Reproduction of mold occurs with the release of mold spores into the air. When a mold spore lands on a surface or substrate the spore releases enzymes to digest the surface or food source. The mold spore then germinates and produces filaments called hyphae.

The hyphae are the basic cellular unit of the fungi. The hyphae form a protective mat called the myceilium. The myceiliel mat keeps the substrate moist even if the surrounding air is dry. Condia then generate and release mold spores into the air and the process starts over.

The growth cycle of mold can be as little as four (4) to twelve (12) hours. It is left
undisturbed, fungi can spread in 24 to 72 hours. It should be noted that the growth cycle depends on what species of fungi and environmental conditions.

Microbial Volatile Organic Compounds (mVOCs) are the source of “musty” or “moldy” odors that are commonly associated with mold growth. mVOC’s and are the product of metabolism. Exposure to mVOCs from molds have been linked to symptoms such as headaches, nasal irritation, dizziness, fatigue, and nausea.

Mycotoxins are toxins that can be produced by certain species of mold. The mold spore uses mycotoxins (or cytotoxins) to inhibit the growth of other organisms including different species of mold. There are over 300 species of mold that can produce mycotoxins. Exposure to mycotoxins can from come from ingestion, dermal exposure or inhalation.

“Aflatoxin B1 is perhaps the most well known and studied mycotoxin. It can be produced by the molds Aspergillus flavus and Aspergillus parasiticus and is one of the most potent carcinogens known. Ingestion of aflatoxin B1 can cause liver cancer. There is also some evidence that inhalation of aflatoxin B1 can cause lung cancer. Aflatoxin B1 has been found on contaminated grains, peanuts, and other human and animal foodstuffs. However, Aspergillus flavus and Aspergillus parasiticus are not commonly found on building materials or in indoor environments.”

Mold Many Years Ago
Why is mold a problem now and not 50 years ago?  A common material used in building material used in home 50 years ago was plaster or asbestos containing material (ACM). This material is not an adequate food source and is not a suitable substrate for mold to grow on. With the advent of awareness of the health effects related to exposure to asbestos containing material the transition to cellulose based materials occurred and a transition to paper backing gypsum board/drywall was made.

Health Effects of Mold
The approximate size of a mold spore is 2 – 10 microns in diameter. During breathing in humans generally particles greater than 10 microns in diameter will be caught within the nasopharyngeal region (nose). Particles between 2.5 – 10 microns in diameter will typically be caught by cilia lining the bronchial tube walls and will move the particulate out of the lungs. So given the size of the mold spore our nose cannot filter out a mold spore. Only after the spore reaches our bronchial tubes will the mold spore be filtered and pushed out of the lungs by cilia.

Some people have no adverse health reaction when exposed to mold. Allergic reactions that are similar to animal or pet allergies are the most common. Other health effects such as upper respiratory tract irritation, coughing, asthma etc various from one individual to another. Those individuals who’s immune system is compromised such as cardiac patients, individuals undergoing chemotherapy, elderly, infants etc. are most susceptible to adverse affects from mold exposure.