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A 20 PROFESSIONAL SAFETY AUGUST 2003 www.asse.org Health Hazards Health Hazards Mold Risk Assessment & Remediation Proactive management, prompt action reduce risks By Daniel P. Mahoney and Jerome E. Spear A PROACTIVE ASSESSMENT of building design, site selection and construction management, coupled with ongoing facility operation and maintenance can reduce the risk of developing a mold-related problem within a building. Once mold contamination has developed, potential risks can be mitigated through prompt assessment and remedia- tion. A thorough remediation plan minimizes exposures to both building occupants and remediation workers. “Is Your Office Killing You?” (Business Week) “Beware: Toxic Mold” (Time) “Attack of the Killer Mold?” (KARK, Channel 4, Little Rock, AR) Media headlines such as these have contributed to public awareness and fear about mold contamination in buildings. Although some fungal species produce potent mycotoxins, most mold varieties cannot cause toxic effects or disease unless the exposed person is severely immun- odeficient (ACGIH). However, nearly all types of mold can cause aller- genic effects in sen- sitized individuals and some types (although a rela- tively small num- ber) may produce mycotoxins. Table 1 lists some com- mon indoor molds and their associat- ed health hazards. Prompt investi- gation, assessment and remediation (if needed) must be performed when mold contamination is discovered or suspected. Proactive property management can reduce the potential for mold contamination within a building. Mold risk assessment efforts that address facility design, site selection, construction, operation and maintenance can play a large part in reducing the potential for mold. The New York City Dept. of Health (NYCDH) has published “Guidelines on Assessment and Remediation of Fungi in Indoor Environments,” cit- ing ASHRAE 55-1992; these guidelines state: In all situations, the underlying cause of water accumulation must be rectified or fungal growth will recur. Any initial water infiltration should be stopped and cleaned immediately. An immediate response (within 24 to 48 hours) and thorough cleanup, drying and/or removal of water-damaged materials will prevent or limit mold growth. If the source of water is ele- vated humidity, relative humidity should be maintained at levels below 60 percent to inhib- it mold growth. Emphasis should be on ensur- ing proper repairs of the building infrastructure so that water damage and moisture buildup do not recur (NYCDH Section 3: Remediation). Assessing Mold Contamination When mold contamination has developed, the source of moisture must be identified and the scope of the problem assessed before cleanup begins. In most cases, sampling is not needed to assess mold contamination. Visible mold growing inside a build- ing should be remediated. In some cases, however, sampling may be prudent. For example, it may be warranted in cases that involve litigation, if the con- tamination source(s) is unclear or to mitigate health concerns of building occupants. Before collecting samples during a microbial Daniel P. Mahoney, CSP, CIH, is manager of workers’ compensation services for XL Environmental Inc., an XL Capital company located in Exton, PA. He has 21 years’ experience helping clients control occupational disease exposures, safety hazards and workers’ compensation claims, as well as extensive experience in OSHA compliance, hazard communication, industrial hygiene, and safety and health training. A member of ASSE’s Philadelphia Chapter, Mahoney earned a B.S. from Pennsylvania State University. Jerome E. Spear, CSP, CIH, is regional technical services manager based in Houston for XL Environmental Inc., an XL Capital company. He has 13 years’ experience managing and controlling workplace hazards and exposures, helping clients evaluate and manage safety- and health-related issues, including incident investigations, industrial hygiene, OSHA compliance, indoor air quality, construction safety and training. Spear holds a B.S. in Industrial Engineering, with a specialization in safety engineering, from Texas A&M University. He is a professional member of ASSE’s Gulf Coast Chapter, and belongs to both the Construction and Industrial Hygiene practice specialties.

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20 PROFESSIONAL SAFETY AUGUST 2003 www.asse.org

Health HazardsHealth Hazards

MoldRisk Assessment& Remediation

Proactive management, prompt action reduce risksBy Daniel P. Mahoney and Jerome E. Spear

A PROACTIVE ASSESSMENT of building design, siteselection and construction management, coupled withongoing facility operation and maintenance can reduce therisk of developing a mold-related problem within a building.Once mold contamination has developed, potential riskscan be mitigated through prompt assessment and remedia-tion. A thorough remediation plan minimizes exposures toboth building occupants and remediation workers.

