Seasonal characteristics of ammonia emission in mechanically ventilated sow housing in South Korea

This study evaluated ammonia (NH₃) emissions from a mechanically ventilated sow house over 368 days (January 18, 2021–January 20, 2022). NH₃ concentration (measured using an INNOVA photoacoustic system), ventilation rate, temperature, and humidity were continuously monitored in three identically structured rooms according to the European VERA protocol. Seasonal NH₃ concentrations averaged 8.8 ± 3.2 ppm in spring, 5.4 ± 1.0 ppm in summer, 12.2 ± 5.1 ppm in autumn, and 22.4 ± 4.2 ppm in winter. The seasonal ventilation rates were highest in summer (13,316.4 ± 1,828.6 m³/h) and lowest in winter (6,937.9 ± 1,269.6 m³/h). The corresponding seasonal NH₃ emission factors were 7.9 ± 2.2 g/d/pig in spring, 7.4 ± 1.4 g/d/pig in summer, 11.0 ± 3.0 g/d/pig in autumn, and 16.9 ± 4.6 g/d/pig in winter. The annual average emission factor was 10.6 g/d/pig. NH₃ concentrations were typically highest in the morning and gradually declined throughout the day as ventilation increased. Correlation analysis revealed a strong positive relationship between NH₃ emissions and indoor NH₃ concentrations (r = 0.93), and a moderate negative relationship with ventilation rate (r = –0.57). Compared to Korea’s current official emission factor, the measured emission factor was more than 60% higher, indicating that the current official value likely underestimates emissions. This discrepancy emphasizes the urgent need for revised emission factors and standardized measurement protocols. These findings can support the development of site-specific emission inventories and guide national strategies, including performance-based environmental regulations and targeted mitigation policies in the livestock sector.