Molds are part of the natural environment. Outdoors, molds play a part in nature by breaking down dead organic matter such as fallen leaves and dead trees, but indoors, mold growth really should be avoided.
Molds reproduce by means of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air. Mold may begin growing indoors when mold spores land on surfaces that are wet. There are many types of mold, and none of them will grow without water or moisture. Recognizing there is a mold issue is the first step to solving the problem
Can mold cause health problems?
Molds are usually not a problem indoors, unless mold spores land on a wet or damp spot and begin growing. According to the EPA molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins). 
The EPA also states that inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic responses that include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common. They can be immediate or delayed.
Molds can also cause asthma attacks in people who have asthma and also are allergic to mold. In addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs.
