What Is Mold?
Molds are a type of fungus. Larger fungi include mushrooms. Molds are multicelled, as opposed to yeast which is single-celled.
Molds grow in a network of branching filaments, called hyphae. Groups or colonies of hyphae are called mycelium.
Mold species are found in a number of taxonomic divisions, so different species of mold may not be as closely related as you think.
No one really knows how many species of mold exist. Estimates are in the hundreds of thousands of species. Some are harmless, some useful and edible. Toxic mold on the other hand, is a real health problem, and some mold is carcinogenic.
Necessity of Mold
Molds form a necessary part of the life cycle in the larger sense. All living things have a lifespan, at the end of which they are recycled to support new life. Mold plays a big part in breaking down materials of all sorts, freeing up nutrients for absorption back into the food chain.
Mold is literally a fact of life.
To grow, mold requires moisture, nutrients, and the correct temperature range. Excessive heat will kill mold. As the temperature decreases, mold growth slows, eventually to a stop.
Understanding what mold needs to grow is the key to eliminating it for good. Make sure that the inside of your house (especially the basement) is dry. The cleaner it is the better, which is one reason that dust can be such a problem.
Mold spreads over long distances by releasing spores into the air. These spores float around until they randomly land on some surface. If the surface is moist and has suitable nutrients, it will eventually spawn a mold colony.
Spores in excessive quantities, when inhaled, can affect your health. They are a trigger for allergies, and may even cause allergies.
Spores in small concentrations are normal and unavoidable. This is not a health concern.
Some molds are not a health concern at all, unless you are allergic to mold. For example, some types of $cheese$ are made with mold.
Many types of mold are unhealthy, because they are toxic or carcinogenic. Molds can trigger an allergic reaction in some people.
- Wikipedia on mold
- Wikipedia on toxic mold
- Wikipedia on indoor air quality
- Washington State Department of Health