Abstract: On July 10, 2003, Employees #1, #2, #3, and #4 were working inside a tanker car that was being removed from service. They were cleaning residual material from the sides of the car, which was used to transport fuel tar. Employee #1 became ill and reported it to his supervisor. Employee #1 described his symptoms as being blue, vomiting, and losing consciousness momentarily. Employee #1 was transported to Weirton Medical Center, treated for methemoglobinemia, and released the following day. Employees #2, #3, and #4 who were inside the tanker car with Employee #1 also reported feeling ill and were also sent to Weirton Medical Center. They were admitted, at least one employee was treated, and all were released the following morning. All employees were cleared to return to work after discharge. The material that the employees were cleaning from the inside of the tankers contained naphthylene, benzene, aniline, toluidines, pyridines, and other compounds. Aniline and naphthylene are known to cause the formation of methemoglobin. The employees were wearing full encapsulating suits with hoods, double gloves, which were chemical resistant, boots, and full facepiece, North respirators with organic vapor and acid mist cartridges. The investigation revealed that an initial assessment of the respiratory hazards inside the tanker had never been done. No assessment of benzene exposure was done. The employees had not been fit tested for the respirators they were wearing.