Indoor Air Quality (IAQ) deals with the content of interior air that could affect health and comfort of building occupants. The IAQ may be compromised by microbial contaminants (mold, bacteria), chemicals(such as carbon monoxide,radon}, allergens, or any mass or energy stressor that can induce health effects. Often it is perceived that outdoor air is polluted, but indoor air is acceptable. Scientific studies illustrate the falsity of this perception, and, in fact, indoor air is often a greater health hazard than the corresponding outdoor setting.