“Is Your Office Killing You?” (Business Week)“Beware: Toxic Mold” (Time)“Attack of the Killer Mold?” (KARK, Channel 4,

Little Rock, AR)Media headlines such as these have contributed to

public awareness and fear about mold contaminationin buildings. Although some fungal species producepotent mycotoxins, most mold varieties cannot causetoxic effects or disease unless the exposed person is

severely immun-o d e f i c i e n t( A C G I H ) .However, nearlyall types of moldcan cause aller-genic effects in sen-sitized individualsand some types(although a rela-tively small num-ber) may producemycotoxins. Table1 lists some com-mon indoor moldsand their associat-ed health hazards.

Prompt investi-gation, assessmentand remediation (ifneeded) must beperformed when

mold contamination is discovered or suspected.Proactive property management can reduce thepotential for mold contamination within a building.Mold risk assessment efforts that address facilitydesign, site selection, construction, operation andmaintenance can play a large part in reducing thepotential for mold.

The New York City Dept. of Health (NYCDH)has published “Guidelines on Assessment andRemediation of Fungi in Indoor Environments,” cit-ing ASHRAE 55-1992; these guidelines state:

In all situations, the underlying cause of wateraccumulation must be rectified or fungalgrowth will recur. Any initial water infiltrationshould be stopped and cleaned immediately.An immediate response (within 24 to 48 hours)and thorough cleanup, drying and/or removalof water-damaged materials will prevent orlimit mold growth. If the source of water is ele-vated humidity, relative humidity should bemaintained at levels below 60 percent to inhib-it mold growth. Emphasis should be on ensur-ing proper repairs of the building infrastructureso that water damage and moisture buildup donot recur (NYCDH Section 3: Remediation).

Assessing Mold ContaminationWhen mold contamination has developed, the

source of moisture must be identified and the scopeof the problem assessed before cleanup begins. Inmost cases, sampling is not needed to assess moldcontamination. Visible mold growing inside a build-ing should be remediated. In some cases, however,sampling may be prudent. For example, it may bewarranted in cases that involve litigation, if the con-tamination source(s) is unclear or to mitigate healthconcerns of building occupants.

Before collecting samples during a microbial

Daniel P. Mahoney, CSP, CIH, is manager of workers’compensation services for XL Environmental Inc., an XLCapital company located in Exton, PA. He has 21 years’experience helping clients control occupational diseaseexposures, safety hazards and workers’ compensation

claims, as well as extensive experience in OSHA compliance,hazard communication, industrial hygiene, and safety andhealth training. A member of ASSE’s Philadelphia Chapter,Mahoney earned a B.S. from Pennsylvania State University.

Jerome E. Spear, CSP, CIH, is regional technical servicesmanager based in Houston for XL Environmental Inc., an XLCapital company. He has 13 years’ experience managing and

controlling workplace hazards and exposures, helpingclients evaluate and manage safety- and health-related

issues, including incident investigations, industrial hygiene,OSHA compliance, indoor air quality, construction safety

and training. Spear holds a B.S. in Industrial Engineering,with a specialization in safety engineering, from Texas A&MUniversity. He is a professional member of ASSE’s Gulf Coast

Chapter, and belongs to both the Construction andIndustrial Hygiene practice specialties.

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www.asse.org AUGUST 2003 PROFESSIONAL SAFETY 21

from upholstered furni-ture with a water-extrac-tion vacuum, and dryingof such items may beaccelerated by usingdehumidifiers and heaters(EPA). However, if thewater source is contami-nated with sewage, orchemical or biologicalagents, additional actionsshould be taken (e.g., PPE,containment).

Visible Mold GrowthWhen prevention has

failed and visible micro-bial growth has occurredin a building, restorationrequires the followingactions:

•Remove porous and semiporous materials thatcontain microbial growth or that are water damaged.

•Physically remove surface microbial growth ornonporous materials to typical background levels.

•Reduce moisture to levels that do not supportmicrobial growth.

