Molds can be found almost anywhere; they can grow on virtually any organic substance, as long as moisture and oxygen are present. There are molds that can grow on wood, paper, carpet, foods, and insulation. When excessive moisture accumulates in buildings or on building materials, mold growth will often occur, particularly if the moisture problem remains undiscovered or unaddressed. It is impossible to eliminate all mold and mold spores in the indoor environment. However, mold growth can be controlled indoors by controlling moisture indoors.

Mold growth is not desirable in a building and must be prevented.  There are three reasons to prevent fungal growth inside a building:  the potential negative health effects of exposure to fungi and their byproducts; the effects of mold contamination on the structural integrity of the building; and the negative aesthetic effects fungi can produce both visually and on the human olfactory system.

Black Mold is a term commonly used to describe a slimy, greenish-black substance which can result in serious health risk. This infamous mold is also known as Strachybotrys chartarum and more often as Strachybotrys atra. It has been closely linked to the death of babies from respiratory bleeding, and as a contributing factor to illnesses such as asthma and bronchitis. According to the CDC (Center of Disease Control), this mold is responsible for over "100 cases of lung disorders".

Virtually everyone has one type or another of mold somewhere in their home. Although not all types are toxic, each person has a different tolerance level. It is difficult to distinguish types of molds without lab testing.

For more information read the article: Is Your House Making You Sick?