A Pilot Study on Baseline Fungi and Moisture Indicator Fungi in Danish Homes

In many complaint cases regarding bad indoor environments, there is no evidence of visible fungal growth. To determine if the problems are fungi-related, dust sampling is the method of choice among building surveyors. However, there is a need to differentiate between species belonging to a normal, dry indoor environment and species belonging to a damp building envelope. The purposes of this pilot study were to examine which fungal species are present in problem-free Danish homes and to evaluate different detection and identification methods. Analyses showed that the fungal diversity outside was different from the diversity inside and that the composition of fungal species growing indoors was different compared to those found as spores, both indoors and outdoors. Common for most homes were Pseudopithomyces chartarum, Cladosporium allicinum and Alternaria sect. Infectoriae together with Botrytis spp., Penicillium digitatum and Pen. glabrum. The results show that ITS sequencing of dust samples is adequate if supported by thorough building inspections and that food products play as large a role in the composition of the baseline spora as the outdoor air and surrounding vegetation. This pilot study provides a list of baseline fungal species found in Danish homes with a good indoor environment.

Automated summary

The fungal diversity in problem-free Danish homes differs from outdoors, and the species composition indoors varies from those found as spores inside and outside. ITS sequencing of dust samples supported by thorough building inspections is an adequate method to assess fungal issues. Food products also play a significant role in the composition of baseline spora.