Examples of environmental controls include isolation or containment of the contaminated area, ventilation of the area, and suppression of dust in the area (e.g., by wet-mopping the mold-contaminated surfaces to reduce airborne mold concentrations). Certain methods of isolation can be used to minimize mold exposure. For example, workers operating heavy equipment during the demolition and removal of mold-contaminated materials can be isolated in sealed, positive-pressure, air-conditioned cabs that contain filtered air recirculation units. Another method of isolation is sealing off of mold-remediation areas in occupied, mold-contaminated buildings. However, such isolated areas must also be adequately ventilated.
Preventing the creation of dust and limiting exposure to dust are essential to minimizing exposure to mold. When cleaning up dust, workers should use wet mops or vacuums with HEPA filters instead of dry sweeping.
Use of PPE
Inhalation is the primary exposure route of concern related to mold for workers, homeowners, and building occupants. Environmental controls are sometimes inadequate to control airborne exposure to mold or dust containing mold. In such cases, respirators protect persons from inhaling airborne contaminated dust and other particulates released during dust-generating processes (e.g., clean-up or debris removal). Recommendations on when to wear a respirator depend on the severity of mold contamination, whether the person's activity is such that mold or particles containing endotoxin or other microbial agents are likely to be released into the air, and the person's health status (Table 1).
The following recommendations are made with the assumption that extensive mold contamination is present.
Recommendations for use of respirators in include:
Healthy persons who are in a building for a short time or who are in a place where activity minimally disturbs contaminated material might not need a respirator (Table 1).
Persons engaged in activities that moderately disturb contaminated material (e.g., light cleaning by removing mold from surfaces with a wet mop or cloth) and persons with health conditions that place them at risk for mold-related health problems should use at least an N-95 respirator that is certified by NIOSH.
Persons doing remediation work that involves extensive exposure to mold should have respiratory protection greater than that provided by a NIOSH-certified N-95 respirator. Full face-piece respirators that have NIOSH-certified N100, R100, P100 particulate filters are recommended. For powered air-purifying respirators, a HEPA filter is recommended.
--- Respirator selection is made after considering the characteristics of the work activities; the specific exposures of concern; and the protection factors, advantages, and disadvantages of various respirators.
--- The determination of whether a person will have extensive exposure to mold should be based on several factors, including the size of the mold-contaminated area, the type of mold-contaminated material, and the activities being performed. Guidelines based solely on area of contamination define extensive contamination as being >100 square feet.
--- Formal fit testing is recommended for anyone engaging in remediation work causing extensive exposure to mold.
Guidelines for respiratory protection use:
Respirators must fit well and be worn correctly.
NIOSH tests and certifies respirators for use by workers to protect against workplace hazards. Respirators certified by NIOSH have "NIOSH Approved" written on them and have a label that identifies the hazard the respirators protect against.
The N-95 respirator is approved only as protection against particulates (including dust) and will not protect persons from vapors or gases such as carbon monoxide.
Eye Protection and Protective Clothing
Eye protection is warranted for workers cleaning up mold-contaminated areas and for persons with health conditions that place them at high health risk (Table 1). To protect eyes, a full face-piece respirator or properly fitted goggles designed to prevent the entry of dust and small particles should be used. Safety glasses or goggles with open vent holes are not appropriate during mold remediation. The CDC/NIOSH publication Eye Safety: Emergency Response and Disaster Recovery, provides further information on this topic (35).
While conducting building inspections and remediation work, persons might encounter hazardous biologic agents and chemical and physical hazards. Consequently, appropriate personal protective clothing, either reusable or disposable, is recommended to minimize cross-contamination between work areas and clean areas, to prevent the transfer and spread of mold and other contaminants to street clothing, and to eliminate skin contact with mold and chemicals. In hot climates, wearing protective clothing might increase risk for dehydration or heat stress, and special precautions to avoid these conditions (e.g., drink plenty of water) might be needed.
Disposable PPE should be discarded after it is used. Such equipment should be placed into impermeable bags and usually can be discarded as ordinary construction waste. Appropriate precautions and protective equipment for biocide applicators should be selected on the basis of the product manufacturer's warnings and recommendations (e.g., goggles or face shield, aprons or other protective clothing, gloves, and respiratory protection). Reusable protective clothing should be cleaned according to the manufacturers' recommendations after the product has been exposed to mold. Hands should be washed with clean potable water and soap after gloves are removed.
General Distribution of PPE
Health officials should consider whether their agencies should supply PPE to residents who might not otherwise be able to acquire the necessary equipment. Providing PPE to the local population would require substantial resources and a mechanism for distributing them.
Items that have soaked up water and that cannot be cleaned and dried should be removed from the area and discarded.
Dehumidifiers and fans blowing outwards towards open doors and windows can be used to remove moisture.
The procedure to remove mold from hard surfaces that do not soak up water (i.e., nonporous) is as follows:
Mix 1 cup of bleach in 1 gallon of water.
Wash the item with the bleach mixture.
Scrub rough surfaces with a stiff brush.
Rinse the item with clean water.
Dry the item, or leave it to dry.
