Sick Building Syndrome first became a problem in the wake of the energy crisis of the seventies when office buildings were starting to be designed to be "tight" to keep air in for the purpose of energy conservation. In theory, it seemed to conserve energy because the air is recirculated and would not have to be heated or cooled as often. Although this process may save energy, long term health hazards have been completely overlooked. The air in the building is constantly recirculated over and over again. If one recirculates the air in a building repeatedly, it's like bathing in someone else's bath water.
Even ventilation systems that appear adequate cause problems. The intake system for the building allows large amounts of contaminants to circulate indoors.

Chemical Contaminants
Polluted outdoor air is used to ventilate the air inside the building. The air that enters the duct system in a building is recirculated over and over for long periods of time. The recirculated air may contain various pollutants such as auto exhausts, chemical fall out from local processing plants, pesticides, carbon emissions from copy machines, computers and other equipment, which collectively emit volatile organic compounds (VOC's).

Biological Contaminants
Bacteria, moulds, pollen, viruses, dust mites, dead insects and rodents are contaminants that breed in ventilation ducts. The above mentioned are related to short term and long term symptoms to include, but not limited to, coughs, tightness in the chest, fever, chills, head and muscle aches, allergic responses, upper respiratory congestion, and Legionella, an indoor bacteria which has caused both legionnaire disease as well as pontiac fever.
As SBS law suits become more commonplace, liability insurance premiums will reflect that risk, and building owners will likely see solid financial incentives to establish viable, proactive healthy building programs.