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Toxic Mold: Preventing Mold-Related Problems in Indoor Workplaces; Guidance from Federal OSHA and California
November 2006
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California was the first state in the nation to pass a law addressing the hazards of toxic mold in buildings: the Toxic Mold Protection Act of 2001. This act required the California Department of Health Services (DHS) to present a study to the legislature evaluating the feasibility of establishing a permissible exposure limit (PEL) for indoor molds. The state agency must also convene a task force to help develop enforceable standards and voluntary guidelines to prevent adverse health effects from exposure to mold in buildings. The DHS report, published in June 2005, determined that it would be very difficult to establish a PEL for mold in buildings because of inadequate toxicity data, the wide variety of potentially harmful molds and their toxins, and other factors that affect indoor air quality. DHS did determine that to protect human health, indoor dampness, water intrusion, and fungal growth must be prevented.

Controlling these factors is the subject of a federal OSHA guidance booklet published in 2006, "Preventing Mold-Related Problems in the Indoor Workplace: A Guide for Building Owners, Managers, and Occupants." We've summarized the information from both the state DHS and federal OSHA below to help you to minimize workplace mold hazards.

Human Health Effects

Molds are fungi—nonplant, non-animal living organisms in the same family as yeasts and mushrooms. They reproduce through spore formation; these tiny cells are in the air we breathe, indoors and out, everywhere we go. When mold spores find a moist place to settle, on just about any type of surface, they may make themselves at home and begin digesting the surface they've colonized. If mold colonies proliferate indoors, humans can experience symptoms of exposure, including:

  • Sensitization and allergic reactions. High concentrations of mold spores can cause respiratory sensitivity and allergies. Symptoms are similar to other types of respiratory allergies.
  • Colonization. Some molds can colonize the respiratory tracts of asthmatic individuals—the mold literally grows inside their respiratory tract.
  • Lung infections. Immunocompromised workers, including those taking corticosteroids, people with AIDS, or pregnant employees, may be susceptible to lung infections caused by molds.
  • Toxicity. Some molds produce toxins (mycotoxins) that can cause kidney and liver damage and increase the risk of liver cancer. Typically, these illnesses occur when fungal toxins are ingested, but there is a possibility that inhalation exposure could also cause toxic health effects.

Drying Up the Problem

Because mold needs moisture to grow, dry surfaces are your main defense, and visual inspections are a key weapon. OSHA's guidelines recommend:

  • Regular visual inspections of the building envelope and drainage systems to ensure that they are intact and functional.
  • Routine leak checks of window and door seals.
  • Venting moisture-generating appliances, combustion appliances, kitchens, bathrooms, and other damp areas to the outside.
  • Regular inspection of building ventilation systems for damp filters and general cleanliness.
  • Aggressive preventive maintenance for building ventilation components that are exposed to moisture, such as drainage pans, coils, cooling towers, and humidifiers.
  • Thorough cleaning of forced-air ducts if dampness is present in any portion of the duct and regular replacement of filters.
  • Isolation of areas under renovation, including ventilation system components, and frequent inspection of any areas where the building envelope has been broken (for example, during roofing work).

If dampness or mold is found in a building, these general steps should be taken:

  • Eliminate the source of moisture, if possible.
  • Remove all visible mold. Ensure that workers involved in this task are protected from both inhalation and skin exposures.
  • If mold is visible on a building's external surface, check for contamination beneath the surface.
  • For serious mold problems, you will probably have to obtain advice or services from a professional consultant or mold remediation firm.

Find Out More

The complete booklet can be downloaded from federal OSHA's web site. The California Department of Health Services maintains an indoor air quality page with many technical links regarding mold and mold remediation in buildings. The Report to the California Legislature on the Implementation of the Toxic Mold Protection Act of 2001 is available online. Federal OSHA maintains a "Molds and Fungi" safety and health topics webpage.

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