Cleaning Hard Surfaces That Do Not Soak Up Water
The procedure to prevent mold growth on hard surfaces that do not soak up water is as follows:
Wash the surfaces with soap and clean water.
Disinfect them with a mixture of 1 cup of bleach in 5 gallons of water.
Allow to air dry.
Additional Safety Guidelines for Mold Clean-up
Persons cleaning moldy or potentially moldy surfaces should:
Wear rubber boots, rubber gloves, and goggles when cleaning with bleach.
Open windows and doors to get fresh air.
Never mix bleach and ammonia because the fumes from the mixture can be fatal.
Health-Outcome Surveillance and Follow Up
State and local public health agencies do not generally collect information on the conditions related to mold exposure. In situations where there are large numbers of flooded and mold-contaminated buildings, such as occurred in New Orleans after hurricanes Katrina and Rita in fall of 2005 (2), the repopulation of those once-flooded areas probably will expose a large number of persons to potentially hazardous levels of mold and other microbial agents.
Efforts to determine the health effects of these exposures and the effectiveness of recommendations to prevent these adverse health effects require a surveillance strategy. Developing such a strategy requires that federal and local health agencies work together to monitor trends in the incidence or prevalence of mold-related conditions throughout the recovery period.
Monitoring trends in health outcomes that might be related to mold exposure will require substantial human and financial resources and will face several challenges. Health outcomes that might be attributed to mold exposure fall into several broad categories. Some potential health outcomes are rare, difficult to diagnose, and relatively specific for fungal exposure (e.g., blastomycosis). Other health outcomes are relatively easy to diagnose, but they have numerous etiologic factors and are difficult to attribute specifically to mold exposure (e.g., asthma exacerbations). Tracking different health outcomes that might be caused by mold exposure requires different surveillance methods. In some cases, follow-up research will be needed to verify that surveillance findings and health outcomes are the result of mold exposure. For some conditions, difficulties in interpreting trends and in relating the outcome to mold exposure might suggest that surveillance is not an appropriate public health approach.
Results of surveillance and follow-up activities will help CDC refine the guidelines for exposure avoidance, personal protection, and clean-up. In addition, these activities should assist health departments to identify unrecognized hazards.
Public health agencies should consider collecting health outcome information from health-care facilities to monitor the incidence or prevalence of selected conditions. State or local agencies should determine the feasibility of this approach and consider the required resources available or attainable to accomplish this goal. Institutions from which data could be collected include hospitals, emergency departments, clinics and, for some outcomes, specific subspecialty providers. Surveillance will require the establishment of case definitions and reporting sources; development of reporting mechanisms; training of data providers; and the collection, analysis, and reporting of data. The surveillance data should be used to identify increases in disease that are substantial enough to trigger public health interventions or follow-up investigations to learn the reason for the increase and establish targeted prevention strategies.
Public health agencies should consider the need for clinicians to report cases of known or suspected mold-associated illnesses (e.g., invasive fungal disease, blastomycosis, hypersensitivity pneumonitis attributed to mold contamination, ODTS attributed to contaminated dust exposure, and alveolar hemorrhage in infants) to public health authorities for tracking and follow-up investigations. Providers caring for patients at high risk for poor health outcomes related to mold exposure could be targeted. For example, hematologists, rheumatologists, and pulmonologists might care for many patients at risk for invasive mold infections because of underlying malignancies and immunosuppression. Enhancing provider-based surveillance requires targeting and educating providers; developing reporting mechanisms; and collecting, analyzing, and reporting data.
Public health agencies should consider the need for establishing laboratory-based surveillance as an efficient method for monitoring mold-related illnesses that involve laboratory analyses (e.g., invasive fungal disease, blastomycosis, invasive aspergillosis, histoplasmosis, Aspergillus preceptins, zygomycosis, and fusariosis).
Health-care providers should be alert for unusual mold-related diseases that might occur (e.g., hypersensitivity pneumonitis, ODTS, and blastomycosis). Otherwise, such diseases might not be recognized. Scientific evidence is insufficient to support the routine clinical use of immunodiagnostic tests as a primary means of assessing environmental fungal exposure or health effects related to fungal exposure. Health-care providers who care for persons who are concerned about the relation between their symptoms and exposure to fungi are advised to use immunodiagnostic test results with care and only in combination with other clinical information, including history, physical examination, and other laboratory data. If appropriate allergy prick skin testing reagents or in vitro tests for serum specific IgE are available, they can be used to show specific IgE-sensitization to causative allergens. Unfortunately, skin testing reagents and blood tests documenting IgE-sensitization to molds are, with few exceptions, poorly standardized and of unclear sensitivity and specificity. The conventional hierarchy of treatment for allergic diseases includes avoidance of exposure to inciting agents, pharmacotherapy and, as a last resort, allergen immunotherapy. Immunotherapy with fungal allergenic extracts is, with a few exceptions, of unknown efficacy. Clinicians should report cases of mold-induced illness to local health authorities to assist in surveillance efforts.
Athena Gemella, MS, coordinated the external review of the document; Marissa Scalia, MPH, and Allison Stock, PhD, provided background and resource materials for the document, National Center for Environmental Health. Kay Kreiss, MD, provided input and feedback during the development of the document, National Institute for Occupational Safety and Health.
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