Bioaerosols from concentrated animal feeding operations pose potential threats to animals and workers, as well as public health, which has been a subject of concern. A growing swine barn with mechanical ventilation in the suburb of Beijing was used for this study. The' airborne concentrations of total bacterial count, Escherichia coli, Streptococcus and Staphylococcus aureus inside and downwind the barn were investigated with cultivation-dependent approaches. Levels of airborne bacteria in the air ofthe swine barn averaged 1.96xl04 ± 1.15><104 colony forming units (CFU)/m3, 2.29><103 ± 1.89x10s CFU/m3, 1.44*104 ± 5.94X103 CFU/m3 and9.16*103±4.15xl03 CFU/m3 for total bacterial count, Escherichia coli, streptococcus and staphylococcus aureus, respectively. When the air was drawn out of the barn via ventilation, the airborne microbe concentrations decreased with the distance downwind the barn. Escherichia coli decreased over 60%, and the other microorganisms decreased by 30%-~-'40% at the site 10m downwind, and all the bioaerosol microbes reduced by 50%~70% at 30m downwind of the swine barn. Airborne bacterial concentration as a function of distance downwind swine barn was plotted, and linear equations was fitted for airborne total bacterial count.
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