fans, heaters, and dehumidifiers for complete drying. Launder
drapes if washable. If foam or stuffing material in upholstered items
cannot be dried completely, remove and replace it. If this is not
possible, discard the item.
iv)Wallboard, drywall, gypsum - Dry in place and check with moisture
meter. If seams separate or swelling occurs, remove and discard.
Ventilate wall cavities to ensure drying of support structures.
v) Wood surfaces (such as floors, furniture, wood structure supports)
- Dry furniture and flooring thoroughly, using heat with caution so as
not to split or crack the wood. Wood paneling should be removed from
the wall for drying.
vi) Hard surfaces & porous flooring (metal, plastic, glass, linoleum,
vinyl, ceramic tile) - Mop or wet vacuum excess water from hard
surface, then air or heat dry. It is important to check sub floors
with a moisture meter to ensure they are dry. If drying is not
successful or flooring warps, cracks, or splits, it will be necessary
to completely remove the floor or wall covering.
Page 6 of 18
vii)Carpet and backing/padding - While carpet can be successfully
cleaned and dried if done correctly, in most cases it is more
economical and practical to remove and discard the carpet and pad.
Individual rugs can be washed or dry-cleaned.
viii) Concrete/ block - Fans and/or heaters will probably be needed
for thorough drying.
3) Cleaning Guide Based on Cleaning Method
a) Damp wiping - For visibly contaminated hard, non-porous surfaces
(metal, glass, hard plastic) and some semi-porous surfaces (wood,
concrete), mold spores and fragments can usually be removed
satisfactorily by wiping the surface and/or scrubbing with water and a
mild detergent solution. Use wood floor cleaner for wood surfaces to
preclude further damage to the wood. Ensure that all wiped surfaces
are completely dried.
b) Wet vacuuming, also called water extraction vacuuming, is used to
remove water from floors, carpets, and hard surfaces. For porous
materials that have been wet less than 48 hours and are not visibly
contaminated, these vacuums can be useful to speed the drying process.
DO NOT use wet vacuums on porous materials after they are dry, as this
can actually spread spores. Thoroughly clean and rinse the vacuum,
hoses, and attachments after use.
c) HEPA vacuuming - Vacuum all surfaces with a HEPA vacuum after
completing the damp wipe step. Ensure items are completely dry before
vacuuming. Properly cleaned and vacuumed items can usually be returned
to service when the area is cleared for reoccupancy.
HEPA vacuum all room surfaces before collecting clearance samples,
making sure to vacuum ledges, cabinet tops, and other hidden surfaces
where spores are likely to settle. The HEPA vacuum filter and contents
should be double bagged, sealed, and disposed of properly.
d) Disposal - Prior to disposal, secure mold-contaminated waste using
the following procedures. Ensure that rags, disposable protective
clothing, and similar items are also placed into disposal bags.
Dispose of wastes in a sanitary landfill.
i) Small/Medium remediation jobs (i.e., less than 100 square feet
(ft2) - Lightly mist contaminated materials that are being discarded
BEFORE disturbing the material. Use a handheld sprayer filled with
water or a water/ mild detergent mixture. Misting will minimize
generating airborne mold or dust during handling. Place materials into
6-millimeter thick polyethylene (6-mil poly) bags, seal, and damp wipe
the outside of the bag before disposal.
ii) Large remediation jobs (over 100 ft2) - Use double 6-mil poly bags
or sheeting for discarding contaminated items and construction debris.
While inside the containment area, place item(s) being discarded into
a bag or onto a sheet. Secure bags with a twist tie or equivalent.
Secure sheeting by folding the sheet around the item and taping.
Page 7 of 18
Transport bags/sheeting for disposal to the decontamination area. Damp
wipe outside of bags or sheeting. Place wiped bag or sheet into second
bag/sheet and secure. Damp wipe the outside of the second layer of
polyethylene. HEPA vacuum outside of bag/sheeting.
4) Antimicrobial Products (Biocides & Sanitizers)
a) In general, antimicrobial or biocide solutions are not recommended
for most cleanups. While the correct selection and use of these
products may be needed in some situations (i.e., if immunocompromised
personnel are involved or to eliminate pathogens from gray/black water
contamination), the preferred procedure is to remove the mold. Though
the biocides will kill the mold, the remaining dead biomass can be
allergenic and toxigenic.
b) Since most antimicrobials are irritants, improper application can
actually cause additional problems when the area is reoccupied. If
biocides are required, prepare and apply according to manufacturer
directions, ensure adequate contact time, and ventilate the area.
Sample antimicrobial agents are listed in Appendix 13.3-A.
c) Antimicrobial pesticides are used to (1) disinfect, sanitize,
reduce, or mitigate growth or development of microbiological
organisms; and (2) protect inanimate objects, industrial processes or
systems, surfaces, water, or other chemical substances (e.g., paints,
metalworking fluids) from contamination, fouling, or deterioration
caused by bacteria, viruses, fungi, protozoa, algae, or slime.
The EPA regulates antimicrobial agents used on inanimate objects and
surfaces as pesticides. More than 5000 antimicrobial products are
currently registered with EPA. Ensure that only registered products
are used and that those applying pesticides are trained and certified
as appropriate for the product used. Go to http://www.epa.gov/oppad001/
for more information.
Note that the EPA does not “approve” biocides for mold remediation
applications. Beware of remediation companies making such claims.
Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA),
the EPA has regulatory authority over pesticides and antimicrobial
products, but supporting legislation to review specific product
applications and issue “approvals” was never adopted or funded.
d) Biocides in ventilation systems - The EPA cautions against using
disinfectants and sanitizers in ventilation systems. In a March 2002
letter to the heating, ventilation, air conditioning and refrigeration
systems (HVAC&R) associations, the EPA states that these products have
not been evaluated for exposure risks to building occupants or
applicators. Consequently, disinfectants and sanitizers should not be
used in HVAC&R systems UNLESS the product contains directions specific
to this application. 3
Page 8 of 18
Biocides can be safely and effectively used in HVAC condensate pans
and/or coils to prevent microbial growth. Such procedures should be
part of the building’s HVAC preventive maintenance plan.
e) “Gassing” the building (i.e., using gaseous chlorine dioxide or
ozone) is not recommended. There is insufficient data on the efficacy
of such wholesale sanitizing. Further, the chemicals themselves are
toxic and may cause harm if used inappropriately.
PROTECTION DURING REMEDIATION
1) Protecting Remediation Personnel. Anyone performing actions that
are likely to disturb or dislodge mold should wear personal protective
equipment (PPE) to prevent inhalation of and direct contact with mold.
Ensure that personnel are instructed on proper donning and doffing
techniques and are enrolled in the appropriate medical surveillance
programs.
Gloves – Use gloves to protect against contact with mold biomass
(allergens), toxins, and/or cleaning solutions that may irritate the
skin. Rubber household gloves are adequate for contact with mold-
contaminated materials. If using biocides or strong cleaners, select
the glove material appropriate for the chemical (usually nitrile,
neoprene, PVC or rubber will be sufficient).
Eye protection – Wear a minimum of tight-fitting goggles to prevent
irritation from particulates.
Respirators – Respiratory protection prevents inhaling the airborne
mold, spores, and particulates that will be in the remediation area.
All personnel wearing a respirator must be trained, fit tested, and
enrolled in the Respiratory Protection Program. Wear only respirators
approved by the National Institute for Occupational Safety and Health
(NIOSH).
Use a N95 air-purifying respirator for small area remediations (<10
ft2).
If the job involves more than 10 ft2 but less than about 100 ft2 of
contaminated material, use, as a minimum, a N95 air-purifying
respirator. A half or full-face air- purifying respirator with HEPA
filters may be used based on site-specific conditions.
If remediating an extensive contaminated area (>100 ft2) or an area
with high concentrations of mold, use, as a minimum, a full-face
powered air purifying respirator (PAPR) with HEPA filters.
Coveralls, Head, and Foot Coverings – Disposable coveralls keep molds
and spores from contaminating personal clothing. Coverings also
prevent direct skin contact with the mold biomass. As a minimum, wear
protective clothing for remediations of more than 10 ft2. For large
remediations, ensure all openings (i.e., zipper, wrists, leg) are
taped.
