Fungi (mold in this case) and its spores are everywhere. It only becomes a problem when it grows in our living and/or working environments. Aspergillus, Cladosporium and Penicillium are just a few groups of common molds found indoors that can grow within 48 hours of a water loss. Some fungi such as Stachybotrys Chartarum (also known as Stachybotrys atra or SA), have been known to produce toxins (mycotoxins) and aflatoxins that are harmful to animals and humans when ingested, inhaled or come in direct contact with the skin.

Mold spores are fungal reproductive cells (seeds) of about the same size, or smaller, as pollen grains. They can occur in various colors and shapes, such as round, spheroid, banana-shaped, or tadpole-shaped. They can occur in enormous quantities, and at all times of the year. Mold spores can be found and generated at serious levels indoors, as well as out (I wear an N95 dust mask when I rake my leaves in the yard).

Fungus can invade healthy individuals and can cause a variety of adverse health effects. The most common response is allergies and flu-like symptoms (runny nose, sneezing, sinus congestion, and skin rashes). Allergies result from inhaling mold spores. When environmental conditions become conducive, many molds develop fungal hyphae, small stock-like appendages containing spores. These spores are analogous to plant seeds and can be spread by the billions when air currents pass over the hyphae. Because of the mycotoxins contained in the cell walls of the hyphae and its spores, even dead fungi are capable of causing allergic symptoms.

Mold spores can be airborne, and get indoors through doors, windows or cracks and crevices, or be carried in from the outdoors on shoes and clothing, pets and insects. Building materials that were left outside before use can harbor viable (living) mold spores for many years. Indoor environments are never entirely free of molds. As a general rule of thumb, in a "healthy" building the concentration of spores and the mix of mold species tend to be similar (better if less than) to the surrounding outdoor environment levels.

If buildings are air-conditioned, or windows and doors are kept closed in the summer, concentration of spores within should even be lower than outside levels. High moisture (70% relative humidity or above) in a building will invariably lead to mold, mildew, or other microbial growth. Fungal growth requires four basic things: a food source (common soils or most building materials), ideal temperature (between 68 and 86 degrees Fahrenheit), mold spores (ubiquitous in ambient air), and moisture.

Some molds also produce metabolites (poisons) which are thought to be useful in killing competing molds in their vicinity. These toxins can also have deleterious effects on humans when ingested, inhaled or in direct contact with the skin. On the other hand these toxins can save tens of thousand lives each year such as an enzyme found in the mold Penicillium called penicillin. The fungi that produce toxins are known as toxigenic fungi. The latest World Health Organization (WHO) publication on mycotoxins, available in 1990, indicated that there are more than 200 mycotoxins produced by a variety of common fungi. Historically, mycotoxins are a problem to farmers and food industries and in Eastern European and third world countries. However, many toxigenic fungi, such as Stachybotrys Chartarum and species of Aspergillus and Penicillium, have been found to infest buildings with known indoor air and building-related problems.

Basic Definitions:

Mycology: The study of fungi. Fungi are broken down into two types; micro fungi and macro fungi.

Micro fungi: Are microscopic and other wise known as molds and mildews, rust, smuts, etc. Unless we're looking into a microscope, micro fungi must be in clumps of advanced colonies of mycelia for us to see them. Mold and mildew often aren't seen as great health threats because they are referred to by common names. However fungi of any variety can contribute to adverse health effects in humans and animals.

Macro fungi: Much larger relatives of macro fungi include mushrooms, bracts, puffballs and poria incrassata. Have you ever wondered why mushrooms pop up above ground? It enables reproduction. By rising above ground macro fungi allows for spore dispersal.

Spores: Seed like spores released by the sporangium carrying and protecting the substances which will produce young fungi. They can be single or multi-celled. Spores range from 2-20 microns (um) in size, although some are larger then 100 um. Spores with thick walls are built to survive extremely harsh conditions. They can lie dormant until a moist environment is available to support growth. Most spores are adapted for air travel dispersal. For example if mold is sprayed with a biocide, the burst of air in front of the biocide can disperse the spores across the room (please don't spray mold with bleach). Spores are designed to survive.

HEPA: High Efficiency Particulate Arrester. Although the "A" stands for air, it should stand for arrestor. Clean air is a by product. The filter is stopping, trapping, arresting the particulates. The filter was designed to filter out nuclear particulate in power plants in the 1950's. Rumor has it that some original filters are still in place and working to this day.

Hypha singular - Hyphae plural: Fungi's growing structure - their roots, stock and branches collectively. They are the thread-like structures that are visible through a microscope. Groups of hyphae are called mycelia.

Metabolites: Mycotoxins, aflatoxins, satratoxins are metabolites. A chemical compound produced by molds to either breakdown the organic matter (food source) it wants to decompose, or to fend off other molds, bacteria or things from growing on, or killing them.

Mycotoxins: Chemicals produced by molds which cause a toxic response to humans if ingested, inhaled, or in direct contact with the skin