Through the years, man has built increasingly elaborated buildings to protect himself from the elements such as rain, snow, and warm air in summer and cool air in winter. However, such buildings do not always ensure protection of the occupants from the pollution present indoors. A person spends 90% of his time inside the buildings (Hoppe and Martinac, 1998). The indoor environment, therefore, can be viewed as a “habitat” or an “ecosystem.” It is a complex “habitat” that consists of various attributes, namely occupants and their activities, the air pathways and ventilation, the building envelope and its environmental settings. Hence, it is necessary to understand the interrelationship between indoor and outdoor environments. The scientic evidence has indicated that the air within the buildings may be more polluted than the outside air causing problems associated with poor indoor air quality (IAQ). Indoor air pollution is responsible for 2.7% of the global burden of disease (WHO, 2002).