More than 100,000 identified species of fungi exist today. Germination occurs when fungi, naturally present in building materials, are exposed to moisture for more the 24-48 hours and then become mold. There are four hazardous molds that can contaminate homes and buildings: Stachybotrys, Aspergillus, Penicillium and Poria.
Stachybotrys is a slow-growing fungus. It grows well on high-cellulose materials like straw, grass, sawdust, lumber and drywall plaster board or ceiling tiles. Like a fungi, it requires a moisture source. About15 species of Stachybotrys can be found worldwide, but it is most common in the Western U.S. Generally, this mold grows where the relative humidity is above 55 percent or the material is water-saturated. In studies conducted in North America, Stachybotrys was found in 2 to 3 percent of home environments sampled.
Stachybotrys altra spores can be inhaled. Persons with chronic exposure to the toxin report cold or flu-like symptoms with sore throat, diarrhea, headaches, fatigue, dermatitis, intermittent local hair loss and general malaise; they may also suppress the immune system. Infants may be particularly susceptible.
Homes and buildings with water damage should be repaired, the source of moisture eliminated and all moldy material removed. Humidity in the home should be reduced with adequate venting of appliances such as dryer vents, bathroom and kitchen cooking vents, shower fans. Even excessively sealed homes with inadequate air movement can have high humidity from showers, cooking and laundry. Although some molds can be killed with chlorine, Stachybotrys often has a germ, mycelium, that is buried inside the water-damaged surface that may be inaccessible to chlorine. Removal is best.
Aspergillus is a group of molds found world-wide, especially in the autumn and winter in the Northern hemisphere. Only a few of these molds can cause illness in humans and animals. Most people are naturally immune and do not develop disease caused by Aspergillus. However, when disease does occur, it takes several forms.
The type of diseases caused by Aspergillus are varied, ranging from an allergy-type illness to life-threatening infections. Diseases caused by Aspergillus are called aspergillosis. The severity of aspergillosis is determined by various factors but one of the most important is the state of the immune system of the person.
Penicillium : Some Penicillium species are fairly common, even in clean environments. This particular specie of fungi can proliferate in abundance at the sub-basement levels of offices and rooms, in libraries, storage rooms of paper materials and in ventilation systems.
Like all other molds, spores have the highest concentrations of mycotoxin, although the vegetative portion of the mold, the mycelium, can also contain the poison.
Poria: The major differences between Poria and ordinary decay fungi are that the latter require the structure to provide the water (green wood, rain, plumbing leaks, condensation), while Poria provides its own water through rhizomorphs connected to moist soil outside the structure. Poria dies quickly when deprived of water, while ordinary decay fungi usually just go dormant. These differences make both the detection and control of Poria very different from those of ordinary decay fungi. An inspector who does not accurately diagnose Poria infection can make a company responsible for repairing extensive decay, including that already repaired, within less than one year; or, in the extreme, razing and rebuilding the entire structure. It’s important to choose a contractor with the experience to determine the difference.