While inspecting the boar pens at a pig farm, at about 10:15 a.m., an employee lifted the effluent access hatch and observed that a crust was forming on the surface. He decided to pass the agitator and then felt discomfort as a result of the H2S that was released. He was able to pick himself up and activate the ventilation control, which operated only at 40% of its maximum speed. At which point he collapsed again. He regained consciousness a few minutes later and alerted his colleagues. The employee, transported to the hospital, was placed under 24-hour surveillance. One of the 5 pigs present in the boar pen area died.

The employee should have warned his co-workers prior to the agitation operation and should have turned on the ventilation to its maximum setting. He was unaware with the dangers associated with H2S.

The operator drafted a memorandum regarding the instructions to follow and the risks associated with H2S and required that all employees read and sign the document. The operator is considering the installation of “dead man switch” type individual alarms.