How to Remedy and Prevent the Growth of Stachybotrys Fungus:
What Building Managers Need to Know
By Larry Hays, Vice President of Training, ESS
Over the past few years, the mold Stachybotrys has become a target as the cause for many Sick Building Syndrome incidents. As professionals, responsible for providing a "Reasonable Standard of Care" for the occupants of their company's facilities, Indoor Air Quality (IAQ) inspectors are expected to develop an understanding of this common indoor pollutant.
The toxins associated with Stachybotrys are found in the mold's fungal spores, which are released into the air. Very low levels of airborne spores are common in indoor air samples and usually do not produce symptoms. However, chronic exposure to the toxin found in Stachybotrys' fungal spores have reportedly produced typical Sick Building Syndrome symptoms like sore throat, diarrhea, headaches, fatigue, dermatitis and general malaise. It is thought that the toxins may also suppress the immune system.
The Utah Department of Health, Bureau of Epidemiology describes Stachybotrys as a type of slow growing saprophytic fungus that grows well on materials that have a high cellulose concentration, such as straw, grass, saw dust and lumber. Wet drywall and ceiling tiles can also support the growth of Stachybotrys.
Stachybotrys is primarily associated with water or water damage and will only grow on water soaked wood, ceiling tiles, wall paneling, unpainted plaster board surfaces, cotton items, cardboard boxes, and stacks of newspapers. This fungus does not grow on plastic, vinyl, concrete products, or ceramic tiles.
The National Center for Environmental Health at the Centers for Disease Control and Prevention (CDC) in Atlanta, says the hazards presented by molds that may contain mycotoxins, like Stachybotrys, should not be considered any more, or less dangerous than the other common molds that can grow in your facility.
However, the CDC cites a few case reports where toxic molds inside offices may have contributed to unique or rare health conditions such as pulmonary hemorrhage or memory loss. The CDC says that these cases are rare, and a causal link between the presence of the toxic mold and these conditions has not been proven.
There are about 15 species of Stachybotrys, with a worldwide distribution. Stachybotrys appears as a dark, olive-gray pigmented, slimy mass, with smooth margins, and either a smooth or ridged surface. The mold's spores are more brownish in color, and when the growth sporulates, the colony may appear to have a powdery surface.
Remember, there are hundreds of fungi and they cannot be identified by their visual appearance alone. Identification of Stachybotrys requires examination of the fungal spores under a microscope by competent professionals.
If a hygienist discovers mold in your facility, check your HVAC system for possible pathways that could spread the mold to occupied spaces. If you have had plumbing leaks, roof leaks, flooding in the basement or sewer backup in the past year, look for mold or a musty odor.
It may be within the capability of your facility maintenance personnel to take initial corrective actions with areas of light growth. However, if you think you may have found stachybotrys and observe extensive mold growth of more than two square feet, seek advice from your local health department or an IAQ professional on how to perform cleanup before proceeding.
Bacteria, viruses, mold and fungi must be killed in the cleanup process. The most widely accepted, safe, and effective sanitizing agent is a chlorine solution in the form of household bleach. Most professionals recommend a solution of one cup of bleach to one gallon of water. This solution has been proven to be of sufficient strength to kill the Stachybotrys organisms.
Time is also an important consideration in clean up. The organisms will not become airborne as long as they remain wet. As long as surfaces remain wet, the only way Stachybotrys can enter the body and cause disease is by splashing into the mouth, eyes or open wounds. Once dry, the mold's organisms can spread on dust particles in the air. For this reason, it is important to use the bleach solution on contaminated surfaces as soon as possible, after rinsing off heavy soil. In order to prevent decomposition and rotting of wet items, it is necessary to immediately dry an area after disinfecting.
If you make the decision to have your facility maintenance personnel begin cleanup activities, consider the following issues:
- You should conduct these cleanup activities when occupancy of the building is at its lowest. If possible, only those individuals doing the clean up should be in the facility. People with any respiratory health problems must not be in the facility or involved with the cleanup.
- Tight-fitting dust masks and goggles should be worn during all clean up activities.
- Rubber or vinyl gloves and waterproof boots should also be worn.
- Open all windows for drying and ventilation.
Note: ESS assumes no responsibility for consequences related to the above guidelines. Consult an IAQ professional for specific recommendations regarding your particular situation.
Your facility maintenance personnel can employ some basic procedures for the initial cleanup of areas of light growth.
- First, the source of all leaks or flooding must be identified and corrected.
- All moldy surfaces should be cleaned with a mixture of one cup of household bleach mixed in one gallon of water. You can add a small amount of dishwashing liquid to the bleach solution to cut dirt and oil on the surface, which can hold mold. With good ventilation, apply the bleach water mix to the surface with a sponge; let it sit for 15 minutes, then thoroughly dry the surface.
- If the area cannot be cleaned, such as wet, broken ceiling tiles, is too damaged, or is disposable, discard the items and replace with new.
- It may be necessary to do a more extensive cleanup if you have a mold problem in areas such as carpets or crawl spaces.
- Do not mix any cleaning agents, other than mild soap, with the chlorine solution.
- Apply the solution with mops and sponges.
Note: ESS assumes no responsibility for consequences related to the above guidelines. Consult an IAQ professional for specific recommendations regarding your particular situation.
For areas of heavy growth, you will need to negotiate a contract with an IAQ professional. When flooding of an area has occurred, either due to heavy rains or sewer backups, important steps must be taken to assure the health and safety of individuals involved. It must be assumed during cleanup operations of heavily contaminated areas that all surfaces have been contaminated with disease-causing organisms. This important assumption will direct decisions involving personal safety of cleanup personnel, as well as which items may be salvaged and which must be discarded.
Preventive maintenance can reduce the risk of a problem with molds growing inside your facility. The following preventative recommendations are available from the CDC's National Center for Environmental Health website in its article " Questions and Answers on Stachybotrys Chartarum and Other Molds."
- Keep the humidity level in the facility below 50 percent.
- Use an air conditioner or a dehumidifier during humid months.
- Be sure the facility has adequate ventilation, including exhaust fans in kitchen areas and bathrooms.
- Be sure mold inhibitors are added to paints.
- Clean bathrooms with disinfectants that kill molds.
- Do not carpet bathrooms.
- Remove and replace flooded carpets.
Growth of Stachybotrys and other molds can be prevented with these basic considerations, but should mold be found, it should be identified and removed carefully and thoroughly. In most cases a simple bleach solution will remedy the problem. However, because molds can be difficult for an untrained eye to identify, it is always best to consider the advice of an IAQ professional before beginning any cleaning process. A professional hygienist will help determine the extent of the contamination, and the procedures employees and IAQ professionals will follow to ensure the health and safety of everyone in the facility.
ESS, Inc, Tempe, Ariz. provides compliance software, training and consulting to organizations affected by refrigerant, indoor air quality, waste, and health & safety issues.
