Characteristics of ammonia, hydrogen sulfide, carbon dioxide, and particulate matter concentrations in high-rise and manure-belt layer hen houses

Indoor air pollutants at high concentrations in poultry houses can potentially affect workers' health, and animal welfare and productivity. This paper presents research results of a 2-year continuous monitoring of ammonia (NH ₃), carbon dioxide (CO ₂), hydrogen sulfide (H ₂S), and particulate matter (PM) concentrations from to date the most comprehensive study on a single farm in two 180,000-bird high-rise (HR) and two 200,000-bird manure-belt (MB) layer hen houses located in Indiana, USA. Air was sampled at ventilation fans of the mechanically-ventilated houses. Concentrations of NH ₃ and CO ₂ were measured with photoacoustic multi-gas monitors. Concentrations of H ₂S and PM ₁₀ were monitored with pulsed fluorescence analyzers and Tapered Element Oscillating Microbalances (TEOM), respectively. The 2-year mean ± standard deviation concentrations at ventilation fans of the four layer hen houses were 48.9 ± 39 and 51.9 ± 40.7 ppm in HR, and 13.3 ± 9.1 and 12.9 ± 10.5 ppm in MB for NH ₃; 26.4 ± 17.6 and 24.9 ± 19 ppb in HR, 40.0 ± 21.1 and 41.2 ± 31.5 ppb in MB for H ₂S; 1755 ± 848 and 1804 ± 887 ppm in HR, and 2295 ± 871 and 2285 ± 946 ppm in MB for CO ₂; and 540 ± 303 and 552 ± 338 μg m ^-3 in HR, and 415 ± 428 and 761 ± 661 μg m ^-3 in MB for PM ₁₀. Compared with the MB houses, concentrations of the HR houses were higher for NH ₃, and lower for CO ₂, H ₂S, and PM ₁₀ (P < 0.05). High concentrations of NH ₃ detected in winter represent potential challenges to workers' health and animal welfare. Variations in pollutant concentrations at the exhaust fans were affected by outdoor temperature, ventilation, bird condition, and farm operation. A new weekly variation, characterized by significantly lower PM ₁₀ concentrations on Sundays, was identified and was related to the weekly schedule of house operational activities.