Molds are neither plant nor animal, but fungi that can be found almost anywhere; they can grow on virtually any organic substance, as long as moisture and oxygen are present. Wet cellulose materials, including paper and paper products, (books, books and more books), cardboard, ceiling tiles, wood, and wood products, are particularly conducive for the growth of many types of molds. Molds grow by digesting and destroying these organic material. Many other materials in your home such as paints, tile grout, wallpaper, insulation, drywall, carpet, shower curtains, window shades, and upholstery, also serve as excellent locations for mold growth. Indoor molds are ubiquitous, but are not usually a problem unless there is a moisture problem.
The most common indoor molds are Cladosporium, Penicillium, Aspergillus, and Alternaria. However, Stachybotrys chartarum is a greenish-black cellulose loving mold that has gotten a tremendous amount of attention as the “toxic mold” of 2001 fame. That term is not accurate. While certain molds can produce mycotoxins, and are thus are toxigenic, the molds themselves are not toxic, or poisonous. After much research, the US Environmental Protection Agency (EPA) and the US Center for Disease Control and Prevention (CDC) and the California Department of Health Services (CDPH) and the public health community at large agree that allergic reactions to mold in buildings occur, particularly for sensitized persons. However, in the present peer-reviewed medical literature, there is no conclusive evidence that mold toxins in buildings cause any human health illness. Though there are case reports of symptoms caused by mold toxins; evidence is inconclusive. Breathing in mold or other dampness related bacteria may cause hypersensitivity pneumonitis, an uncommon disease that resembles bacterial pneumonia. In addition, mold exposure may result in opportunistic infections in persons whose immune systems are weakened or suppressed, have existing lung disease, or asthma.
After considerable research into this issue, scientists and the World Health Organization concluded in October 2006 that although recent studies have strengthened the evidence between living and/or working in a damp environment and increased risk for respiratory symptoms, the role of mold growth in these complex environments is still unclear. Damp buildings also encourage the growth of bacteria, dust mites and cockroaches, as well as degradation of wet building materials that can also release irritant chemicals indoors. Some or all of these chemicals or biological organisms may contribute to occupant illness. Thus, science based exposure limits for indoor molds cannot be established at this time. However, the presence and health risks of biological contaminants in indoor air are all caused by moisture which should be prevented or stopped as soon as possible.
In summary, Stachybotrys chartarum (Stachybotrys atra) and other molds may cause health symptoms that are nonspecific. At present there is no scientific evidence that proves a cause and effect relationship between Stachybotrys chartarum and a particular health symptom or condition. Reliable sampling for mold can be expensive, and standards for judging the level of mold exposure that is not acceptable or cannot be safely tolerated have not been established. So testing for any particular type of mold is a waste of money. It is not necessary to identify the species of mold growing in a residence, and CDC does not recommend routine sampling for molds. Currently, there is no air sampling or environmental test that can determine if mold found in buildings is producing toxins, nor can any blood or urine test establish that an individual has been exposed to Stachybotrys chartarum spores or toxins. To the susceptible population any mold that is seen or smelled is a potential health risk; therefore, no matter what type of mold is present, you should remediate the problem beginning with solving the moisture problem.
Molds can multiply by producing microscopic spores (2 - 100 microns in diameter) that easily float through window screens, attach to clothing or pets or is pulled into a home through a fresh air ducts. Mold spores are ubiquitous, but are not usually a problem inside a home unless there is a moisture problem. Molds only grow when there is moisture from water damage, excessive humidity, water leaks, condensation, water infiltration, or flooding. Constant moisture is required for mold to grow. Thus, your first defense against mold is keeping moisture out. As part of routine building maintenance, buildings should be inspected for evidence of water infiltration in ceiling or walls, water stains from small leaks, water damage around windows and doors, indications of small plumbing or other water leaks and visible mold. The conditions causing mold (such as water leaks, condensation, infiltration, or flooding) should be corrected to prevent mold from growing.
Well-designed, well-constructed, well-maintained building envelopes are essential to prevent and control moisture and microbial growth. Management of moisture requires proper control of temperature and ventilation to avoid excess humidity, condensation on surfaces and excess moisture. Ventilation should be distributed effectively throughout spaces. Specific Recommendations:
- Inspect your home for signs of moisture.
- Keep humidity level in house between 40% and 60%.
- Use air conditioner or a dehumidifier during humid months.
- Be sure the home has adequate ventilation, including exhaust fans in kitchen and bathrooms.
- Fix leaky plumbing, roof leaks and basement water infiltration as soon as possible.
- Dry wet or damp areas within 24-48 hours.
- Keep heating and air conditioning drip plans clean and flowing.
- Perform regular heating and air conditioning inspections to identify problems early.
- Use mold inhibitors which can be added to paints.
- Clean bathroom with mold-killing products.
- Do not carpet bathrooms.
- Remove and replace flooded carpets.
- Do not let foundations stay wet.
- Provide drainage and slope the ground away from the foundation.