Distinguishing between healthy and sick preschools by chemical classification

The Swedish building code of 1975 emphasizes energy conservation and encourages the construction of tightly insulated structures with adequate ventilation systems. Some of the new buildings constructed along these guidelines have been labeled “sick,” because people working in them report an unusual number of health problems—e.g., eye irritation, skin rashes, and fatigue. One possible indicator of whether a building is “healthy” or “sick” may exist in the pattern of chemicals present in the air. This article outlines an approach designed to find sets of chemicals that can be used to separate buildings according to their designation as sick and healthy. Air samples were taken from a healthy and sick preschool and subsequently analyzed by gas chromatography. The prevalence of different chemical substances was determined and compared across 16 different locations from which air samples were obtained, including outdoor, supply, room, and exhaust air. In all, 158 different chemical substances were found; more in the healthy building than in the sick one. Cluster analysis, based on the pattern of presence and absence of chemicals, was able to separate locations within and between the two types of building. A large number of chemicals (approx. one-half the total) were effective in distinguishing among locations. The ten most critical chemicals in this respect were subjected to more complete statistical analysis in order to highlight further possible differences between the buildings. The general approach described may prove useful in recognizing the environmental conditions associated with the “sick building syndrome.”