Characterisation of exposure to airborne fungi: measurement of ergosterol

In order to gain a clearer understanding of the level of fungal air contamination in indoor environments, we have adapted and tested a method to evaluate fungal biomass. Liquid phase chromatography (HPLC) of ergosterol, a component of the cell membrane of microscopic fungi, was employed. This method permits the detection and identification of ergosterol molecules at a concentration of 40 microg/ml (n=33, sigma=5). By combining this assay with a rotating cup collection apparatus, it was possible to measure fungal flora levels with a limit of quantification of 0.4 ng/m3 or a theoretical value of 150 spores per cubic meter (m3). Measurements of ergosterol levels performed on different sites showed that this method reflected the different situations of exposure of occupants to airborne fungal flora.