Concentration and Size Distribution of Bacterial and Fungal Bioaerosols and the Related Exposure Dose

Abstract

In this study, concentration and size distribution of bioaerosols (bacteria and fungi) were obtained in indoor at minimum ventilation and during the operation of air condition system (ACS). Indoo/Outdoor concentration ratio (I/O) of bacteria and fungi were also determined. In addition, the indoor exposure dose (IED) of bacteria and fungi were calculated. A six-stage Andersen cascade impactor was used for sampling the microorganisms during summer season at Minia University, El-Minia (Egypt). Mean bacterial and fungal concentrations were higher (727±160 and 252±60 CFU/m3, respectively ) at minimum ventilation than the concentrations during ACS (506±120 and 176±44 CFU/m3, respectively ). Indoor bacterial concentration level is three times higher than the fungal level. On the other hand, outdoor bacterial concentration (220±55 CFU/m3) is lower than the outdoor fungal level (300±77 CFU/m3). I/O concentration ratio of bacteria was greater than unity indicating that the main source of bacteria is the human occupancy while the corresponding I/O concentration ratio of fungi was less than unity indicating that the fungi are released from outdoor sources. Mean IED of bacteria (38.5 CFU/kg) was about three times higher than the IED of fungi (13.4 CFU/kg) .