The aim of the study was to investigate whether the concentration of fungal spores in the room air as well as the variety of species is affected by visible indoor growth of mold. Measurements of airborne fungi were conducted both indoor air and corresponding outdoor air in 66 households in Austria between October 2002 and September 2003. Samples were taken by using a one-stage MAS-100 Merck® air sampler. Malt extract agar (MEA) and dichloran glycerol agar (DG18) were used as media for sampling. The total colony forming units (CFU) per m³ were determined. All isolated colonies were identified on the species level.
The results show that in 37 homes visibly affected by mold, the median values of 1.5x103 CFU/m³ air for MEA and 1.7x103 CFU/m³ air for DG18 agar were ten times higher than those of the corresponding outdoor air. In 29 homes without visible growth of mold the median values of 2.6x102 CFU/m³ air for MEA and 3.5x102 of the CFU/m³ air for DG18 agar correlated well with the corresponding outdoor air.
In households visibly affected by mold the mean concentration of Penicillium and Aspergillus spores in the air rises significantly with increasing size of the moldy patches. In households without visible mold, Cladosporium sp. and Penicillium sp. predominated.
For further assessing airborne fungi in households with or without mold growth, it is recommended to use the total fungal concentration of Penicillium sp. as well as Aspergillus sp.