ASSOCIATIONS BETWEEN TYPE OF VENTILATION AND AIR-FLOW RATES IN OFFICEBUILDINGS AND THE RISK OF SBS-SYMPTOMS AMONG OCCUPANTS (REPRINTED FROM ENVIRONMENT INTERNATIONAL, VOL 20, PG 239-251, 1994)

The association between type of ventilation and outdoor-air flow rates and Sick Building Syndrome (SBS) and SBS symptoms was studied in a cr oss-sectional questionnaire and field study comprising 160 office buil dings, and 260-2649 respondents with case-controls as well as prevalen ce comparisons. Measured ventilation rates were higher than required b y most building codes and consisted of fresh-air (outdoor-air) inflow of 17+/-14 L/p and 2.0+/-1.3 air changes/h. Increased risk of SBS and elevated prevalence of general SBS symptoms were associated with low o utdoor-air flow rates presence of copying machines in office rooms, an d ventilation operating hours was less than 10 h/d. There was a suspec ted association between SBS and air humidification, recirculation of e xhaust air at high outdoor-air flow rates but not at low outdoor-air f low rates, and with natural or mechanical exhaust ventilation systems. SBS was not associated with the presence of a rotary heat exchanger o r with the supply air temperature higher than the room air temperature .