Page 9 of 18
2) Protecting Occupants
a) Scheduling Remediation - Consider scheduling remediation work
during minimum occupancy hours to incur the least disruption.
b) Relocation - In most cases, it is not necessary to vacate the
building during remediation as long as the work area is properly
controlled. However, occupants in the actual work site should be
relocated until remediation is complete. During large remediations,
offices adjacent to the enclosure should be vacated to remove
occupants from the noise, construction traffic, and disruption
associated with the work.
i) If contamination results from gray or black water, especially in
sewage situations, occupants should be removed from the building until
cleanup and disinfection are complete.
ii) Work with the local occupational medicine department to determine
if occupants with health problems should be relocated until cleaning/
remediation is complete and the building is cleared for reoccupancy.
Health care providers may recommend temporary relocation based on
individual medical evaluations. For example, people with
hypersensitivity pneumonitis, severe allergies, asthma, immune
suppression, or chronic inflammatory lung diseases are at higher risk
and may require relocation or other accommodations during remediation.
Section 13.4 discusses medical evaluations specific to mold
contamination events.
3) Protecting the Environment
a) Containments (enclosures) are used to prevent the release of mold,
mold spores, and remediation debris into the surrounding building
areas and into the environment. Although the remediation procedures
are loosely associated with the size of the contamination area, you
have to consider actual mold concentrations. Small contaminated areas
do not usually need to be enclosed before removal. If an area is
heavily contaminated (i.e., “covered” with mold), there is a high
potential for mold/spore release and subsequent spread of
contamination to other areas. In this situation, an enclosure would be
appropriate.
b) Table 13.3-1 provides minimum containment procedures. Any
remediations with high concentrations of mold and/or extensive
contamination areas should institute the strictest containment
procedures. Also consider more extensive containments if demolition
actions (i.e., cutting, hammering) are required to remove contaminated
material. If removal work is contracted, acceptable containment
requirements should be specified in the contract.
c) When containments are properly constructed, the polyethylene
sheeting will billow inwards when placed under negative pressure. If
the sheeting billows outward or flutters, the containment is not
properly sealed. Stop work until the containment is restored to full
negative pressure.
Page 10 of 18
Table 13.3-1. Mold remediation containment guide.
CONTAMINATED AREA, ft2
PROCEDURE or ACTION
< 10
10-100
>100
HVAC1
Remove occupants from work area2.
Remove occupants from adjacent areas2.
No containment needed.
Seal off work area with flame-retardant 6-mil polyethylene sheeting
(i.e., critical barrier)3. Seal seams.
double poly
Seal off all supply and return air ducts and doors into/out of the
contained area.
Secure ventilation system.
Place work area under negative pressure using exhaust fan(s) equipped
with HEPA filters. Exhaust air outside.
4
Use airlocks into/out of the work area.
4
Establish decontamination room outside of the enclosure.
4
Use dust suppression methods (misting) on any material or object to be
removed, cut, or discarded.
Dispose of contaminated material and cleaning rags per Disposal
guidelines.
Mop or wipe down area after cleaning/removal is complete.
After damp wiping, clean the same area with a HEPA-filtered vacuum
Visually inspect work area for cleanliness (no dust).
Conduct clearance sampling before removing containment.
1 HVAC = heating, ventilation, and air-conditioning system.
2 Consult occupational medicine physician. Some occupants may be
removed based on medical conditions such as recent surgery, chronic
lung disease, immunosuppression, etc.
3 Cover area with poly sheeting from ceiling to floor. Tape (or
otherwise attach) poly to the framing or room perimeter. Tape all
seams shut. Provide slit entry with covering flap. Maintain high
negative pressure using HEPA filtered fan. Block supply and return
vents in the contaminated area.
4 If contaminated area is >30 ft2.
THE MOLD REMEDIATION WHEEL
1) The Mold Remediation Wheel, Figure 13.3-1, consolidates the
guidance discussed in this section and provides remediation
procedures, protection recommendations, and engineering controls in a
single page. The guidance is based on total contaminated area - simply
as a way of delineating job complexity. There is no known correlation
between total contaminated area and occupant health effects.
The Mold Remediation Wheel can be viewed, saved, or printed from
http://www-nmcphc.med.navy.mil/downloads/ih/ihfom/MR_wheel.pdf or
http://www-nmcphc.med.navy.mil/downloads/ih/ihfom/IHFOM_CH13-3_Figure_1.pdf.
2) The remediation wheel is adapted from The Education Safety
Association of Ontario (ESAO), Mould Growth Prevention and Remediation
4, which is based on the EPA guidance in Mold Remediation in Schools
and Commercial Buildings 2. Figure 13.3-1 has been further modified to
incorporate additional guidance and best practices from the New York
Page 11 of 18
City Department of Health Guidelines on Assessment and Remediation of
Fungi in Indoor Environments 1; Institute of Inspection, Cleaning and
Restoration Certification Standard IICRC S500 Standard and Reference
Guide for Professional Water Damage Restoration 5; the Manitoba
Department of Labour & Immigration Guidelines For The Investigation,
Assessment, & Remediation Of Mould In Workplaces 6; Health Canada
guidelines 7; and the American Conference of Governmental Industrial
Hygienists (ACGIH) book Bioaerosols: Assessment and Control 8.
3) The wheel is intended to be a quick reference tool for planning
mold remediation actions based on the type of material that has been
water damaged and/or contaminated. As with any tool where information
is grouped into broad categories, refer to the chapter text and
references for complete discussion.
4) How to use the Mold Remediation Wheel (Figure 13.3-1): Starting in
the center, choose the type of material that has been damaged. Stay
within the quadrant for the selected material and move outward toward
the circle periphery. New conditions, choices, or information are
added with each new ring.
Center – START
1st ring (white) = SELECT TYPE OF MATERIAL
2nd ring (yellow) = ACTION 24-48 HOURS - If response is within 48
hours of clean water damage and there is no visible mold growth, match
the numbers in this ring with the response actions in the yellow box
below the wheel.
3rd ring (white) = ACTION >48 HOURS – If response is more than 48
hours after clean water damage or if there is visible mold growth,
move to the 4th ring.
4th ring (white) = CONTAMINATION AREA - Determine the extent of
contamination. The general categories are:
Less than 10 square feet [<10 ft2] (e.g., a ceiling tiles; small area
of wallboard)
Between 10 ft2 and 100 ft2 [10 –100 ft2] (e.g., 1-3 wallboard panels)
More than 100 ft2 [>100 ft2] (e.g., the whole wall)
5th ring (blue) = CLEANUP / REMEDIATION METHODS - Match the letters in
this ring with the remediation/ cleanup methods shown in the blue box
below the wheel.
6th ring (pink) = PPE – Match the letters with the personal protective
equipment (PPE) codes in the pink box below the wheel.
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7th ring (green) = CONTAINMENT - In the outer ring, determine if
containment is needed and if so, what level. Match the letter in this
ring with the containment code in the green box below the wheel.
Page 13 of 18
QUALIFIED PERSONNEL
There are no specific regulations that govern mold remediation or
define qualifications for personnel who clean and remediate
contaminated areas. In general:
Small and medium isolated areas (e.g., less than 3 sheets of
wallboard) – Remediation can be done by maintenance personnel who have
been specifically trained on mold contamination cleaning procedures,
potential hazards, and proper protective equipment.
Large areas (over 100 ft2; e.g., an entire wall in an office) and HVAC
systems – Only personnel specially trained in mold contamination
cleanup and disposal procedures should do large scale remediation.
Further, an occupational safety and health professional should oversee
the remediation, including reviewing protocols and contract
requirements.
MOLD/ INDOOR AIR QUALITY CERTIFICATIONS
There are certifications that cover the range from indoor air quality
generalist to very specific titles. Below are the sponsoring
organizations and certifications they offer. We have listed only
organizations whose certification requirements include as a minimum:
education and/or experience to qualify; written examination; and
ongoing training and recertification programs.
