Engineering Controls to Reduce Hydrogen Sulphide Exposure of Workers in Swine Buildings

Two engineering controls were developed to protect swine barn workers from exposure to hydrogen sulphide (H2S) gas during manure handling operations. A remote manure pit plug pulling system was successfully developed, and testing in two grower-finisher swine rooms showed that the remote pulling system reduced worker exposure to H2S by allowing the worker to pull the manure pit plug from outside the room. A water sprinkling apparatus was also devised, which, under optimal operating conditions in a laboratory setting, resulted in a 79% reduction of H2S gas concentration in the air above the water sprinkling system. However, the use of a similar system to reduce H2S concentration in the airspace above the manure surface when manure was agitated in a 170-L barrel had the opposite effect. Using a Draeger Pac III monitor in the airspace showed that the H2S concentration actually increased when the water spraying system was in use. Further investigation revealed that the measurement of H2S concentrations in the airspace above agitated manure with this particular monitor seemed to yield results that were larger than those obtained with other measurement methods. Additional work needs to be done to ensure proper measuring techniques are in place to determine the levels of H2S that are present from agitated manure.