Fungal growth in buildings starts at a water activity (aw) near 0.8, but significant quantities of mycotoxins are not produced unless aw reaches 0.95. Stachybotrys generates particularly high quantities of many chemically distinct metabolites in water-damaged buildings. These metabolites are carried by spores, and can be detected in air samples at high spore concentrations. Very little attention has been paid to major metabolites of Stachybotrys called spirocyclic drimanes, and the precise structures of the most abundant of these compounds are unknown. Species of Aspergillus and Penicillium prevalent in the indoor environment produce relatively low concentrations of mycotoxins, with the exception of sterigmatocystins that can represent up to 1% of the biomass of A. versicolor at aw's close to 1. The worst-case scenario for homeowners is produced by consecutive episodes of water damage that promote fungal growth and mycotoxin synthesis, followed by drier conditions that facilitate the liberation of spores and hyphal fragments.

• fungi: components and products

1. Determination of ergosterol on mouldy building materials using isotope dilution and gas chromatography--tandem mass spectrometry
2. Determination of fungal spore release from wet building materials
3. Growth of moulds on building materials under different humidities
4. Microfungal contamination of damp buildings - examples of risk constructions and risk materials
5. Mould growth on building materials: Secondary metabolites, mycotoxins and biomarkers
6. Production of mycotoxins on artificially and naturally infested building materials
7. Production of mycotoxins on artificially inoculated building materials
8. The Danish Research Programme: "moulds in Buildings" 1998-2001
9. The release of fungal spores from water damaged building materials