DISCLAIMER: This list is provided as an information resource to assist
Navy Industrial Hygienists in making an informed decision about mold
remediators’ qualifications. Listing does not imply endorsement by the
Department of Defense, the Navy, or the Navy and Marine Corps Public
Health Center, nor does it mean that these certifications have merit.
American Indoor Air Quality Council – Council Certified Indoor
Environmental Consultant (CIEC™); Council Certified Indoor
Environmentalist (CIE™); Council Certified Microbial Consultant
(CMC™); Council Certified Microbial Investigator (CMI™); Council
Certified Residential Mold Inspector (CRMI™); Council Certified
Microbial Remediation Supervisor (CMRS™); Council Certified Microbial
Remediator (CMR™); Council Certified Indoor Air Quality Manager
(CIAQM™); Council Certified Microbial Claims Adjuster (CMCA™) (http://
www.iaqcouncil.org./certification/becomecertified.htm).
Association of Energy Engineers – Certified Indoor Air Quality
Professional (CIAQP®) (www.aeecenter.org/certification).
Professional Certification Institute – Certified Mold Inspector
(Certified Toxic Mold Investigator); Certified Mold Remediator
(Certified Black Mold Contractor); Certified Environmental Hygienist
(www.certifiedmoldinspectors.com).
Institute of Professional Environmental Practice – Qualified
Environmental Professional (QEP); Environmental Professional Intern
(EPI) (http://www.ipep.org/).
Page 14 of 18
Figure 13.3-1
National Air Duct Cleaners Association – Certified Air Systems
Cleaning Specialist (ASCS); Certified Ventilation Inspectors (CVI);
Ventilation System Mold Remediator (VSMR) (www.nadca.com/certification/
index.aspx).
CLEARANCE SAMPLING
The New York City Department of Health Guidelines on Assessment and
Remediation of Fungi in Indoor Environments 1, EPA’s Mold Remediation
in Schools and Commercial Buildings 2, and the ACGIH Bioaerosols:
Assessment and Control 8 provide guidance on assessing and remediating
fungal contamination in buildings. Though there are differences in the
documents, they all agree that visible fungal growth should not be
present in indoor occupied space, regardless of the number or type of
fungi. Consequently, the goals of remediation are to (1) completely
remove microbial reservoirs, and (2) thoroughly clean the air and all
surfaces in the affected area.
Successful remediation has been defined as reoccupancy without
subsequent complaints or reported symptoms associated with fungal
contamination. Sampling may help determine the likelihood of achieving
this success.
Before sampling in any building, be sure there is a clear plan for
data evaluation. Understand the sampling limitations and what the
results may – or may not – mean.
General area, HVAC system, and/or surface sampling both before and
after cleaning may be useful to show remediation success. Develop a
sampling plan that explains where and how to sample, pass-fail
criteria, and what action is required if samples fail.
Remember that the area will not be sterile even after a successful
remediation! In general, you are looking for a decrease in the number
and types of fungi.
Clearance sampling is not always needed, especially for small
remediation jobs.
Sampling should be done when you must:
• Assure personnel that mold was successfully removed.
• Document that the containment was not compromised.
• Show that a remediated area is ready for occupancy.
• Remediate more than 10 ft2 of the HVAC system. After the ventilation
system is cleaned and visually inspected, sample in the ducts, at the
supply registers, and/or in the ambient spaces served by the
remediated system to make sure the ducts are clean and adjacent spaces
are not contaminated.
Page 15 of 18
1) Clearance Procedure. (See Figure 13.3-2 for process diagram).
a) Perform a visual inspection of the cleaned, remediated area to
ensure absence of visible fungal growth. It may be helpful to do a
“white glove inspection” – that is, use a clean white glove, sterile
cotton gauze square or equivalent. Wipe across surfaces to check for
dust or debris. This is particularly helpful for quickly checking
ledges, recessed surfaces, and out-of-the-way areas. Carefully inspect
hard to reach spots since they may have been missed or insufficiently
cleaned during remediation.
b) Any areas or surfaces that do not pass the visual inspection must
be re-cleaned, i.e., damp wipe with water/detergent, then HEPA vacuum.
c) If the remediated area includes a containment, conduct clearance
sampling with the containment in place. Leave negative air systems
running so any remaining contamination will not be distributed.
d) Collect air samples inside the work area using aggressive
techniques (i.e., use a leaf blower to move the air in the room before
sampling). Total spore counts are sufficient for clearance sampling
except in very unusual cases.
e) Collect air samples outside, preferably at the fresh air intake
that supplies the remediated area, to use as ambient controls for
comparing with inside results.
f) You may want to collect control samples in non-contaminated areas
of the building that can be used for comparing the inside contaminated/
remediated site with a comparable inside non-contaminated/non-
complaint area.
g) Swab or tape samples are usually sufficient to check for adequate
surface cleaning.
2) Interpreting Clearance Sample Results
a) Inside sample results should be less than or equal to outside
sample results for total spores, rank order, and biodiversity of taxa.
b) In pre- and post-remediation sampling comparisons, post results
should show essentially zero spores. As a minimum, post-cleaning
results should be significantly less than pre, with no indicator
species present.
c) Indicator species (Aspergillus, Penicillium, Chaetomium,
Stachybotrys, Memnoniella) in inside samples should be absent or lower
than outside control samples.
For practical purposes, finding 1 or 2 spores of an indicator species
inside during clearance sampling should not automatically trigger re-
cleaning. However, because the mere presence of some indicator
species, like Stachybotrys, may cause employee concern, it may be
prudent to repeat the cleaning protocol until no spores are found
during clearance sampling. The investigating team should determine
whether zero
Page 16 of 18
indicator species spores will be required to pass the clearance test.
Document the decision in the sampling plan along with the criteria for
clearance.
d) If indoor total spore concentrations are greater than outdoor
results, or if there are reversals/differences in rank order and
biodiversity, this indicates that fungal reservoirs may still be
present in the work area. Inspect the area for visible contamination.
If mold is found, repeat the remediation protocol for the affected
area and contents. If unable to locate visible contamination, search
for hidden mold reservoirs and, if found, repeat the complete
protocol.
e) In general, if inside sample results are less than or equal to
outside results (total spores, rank order, biodiversity of taxa, and
indicator species), the area can be reoccupied. Actual reoccupancy
criteria will be specified in the remediation plan.
f) Medical Support Sampling - In cases with medical diagnoses that
indicate suspected or specific fungi, clearance sampling should
include viable sample collection so that recovered fungi can be
speciated.
If diagnosis is linked to allergic symptoms, total spore counts are
essential for clearance sampling because analysis counts all
particulates. Remember that dead mold spores can still elicit
allergenic responses.
If a genetic signature (target specific primer) is available for a
suspected causative fungus, polymerase chain reaction (PCR) testing
may also be useful.
OTHER POST-REMEDIATION TESTS
1) Carpet. If carpet was cleaned rather than removed, clearance
sampling should include collecting representative samples with a
microvacuum on a 1 ft. x 1 ft. template. Sample results should show
spore counts, rank order, and biodiversity less than pre-cleaned
carpet samples.
Remember that it is almost always best to remove and discard water-
damaged carpet. Carpet damaged from clean water may be successfully
cleaned if it is properly dried within 24-48 hours and has no visible
growth. For gray water damage, salvaging carpet will depend on the
extent of damage and the responder’s professional judgment. Without
exception, discard carpet damaged by black water.
2) Surface Cleaning Effectiveness. If you need to confirm surface
cleaning effectiveness for decontamination of non-porous or semi-
porous materials, collect surface samples using scotch tape, swabs, or
wipes. Surfaces should be spore-free.
3) Moisture Testing. Moisture meters can be useful to monitor the
drying process for wood (e.g., flooring; structural supports; siding),
concrete, brick, carpet, wallboard, and exterior insulation and finish
systems (EIFS).
Page 17 of 18
AFTER THE REMEDIATION: ENSURING SUCCESS
Follow-up inspections are required to ensure that contamination
conditions do not recur.
