Sick building syndrome: the acoustic environment.

The acoustic environment was investigated in an office building with a history of occupant complaints. A scoring system was developed for rating occupants' sick building symptoms. High scores were associated with the occurrence of high levels of infrasound (< 20 Hz) in the rooms, und low levels with low scores. The infrasound came from the ventilation system as airborne noise, rather than structural-borne vibration. Levels of infrasound were often amplified in the tightly sealed rooms, and could be higher at work stations than at supply grilles. Repeated or long-term exposure to infrasound may be triggering an allergic-type response.