•Perform HEPA vacuuming.•Contain work areas.•Dehumidify the area.•Conduct clearance inspections and sampling

(ACGIH).In “Guidelines on Assessment and Remediation

of Fungi in Indoor Environments,” NYCDH definesthe potential degree of risk and provides suggestedcleanup methods based on the extent of damage and

investigation, a sampling planshould be devised to ensurethat useful data are collected.The following types of sam-pling may be incorporated intoa strategy to assess mold con-tamination in a building:

•Bulk sampling. Bulk sam-ples are materials (e.g., settleddust, sections of wallboard, car-pet segments) that are tested todetermine whether they con-tain biological contamination.These samples may provideinformation about the possiblesource of contamination andthe general composition andrelative concentrations in thesesources (ACGIH).

•Surface sampling (tape,swab, contact plates). Surfacesamples may provide informa-tion similar to bulk samples.Surface sampling is preferredover bulk sampling when aless-destructive method isdesired (ACGIH).

•Bioaerosol sampling (culture plate, spore trap).Bioaerosols are defined by ACGIH as airborne parti-cles, large molecules or volatile compounds that areliving, contain living organisms or were released fromliving organisms. Bioaerosol samples are collectedusing a suction pump to capture the contaminantsonto a media (e.g., culture plate, spore trap). Culture-based sampling is the most common method; itinvolves capturing the contaminants on a cultureplate and subsequently incubating the sample in alaboratory. ACGIH has not established thresholdlimit values for most bioaerosols. Consequently, inter-pretations of bioaerosol sampling are made by com-paring the results of indoor air samples to outdoor airsamples. Table 2 outlines the advantages and disad-vantages of the various sampling methods.

Mold sampling should be conducted by qualifiedpersonnel experienced in designing mold samplingprotocols, sampling methods and interpretingresults. Samples should be analyzed by a laboratorythat participates in the Environmental MicrobiologyProficiency Analytical Testing Program (EMPAT)administered by the American Industrial HygieneAssn. (AIHA).

The Remediation PlanA Greek proverb guides, “Act quickly but think

slowly.” If water damage occurs in a building, micro-bial growth typically occurs within 24 to 48 hours, soaction must be taken quickly in order to preventmold growth. For example, damaged ceiling tiles orinsulation must be discarded and replaced immedi-ately. Hard-surface porous flooring may be vacu-umed or damp wiped with water and a milddetergent and allowed to dry. Water may be removed

Common Indoor Molds & Health HazardsMold & Fungi Species Health Impact Where Found

Alternaria

Aspergillusfumigatusflavusniger

Cladosporium

Penicillium

Mucor

Cryptococcus neoformans

Histoplasma capslulatum

Stachybotrys chartarum

Table 1Table 1

•Asthma•Eye infections•Severe allergic lung disease

•Very common allergenicresponses

•Fungal infections

•Pathogenic rarely•Systemic infections•Infections•Can progress to meningitis•Target AIDS patients•Infections•TB-like lung disease•Debatable/health effects•Fatigue, rashes, headache,nausea, coughing, diarrhea

•Aging plants•Cellulose tiles and wallpaper•Decaying leaves•Damp lining of HVAC systems•Warm environments

•Where freestanding water isavailable•Tile grout, bathroom sealants•Ceiling with condensed waterfrom piping•Cold temperatures•Refrigerated food spoilage•Very common in air•Grow on sugar and starches

•Pigeon and chicken droppings•Guano fertilizer

•Soil containing bird and batdroppings•Damp cellulose materials•Greenish black appearance•Water-damaged areas

PHO

TO C

REA

TED

BY

JEN

EAN

MIL

LS

Mold riskassessment effortsthat addressfacility design,site selection,construction,operation andmaintenance canplay a large partin reducing thepotential for mold.

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ing and draperies that can be removed for thoroughcleaning and drying may be salvageable.Nonporous surfaces may be damp wiped orscrubbed with water and mild detergent andallowed to dry. However, remediation and removalmethods should be based on the nature and extent ofcontamination (i.e., particular microorganisms pres-ent and the amount of material or area affected)(ACGIH).

