People may have health problems when mold grows to a particular level in a structure. People who are immuno-compromised or who have suppressed immune systems such as children, the elderly, chronically ill, or those with breathing and lung problems may be more susceptible to mold.
Remember, there are many kinds of mold. Some types of mold may cause a cough, congestion, headaches, fatigue, a runny nose, and aggravated asthma. Other molds can cause more serious symptoms such as a flu like illness or worse. The intensity of the mold and the length of exposure are also factors in how people react to it.
Mold can produce allergens, irritants, and in some cases potentially harmful mycotoxins. These allergens and toxins can cause people to become ill.