[Microbial Properties of Different Size Aerosols at Human Average Respiratory Height During Fog-haze Days]

Size distribution and microbial population structure are typical characteristics of bioaerosols that are relevant to human health. The concentrations and population structure of bioaerosols associated with size-segregated airborne particulate matter at human average respiratory height were studied using a 6-stage Andersen impactor during and after fog-haze days in the area of Beijing. The results showed that the size distribution of the cultured microbial populations was uneven during fog-haze days, and that the microbial concentration and the difference in the population structure of the size-segregated airborne particulate matter were higher during than after the fog-haze days. During the fog-haze days, Bacillus sp. was the dominant bacteria present in bioaerosols of >3.3 μm, whereas Bacillus sp. and Bacillus amyloliquefaciens were the dominant bacteria in bioaerosols of <3.3 μm. In contrast, after the fog-haze days, Bacillus amyloliquefaciens was dominant in all the bioaerosol sizes. Five species (Alternaria sp., Penicillium italicum, Talaromyces stollii, Cladosporium sp., and Davidiella sp.) were detected as the dominant fungi in the bioaerosols >3.3 μm during the fog-haze days, and only Alternaria sp. was detected in the bioaerosols >3.3 μm after fog-haze. Penicillium italicum and Talaromyces stollii were also detected in the bioaerosols of <3.3 μm during and after the fog-haze. There were significant differences in the concentration and population structure of the size-segregated airborne particulate matter at human average respiratory height collected during and after the fog-haze days. The high concentration of microorganisms and the relatively complex population at human average respiratory height on haze days indicate that the potential risks of the microbiological characteristics of the bioaerosols to human health cannot be ignored.