Reinspect the remediated area every 2-3 weeks until satisfied that
water intrusion has stopped and mold growth is unlikely to recur. Look
for any new water sources. Also check to ensure that porous/semi-
porous building materials that were cleaned remain free of visible
contamination.
Provide update reports to employees/occupants until the investigation
team determines that the contamination has been successfully
remediated. Provide a final report to occupants when remediation is
complete.
Ensure there is an appropriate preventive maintenance plan for the
HVAC system and that the building owner understands the importance of
strict maintenance.
REFERENCES CITED
1. Guidelines on Assessment and Remediation of Fungi in Indoor
Environments. New York City Department of Health. Available at
www.nyc.gov/html/doh/html/epi/moldrpt1.shtml.
2. Mold Remediation and Schools and Commercial Buildings. United
States Environmental Protection Agency, Office of Air and Radiation,
Indoor Environments Division (6609-J) EPA 402-K-01-001. March 2001.
Available at www.epa.gov/mold/mold_remediation.html.
3. Use of Disinfectants and Sanitizers in Heating, Ventilation, Air
Conditioning, and Refrigeration Systems. United States Environmental
Protection Agency, Office of Pesticide Programs. March 14, 2002.
Available at http://www.epa.gov/oppad001/hvac.htm.
4. Mould Growth Prevention and Remediation. Education Safety
Association of Ontario (ESAO). Available at (www.esao.on.ca/downloads/
policies_pdfs/mould_procedure.pdf; www.esao.on.ca/clients/safety_specific/links.htm).
5. Standard and Reference Guide for Professional Water Damage
Restoration. Institute of Inspection, Cleaning and Restoration
Certification Standard IICRC S500. 2006. Available at
www.iicrc.org/iicrcstandards.shtml.
6. Guidelines For The Investigation, Assessment, & Remediation Of
Mould In Workplaces. Manitoba Department of Labour & Immigration.
March 2001. Available at www.gov.mb.ca/labour/safety/pdf/mouldguide.pdf.
7. Health Canada guidelines. Available at www.hc-sc.gc.ca/ewh-semt/air/in/index_e.html.
8. Bioaerosols: Assessment and Control. American Conference of
Governmental Industrial Hygienists (ACGIH). 1999. Available at
www.acgih.org/store/ProductDetail.cfm?id=349.
Page 18 of 18
CHAPTER 13, SECTION 3
MOLD CLEANUP, REMEDIATION, AND CLEARANCE SAMPLING
IINTRODUCTION
The previous section stressed that prevention is the best policy: if
water does not get into the building, mold will not grow. However, if
you do find mold, it is crucial that you know how to safely and
effectively remove the contamination and to assess the project
success. Be prepared to review contract requirements, oversee the
remediation, or liaise with occupants about associated concerns.
This section is a compilation of the most widely practiced mold
remediation guidance, using the New York City Department of Health
Guidelines on Assessment and Remediation of Fungi in Indoor
Environments 1 as the foundation. Originally issued in 1993
specifically for Stachybotrys remediation, these guidelines were
expanded in 2000 to cover all mold remediation in indoor environments.
Information from the Environmental Protection Agency’s (EPA’s) Mold
Remediation and Schools and Commercial Buildings 2 and several other
documents is also incorporated.
“RULES” FOR RESPONSE AND REMEDIATION
1) Act Quickly. Rapid response and proper actions following water
damage are essential to significantly reduce or even prevent microbial
damage.
Ideally, response actions following water intrusion should begin
within 8 hours. Response within 24 hours will usually prevent mold
growth. If actions are not underway within 48 hours, chances are good
that mold will grow in or on water damaged materials and remediation
will be needed.
2) Locate and Fix Water Intrusion Source(s). This is essential to stop
additional water infiltration and damage. Make repairs before or
concurrent with removing water and drying the area.
Likely sources to check as water intrusion points include: the roof
(missing or damaged shingles/finish or flashing); loose or damaged
soffitts and gutters; chimneys; through-roof pipes or vents;
improperly sloped drains; improperly vented appliances, uncontrolled
humidity (i.e., moisture condenses on inside surfaces); improperly
installed vapor/moisture barriers or surface finishes (e.g., exterior
insulation and finish system [EIFS] or unsealed stucco); poorly fitted
or sealed windows; crawlspace, slab or other foundation material
(standing water or episodic incursion from rising water table);
heating and cooling system; visible signs of flooding or recurrent
water damage.
Revised 4/30/2008
3) Remove the Water and Protect Materials. Water can be removed from
hard surfaces by soaking it up or mopping. If large volumes of water
are in the building, it may be necessary to actively pump out standing
water and/or use wet vacuums. Other actions that may be helpful for
complete drying include:
a) Remove all wet carpet, rugs and padding.
b) Remove wall moldings (baseboard, decorative trim) to allow drainage
if water has entered the wall cavity.
c) Drill holes in the wallboard to facilitate drying inside the wall
cavities. Remove wet wallboard. This allows you to assess wall cavity
damage, determine when structural components are dry, and removes a
likely growth substrate for mold.
d) If built-in cabinets are wet, remove kick plates or drill holes for
drying.
e) Check for water in the ventilation ducts, pipe chases, crawl
spaces, basements, and attics.
Furnishings and other building contents that are not wet or damaged by
the water intrusion should be moved temporarily to a dry location. If
such items cannot be moved, protect them as much as possible, e.g., by
covering in plastic if water is still leaking into the area or by
elevating off the floor to remove from direct water contact.
If this is not possible, you might consider moving wet items to a
separate dry location. This can decrease dry time since you are not
trying to dry out the furniture and the room simultaneously.
4) Dry the Area. Control Humidity and Temperature. Once excess water
is removed, use fans/air moving devices to promote evaporation and
help drive off remaining moisture from furnishings and building
materials. This step, in turn, increases the amount of moisture in the
air, which must be removed by using dehumidifiers or by actively
exhausting air outside. Take care to ensure that partially dried areas
and/or those not initially damaged by water are stabilized as other
wet areas are being processed. Ideally, maintain relative humidity at
30-50%.
If weather permits, move wet furnishings outside to help with drying.
Do not use any building ventilation systems unless you have confirmed
that they are not damaged, contaminated, or electrically compromised
(wiring damage or electrical hazards).
There are two basic types of drying systems: open and closed. An open
or natural dehumidification system exchanges the moist air inside the
structure with dryer air from outside. For example, if outside
conditions are favorable (i.e., relative humidity less than about 40%
with moderate temperatures), opening windows and doors and
continuously ventilating the area with air movers, building exhaust
fans and/or ceiling fans will speed the drying process.
Page 2 of 18
A closed or mechanical system uses equipment to remove the evaporated
water from the remediation area. Be careful to ensure that the
dehumidification rate does not go below the evaporation rate or you
will slow drying time and may actually cause additional damage.
Controlling the temperature in the building will enhance both
evaporation and dehumidification efforts.
You should routinely check the temperature, relative humidity, and
material moisture to monitor drying progress. A moisture meter is
essential for determining the status of structural components and
furnishings.
5) Clean the area. Remove Mold if Required.
a) Once water is removed, assess remaining structural materials and
building contents to determine what can be saved. The general rule is
to remove all porous materials that were/are wet or damaged. Use a
mild detergent and water solution to clean non-porous materials.
b) If mold is visible or materials have been wet longer than 48 hours,
more extensive actions are needed to ensure that mold is completely
removed and unlikely to reappear. Mold removal plans must be approved
by the cognizant industrial hygiene, safety, and facilities personnel.
c) As a minimum, the plan should specify exactly what will be done
during remediation, how it will be accomplished, acceptable criteria
for reoccupancy, required sampling procedures and how to interpret
results. For example, include detailed removal procedures; protective
equipment for remediators; type of containments; contaminated material
disposal; special cleaning requirements (books, carpet): sampling
method(s) and interpretation criteria if sampling is required;
employee relocation requirements if needed; and risk communication
plan (e.g., meetings with employees, method and frequency of status
reports to employees and management, points of contact).
d) The cleanup and remediation guidance in this section applies only
when the contamination results from clean water intrusion, such as
broken water supply lines, roof or window leaks, or condensate from
high relative humidity. Cleanup of gray water (contains some
contamination, e.g., dishwasher or washing machine overflows; toilet
overflow (no feces)) or black water (unsanitary, pathogenic water
source, e.g., sewage; storm flooding) requires more extensive
procedures and protection because of the unsanitary conditions.
e) All procedures discussed in this section are minimum
recommendations for cleaning and/or decontaminating materials that
have been subjected to water damage, including building contents,
ventilation systems, and structural components. The investigative team
may recommend more stringent procedures based on actual conditions at
the site.
