Six pig farms were studied to assess the barn worker exposure to hydrogen sulphide (H2S) while pulling pit plugs and power-washing production rooms. Results indicate that plug pulling generated high concentrations of H2S, reaching 1,000 ppm in some cases. All of the farms used in this study had plug pulling events that exceeded limits defined by the Occupational and Safety Regulations of Saskatchewan. The H2S released when a plug was pulled did not follow a predictable pattern over time and within the room. Power washing generated lower H2S concentrations than plug pulling but workers were exposed for a longer time period. Based on that study, swine barn workers may be exposed to H2S concentrations that exceed acceptable limits when pulling pit plugs and power-washing. Personal monitors should be provided to all barn workers, training and standard operating procedures are needed so workers can learn how to deal with routine operations and emergency situations generating high H2S concentrations.