Toxic gas and respirable dust concentrations and emissions from broiler and cage-layer barns in the Canadian Prairies.

Abstract

This study monitored concentrations and emissions of ammonia (NH3), hydrogen sulfide (H2S), and respirable dust for a commercial broiler and a cage-layer barn in the Canadian Prairies over a year between March 2015 and February 2016. Seasonal concentration and emission profiles were acquired by monthly measurements, while diurnal profiles were generated in different seasons. The indoor air quality was evaluated considering both the individual and the additive health effect (respiratory irritation) of the three air pollutants. In winter, both 8-h and 15-min exposure limits (threshold concentrations) of NH3 were exceeded in the broiler barn; the highest additive level was more than two times of the limit. Seasonal average emissions of NH3, H2S, and respirable dust were 57gd-1AU-1, 1.35gd-1AU-1, and 1.99gd-1AU-1, respectively, for the layer barn, all with higher levels in the mild and warm seasons than in the cold season. The emission data were only obtained for the worst-case scenarios (last week of the production cycle) of the broiler barn, with annual averages of 92gd-1AU-1 for NH3, 1.19gd-1AU-1 for H2S, and 4.32gd-1AU-1 for respirable dust, with obvious higher NH3 levels in winter. Additionally, manure removal once every 3-4days for the layer barn reduced NH3 emissions by 62% and 90% in the cold and mild seasons, respectively. This study also found significant negative influence of outdoor T (Tout) on NH3 emissions for the broiler barn but positive impact of Tout on NH3 emissions for the layer barn.