Page 3 of 18
f) Killing mold is not sufficient. Because residual biomass can still
elicit allergenic responses from sensitive individuals, mold must be
removed.
6) Ensure Personnel Protection and Communication.
a) Protect personnel, including occupants and cleanup/ remediation
personnel - A successful remediation means that all mold, spores, and
dusts are removed without exposing personnel or releasing any of the
contamination to other parts of the building or to the environment.
Protection is discussed in detail later in this section.
b) Communication - A critical component of the assessment phase is
open and honest communication and information exchange between the
investigators, managers, and occupants. This is even more important
during remediation. People need assurance that their work environment
is safe and that they are not exposed to the mold during cleaning or
removal procedures. Inform occupants of exactly what will occur during
remediation and what precautions are in place to protect them.
7) Follow up. After cleanup/ remediation is complete, revisit the area
periodically to ensure that leak repairs were effective, materials are
still dry, occupants have no complaints, and mold has not returned.
CLEANING AND REMEDIATION PROCEDURES
1) General Considerations
a) In most cases, at least some kind of cleaning will be required
following water infiltration. Even with quick response actions, the
area will have to be dried out and surfaces wiped down to prevent mold
growth. If mold is visible, it must be completely removed. This can be
as simple as washing and (high efficiency particulate air (HEPA)
vacuuming, or as complex as demolition and reconstruction.
b) Successful cleaning requires an understanding of the location of
contamination and the reason why fungal growth initially occurred. The
more extensive the moisture damage, the more likely it is that you
need to look for hidden mold colonization. Thus it may be necessary to
open and inspect representative structural components (i.e.,
destructive investigation) to estimate the extent of mold growth and
determine the best remediation approach.
c) When writing or reviewing a cleaning and remediation plan, think
about the following issues. While the plan should be written by the
facility, public works, or the contractor, it should be coordinated
with and reviewed by IH, safety, occupational medicine, and other
appropriate members of the investigative team.
i) Type of Occupant – Use more conservative guidelines for cleaning
mold in high risk populations, such as health care facilities or child
care centers.
Page 4 of 18
ii) Building Structure - Residential buildings generally have more
wood (framing) than commercial buildings. Commercial building may have
steel support structures that are less likely to support mold growth
and are usually easier to clean if they become contaminated.
iii) Building Use - Special protocols are needed to clean mold in
libraries or museums where discarding contaminated contents may not be
an option.
iv) Extent of contamination – Small areas of visible mold growth can
be cleaned quickly and easily. At the other extreme, buildings with
extensive contamination may need to be demolished down to the
structural framing for successful remediation.
v) Potential health effects - Are occupants reporting symptoms? Are
there confirmed diagnoses from a physician (vs. self-reported
diagnosis)?
vi) Potential for personnel exposure – Define the exposure pathway to
ensure remediation addressees the complete process.
vii)Remediation risks - Consider the potential for spreading
contamination and possible health impacts to occupants and
remediators.
viii) Remediation costs - Can the area be cleaned successfully? What
are the costs for remediation vs. relocating employees to another
site?
ix) Building plans – Is the contaminated building already scheduled
for demolition or extensive renovation?
2) Cleaning Guide Based on Type of Material. In general, the success
and ease of cleaning building materials is based on their porosity.
a) Non-porous - Materials that do not absorb moisture and will dry
quickly, such as metal, glass, hard plastic, tile. These materials can
usually be salvaged by thoroughly cleaning with a mild detergent
solution. If visibly contaminated, materials should also be HEPA
vacuumed before returning to service. Ensure that ALL surfaces of the
object(s) are clean.
b) Semi-porous – Materials like wood, concrete, linoleum and vinyl
floor covering, vinyl wall covering, hardboard furniture, painted
drywall or plaster. These will absorb moisture if exposed to water for
a long time. If semi-porous materials are very wet, it is best to
discard them. Otherwise, they can be dried thoroughly and cleaned the
same as non-porous materials.
c) Porous – Because porous materials readily absorb and retain water,
they should almost always be discarded. Examples include carpet,
padding, mattresses, stuffed furniture,
Page 5 of 18
wicker, fabrics, wallboard, insulation, and ceiling tiles. You can
usually save linens, drapes, and clothes after thorough washing or
professional dry-cleaning.
i) Damp wiping and vacuuming will not work because you cannot clean
the air spaces and channels that are an inherent part of the structure
of porous materials. For example, damp wiping gypsum wall board will
remove vegetative colonies and mold components on the surface but will
not remove colonies or spores that have infiltrated the “nooks and
crannies” within and throughout the wallboard. This is why if you wash
mold off a wall but take no further action, the mold will usually
reappear in a week or so.
ii) The exception to discarding porous materials is when dealing with
items that have historic or high monetary value, are irreplaceable, or
have sentimental or other inherent value (i.e., furniture, books, art,
carpets). Such articles may be cleaned, but it requires special
procedures and hiring a specialist is usually the best option. This is
very expensive and may not be successful.
d) Following is general guidance for cleaning groups of material that
are damaged by clean water and/or have visible mold growth. Check
material dryness with a moisture meter. For floors and structural
components, a meter with drivable pins is best so that the probes can
penetrate to the center of the material.
i) Papers and Books - Consider photocopying important documents and
discarding the originals. You may be able to freeze or freeze dry
paper items.
ii) Ceiling tiles & insulation - Discard.
iii) Upholstery & drapes, including upholstered furniture - May
require fans, heaters, and dehumidifiers for complete drying. Launder
drapes if washable. If foam or stuffing material in upholstered items
cannot be dried completely, remove and replace it. If this is not
possible, discard the item.
iv)Wallboard, drywall, gypsum - Dry in place and check with moisture
meter. If seams separate or swelling occurs, remove and discard.
Ventilate wall cavities to ensure drying of support structures.
v) Wood surfaces (such as floors, furniture, wood structure supports)
- Dry furniture and flooring thoroughly, using heat with caution so as
not to split or crack the wood. Wood paneling should be removed from
the wall for drying.
vi) Hard surfaces & porous flooring (metal, plastic, glass, linoleum,
vinyl, ceramic tile) - Mop or wet vacuum excess water from hard
surface, then air or heat dry. It is important to check sub floors
with a moisture meter to ensure they are dry. If drying is not
successful or flooring warps, cracks, or splits, it will be necessary
to completely remove the floor or wall covering.
Page 6 of 18
vii)Carpet and backing/padding - While carpet can be successfully
cleaned and dried if done correctly, in most cases it is more
economical and practical to remove and discard the carpet and pad.
Individual rugs can be washed or dry-cleaned.
viii) Concrete/ block - Fans and/or heaters will probably be needed
for thorough drying.
3) Cleaning Guide Based on Cleaning Method
a) Damp wiping - For visibly contaminated hard, non-porous surfaces
(metal, glass, hard plastic) and some semi-porous surfaces (wood,
concrete), mold spores and fragments can usually be removed
satisfactorily by wiping the surface and/or scrubbing with water and a
mild detergent solution. Use wood floor cleaner for wood surfaces to
preclude further damage to the wood. Ensure that all wiped surfaces
are completely dried.
b) Wet vacuuming, also called water extraction vacuuming, is used to
remove water from floors, carpets, and hard surfaces. For porous
materials that have been wet less than 48 hours and are not visibly
contaminated, these vacuums can be useful to speed the drying process.
DO NOT use wet vacuums on porous materials after they are dry, as this
can actually spread spores. Thoroughly clean and rinse the vacuum,
hoses, and attachments after use.
c) HEPA vacuuming - Vacuum all surfaces with a HEPA vacuum after
completing the damp wipe step. Ensure items are completely dry before
vacuuming. Properly cleaned and vacuumed items can usually be returned
to service when the area is cleared for reoccupancy.