To mitigate occupant concerns, minimize expo-sures and reduce cost, the remediation plan must bethorough. It should detail:

•personnel involved with the work;•how the moisture source will/has been corrected;•how exposure to bioaerosols to both remediation

workers and building occupants will be minimized;•specific cleanup methods;•final cleanup inspection and clearance sampling

procedures.

the building materials involved. These guidelinesoutline general abatement strategies (levels) basedon the square footage of the contaminated area:

•Level I: Small isolated areas (10 sq. ft. orless)—such as ceiling tiles, small areas on walls;

•Level II: Mid-sized isolated areas (10 to 30 sq.ft.)—such as individual wallboard panels.

•Level III: Large isolated areas (30 to 100 sq. ft.)—such as several wallboard panels.

•Level IV: Extensive contamination (greater than100 contiguous sq. ft. in an area).

•Level V: Remediation of HVAC systems.Table 3 provides guidance on cleanup methods,

as well as PPE and containment recommendations(NYCDH; EPA).

The remediation plan should be developed uponfinding evidence of mold and should be based onthe size of the mold and/or moisture problem andthe type of damaged materials. For example, carpet-

Advantages & Disadvantages of Sampling MethodologiesSampling Technique Advantages Disadvantages

Bulk

Swab

Tape

Culture Plate

Spore Trap

Source: Wiles, C. “Strategies for Conducting Meaningful Microbial IAQ Investigations.” American Indoor Air Quality Council seminar, Sept. 2001.

Table 2Table 2

•Inexpensive•Can provide rapid spore identification•Can be quantitative•Can identify viable and nonviable spores•Viable assay includes organisms hidden in porousmaterials•Can be cultured•Inexpensive•Nondestructive•Can provide rapid spore identification•Can be quantitative•Can be cultured•Easy to perform sampling•Sample can be collected from irregular-shapedsurface•Convenient to hold and ship•Inexpensive•Can provide rapid spore identification•Quick and easy•Convenient to hold and ship•Nondestructive•Easy to perform sampling

•Can sample for both fungi and bacteria•Relates directly to airborne exposure•Qualitative and quantitative•Can select different media to target specific organisms•Can compare to bulk, swab or tape results for iden-tifying amplification sites

•Cassettes are easy to store•Cassettes have long shelf life•Provides qualitative results•Provides semiquantitative results•Relates directly to airborne exposure•Rapid results

•Usually destructive•Removal of material may expose occupants•Does not directly relate to airborne exposures•May not be the source of amplification•Laboratory process can be difficult

•Commercial swab may have preservatives to pre-serve spores (if so, cannot be cultured)•Does not directly relate to airborne exposure•May not be the source of amplification•Fungal structures may be damaged during swab-bing, making identification less accurate•Spores may germinate before laboratory analysis•May not capture organisms in porous materials

•Cannot culture•Not quantitative•Tape pressure can deform or destroy spores•Does not directly relate to airborne exposure•May not be the source of amplification•Small sample area•May be damaged in transit•Initial equipment expensive•Sampling is cumbersome and noisy•Can isolate only viable microbials•Takes seven to 10 days to complete the analysis•Some fungi may overgrow others•Can speciate, but takes longer•Low recovery rate for Stachybotrys•Media has short shelf life•Samples are perishable•Initially expensive•Sampling is cumbersome and noisy•Does not differentiate between viable and nonviable•Large lab-to-lab variation in identification•Methodology not accepted by all within theindustry

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remediators, insurance companies are often payingfor the same job two or three times (Allen).

Since poor remediation practices can be costly tothe building owner or insurer, the remediation con-tractor should be thoroughly screened to ensure thatthe firm has experience cleaning up mold. In addi-tion, “reputable mold remediators should possessone of two certifications: certified microbial remedi-ation supervisor (CMRS) from the American IndoorAir Quality Council or the certified microbial reme-diator (CMR) from the Indoor Air Quality Assn.”(Williams 49). Before hiring a contractor, referencesshould be checked; once the project begins, the workshould be monitored to ensure that best manage-ment practices are followed.

