Fungi (mold) and bacteria grow in moist environments in the presence of suitable substrates that provide the necessary nutrients. Gypsum wallboard, ceiling tile and insulation materials are some of the suitable substrates that fungi infest. In all situations, the underlying cause of mold is the accumulation of water. If water accumulation is not rectified, fungal growth will recur. HVAC systems should be cleaned and maintained whenever an active growth and contamination is found.

Molds reproduce by sending out spores, which are a seed like structure that in many cases can become, easily airborne. These microscopic seeds are transported in many ways. Airborne spores are present in the wind and enter the house just as dust particles do: through windows, doors, on clothing, pets etc. Indoor sources are of concern to all. Once a small colony is established, the mold sporulates and cannot be dispersed as it can outdoors.

To prevent the reoccurrence of elevated mold levels, crawl spaces should be deprived of moisture conducive to mold growth. Dehumidification is a recommended option to remove moisture. Alternatively, germicidal lamps can be purchased and used to minimize mold growth.

The center for disease control considers that any visible mold growth is unacceptable "it must be removed". A single mold species can produce more than one mycotoxin (by-products of metabolism, gasses given off by colonies and spores) and the same mycotoxin can be produced by more than one species of mold. Even non-viable (dead) spores and molds are known to give off mycotoxins.

Effects of these mycotoxins can range from a dry cough to infection of the lungs. In the most severe circumstance, death can occur to those with weakened immune systems or infants. See Mold Remediation.

For more educational material on mold, go to the Industry Links page.