HEPA vacuum all room surfaces before collecting clearance samples,
making sure to vacuum ledges, cabinet tops, and other hidden surfaces
where spores are likely to settle. The HEPA vacuum filter and contents
should be double bagged, sealed, and disposed of properly.
d) Disposal - Prior to disposal, secure mold-contaminated waste using
the following procedures. Ensure that rags, disposable protective
clothing, and similar items are also placed into disposal bags.
Dispose of wastes in a sanitary landfill.
i) Small/Medium remediation jobs (i.e., less than 100 square feet
(ft2) - Lightly mist contaminated materials that are being discarded
BEFORE disturbing the material. Use a handheld sprayer filled with
water or a water/ mild detergent mixture. Misting will minimize
generating airborne mold or dust during handling. Place materials into
6-millimeter thick polyethylene (6-mil poly) bags, seal, and damp wipe
the outside of the bag before disposal.
ii) Large remediation jobs (over 100 ft2) - Use double 6-mil poly bags
or sheeting for discarding contaminated items and construction debris.
While inside the containment area, place item(s) being discarded into
a bag or onto a sheet. Secure bags with a twist tie or equivalent.
Secure sheeting by folding the sheet around the item and taping.
Page 7 of 18
Transport bags/sheeting for disposal to the decontamination area. Damp
wipe outside of bags or sheeting. Place wiped bag or sheet into second
bag/sheet and secure. Damp wipe the outside of the second layer of
polyethylene. HEPA vacuum outside of bag/sheeting.
4) Antimicrobial Products (Biocides & Sanitizers)
a) In general, antimicrobial or biocide solutions are not recommended
for most cleanups. While the correct selection and use of these
products may be needed in some situations (i.e., if immunocompromised
personnel are involved or to eliminate pathogens from gray/black water
contamination), the preferred procedure is to remove the mold. Though
the biocides will kill the mold, the remaining dead biomass can be
allergenic and toxigenic.
b) Since most antimicrobials are irritants, improper application can
actually cause additional problems when the area is reoccupied. If
biocides are required, prepare and apply according to manufacturer
directions, ensure adequate contact time, and ventilate the area.
Sample antimicrobial agents are listed in Appendix 13.3-A.
c) Antimicrobial pesticides are used to (1) disinfect, sanitize,
reduce, or mitigate growth or development of microbiological
organisms; and (2) protect inanimate objects, industrial processes or
systems, surfaces, water, or other chemical substances (e.g., paints,
metalworking fluids) from contamination, fouling, or deterioration
caused by bacteria, viruses, fungi, protozoa, algae, or slime.
The EPA regulates antimicrobial agents used on inanimate objects and
surfaces as pesticides. More than 5000 antimicrobial products are
currently registered with EPA. Ensure that only registered products
are used and that those applying pesticides are trained and certified
as appropriate for the product used. Go to http://www.epa.gov/oppad001/
for more information.
Note that the EPA does not “approve” biocides for mold remediation
applications. Beware of remediation companies making such claims.
Under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA),
the EPA has regulatory authority over pesticides and antimicrobial
products, but supporting legislation to review specific product
applications and issue “approvals” was never adopted or funded.
d) Biocides in ventilation systems - The EPA cautions against using
disinfectants and sanitizers in ventilation systems. In a March 2002
letter to the heating, ventilation, air conditioning and refrigeration
systems (HVAC&R) associations, the EPA states that these products have
not been evaluated for exposure risks to building occupants or
applicators. Consequently, disinfectants and sanitizers should not be
used in HVAC&R systems UNLESS the product contains directions specific
to this application. 3
Page 8 of 18
Biocides can be safely and effectively used in HVAC condensate pans
and/or coils to prevent microbial growth. Such procedures should be
part of the building’s HVAC preventive maintenance plan.
e) “Gassing” the building (i.e., using gaseous chlorine dioxide or
ozone) is not recommended. There is insufficient data on the efficacy
of such wholesale sanitizing. Further, the chemicals themselves are
toxic and may cause harm if used inappropriately.
PROTECTION DURING REMEDIATION
1) Protecting Remediation Personnel. Anyone performing actions that
are likely to disturb or dislodge mold should wear personal protective
equipment (PPE) to prevent inhalation of and direct contact with mold.
Ensure that personnel are instructed on proper donning and doffing
techniques and are enrolled in the appropriate medical surveillance
programs.
Gloves – Use gloves to protect against contact with mold biomass
(allergens), toxins, and/or cleaning solutions that may irritate the
skin. Rubber household gloves are adequate for contact with mold-
contaminated materials. If using biocides or strong cleaners, select
the glove material appropriate for the chemical (usually nitrile,
neoprene, PVC or rubber will be sufficient).
Eye protection – Wear a minimum of tight-fitting goggles to prevent
irritation from particulates.
Respirators – Respiratory protection prevents inhaling the airborne
mold, spores, and particulates that will be in the remediation area.
All personnel wearing a respirator must be trained, fit tested, and
enrolled in the Respiratory Protection Program. Wear only respirators
approved by the National Institute for Occupational Safety and Health
(NIOSH).
Use a N95 air-purifying respirator for small area remediations (<10
ft2).
If the job involves more than 10 ft2 but less than about 100 ft2 of
contaminated material, use, as a minimum, a N95 air-purifying
respirator. A half or full-face air- purifying respirator with HEPA
filters may be used based on site-specific conditions.
If remediating an extensive contaminated area (>100 ft2) or an area
with high concentrations of mold, use, as a minimum, a full-face
powered air purifying respirator (PAPR) with HEPA filters.
Coveralls, Head, and Foot Coverings – Disposable coveralls keep molds
and spores from contaminating personal clothing. Coverings also
prevent direct skin contact with the mold biomass. As a minimum, wear
protective clothing for remediations of more than 10 ft2. For large
remediations, ensure all openings (i.e., zipper, wrists, leg) are
taped.
Page 9 of 18
2) Protecting Occupants
a) Scheduling Remediation - Consider scheduling remediation work
during minimum occupancy hours to incur the least disruption.
b) Relocation - In most cases, it is not necessary to vacate the
building during remediation as long as the work area is properly
controlled. However, occupants in the actual work site should be
relocated until remediation is complete. During large remediations,
offices adjacent to the enclosure should be vacated to remove
occupants from the noise, construction traffic, and disruption
associated with the work.
i) If contamination results from gray or black water, especially in
sewage situations, occupants should be removed from the building until
cleanup and disinfection are complete.
ii) Work with the local occupational medicine department to determine
if occupants with health problems should be relocated until cleaning/
remediation is complete and the building is cleared for reoccupancy.
Health care providers may recommend temporary relocation based on
individual medical evaluations. For example, people with
hypersensitivity pneumonitis, severe allergies, asthma, immune
suppression, or chronic inflammatory lung diseases are at higher risk
and may require relocation or other accommodations during remediation.
Section 13.4 discusses medical evaluations specific to mold
contamination events.
3) Protecting the Environment
a) Containments (enclosures) are used to prevent the release of mold,
mold spores, and remediation debris into the surrounding building
areas and into the environment. Although the remediation procedures
are loosely associated with the size of the contamination area, you
have to consider actual mold concentrations. Small contaminated areas
do not usually need to be enclosed before removal. If an area is
heavily contaminated (i.e., “covered” with mold), there is a high
potential for mold/spore release and subsequent spread of
contamination to other areas. In this situation, an enclosure would be
appropriate.
b) Table 13.3-1 provides minimum containment procedures. Any
remediations with high concentrations of mold and/or extensive
contamination areas should institute the strictest containment
procedures. Also consider more extensive containments if demolition
actions (i.e., cutting, hammering) are required to remove contaminated
material. If removal work is contracted, acceptable containment
requirements should be specified in the contract.
c) When containments are properly constructed, the polyethylene
sheeting will billow inwards when placed under negative pressure. If
the sheeting billows outward or flutters, the containment is not
properly sealed. Stop work until the containment is restored to full
negative pressure.
