In Is Mold Causing Your Indoor Air Quality Problem?, environmental health and safety expert James L. Unmack, PT, CIH, CSP, REA, writes:
We have all seen molds on food or paper products (books, bathroom walls, etc.). These visible manifestations are only indicators of potential problem. The problem is actually not seen by the naked eye. It is the reproductive result of these indicators that is of concern.
Molds and yeasts are grouped under a heading of fungus (plural, fungi). Fungus is a primitive plant form that does not contain chlorophyll. Fungi must have a source of food and water to grow. Where there is sufficient food and water, fungi grow and multiply at an astounding rate. It is this growth rate that is one of two conditions for concern. Many fungi grow by expelling (1) spores or (2) small bits of growth material, into the air for creation of colonies in other areas. If these spores or growth material are created in air handling systems for instance, they can be part of the air we breath and can find their way into our bodies, impacting our immune system. The second condition is the dormant stage of fungi. Long after the water has been removed (remember food and moisture are required for growth), colonies can remain quasi-dormant: that is, spores can become air borne by disturbance such as pulling affected books off a shelf, cleaning carpets with a vacuum, removing wall board from affected areas, etc. When this happens, spores can be released and inhaled into the respiratory system where it is moist and may have food sources.
