Effect of building frame and moisture damage on microbiological indoor air quality in school buildings

The effect of building frame and moisture damage on microbial indoor air quality was characterized in 17 wooden and 15 concrete or brick school buildings. Technical investigations to detect visible moisture and mold damage were performed according to a standardized protocol. Viable airborne microbes were determined by using a six-stage impactor (Andersen 10-800). Mean concentrations of viable airborne fungi were significantly higher in wooden schools than in concrete schools, showing that the frame material was a determinant of concentrations of airborne fungi. Moisture damage of the building did not alter the fungal concentrations in wooden school buildings. In contrast, in concrete schools the effect of moisture damage was clearly seen as higher concentrations compared with the reference schools. Aspergillus versicolor, Stachybotrys, and Acremonium were detected only in samples from moisture damaged buildings, and can be considered marker fungi of such damage in school buildings. In addition, the presence of Oidiodendron as well as elevated concentrations of Cladosporium and actinobacteria were associated with moisture damage in concrete schools.