Minimizing Exposure to BioaerosolsAccording to the California Dept. of Health,

remediation processes may expose workers to air-borne mold spores from 10 to 1,000 times more thanbefore the remediation (Reese). Therefore, the reme-

Remediation PersonnelEPA recommends that a remediation manager be

selected for projects that involve more than 10 sq. ft.of contamination or for smaller projects if the reme-diation requires more than one person (EPA). Thismanager develops the remediation plan and selectsthe remediation contractor or workers. Based onhis/her specific experience, the designated remedia-tion manager may need to consult with an SH&Eprofessional or consultant who has direct experiencewith the type of remediation to be performed. Thetop priority is to protect the safety and health ofbuilding occupants and remediation workers (EPA).

After assessing the problem’s scope, the first criti-cal management decision is to determine whether tocorrect the problem using in-house staff or outsidecontractors. Insurance companies report average pay-outs of $45,000 to $55,000 per claim, while reputableremediation companies report project cost averagesof closer to $12,000 per claim (Allen). Because of poorworkmanship and inadequate training of some mold

Comparison of Remediation GuidelinesClearance

Parameter Containment PPE Sampling

Source: NYCDH, EPA

Table 3Table 3

None

Local containment (i.e., cover withplastic sheets and seal with tape)Immediate and adjacent work areas(cover with plastic sheets, sealedwith tape and seal ventilationducts/grills)Immediate and adjacent work areas(i.e., negative-pressure containmentwith HEPA filters, airlocks anddecontamination room; seal fixtures,ventilation ducts/grills and otheropenings)Cover with plastic sheets sealedwith tapeCover with plastic sheets sealed withtape; negative-pressure containmentwith HEPA filters, airlocks anddecontamination room if contamina-tion is more than 30 sq. ft.None

Limited (i.e., negative-pressure con-tainment using single layer of 6-mil,fire-retardant polyethylene sheetingfrom ceiling to floor; seal ventilationopenings)

Full (i.e., negative-pressure contain-ment using two layers of fire-retar-dant polyethylene sheeting with oneairlock chamber; seal ventilationopenings)

Disposable N95 particulate respira-tor, gloves, eye protectionDisposable N95 particulate respira-tor, gloves, eye protectionDisposable N95 particulate respira-tor, gloves, eye protection

Full-face respirators with HEPA (i.e.,N99) cartridges, disposable protec-tive clothing covering head, shoesand gloves

Disposable N95 particulate respira-tor, gloves, eye protectionDisposable N95 particulate respira-tor, gloves, eye protection; full-facerespirator with HEPA (i.e., N99) car-tridge and protective clothing if con-tamination is more than 30 sq. ft.Limited (i.e., disposable N95 particu-late respirator, gloves, eye protection)

Limited or full (i.e., full-face respira-tor with HEPA cartridge, gloves,disposable full-body clothing withhead gear and foot coverings) basedon professional judgment of quali-fied personFull

NYCDH: Level I (10 sq. ft. or less)NYCDH: Level II (10 to 30 sq. ft.)NYCDH: Level III (30 to 100 sq. ft.)

NYCDH: Level IV(more than 100 con-tiguous sq. ft.)

NYCDH: Level V(HVAC Systems)NYCDH: Level V (HVAC Systems—more than 10 sq. ft.)

EPA: Small (less than 10 sq. ft.)

EPA: Medium (10 to 100 sq. ft.)

EPA: Large (more than 100 sq. ft.)

None

None

None

Yes

None

Yes

Based on profes-sional judgment ofqualified personBased on profes-sional judgment ofqualified person

Based on profes-sional judgment ofqualified person

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ers should wear disposable N95 particulate respira-tors, gloves and eye protection (such as goggles) forprojects that have less than 30 sq. ft. of mold growth.For larger remediation projects, the level of PPE mayneed to increase to include full-face HEPA (i.e., N99)particulate respirators, gloves and disposable full-body clothing with headgear and foot coverings. Asnoted, Table 3 provides a comparison of PPE guide-lines for remediation activities.

