Characterizing Mold Problem Buildings – Concentrations And Flora Of Viable Fungi

The purpose of this study was to characterize mold problem buildings by determining concentrations and flora of viable fungi. The composition and concentrations of fungal flora in mold problem (n = 9) and reference buildings (n = 9) were determined by means of four different sampling methods: six-stage impactor (Andersen sampler), sedimentation plate, surface and house dust samples. Samples were taken in the fall and in the winter, and the concentrations and flora in mold problem buildings were compared with those of matched reference buildings. The differences between mold problem and reference buildings were most clearly seen with the impactor samples. The total concentrations of airborne fungi were higher in moldy buildings. In addition, the concentrations of the genera Aspergillus and Oidiodendron in the fall and the concentrations of Aspergillus and Penicillium in the winter were higher in mold problem than in reference buildings. In the winter, certain fungal genera (Stachybotrys, Acremonium, Oedocephalum and Botryosporium) were detected only in the problem buildings in impactor samples. These results indicate that there may be an unusual composition of fungal flora in mold problem buildings. The results of the sedimentation plate samples showed a trend similar to that of impactor samples in the winter. In addition, the results of surface samples supported the data on the fungal flora in the winter-time air samples. The house dust samples did not reveal any differences between mold problem and matched reference buildings.