Assessment of indoor air in Austrian apartments with and without visible mold growth

Fungal spores are transported across great distances in the outdoor air and are also regularly found indoors. Building conditions and behavior-related problems in apartments may lead to massive growth of mold within a very short period of time. The aim of this study was to evaluate whether the visible growth of mold indoors influences the concentration of fungal spores in the air as well as the variety of their species. Samples were collected from 66 households in Austria. For each sampling, the corresponding outdoor air was measured as reference value. The size of the visible mold growth was categorized in order to correlate the extent of mold growth with the concentration of airborne spores as well as the fungal genera. In order to determine fungal spore concentrations in the air, the one-stage MAS-100® air sampler was used. Malt extract agar (MEA) and dichloran glycerol agar (DG18) plates were used as culture media. The total colony forming units (CFU) per m3 were determined. The fungi were identified from the isolated colonies. The results show that in apartments visibly affected by mold, the median values were significantly higher than those of apartments without visible mold growth. The extent of visible mold growth is significantly correlated with both concentration of fungal spores (p<0.001) as well as the predominance of Penicillium sp. and Aspergillus sp. (p<0.001) in indoor air. The total fungal concentration of Penicillium and Aspergillus in the air of apartments is recommended for assessing fungal exposure.