LAUSR

Abstract. Bioaerosols from concentrated animal feeding operations (CAFOs) pose potential adverse effects on the health and well-being of animals, workers, and the general public. Consequently, the topic of characterizing and mitigating bioaerosols associated with CAFOs continues to draw attention as the scale of animal production increases, especially in developing countries. This study was conducted to quantify indoor and downwind concentrations of airborne bacteria, including total bacterial count (TBC), , , and , of a mechanically ventilated growing swine barn (210-head capacity) in suburban Beijing, China. The results revealed that the indoor airborne bacterial levels averaged 1.96 × 104 ±3.08 × 103 colony forming units (CFU) m-3 for TBC, 2.29 × 103 ±5.04 × 102 CFU m-3 for , 1.44 × 104 ±1.59 × 103 CFU m-3 for , and 9.16 × 103 ±1.11 × 103 CFU m-3 for . The airborne microbe concentrations decreased with distance downwind of the swine barn. Specifically, at 10 m downwind, concentration decreased by more than 60%, while the other microorganisms decreased by 30% to 40%. All the bioaerosol microbes decreased by 55% to 70% at 30 m downwind. The relationships between the airborne bacterial concentration and downwind distance were depicted graphically and through linear regression equations. Keywords: Bioaerosols, Emissions, Intensive swine production, Microorganisms.