Page 10 of 18
Table 13.3-1. Mold remediation containment guide.
CONTAMINATED AREA, ft2
PROCEDURE or ACTION
< 10
10-100
>100
HVAC1
Remove occupants from work area2.
Remove occupants from adjacent areas2.
No containment needed.
Seal off work area with flame-retardant 6-mil polyethylene sheeting
(i.e., critical barrier)3. Seal seams.
double poly
Seal off all supply and return air ducts and doors into/out of the
contained area.
Secure ventilation system.
Place work area under negative pressure using exhaust fan(s) equipped
with HEPA filters. Exhaust air outside.
4
Use airlocks into/out of the work area.
4
Establish decontamination room outside of the enclosure.
4
Use dust suppression methods (misting) on any material or object to be
removed, cut, or discarded.
Dispose of contaminated material and cleaning rags per Disposal
guidelines.
Mop or wipe down area after cleaning/removal is complete.
After damp wiping, clean the same area with a HEPA-filtered vacuum
Visually inspect work area for cleanliness (no dust).
Conduct clearance sampling before removing containment.
1 HVAC = heating, ventilation, and air-conditioning system.
2 Consult occupational medicine physician. Some occupants may be
removed based on medical conditions such as recent surgery, chronic
lung disease, immunosuppression, etc.
3 Cover area with poly sheeting from ceiling to floor. Tape (or
otherwise attach) poly to the framing or room perimeter. Tape all
seams shut. Provide slit entry with covering flap. Maintain high
negative pressure using HEPA filtered fan. Block supply and return
vents in the contaminated area.
4 If contaminated area is >30 ft2.
THE MOLD REMEDIATION WHEEL
1) The Mold Remediation Wheel, Figure 13.3-1, consolidates the
guidance discussed in this section and provides remediation
procedures, protection recommendations, and engineering controls in a
single page. The guidance is based on total contaminated area - simply
as a way of delineating job complexity. There is no known correlation
between total contaminated area and occupant health effects.
The Mold Remediation Wheel can be viewed, saved, or printed from
http://www-nmcphc.med.navy.mil/downloads/ih/ihfom/MR_wheel.pdf or
http://www-nmcphc.med.navy.mil/downloads/ih/ihfom/IHFOM_CH13-3_Figure_1.pdf.
2) The remediation wheel is adapted from The Education Safety
Association of Ontario (ESAO), Mould Growth Prevention and Remediation
4, which is based on the EPA guidance in Mold Remediation in Schools
and Commercial Buildings 2. Figure 13.3-1 has been further modified to
incorporate additional guidance and best practices from the New York
Page 11 of 18
City Department of Health Guidelines on Assessment and Remediation of
Fungi in Indoor Environments 1; Institute of Inspection, Cleaning and
Restoration Certification Standard IICRC S500 Standard and Reference
Guide for Professional Water Damage Restoration 5; the Manitoba
Department of Labour & Immigration Guidelines For The Investigation,
Assessment, & Remediation Of Mould In Workplaces 6; Health Canada
guidelines 7; and the American Conference of Governmental Industrial
Hygienists (ACGIH) book Bioaerosols: Assessment and Control 8.
3) The wheel is intended to be a quick reference tool for planning
mold remediation actions based on the type of material that has been
water damaged and/or contaminated. As with any tool where information
is grouped into broad categories, refer to the chapter text and
references for complete discussion.
4) How to use the Mold Remediation Wheel (Figure 13.3-1): Starting in
the center, choose the type of material that has been damaged. Stay
within the quadrant for the selected material and move outward toward
the circle periphery. New conditions, choices, or information are
added with each new ring.
Center – START
1st ring (white) = SELECT TYPE OF MATERIAL
2nd ring (yellow) = ACTION 24-48 HOURS - If response is within 48
hours of clean water damage and there is no visible mold growth, match
the numbers in this ring with the response actions in the yellow box
below the wheel.
3rd ring (white) = ACTION >48 HOURS – If response is more than 48
hours after clean water damage or if there is visible mold growth,
move to the 4th ring.
4th ring (white) = CONTAMINATION AREA - Determine the extent of
contamination. The general categories are:
Less than 10 square feet [<10 ft2] (e.g., a ceiling tiles; small area
of wallboard)
Between 10 ft2 and 100 ft2 [10 –100 ft2] (e.g., 1-3 wallboard panels)
More than 100 ft2 [>100 ft2] (e.g., the whole wall)
5th ring (blue) = CLEANUP / REMEDIATION METHODS - Match the letters in
this ring with the remediation/ cleanup methods shown in the blue box
below the wheel.
6th ring (pink) = PPE – Match the letters with the personal protective
equipment (PPE) codes in the pink box below the wheel.
Page 12 of 18
7th ring (green) = CONTAINMENT - In the outer ring, determine if
containment is needed and if so, what level. Match the letter in this
ring with the containment code in the green box below the wheel.
Page 13 of 18
QUALIFIED PERSONNEL
There are no specific regulations that govern mold remediation or
define qualifications for personnel who clean and remediate
contaminated areas. In general:
Small and medium isolated areas (e.g., less than 3 sheets of
wallboard) – Remediation can be done by maintenance personnel who have
been specifically trained on mold contamination cleaning procedures,
potential hazards, and proper protective equipment.
Large areas (over 100 ft2; e.g., an entire wall in an office) and HVAC
systems – Only personnel specially trained in mold contamination
cleanup and disposal procedures should do large scale remediation.
Further, an occupational safety and health professional should oversee
the remediation, including reviewing protocols and contract
requirements.
MOLD/ INDOOR AIR QUALITY CERTIFICATIONS
There are certifications that cover the range from indoor air quality
generalist to very specific titles. Below are the sponsoring
organizations and certifications they offer. We have listed only
organizations whose certification requirements include as a minimum:
education and/or experience to qualify; written examination; and
ongoing training and recertification programs.
DISCLAIMER: This list is provided as an information resource to assist
Navy Industrial Hygienists in making an informed decision about mold
remediators’ qualifications. Listing does not imply endorsement by the
Department of Defense, the Navy, or the Navy and Marine Corps Public
Health Center, nor does it mean that these certifications have merit.
American Indoor Air Quality Council – Council Certified Indoor
Environmental Consultant (CIEC™); Council Certified Indoor
Environmentalist (CIE™); Council Certified Microbial Consultant
(CMC™); Council Certified Microbial Investigator (CMI™); Council
Certified Residential Mold Inspector (CRMI™); Council Certified
Microbial Remediation Supervisor (CMRS™); Council Certified Microbial
Remediator (CMR™); Council Certified Indoor Air Quality Manager
(CIAQM™); Council Certified Microbial Claims Adjuster (CMCA™) (http://
www.iaqcouncil.org./certification/becomecertified.htm).
Association of Energy Engineers – Certified Indoor Air Quality
Professional (CIAQP®) (www.aeecenter.org/certification).
Professional Certification Institute – Certified Mold Inspector
(Certified Toxic Mold Investigator); Certified Mold Remediator
(Certified Black Mold Contractor); Certified Environmental Hygienist
(www.certifiedmoldinspectors.com).
Institute of Professional Environmental Practice – Qualified
Environmental Professional (QEP); Environmental Professional Intern
(EPI) (http://www.ipep.org/).
Page 14 of 18
Figure 13.3-1
National Air Duct Cleaners Association – Certified Air Systems
Cleaning Specialist (ASCS); Certified Ventilation Inspectors (CVI);
Ventilation System Mold Remediator (VSMR) (www.nadca.com/certification/
index.aspx).
CLEARANCE SAMPLING
The New York City Department of Health Guidelines on Assessment and
Remediation of Fungi in Indoor Environments 1, EPA’s Mold Remediation
in Schools and Commercial Buildings 2, and the ACGIH Bioaerosols:
Assessment and Control 8 provide guidance on assessing and remediating
fungal contamination in buildings. Though there are differences in the
documents, they all agree that visible fungal growth should not be
present in indoor occupied space, regardless of the number or type of
fungi. Consequently, the goals of remediation are to (1) completely
remove microbial reservoirs, and (2) thoroughly clean the air and all
surfaces in the affected area.