Correcting the Source of MoistureIdentifying conditions that contribute to microbial

growth in a building is the most important step inremediation (ACGIH). Therefore, the remediationplan should detail steps to correct the moisture prob-lem. Potential problems include high humidity, con-densation problems, water leaks and maintenanceissues, as well as issues related to heating, ventilation,and air-conditioning (HVAC) systems. The timing ofthe corrective action may be critical in minimizingexposure during remediation since sporation increas-es as moisture is removed (ACGIH). Thus, when prac-tical, the moisture should not be removed until thematerial is removed or cleaned.

Cleanup MethodsTo minimize exposure to personnel not performing

remediation activities, negative-pressure (full-scale)containment, local containment or no containmentmay be used depending on the size of the project.

diation plan should specify how both occupants andremediation workers will be protected. Controllingpotential exposures to bioaerosols depends largelyon the cleanup method used. In addition, adminis-trative controls and PPE should be incorporated intothe plan to further minimize exposure.

ACGIH recommends that those involved in theremoval of extensive microbial contamination beinformed in writing by a physician of the potentialhealth risks of bioaerosol exposure, and thatimmunocompromised workers should avoid reme-diation activities (ACGIH). Those performing majorcleanup activities should receive a baseline medicalevaluation using a medical questionnaire evaluatedby an occupational/environmental physician as aminimum.

Individuals recovering from recent surgery andpeople with immune suppression, asthma, hypersen-sitivity pneumonitis, severe allergies, sinusitis orchronic inflammatory lung diseases should not beemployed as remediation workers (AIHA). A follow-up medical evaluation using a symptom question-naire at the completion of a project would alsoprovide both the worker and employer assurance thatany effects of exposure are likely to be detected andtreated properly (ACGIH).

Personal Protective EquipmentThe level of PPE required depends on the extent

of contamination. At a minimum, remediation work-

Figure 1Figure 1

Regional Weather Conditions: Mold Risk Based on Precipitation & Humidity

©2001 ECS Risk Control Inc. Reprinted with permission.

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less likely to be affected. In all cases, infants (age 12months and younger), and people with suppressedimmune systems or chronic inflammatory lung dis-eases, or who have undergone a recent surgery

NYCDH recommends local containment(i.e., cover the contamination area withplastic sheets sealed with tape) for projectswith 10 to 100 sq. ft. of mold growth. Theagency recommends that full-scale negativepressure containment (with airlocks and adecontamination room) be erected for proj-ects with more than 100 sq. ft. of moldgrowth (NYCDH). EPA recommends nega-tive-pressure containment if more than 10sq. ft. of contamination is present. Table 3offers a comparison of containment guide-lines for mold remediation activities. In allcases, contaminated materials should bebagged and sealed immediately in the con-tainment area.

Since drying the contamination areamay cause increased levels of airbornemold spores, the moisture should not beremoved until the material is removedand/or water misting (not soaking) isapplied to the contaminated area. Othercleanup methods include wet vacuuming,damp wiping and HEPA vacuuming.Water-extraction vacuums can be used toremove water from floors, carpets and hardsurfaces where water has accumulated.These devices should only be used whenmaterials are still wet, however, as theymay spread spores if sufficient liquid is notpresent. Vacuum tanks, hoses and attach-ments should be thoroughly cleaned anddried after use since mold spores may stickto the surfaces of the equipment (EPA).

In most cases, mold may be removedfrom nonporous surfaces by wiping orscrubbing with water, or water and deter-gent. These surfaces should be quickly andthoroughly dried to prevent further moldgrowth. Porous materials that are wet andhave mold growing on them should be dis-carded (EPA). HEPA vacuums are recom-mended for final cleanup of remediationareas; this should occur after materials havebeen thoroughly dried and contaminatedmaterials have been removed. AppropriatePPE should be worn when changing the fil-ter. Use of biocides is not generally recom-mended since dead mold spores are stillallergenic, and some dead mold spores arepotentially toxic (EPA). In addition, “theeffectiveness of bleach in reducing aller-genic and toxigenic materials in remedia-tion work has not been demonstrated”(AIHA). Furthermore, the use of some bio-cides may create additional indoor air qual-ity issues due to vaporization of respiratoryirritants such as chlorine, ammonia prod-ucts and volatile organic compounds.

