Improving Air Quality in Swine Farrowing Operations: Engineering Intervention Results

Abstract. Poor indoor air quality inside livestock buildings affects both worker and animal health, and in Midwestern farms during the winter, building contaminants increase as fresh air into the building is reduced to save heating costs. This study has examined using engineering controls to reduce concentrations in an educational swine farrowing building. A recirculating ventilation system (1000 cfm) incorporated one of two dust control options (filtration, cyclone). Respirable and inhalable dust concentrations were significantly reduced: the filtration system performed better than an equivalently-sized cyclone. Room concentrations of hazardous gases were measured to examine whether increased air movement in the room resulted in drawing these contaminants from the manure pits: hydrogen sulfide (H₂S) and ammonia (NH₃) were not increased by using the ventilation system. In year 1, carbon dioxide (CO₂) concentrations averaged 2480 ppm, exceeding the recommended 1540 ppm limit. Mathematical modeling indicated that standard barn heaters generated significant contributions of CO₂. Year 2 operated with heaters that vented combustion gases outside of the room, reducing in-room concentrations (mean = 1420 ppm). The heater itself was associated with 800 ppm CO₂ reduction, while between-winter differences in temperature and pig counts accounted for a 200 ppm CO₂ reduction between study years. Replacing heaters present a low-cost solution to reducing one of the three main air contaminants in this building. Testing the ventilation system in a production barn while tracking human and animal health improvements is under way to demonstrate the cost benefit of these changes to producers.