This study explored the possible connections between the incidence and prevalence of sick building syndrome (SBS), indoor exposures, and personal factors. This was accomplished by a four year longitudinal study of workers in six primary schools. The mean concentration of Carbon Dioxide exceeded the recommended value of 0.08 microlitres/l (800 ppm) in all schools, which suggested a poor outdoor air supply. Indoor levels of volatile hydrocarbon (VOC) was increased at high room temperatures. Respirable dust, but not the level of VOC was increased at lower ventilation rates and higher air humidity. Chronic SBS was connected to VOC, previous wall to wall carpeting, hyperreactivity, and psychosocial factors. The incidence of new SBS was related to the concentration of respirable dust, the current levels of smoking and the psychosocial climate. The remission of hyperreactivity, a fall in sick leave owing to respiratory illnesses, the removal of the schools' carpets, and moving from new to old dwellings caused a decrease in SBS score. The study concludes that SBS is produced by several factors, and the level of exposure to each of them. The overall concentration of hydrocarbons is an easy and useful measure of exposure, which also seems to be a good predictor of chronic symptoms of SBS. Further studies of the effect of temperature, ventilation, and air humidity on SBS should include a consideration of how these factors could influence the air's chemical composition. The study concludes by making the point that poor air quality in schools could also affect the children and may have wide implications for the healthiness of a large section of the population.