<P> At the end of the 1990s came an increased distrust of the concept of "sick building". A dissertation at the Karolinska Institutet in Stockholm 1999 questioned the methodology of previous research, and a Danish study from 2005 showed these flaws experimentally . It was suggested that sick building syndrome was not really a coherent syndrome and was not a disease to be individually diagnosed . In 2006 the Swedish National Board of Health and Welfare recommended in the medical journal Läkartidningen that "sick building syndrome" should not be used as a clinical diagnosis . Thereafter, it has become increasingly less common to use terms such as "sick buildings" and "sick building syndrome" in research . However, the concept remains alive in popular culture and is used to designate the set of symptoms related to poor home or work environment engineering . "Sick building" is therefore an expression used especially in the context of workplace health . </P> <P> Sick building syndrome made a rapid journey from media to courtroom where professional engineers and architects became named defendants and were represented by their respective professional practice insurers . Proceedings invariably relied on expert witnesses, medical and technical experts along with building managers, contractors and manufacturers of finishes and furnishings, testifying as to cause and effect . Most of these actions resulted in sealed settlement agreements, none of these being dramatic . The insurers needed a defense based upon Standards of Professional Practice to meet a court decision that declared--that in a modern, essentially sealed building, the HVAC systems must produce breathing air for suitable human consumption . ASHRAE (American Society of Heating, Refrigeration and Air Conditioning Engineers, currently with over 50,000 international members) undertook the task of codifying its IAQ (Indoor Air Quality) standard . </P> <P> ASHRAE empirical research determined that "acceptability" was a function of outdoor (fresh air) ventilation rate and used carbon dioxide as an accurate measurement of occupant presence and activity . Building odors and contaminants would be suitably controlled by this dilution methodology . ASHRAE codified a level of 1,000 ppm of carbon dioxide and specified the use of widely available sense - and - control equipment to assure compliance . The 1989 issue of ASHRAE 62.1 - 1989 published the whys and wherefores and overrode the 1981 requirements that were aimed at a ventilation level of 5,000 ppm of carbon dioxide, (the OAHA workplace limit), federally set to minimize HVAC system energy consumption . This apparently ended the SBS epidemic . </P> <P> Over time, building materials changed with respect to emissions potential . Smoking vanished and dramatic improvements in ambient air quality, coupled with code compliant ventilation and maintenance, per ASHRAE standards have all contributed to the acceptability of the indoor air environment . Only time and the courts will tell how right, or wrong ASHRAE is . </P>

Sick building syndrome does not result from poor indoor air quality