Sick building syndrome symptoms and performance in a field laboratory study at different levels of temperature and humidity

Thirty female subjects were exposed for 280 minutes to four conditions in balanced order of presentation: to 20 C/40%, 23 C/50%, 26 C/60% RH at10 L/s/p outside air, and to 20 C/40% RH at 3.5 L/s/p. They performed simulated office work throughout each exposure and repeatedly marked a set of visual-analogue scales to indicate their perception of environmental conditions and of the intensity of SBS symptoms at the time. They were repeatedly reminded to adjust their clothing so as to remain in thermal comfort, and succeeded in doing so. Although perceived air quality improved at lower indoor air temperature and humidity and at the higher ventilation rate, this could not be shown to be associated with any effects on task performance. However, subjects reported significantly more intense SBS symptoms associated with decreased productivity, including fatigue, headache and difficulty in thinking clearly, when they were exposed to raised levels of temperature and humidity.