Common house mold can be caused by one of many types of fungus and can lead to health problems and structural impacts in the home. Though the terms "mold," "house mold" and "mildew" are used interchangeably, generally speaking, there are two broadly different kinds of fungi that lead to house mold:
1. Fleshy macrofungi, which grow fruiting bodies that we call mushrooms or toadstools.
2. Powdery microfungi, or what laymen call mold, house mold or mildew, which produce microscopic spores along the surface of the fungal growth, causing spotty, light or dark patches.
Macrofungi can degrade cellulose (the main component in wood). Homes with this type of mold can suffer structural damage, if the wood is wet enough and the fungal growth is extensive.
On the other hand, with some exceptions, microfungi do not degrade structural cellulose (or they degrade it only at the surface) and do not pose structural threats to homes with this type of mold. Microfungi like mold do, however, produce spores that can impact health.
Mold, house mold or mildew growth indoors, therefore, is a potential health hazard only to those who are sensitized--who react to the spores or fragments arising from a particular mold. Children can also be particularly susceptible to house mold.