Use of prototype side stream filtration system to control dust levels in a commercial swine farrowing building

Swine meat provides an essential global food source. Due to economies of scale, modern U.S. swine production primarily occurs indoors to maintain an optimal environment across the stages of swine production. Indoor concentrations of dust and contaminant gases in swine production buildings increase in the winter months due to reduced ventilation to optimal building temperature. In this study, an engineering control technology designed to recirculate the air in a swine farrowing room through a mobile air handling unit containing high-efficiency particulate filters was presented. A mobile solution could be easily deployed as an intervention method if an infectious disease outbreak occurs at a swine operation. The performance of this control technology was evaluated following deployment in a production farrowing barn for a period of 6 weeks during the winter in the Midwestern United States. Contaminant concentrations of inhalable dust, respirable dust, and carbon dioxide were measured in the room treated by the prototype system and compared to contaminant concentrations measured in an untreated "control" room. Over 6 weeks, the mean inhalable and respirable dust concentrations observed during the study period for the "treatment" room were 2.61 and 0.14 mg/m³, respectively, compared to 3.51 and 0.25 mg/m³, respectively, for the control room. The mobile recirculating ventilation system, operating at a flow rate of 45 m³/min (5 room air exchanges per hour), reduced the inhalable dust by 25% and respirable dust by 48% as measured with a real-time aerosol monitor, when compared to the control room. In addition, no concentration differences in carbon dioxide and relative humidity between the treatment and the control rooms were observed. Inhalable and respirable concentrations of dust were significantly reduced (p = 0.001), which demonstrates an essential improvement of the air quality that may prove beneficial to reduce the burden of disease among both workers and animals.