Airborne and dust borne microorganisms in selected Polish libraries and archives

Abstract The aims of this work were to quantitatively and qualitatively study culturable fungi and bacteria in the air and settled dust in the storerooms of five Polish libraries and archives as well as to estimate the effect of water intrusion on the microbial air quality indoors. In all studied storerooms, the total bioaerosol concentrations at the workplaces ranged from 100 to 1000 cfu/m3. The most prevalent part of the storerooms’ bioaerosol consisted of bacteria, mainly Staphylococcus spp. and Micrococcus spp., followed by filamentous fungi. In four of the studied premises, fungal aerosol concentrations were below 100 cfu/m3. The only exception was observed in the fifth storeroom, which has been periodically flooded with rainwater and where significantly higher concentrations of fungal aerosol were measured. Among the identified fungal species, those of the genus Penicillium were the most numerous. Moreover, Trichothecium laxicephalum and Alternaria tenuis were present in all of the examined storerooms. The other objective of this study was to evaluate the effect of renovation and mechanical cleaning of the flooded storeroom collection on the level of microbial contamination. The obtained results show that both of the applied procedures reduced the concentration of fungal and bacterial aerosols by almost 80% and 50%, respectively. A significant reduction in the number of airborne microbial species was also noted. Hence, if the source of moisture is removed and mechanical cleaning is subsequently applied, the hygienic quality of a storeroom collection can be significantly improved.