THE USE OF ERGOSTEROL TO MEASURE EXPOSURE TO FUNGAL PROPAGULES IN INDOOR AIR

This report concerns the development of a method for the measurement o f ergosterol in indoor air as a determinant of fungal exposure. Ergost erol was determined in spores of 11 species of Aspergillus, Penicilliu m, and Cladosporium selected from the most common molds in 400 homes i n Ontario. Spore ergosterol content was about 1 mu g/mg, which is the range reported for mycelia, and varied by about 25% for the species te sted. Ergosterol was determined in bedroom air samples taken in the wi nter in homes in southern Ontario. The median ergosterol value corresp onded to a total concentration of fungal spores on the order of 10 to 10(2) per m(3), in the range for other studies where total and viable propagules were determined by other methods. The sampling of air for e rgosterol is a robust method for assessing fungal biomass in air, but provides no information on the species present.