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Controlled Experiments for Studies of the Sick Building Syndrome

The establishing of causality between an environmental exposure factor and health effects involves several investigational elements such as mapping of the occurrence of exposures and effects, and identification of covariables and of risk groups. Often, the establishment of causality is initiated by several such independent investigations. Then a biologically reasonable explanation of the effects and their mechanisms is suggested, and subsequently this suggested causality is tested, for example, in controlled experiments or investigations. A broad spectrum of methods and principles of investigation is available. The spectrum ranges from epidemiological field investigations to controlled laboratory experiments. Each of these tools has advantages and disadvantages that unfortunately often are neglected in their planning. This paper illustrates some of the problems encountered during the design of controlled laboratory exposure experiments in relation to indoor air quality (IAQ) and subjective unspecific symptoms. The sick building syndrome (SBS) and exposures to low levels of volatile organic compounds (VOCs) are used as examples. The paper is not intended to be a scientific deduction of an optimal protocol for such experiments, but will identify some high-priority questions to address during the planning of research protocols dealing with the IAQ and subjective symptoms.