In recent years an increasing amount of health evidence from building occupants has confirmed the existence of sick building syndrome (SBS). This is where occupants within a building begin to report feelings of nausea, headaches and general feelings of illness. Additional symptoms of this health problem include eye, nose and throat irritation, coughing and fatigue. The fact that most people nowadays spend a lot of time indoors further emphasises the fact that IAQ is of great importance and should be seriously investigated.
Health has become more of an important issue in the past decade, as people have become more educated about their own health and the global environmental protection issue. The growing awareness of employers of the relation between the quality of the workplace and the performance of workers has fuelled interest in IAQ of office buildings and workplaces. These many factors have resulted in the demand for more efficient and cost effective heating, ventilation and air conditioning (HVAC) systems.
The recent literature on indoor air pollution indicates that carbon dioxide (CO2) is a major pollutant. To assess the IAQ of an office building, Cheong monitored the number of indoor pollutants including CO2 . Fleming in his investigations measured radon, nitrogen dioxide (NO2), formaldehyde, suspended particles and carbon monoxide (CO) .