Abstract: At approximately 9:54 a.m. on March 29, 2004, an employee was opening valves on process lines at a heat exchanger, Atlas, which was being brought into service for the first time after a repair 9 months previously. It was reinstalled on June 24 through June 26, 2003. Employee was on the second level of the Building Number 337, which is Plant Number 22. The employee inhaled hot vapors leaking from heat exchanger head gasket and flange. The hot, toxic vapors released included methyl iodide, acetic anhydride, acetic acid, methyl acetate, acetone, and ethylidene diacetate. The exposure caused respiratory distress for which the employee was immediately hospitalized. Employee's eyes were also affected. The employee remained hospitalized until he passed away on April 9, 2004. The apparent cause of exposure was a leaking flange connection at heat exchanger.