Abstract: On or about March 22, 1984, employees were draining gasoline from an automobile gas tank into the Sears, Roebuck, and Co. sanitary sewer line located on the south side of the Sears garage in Topeka, KS. The gasoline drained into the sanitary sewer line that serviced other buildings, and gasoline vapors infiltrated the floor drains and commodes in three buildings. Approximately 60 employees in the buildings were exposed to a potentially explosive atmosphere and were evacuated because of the gasoline vapors. Employees #1 through #3, who were working in the American States Insurance Co. office in one of the three buildings, were hospitalized for treatment of gasoline vapor inhalation.