A new approach to the investigation of sick building syndrome.

Most large-scale investigations of sick building syndrome (SBS) have relied on comparisons among buildings, which necessarily involve many confounding factors. We are now conducting a study based on systematic modification of environmental conditions in a building, with double-blind monitoring of occupants' responses to the changes. Different changes (e.g. repairing or cleaning the ventilation systems, improving office cleaning), are carried out in different rooms in a series of study "modules", including a control module. This paper describes the study design and presents some early results to exemplify the approach. These results indicate that intensive office cleaning reduced the symptoms of SBS.