Abstract: At about 7:00 a.m. on June 23, 1989, construction employees began complaining of headache & nausea (symptoms similar to metal fume fever) in the meat cutting room and box room of the IBP meat processing plant. The meat processing plant was undergoing re-construction. Various construction trades were working inside at the close of the second shift (scheduled from 6:00 p.m. to 6:00 a.m.) Operations involving welding and the use of resins were occurring at the time of the accident. About 1,500 lbs. of Corve 8521, a polyester resin containing 33 percent styrene, was being used. The fast curing resin produced about 500 lbs. of styrene vapors in the fourth cooler (420-ft by 60-ft). The floor contractor placed two 21-in. box fans outside fourth cooler in the adjacent room, the box room (40-ft by 280-ft by 15-ft). The fans did not exhaust to the exterior of the building. To expedite the welding work, additional welders using gas-powered generating units, were added to the existing electric-arc welders. The gas-powered units were placed outside the building near the shipping doors. Negative pressure inside the building drew the gas exhaust (carbon monoxide) into the plant. Welders (estimated at 8 to 10) were generating fumes from various welding processes (i.e., tungsten arc for gas welding of stainless metal, inert gas welding, and possibly oxy-fuel cutting of hot-dipped galvanized steel; however, this could not be substantiated). The gas-powered generating units where emitting carbon monoxide. Eleven employees working in the box room were overcome by the styrene vapor and left the building to get fresh air. Eleven employees were instructed to report to the company nurse (IBP) and then were transported to the Dallas County Hospital where four employees were diagnosed with chemical pneumonia.