Abstract: During the second shift on May 28, 1992, an employee operating a homemade endplug brazer shut off the compressed air line instead of the natural gas line. Natural gas, which is 85 percent methane, filled the building overnight. On May 29, 1992, all 200-plus scheduled employees reported to work. They smelled gas but remained in the building. After an hour or so employees started to feel ill from the gas. The brazer was in the machine shop, but the gas leak was not contained there. Employees throughout the facility were affected. Although the employer, IMO Industries, Inc., evacuated all employees, 26 employees needed medical attention. These 26 employees were monitored for adverse/permanent effects but none were found, therefore, 24 employees were released the next day and only Employees #1 and #2 were hospitalized overnight.