Size distribution and concentration of indoor culturable bacterial and fungal bioaerosols

Exposure to bioaerosols in indoor environments may adversely affect human health. Herein, we present the concentrations and size distributions of bacterial and fungal bioaerosols measured in 5 locations (café, cafeteria, building lobby, classroom, and meeting room) within one building during winter. Sampling was conducted using a six-stage Andersen cascade impactor and the size-specific concentration of culturable bioaerosols was quantified via the colony counting method. The concentration and size distribution of bioaerosols differed among locations. The highest average concentrations of bacterial and fungal bioaerosols were found in the café (170 colony-forming unit [CFU]/m3) and cafeteria (205 CFU/m3). In the winter indoor environment, both fungal and bacterial bioaerosols were concentrated at respirable sizes <3.3 μm, and significant levels of bacterial bioaerosols <1.1 μm were observed in the café. This quantitative characterization of the physical properties of bioaerosols in indoor environments can be used to establish effective protection measures against the health impacts of bioaerosols.