Administrative ControlsIf feasible, remediation activities should be sched-

uled during off-hours when building occupants are

Proactive Property Management:Minimizing the Risks of MoldWhen buying, renting or constructing properties, many factors must be consid-ered in order to reduce the risk of mold contamination.

•Preventive maintenance of HVAC, plumbing and other building systemscan reduce the potential for mold growth. Owners that disregard maintenance ofbasic HVAC components—such as filter and condensate drains—face increasedrisk. HVAC systems that cycle off during non-occupancy hours to save energycan create fluctuations in temperature and humidity conditions, which may pro-mote mold growth. Undersized and oversized HVAC systems are also associat-ed with inadequate moisture control (ASHRAE 62-2001).

•Roof leaks, plumbing leaks or sewer back-ups that allow water into thestructure often trigger a mold and bacteria problem. Water intrusion that occursduring construction and renovation is also associated with uncontrolled moldgrowth. The key to mold risk reduction is preventive maintenance of buildingsystems, as well as regular inspections to identify leaks. Thorough planningprior to construction activities can prevent moisture from entering the structure.Consideration should also be given to protecting construction materials fromprecipitation once they arrive on site. Additionally, building openings should beprotected when possible to reduce the amount of moisture that enters the interi-or of the structure during the construction process.

•Local weather conditions influence the degree of mold risk. Buildings locat-ed in areas with high precipitation or persistent high humidity must defendagainst outdoor conditions (Figure 1). To control indoor mold growth, the rela-tive humidity should remain below 60 percent (ASHRAE 55-1992). Propertieslocated within a flood plain may also need special design considerations such assump pumps, moisture barriers and exterior grading to prevent rising surfaceand groundwater from entering the structure. Properties in a 100-year floodplain should be evaluated for suitability. Basements and crawlspaces that arepersistently high in humidity can be sources of mold which can damage storedcontents as well as structural integrity.

•Interior moisture sources can also contribute to humidity levels within astructure. Indoor pools, spas, laundries or other wet processes add a significantmoisture load. Therefore, HVAC systems should be designed to remove thisextra moisture from the structure.

•Buildings with a history of water leaks present a high degree of mold risk aswell. Persistent small leaks that are not resolved—such as roof leaks or leaksaround window frames—are commonly associated with uncontrolled moldgrowth. More extensive leaks that take more than than two days to clean up anddehumidify are also high-risk indicators. If porous or semiporous materials havebeen wetted and remain within the building, these materials are likely to harbormold growth. Buildings constructed of biodegradable materials are also likely toharbor biological activity as the building envelope and structure members canabsorb moisture.

To reduce the risk of indoor mold contamination, consider the followingwhen purchasing and managing properties:

•Avoid buildings with basements.•Do not locate properties within a flood plain.•Any visible mold should be less than 10 sq. ft.•Design HVAC systems to handle excess humidity sources.•Maintain roofs and plumbing systems to prevent sudden or chronic leaks.•Choose nonbiodegradable building materials.•Avoid properties that have a history of water leaks.•Ensure that recent renovations have not allowed water intrusion or used

wetted construction materials.•Ensure that HVAC systems are maintained and run continuously to control

temperature and humidity levels.•Cleanup should be performed within 48 hours using documented

processing for containment dehumidification, and disposal of wet porousand nonporous materials.

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•Are materials dry and visibly freefrom contamination?

•If clearance sampling has been con-ducted, are the types and concentrationsof mold spores in the building similar tothose found outside?

ConclusionOccupant concerns and fears are miti-

gated through prompt assessment andremediation of mold contamination. Athorough remediation plan minimizesexposures to both building occupants andremediation workers. This plan must des-ignate a remediation manager; ensure thatqualified and trained personnel performthe remediation; ensure that the source

of moisture is corrected; specify cleanup methodsthat minimize bioaerosols; and detail PPE use aswell as administrative controls and containmentmethods where appropriate. A proactive assessmentof the building design, site selection and construc-tion management, combined with ongoing buildingoperation and maintenance can reduce the risk ofdeveloping a mold-related problem. �

ReferencesAllen, M. “Mold: New Business Dream or Liability

Nightmare?” Air Conditioning Heating & Refrigeration News.215(2002): 13-14.

