Abstract: At approximately 7:15 a.m. on May 20, 2009, five employees were on the floor of a drilling rig when the drill string was being removed from the well bore. As the employees raised and separated two sections of the drill string, all of the employees were exposed to the fumes coming from the center of the drill string. The five employees started having breathing problems and evacuated the drilling rig. After they were off of the rig, all started vomiting. The five employees were immediately transported to a local hospital, and all stayed overnight. Four of the employees were released the following day. The fifth employee was transported to a second hospital and was released on May 22, 2009.