Airborne microbiological characteristics in public buildings of Korea

Characteristics of airborne bacteria and fungi were surveyed in the public buildings regulated in Korea, with the six-stage cascade impactor. The total concentrations of airborne bacteria and fungi were averaged to 404 and 382 cfu m⁻³ in hospital, 931 and 536 cfu m⁻³ in kindergarten, 294 and 334 cfu m⁻³ in elderly welfare facility, and 586 and 371 cfu m⁻³ in postpartum nurse center. Mean respirable concentrations of airborne bacteria and fungi were 194 and 292 cfu m⁻³ in hospital, 358 and 347 cfu m⁻³ in kindergarten, 134 and 266 cfu m⁻³ in elderly welfare facility, and 254 and 289 cfu m⁻³ in postpartum nurse center, respectively. Based on this results, total and respirable concentrations of airborne bacteria and fungi were significantly highest in kindergarten and lowest in elderly welfare facility (p<0.05$p<0.05$). The ratios of indoor and outdoor concentration for airborne bacteria and fungi were below 1.0 in all the investigated public buildings regardless of size distribution. The dominant genera identified in the public buildings were Staphylococcus spp., Micrococcus spp., Corynebacterium spp., and Bacillus spp., for airborne bacteria and Penicillium spp., Cladosporium spp., and Aspergillus spp., for airborne fungi, respectively. Size distributions of airborne bacteria and fungi in terms of the dominant genera were not observed consistently except for Staphylococcus spp., which was detected mainly on the first stage (>7.0 μm) and second stage(4.7–7.0 μm), and Penicillium spp., and Cladosporium spp., showing the highest collection rate at stage 3 (3.3–4.7 μm) regardless of the kind of the public buildings.