Molds (along with the broader term fungi) are living organisms that live on plant or animal matter. Molds produce microscopic spores, reproductive bodies similar to seeds, that are very light and travel through the air. With the right conditions, these spores reproduce quickly (often within 24-48 hours) to create more colonies of mold.
Mold can grow on almost any surface and only requires dampness and a source of food to thrive. The nutrients required to sustain mold are plentiful and include dust, paper, ceiling tiles, cardboard, and wood. Materials that support mold growth will eventually be consumed and destroyed if the mold is allowed to grow unabated.
Estimates place the number of mold species at between 50,000 and 250,000. Over 1,000 different kinds of molds have been found in U.S. homes. Some strains of mold can cause more serious problems with building occupants. These include Aspergillus, Penicillium, and Stachybotrys. Because of the severe reactions people can have from these molds, they are often labeled “toxic mold”.
There is no reliable way to visually tell what type of mold may be in a building. Samples need to taken by a professional and sent to a laboratory. It is often wise, then, to treat all molds with some level of caution and concern.
According to the CDC, “it is not known what quantity of mold is acceptable in indoor environments with respect to health”. A common rule of thumb, therefore, is that if you can see or smell mold (often described as a “musty” odor) inside a building, then there is too much.
It is impractical to completely eliminate all mold spores from our environment. Home owners should concentrate on eliminating water sources, removing mold colonies when discovered, and inhibiting a spores’ ability to reproduce in their building.