Molds are simple, microscopic organisms, present virtually everywhere, indoors and outdoors.  Molds, along with mushrooms and yeasts, are fungi and are needed to break down dead plant and animal material and to recycle nutrients in the environment.  Molds can grow on surfaces or objects in buildings.  They may be visible or, if inside walls or building structures, not visible to you.

For molds to grow and reproduce, they need only a food source—any organic matter, such as leaves, wood, or paper—and moisture.  Because molds grow by digesting organic material, they gradually destroy whatever they grow on.  Mold growth on surfaces can often be seen in the form of discoloration: frequently white, gray, brown, or black but also green and other colors.

Common sources of moisture that may lead to indoor mold problems include:

•   Flooding
•   Leaky roof
•   Sprinkler spray hitting a building
•   Plumbing leaks
•   Overflow from sinks or sewers
•   Damp basement or crawl space
•   Steam from showers or cooking
•   Humidifiers
•   Wet clothes hung to dry indoors 
•   A clothes dryer that exhausts air indoors

Prevention is important to avoid mold problems.  Inspect your home, school, or workplace regularly for the signs and sources of indoor moisture and mold. 

Health Effects of Mold

Molds release tiny spores and even smaller particles that travel through the air.  Everyone inhales some mold every day without apparent harm; however, molds can cause inflammation, allergy, or infection.  Allergic reactions are the most well-recognized responses to inhaling mold spores.

While we know there are health effects associated with indoor dampness and mold, we do not know how much specific molds are responsible, and how much of the effects might be caused by bacteria or chemical emissions.  We know that dampness and mold cause health effects both in allergic and non-allergic people.  The health effects consistently associated with indoor dampness and molds include:

•   Allergic rhinitis (runny nose)
•   Upper respiratory symptoms, such as stuffy or congested nose or sinuses, sore throat, or irritated nose or throat
•   Lower respiratory symptoms, such as wheezing, difficulty breathing, shortness of breath, or cough
•   Asthma attacks in those who already have asthma
•   Causation of new asthma
•   Respiratory infections such as acute bronchitis
•   Eye irritation (burning, watery, or reddened eyes)
•   Eczema, and skin rashes or irritation