Sight and smell are the primary methods of identifying large mold infestations, and while additional microscopic examination is required for determining if black mold is present, the Centers for Disease Control and Prevention recommends treating all molds as a potential health risk and removing them.
Mold reproduces through spores that travel through the air. Spores enter a room through open doors and windows or by attaching to humans and animals that enter the space, according to the CDC. They require moisture and nutrients to grow. The moisture comes from leaks and condensation, and building materials, such as wallboard, that contain cellulose provide the nutrients for the mold to begin growing.
Molds are common in buildings and homes. The most common mold species are Cladosporium, Penicillium, Aspergillus and Alternaria. The CDC indicates black mold, Stachybotrys chartarum, while less common than the other species, is not rare. It requires constant moisture for growth.
Mold growth in a building does not always affect the health of the occupants, according to the CDC. In some individuals, exposure causes watery eyes, nasal stuffiness and wheezing. In cases of repeated exposure, more severe reactions sometimes occur. In individuals with compromised immune systems or severe lung problems, mold may begin to grow in the lining of the lungs, causing severe health problems.