[Background concentrations of molds in air. Determination of mold concentrations in dwellings without known mold infestations in three parts of Germany]. / Hintergrundkonzentrationen von Schimmelpilzen in Luft. Erhebung von Schimmelpilzkonzentrationen in Wohnungen ohne bekannte Schimmelpilzschäden in 3 Regionen Deutschlands.

The mold concentration of indoor air and outdoor air in three parts of Germany was investigated in both winter and summer. In total, air samples from 80 dwellings, reportedly free from mold infestations, were analysed with both the cultivation method and the total spore count method. With the cultivation method, 40 mold species and genera were differentiated, while with the total spore count method, 11 spore types were distinguished. The concentration of the genera Alternaria, Cladosporium, Fusarium and yeast increased in summertime. In contrast, the concentrations of Aspergillus and Penicillium measured in summer were nearly equal to those measured in winter. The majority of the various molds were only found in a small number of samples, too small for a reliable comparison of the winter and summer findings. The 95th percentile of the indoor mold concentrations is suggested as the upper limit of the background concentration. The results are discussed comparing the assessment proposals of various authors, and a new assessment proposal is described.