title: The effect of varying levels of outdoor-air supply on the symptoms of sick building syndrome.
abstract: BACKGROUND
  The sick building syndrome is the term given to a constellation of symptoms reported by workers in modern office buildings, hypothesized to occur when the supply of outdoor air is reduced, because of the accumulation of contaminants arising from within the building. We undertook this study to determine the effect of changing the supply of outdoor air in four office buildings on the symptoms reported by workers and their perception of the indoor environment.
  
  
  METHODS
  Within each of three consecutive two-week blocks, the ventilation systems in each building were manipulated, in random order, to deliver to the indoor environment an intended 20 or 50 ft3 (0.57 or 1.4 m3) of outdoor air per minute per person for one week at a time. Each week, the participants, unaware of the experimental intervention, reported symptoms and the indoor environment was thoroughly evaluated.
  
  
  RESULTS
  Of 1838 eligible workers in the four buildings, 1546 (84 percent) participated in the study. The supply of outdoor air averaged 7 percent and 32 percent in the ventilation systems and 30 and 64 ft3 (0.85 and 1.8 m3) per minute per person in the work sites at the lower and higher ventilation levels, respectively. These changes in the supply of outdoor air were not associated with changes in the participants' ratings of the office environment or in symptom frequency (crude odds ratio, 1.0; 95 percent confidence interval, 0.9 to 1.1). After work-site measures of ventilation, temperature, humidity, and air velocity were included in the regression analysis, the adjusted odds ratio was also 1.0 (95 percent confidence interval, 0.8 to 1.2).
  
  
  CONCLUSIONS
  Increases in the supply of outdoor air did not appear to affect workers' perceptions of their office environment or their reporting of symptoms considered typical of the sick building syndrome.
authors.affiliation: Department of Epidemiology, McGill University, Montreal, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Menzies
authors.forename: R
authors.initials: R
authors.lastname: Tamblyn
authors.forename: J P
authors.initials: JP
authors.lastname: Farant
authors.forename: J
authors.initials: J
authors.lastname: Hanley
authors.forename: F
authors.initials: F
authors.lastname: Nunes
authors.forename: R
authors.initials: R
authors.lastname: Tamblyn
mesh_terms: D000328:Adult; D000388:Air / Q000032:analysis; D016902:Air Pollution, Indoor / Q000517:prevention & control*; D002245:Carbon Dioxide / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D011795:Surveys and Questionnaires; D014691:Ventilation / Q000379:methods* / Q000592:standards
chemical_list: D002245:Carbon Dioxide