WHAT ARE MOLDS?

“Mold” is the common term for multicellular fungi that grow as a mat of intertwined microscopic filaments (hyphae). Fungi are plant-like organisms that, because they lack chlorophyll, are dependent upon external food sources. Familiar fungi include yeasts, smuts, rusts, mushrooms, puffballs, and bracket fungi. Molds live in the soil, on plants, and on dead or decaying matter. Outdoors, molds play a key role in the breakdown of leaves, wood, and other plant debris. Without molds, our environment would be overwhelmed with large amounts of dead plant matter.

WHAT CAUSES MOLDS TO GROW INDOORS?

Molds reproduce by means of spores. Mold spores are microscopic and are naturally present in both indoor and outdoor air. Some molds have spores that are easily disturbed and waft into the air and settle repeatedly with each disturbance. Other molds have sticky spores that cling to surfaces. When mold spores land on a damp spot indoors, they may begin growing and digesting whatever they are growing on in order to survive. Mold can grow on wood, paper, carpet, and food. When excessive moisture or water accumulates indoors, mold growth often occurs, particularly if the moisture problem continues unabated (Figure 1). Spores may remain able to grow for years after they are produced. In addition, whether or not spores are alive, the allergens in and on them may remain potent for years. There is no practical way to eliminate all molds and mold spores in the indoor environment; the only way to control indoor mold growth is through moisture control.