Work-related illness in offices: a proposed model of the "sick building syndrome".

This study was based on a nationwide survey of 4373 workers at 47 offices to determine the incidence of sick building syndrome and to study associated factors. The buildings had a variety of ventilation systems - natural, mechanical, forced air, air conditioning or comfort cooling. Comfort cooling systems included fan-coil, induction, and constant or variable air volume systems. The survey revealed a higher incidence of reports of work-related symptoms of dry eyes, dry throat, stuffy/congested nose, itchy/watery eyes, runny nose, lethargy/tiredness, and headache in air conditioned rather than unconditioned buildings. Symptoms were more often reported in buildings with water-based cooling ventilation systems, e.g. fan-coil or induction systems, than in those with all-air systems. A significant correlation was found between the type of humidification used in air-conditioned buildings (none, evaporative/spray, or steam) and the number of complaints of itchy eyes, stuffy nose, lethargy, breathing difficulty and chest tightness. The survey suggests that the "sick building syndrome" is connected to a whole range of factors. One was personal characteristics such as gender or age. Another was occupational factors, including job type, length of video display unit use, length of time in building and job stress. A third was architectural features - for example the type of office, the type of building ventilation system. The final factor was psychological processes based on perceptions of environmental control, ambient conditions and environmental satisfaction. The study concludes with a path analytic model which suggests that psychological processes mediate the connection between individual, occupational, and environmental factors and reports of the "sick building syndrome".