Airborne enzyme measurements to detect indoor mould exposure

Mould in buildings constitutes a threat to health. Present methods to determine the moulds comprise counting of spores or determination of viable moulds which give imprecise measures of total mould cell biomass. Analysis of ergosterol and beta-glucan as markers of mould cell biomass is expensive and cumbersome. To evaluate if airborne enzyme activity was related to mould in buildings air samples were taken using an impinger technique or cellulose filters in 386 rooms in 141 buildings. The samples were analysed for the activity of N-acetylhexosaminidase (NAHA) and expressed as enzyme units per m(3) (EU per m(3)). The highest value found in a building was used for the classification of the building and was related to the results from the subsequent technical inspection. In buildings without mould damage, the NAHA activity was generally below 20 EU per m(3). In buildings with mould damage, almost all the buildings had activities above 20 EU per m(3) (specificity 85%). At 30 EU per m(3) the specificity was 100%. Measurements of airborne enzyme activity have a high sensitivity and specificity to identify buildings with mould problems. The method can be used in the investigations of building related symptoms or for home exposure characteristics when investigating diseases such as asthma that can be related to mould exposure.