Long-term exposure to indoor air pollution is becoming a worldwide epidemic. It is suggested that up to 30% of new or remodeled buildings worldwide may be subject to excessive complaints related to poor indoor air quality. It is most often identified when the symptoms are relieved shortly after leaving the building. Other conditions that may be present i.e. allergies, asthma etc. could be aggravated by indoor air problems.
Some causes are of Sick Building Syndrome are poor ventilation, chemical contaminants (environmental tobacco smoke, household products, building materials, etc.) and biological contaminants (ie. dust mites, mould, legionnaires).
Standards for ventilation in early 1900s were 15 cubic feet per minute (cfm) for each building occupant and later changed to 5 cfm due to the energy crisis in the 1970s. The American Society of Heating, Refrigeration and Air Conditioning Engineers recently revised it back to 15 cfm, 20 in office spaces and up to 60 in areas like smoking lounges.