Sick Building Syndrome: Cleanliness is Next to Healthiness

There is evidence that sick building syndrome (SBS) is caused, in part, by indoor surface pollution (ISP): contaminants such as dust, fibres and micro-organisms, deposited on or in surfaces in buildings. A study is described which clarifies the relative importance of a number of possible causes of SBS in a single building. The building, which had a high initial prevalence of SBS symptoms, was used in a doubleblind controlled intervention study with weekly symptom questionnaires. The four interventions were: ventilation system cleaning, air filtration, hot-water extraction cleaning of chairs and carpets, plus high grade filter vacuuming and dusting, and dust mite treatment (application of liquid nitrogen). Only the last two interventions brought about a reduction in symptoms. It is concluded that cleaning which effectively reduces ISP can reduce SBS symptoms. This may be related to the presence of dust mites in furnishings. Improved cleaning may entail better cleaning specifications and/or consideration of requirements for cleaning when selecting and positioning office furniture. If ISP and the temporary local pollution levels created by it are a problem, then monitoring of ambient conditions (by instruments or by human assessors) will not adequately represent the conditions to which occupants are exposed