Successful remediation has been defined as reoccupancy without
subsequent complaints or reported symptoms associated with fungal
contamination. Sampling may help determine the likelihood of achieving
this success.
Before sampling in any building, be sure there is a clear plan for
data evaluation. Understand the sampling limitations and what the
results may – or may not – mean.
General area, HVAC system, and/or surface sampling both before and
after cleaning may be useful to show remediation success. Develop a
sampling plan that explains where and how to sample, pass-fail
criteria, and what action is required if samples fail.
Remember that the area will not be sterile even after a successful
remediation! In general, you are looking for a decrease in the number
and types of fungi.
Clearance sampling is not always needed, especially for small
remediation jobs.
Sampling should be done when you must:
• Assure personnel that mold was successfully removed.
• Document that the containment was not compromised.
• Show that a remediated area is ready for occupancy.
• Remediate more than 10 ft2 of the HVAC system. After the ventilation
system is cleaned and visually inspected, sample in the ducts, at the
supply registers, and/or in the ambient spaces served by the
remediated system to make sure the ducts are clean and adjacent spaces
are not contaminated.
Page 15 of 18
1) Clearance Procedure. (See Figure 13.3-2 for process diagram).
a) Perform a visual inspection of the cleaned, remediated area to
ensure absence of visible fungal growth. It may be helpful to do a
“white glove inspection” – that is, use a clean white glove, sterile
cotton gauze square or equivalent. Wipe across surfaces to check for
dust or debris. This is particularly helpful for quickly checking
ledges, recessed surfaces, and out-of-the-way areas. Carefully inspect
hard to reach spots since they may have been missed or insufficiently
cleaned during remediation.
b) Any areas or surfaces that do not pass the visual inspection must
be re-cleaned, i.e., damp wipe with water/detergent, then HEPA vacuum.
c) If the remediated area includes a containment, conduct clearance
sampling with the containment in place. Leave negative air systems
running so any remaining contamination will not be distributed.
d) Collect air samples inside the work area using aggressive
techniques (i.e., use a leaf blower to move the air in the room before
sampling). Total spore counts are sufficient for clearance sampling
except in very unusual cases.
e) Collect air samples outside, preferably at the fresh air intake
that supplies the remediated area, to use as ambient controls for
comparing with inside results.
f) You may want to collect control samples in non-contaminated areas
of the building that can be used for comparing the inside contaminated/
remediated site with a comparable inside non-contaminated/non-
complaint area.
g) Swab or tape samples are usually sufficient to check for adequate
surface cleaning.
2) Interpreting Clearance Sample Results
a) Inside sample results should be less than or equal to outside
sample results for total spores, rank order, and biodiversity of taxa.
b) In pre- and post-remediation sampling comparisons, post results
should show essentially zero spores. As a minimum, post-cleaning
results should be significantly less than pre, with no indicator
species present.
c) Indicator species (Aspergillus, Penicillium, Chaetomium,
Stachybotrys, Memnoniella) in inside samples should be absent or lower
than outside control samples.
For practical purposes, finding 1 or 2 spores of an indicator species
inside during clearance sampling should not automatically trigger re-
cleaning. However, because the mere presence of some indicator
species, like Stachybotrys, may cause employee concern, it may be
prudent to repeat the cleaning protocol until no spores are found
during clearance sampling. The investigating team should determine
whether zero
Page 16 of 18
indicator species spores will be required to pass the clearance test.
Document the decision in the sampling plan along with the criteria for
clearance.
d) If indoor total spore concentrations are greater than outdoor
results, or if there are reversals/differences in rank order and
biodiversity, this indicates that fungal reservoirs may still be
present in the work area. Inspect the area for visible contamination.
If mold is found, repeat the remediation protocol for the affected
area and contents. If unable to locate visible contamination, search
for hidden mold reservoirs and, if found, repeat the complete
protocol.
e) In general, if inside sample results are less than or equal to
outside results (total spores, rank order, biodiversity of taxa, and
indicator species), the area can be reoccupied. Actual reoccupancy
criteria will be specified in the remediation plan.
f) Medical Support Sampling - In cases with medical diagnoses that
indicate suspected or specific fungi, clearance sampling should
include viable sample collection so that recovered fungi can be
speciated.
If diagnosis is linked to allergic symptoms, total spore counts are
essential for clearance sampling because analysis counts all
particulates. Remember that dead mold spores can still elicit
allergenic responses.
If a genetic signature (target specific primer) is available for a
suspected causative fungus, polymerase chain reaction (PCR) testing
may also be useful.
OTHER POST-REMEDIATION TESTS
1) Carpet. If carpet was cleaned rather than removed, clearance
sampling should include collecting representative samples with a
microvacuum on a 1 ft. x 1 ft. template. Sample results should show
spore counts, rank order, and biodiversity less than pre-cleaned
carpet samples.
Remember that it is almost always best to remove and discard water-
damaged carpet. Carpet damaged from clean water may be successfully
cleaned if it is properly dried within 24-48 hours and has no visible
growth. For gray water damage, salvaging carpet will depend on the
extent of damage and the responder’s professional judgment. Without
exception, discard carpet damaged by black water.
2) Surface Cleaning Effectiveness. If you need to confirm surface
cleaning effectiveness for decontamination of non-porous or semi-
porous materials, collect surface samples using scotch tape, swabs, or
wipes. Surfaces should be spore-free.
3) Moisture Testing. Moisture meters can be useful to monitor the
drying process for wood (e.g., flooring; structural supports; siding),
concrete, brick, carpet, wallboard, and exterior insulation and finish
systems (EIFS).
Page 17 of 18
AFTER THE REMEDIATION: ENSURING SUCCESS
Follow-up inspections are required to ensure that contamination
conditions do not recur.
Reinspect the remediated area every 2-3 weeks until satisfied that
water intrusion has stopped and mold growth is unlikely to recur. Look
for any new water sources. Also check to ensure that porous/semi-
porous building materials that were cleaned remain free of visible
contamination.
Provide update reports to employees/occupants until the investigation
team determines that the contamination has been successfully
remediated. Provide a final report to occupants when remediation is
complete.
Ensure there is an appropriate preventive maintenance plan for the
HVAC system and that the building owner understands the importance of
strict maintenance.
REFERENCES CITED
1. Guidelines on Assessment and Remediation of Fungi in Indoor
Environments. New York City Department of Health. Available at
www.nyc.gov/html/doh/html/epi/moldrpt1.shtml.
2. Mold Remediation and Schools and Commercial Buildings. United
States Environmental Protection Agency, Office of Air and Radiation,
Indoor Environments Division (6609-J) EPA 402-K-01-001. March 2001.
Available at www.epa.gov/mold/mold_remediation.html.
3. Use of Disinfectants and Sanitizers in Heating, Ventilation, Air
Conditioning, and Refrigeration Systems. United States Environmental
Protection Agency, Office of Pesticide Programs. March 14, 2002.
Available at http://www.epa.gov/oppad001/hvac.htm.
4. Mould Growth Prevention and Remediation. Education Safety
Association of Ontario (ESAO). Available at (www.esao.on.ca/downloads/
policies_pdfs/mould_procedure.pdf; www.esao.on.ca/clients/safety_specific/links.htm).
5. Standard and Reference Guide for Professional Water Damage
Restoration. Institute of Inspection, Cleaning and Restoration
Certification Standard IICRC S500. 2006. Available at
www.iicrc.org/iicrcstandards.shtml.
6. Guidelines For The Investigation, Assessment, & Remediation Of
Mould In Workplaces. Manitoba Department of Labour & Immigration.
March 2001. Available at www.gov.mb.ca/labour/safety/pdf/mouldguide.pdf.
7. Health Canada guidelines. Available at www.hc-sc.gc.ca/ewh-semt/air/in/index_e.html.
8. Bioaerosols: Assessment and Control. American Conference of
Governmental Industrial Hygienists (ACGIH). 1999. Available at
www.acgih.org/store/ProductDetail.cfm?id=349.
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