Bioaerosol Concentrations and Emissions from Tunnel-Ventilated High-Rise Layer Houses in North Carolina

Abstract. In this study, concentrations of bacteria and fungi were measured in two high-rise, tunnel-ventilated egg production houses in North Carolina during winter, spring, and summer using Andersen six-stage samplers. Average concentrations of culturable airborne bacteria and fungi ranged from 2.2 × 10⁵ colony forming units (CFU) m^-3 to 1.1 × 10⁶ CFU m^-3 and from 1.5 × 10³ to 2.8 × 10³ CFU m^-3, respectively. In-house bacterial concentrations significantly differed over the three seasons but did not vary by time of day. In-house fungal concentrations were not significantly different over seasons or at different times of day. Among all influencing factors, indoor air temperature (T), relative humidity (RH), and house ventilation rate (Q) had significant impacts on in-house bioaerosol concentrations. Bacterial concentrations were significantly higher on the second floor of the high-rise layer house, while fungal concentrations were not significantly different on the two floors. Emission rates of both bacteria and fungi were highest in summer, possibly due to the elevated ventilation rates during the summer season. The findings of this study advance our knowledge about bioaerosol concentrations and emissions as impacted by various factors in egg production facilities.