Annual Dynamics of Concentrations and Emission Rates of Particulate Matter and Ammonia in a Large-Sized, Low-Profile, Cross-Ventilated Dairy Building

Abstract

Low-profile, cross-ventilated (LPCV) dairy barns represent a modern trend in farm buildings but are associated with notable air quality challenges. To evaluate the annual variations in the pollutants in an LPCV dairy barn, an Internet-of-Things (IoT)-based environmental monitoring system was installed to continuously measure the total suspended particle (TSP), particle with aerodynamic diameters of ≤2.5 μm (PM2.5), and NH3 concentrations year round at multiple points. Spatiotemporal distributions and main factors were analyzed. The results showed that the annual average concentrations of indoor TSP, PM2.5, and NH3 were 86.4, 28.5, and 875.0 μg/m3, respectively. Corresponding emission rates were 140.6, 28.5, and 3461.1 mg/(h·cow). TSP concentrations were significantly higher during winter and spring (p < 0.05) and were elevated during daily operational hours, particularly in feeding alleys and downwind areas. Emissions were significantly higher in winter and summer (p < 0.05). Indoor PM2.5 concentrations in winter exceeded China’s standards for 24.9% of the time, which were 2.2 times higher than those in other seasons (p < 0.05), peaking in the morning hours. NH3 concentrations and emissions were consistently high throughout the year, with peak levels in manure and downwind areas. The building’s structure, ventilations, and daily operations were key factors affecting air pollutant levels, which need to be considered when implementing mitigation measures.