Mold is an all-encompassing term to describe the growths such as fungi, mushrooms, rusts, mildew, and yeast. Molds are eukaryotic organisms (have a defined nucleus) that lack flagella and reproduce by means of spores. There are only a few places on earth that are uninhabitable by mold. As an expected part of the environment, they are present almost everywhere and vary naturally in genera and concentrations based upon geographic locations and seasonal conditions.
There are an estimated 100,000 accurately described species of fungi and at least as many species waiting to be discovered. Almost all of these fungi are aerobes meaning they require oxygen to survive. They do not ingest their food but rather absorb nutrients by attacking dead organic matter or parasitizing living organisms. Many live in the soil and take an active part in the decomposition of organic matter. Unfortunately, many porous building materials such as drywall, wallpaper, and insulation are either constructed of, or contain some type of organic material.
When building components become moist from flooding or excessive humidity the fungi will initiate the reproductive phase of their life cycle and produce spores. It is their ability to reproduce very rapidly through these spores that make them thrive virtually anywhere. As long as moisture is present, microbial growth will continue unchecked until the moisture and/or nutrient sources are removed.
Certain fungi or fungal products (i.e. mycotoxins) can be the primary causes of human disease. Systemic, opportunistic or dermatophytic infections can occur from over 100 species known to affect humans. However, the majority of fungi found in the environment are unable to cause infectious disease unless the exposed individual is severely immunocompromised. The most common health effect from exposure to fungi is allergy like symptoms, mucous membrane irritation, headache, fatigue, and cold/flu-like symptoms.
High levels of fungi in an indoor environment as compared to normal outdoor levels are of particular concern. In the event that fungal contamination is determined within a dwelling, a professional investigation is essential to thoroughly evaluate the occupant space and determine appropriate clean-up measures.