No consistent risk factor pattern for symptoms related to the sick building syndrome:: a prospective population based study

Objectives: To examine associations between perceived indoor environment at work and the non-specific symptoms that are often referred to as the sick building syndrome (SBS), using cross-sectional and prospective analyses for a large cohort from the general population. Methods: The sample comprised 2,164 adults in employment, who completed a postal questionnaire in April 2001. Of these 1,402, who were still working and living in the same place, completed a second questionnaire a year later. The outcome measures were the prevalence of mucous membrane symptoms and general symptoms at baseline and the incidence and persistence of these symptoms at follow-up. Self-reports of the indoor environment from the baseline questionnaire were used as predictors in the analyses. Results: Inconsistent results were found between the cross-sectional and the longitudinal analyses for the associations between perceived indoor environment factors at work and symptoms. Whereas mucous membrane symptoms in the cross-sectional analysis were significantly associated with self-reported high temperature and dry air, the prospective analyses showed that onset of mucous membrane symptoms was associated with the sensation of draught, dry air, and noise. Persistent mucous membrane symptoms were associated only with stuffy air. General symptoms were associated with self-reported stuffy air and dry air in the cross-sectional analysis, while draught was the only predictor of onset of general symptoms. We found no predictors in the indoor environment for the persistence of general symptoms. Conclusions: The symptoms that are often connected with SBS are very common symptoms in the general population among manual workers as well as non-manual workers. Our study gives only limited support to the hypothesis of causal relationships between the indoor environment and these symptoms. We found no evidence of persistent mucous membrane symptoms and general symptoms related to specific factors in the indoor environment.