Different indoor substrates tend to support the growth of a variety of fungal populations, depending on nutrient and water requirements. We have analyzed our data set of 76,000 direct microscopic examinations of materials from indoor environments to elucidate the population structures on different types of materials. We grouped substrates into 10 categories as follows: (i) dry wall/wallboard/other paper materials, (ii) asphalt paper, (iii) fiberglass material, (iv) other insulation materials, (v) carpeting material, (vi) wood and wood products, (vii) dust, (viii) soil material, (ix) fabric material, and (x) painted surfaces. For each of these categories, we evaluated the frequency of identification of more than 225 fungal taxa, many of which were reported for the first time from indoor environments. Stachybotrys species was the dominant fungus seen on dry wall (26.8%), wallboard (21.8%) and on other paper materials (22.7%). Cladosporium species were dominant on fiberglass (29.1%), wood (13.4%), painted surfaces (23.9%), and fabrics (15.4%). Acremonium species dominated asphalt paper samples (24.2%). Penicillium and Aspergillus species were most frequent in dust and on carpeting materials. Ascomycetes were most common in soil samples. In general, Cladosporium, Penicillium, Aspergillus, and Stachybotrys species were seen on all indoor substrate types. Few fungi that have not been or are rarely reported from indoor substrates included Microascus, Ascotricha, Monodictys, Engyodontium, Gliomastix, Graphium, Petriella species (all recovered on at least 1% of samples), and others that were less commonly recovered. These data document the different population structures that occupy materials in the indoor environment. Extensions of this study could permit predictions of the types of fungi likely to become abundant following specific water events.

• fungi and molds in buildings and their envelopes

1. An update on pollen and fungal spore aerobiology
2. Characterization of fungi occurring on "new" gypsum wallboard
3. Dustborne and airborne fungal propagules represent a different spectrum of fungi with differing relations to home characteristics
4. Fungal growth in buildings: the aerobiological perspective
5. Health risk assessment of fungi in home environments
6. Indoor allergens: assessing and controlling adverse health effects
7. Moisture, organisms, and health effects
8. Populations and determinants of airborne fungi in large office buildings
9. Quantification of ergosterol and 3-hydroxy fatty acids in settled house dust by gas chromatography-mass spectrometry: Comparison with fungal culture and determination of endotoxin by a Limulus amebocyte lysate assay
10. Review of concentration standards and guidelines for fungi in indoor air