Mold is the common term used to describe a downy or furry growth on the surface of organic matter, caused by fungi, especially in the presence of dampness and decay. A fungus (pl. fungi) may be any of a large number of microorganisms that are parasites feeding on living organisms or dead organic matter.

Mildew is often used interchangeably with the word mold. These are the generic terms that describe a variety of microorganisms, including fungi, algae, rusts, yeasts, and bacteria, that are agents of deterioration. They can permanently damage an object.

The Microorganisms

Fungi are simple-celled organisms that do not need energy from light for growth. The fungi bear microscopic spores that are produced in enormous quantities, are always present in the air, and spread via air currents. They are often water repellant and are resistant to desiccation (drying out). Extreme cold and heat will destroy them.

When the spores are in a favorable environment they will germinate. What constitutes a favorable environment is different for each species. After landing on a host material, a spore must obtain sufficient moisture to germinate and find enough food. Without moisture, the spores will lie dormant until favorable conditions occur.

Susceptible Materials

Microorganisms need organic materials to supply nutrients and, therefore, all construction materials composed of organic materials are potentially at risk. Cellulose-based materials suchas wallpaper, the paper liner of gypsum wall board, and wood are particularly susceptible to direct attack by microorganisms.

Inhospitable materials, such as plastics, are not immune from fungal growths but how they support these growths is not fully understood by biologists. Certain mites feed on fungi and can carry spores onto normally resistant materials. As the mites die, they become the nutrients for a new fungal colony. This ability to exist on almost any material characterizes molds as primary agents of deterioration.

Permanent Damage

The microorganisms that comprise mold will permanently damage the materials supporting them. They will stain paper and wood and decrease the strength of these materials. As a by-product, fungi can produce organic acids that will corrode and etch inorganic materials.

Mold can be Dangerous

Some species of microorganisms cause health risks in the form of chronic lung irritation. Always exercise caution when handling badly infested materials, i.e. wear a high-efficiency particulate air (HEPA) filter respirator and disposable gloves. For this reason the services of professional mold inspection and remediation experts is recommended.