The effect of varying levels of outdoor-air-supply on the symptoms of sick building syndrome.

The study was undertaken to find out the effect of changing the supply of outdoor air in four office buildings on the sick building syndrome symptoms reported by workers. The ventilation systems in each building were manipulated in random order to deliver to the indoor environment 20 or 50 ft3 of outdoor air per minute per person for one week at a time. Each week the workers, who knew nothing of the scheme, were invited to report symptoms. The changes in the supply of outdoor air were not associated with changes in the participants' rating of the office environment or in symptom frequency. Nor was there any change when work-site measurements of ventilation, temperature, humidity and air velocity were included.