American Conference of Governmental IndustrialHygienists (ACGIH). Bioaerosols Assessment and Control.Cincinnati: ACGIH, 1999.

American Industrial Hygiene Assn. (AIHA). “Report ofMicrobial Growth Task Force.” Fairfax, VA: AIHA, 2001.

American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Thermal EnvironmentalConditions for Human Occupancy. ANSI/ASHRAE Standard 55-1992. Atlanta: ASHRAE, 1992.

ASHRAE. Ventilation for Acceptable Indoor Air Quality.ANSI/ASHRAE Standard 62-2001. Atlanta: ASHRAE, 2001.

Conlin, M. and J. Carey. “Is Your Office Killing You?”Businessweek.com. June 5, 2000. May 7, 2002 <http://www.businessweek.com:/2000/00_23/b3684001.htm>.

EPA. “Mold Remediation in Schools and CommercialBuildings.” Washington, DC: EPA, Office of Air and Radiation,Indoor Environments Div., 2001.

Finley, J. “Attack of the Killer Mold?” KARK.com. July 3, 2001.Hamilton, A. “Beware: Toxic Mold.” TIME.com. June 24, 2001.

<http://www.odatus.org/time>.New York City Dept. of Health (NYCDH). Guidelines on

Assessment and Remediation of Fungi in Indoor Environments.New York: NYCDH, 2000.

Reese, R. “Remediation Standards Help Avoid Lawsuits.”National UnderwriterProperty and Casualty.May 1999: 22-23.

Wiles, C. “Strategiesfor Conducting Meaning-ful Microbial IAQInvestigations.” Ameri-can Indoor Air QualityCouncil Seminar.Phoenix, AZ, Sept. 2001.

Williams, D. “ToxicMold: Breathing Easierwith Remediation.”Journal of PropertyManagement.March/April 2002: 46-49.

should be removed fromadjacent work areas (NYCDH). Otheradministrative controls include training remediationworkers and providing ongoing communications tobuilding occupants.

As part of a comprehensive hazard communicationprogram, remediation workers should, at a minimum,be trained about the hazards of mold and bioaerosols,as well as about the details of the remediation plan.Such information and training should cover PPE, con-tainment procedures, cleanup methods and actions totake if hidden mold is discovered (such as behindwallpaper). In addition, remediation workers shouldbe trained and fit-tested in accordance with their com-pany’s respiratory protection program. Depending onthe project’s scope, more extensive training may berequired. For example, NYCDH recommends thatmold remediation workers be trained in hazardouswaste operations if the contamination area exceeds 30sq. ft. Status reports should be shared with buildingoccupants before and throughout the project to mini-mize occupant concerns and ensure that complaintsare addressed in a timely manner.

Final InspectionThe final inspection of the containment area should

ensure that all dust and visible debris have beenremoved. Air sampling may also be conducted to ver-ify that air concentrations of fungal spores are qualita-tively and quantitatively similar to ambient outdoorair. Use of surface sampling is advisable to verify thatonly naturally occurring concentrations and types offungi are present on porous surfaces (ACGIH). Bulksamples (e.g., settled dust) may also indicate the effec-tiveness of remediation efforts (ACGIH). NYCDH rec-ommends that clearance air sampling be performedon projects which involve more than 100 contiguoussq. ft. of contamination. EPA recommends surfaceand/or air sampling after cleanup activities based onthe professional judgment of a qualified person.

To ensure proper remediation, the final inspec-tion should answer the following questions:

•Has the moisture or water problem been fixed?•Is mold visible, or are water-damaged materials

or moldy odors present?

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Before collecting samples during a micro-bial investigation, a sampling plan shouldbe devised to ensure that useful data arecollected. Mold sampling should be con-

ducted by qualified personnel experiencedin designing mold sampling protocols,

sampling methods and interpretingresults. Samples should be analyzed by a

laboratory that participates in theEnvironmental Microbiology Proficiency

Analytical Testing Program.

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