Abstract: At approximately 10:00 a.m. on June 27, 2008, Employee #1 and approximately 24 coworkers were working in a cooler grading and repackaging personal size watermelons. The temperature was approximately 80 degrees Fahrenheit with light wind and no precipitation. The area of the cooler was approximately 50 ft by 100 ft with an A-frame ceiling that had a peak height of approximately 19 ft. The cooler had a partial wall which divided it into an east side and a west side with two sliding doors. Only the east side door was open. The doors had insulating plastic strip curtains, and the cooler had a conventional Freon refrigeration system. At the start of the day, the cooler temperature was approximately 50 degrees Fahrenheit. The east side of the cooler had four evaporator fan units and the west side had two. The east side evaporators were not all functioning because new condensers were being installed. Workers were evenly split between the east and west sides. A propane powered Hyster forklift operated inside the cooler throughout the day to move boxes of watermelons. The forklift entered and exited the cooler through the east side cooler door. A semi-trailer and a bus parked at the dock outside of the cooler did not have their engines running while loading and unloading. The forklift was the only combustion engine inside the cooler. The forklift did not run continuously inside the cooler rather it was operated on and off throughout the day. Workers left the cooler for lunch from 11:30 - 12:30 and both sliding doors of the cooler were closed during part of the lunch break. After lunch, the workers resumed work. At approximately 3:00 p.m., Employee #2 fainted. All workers evacuated the cooler, and an ambulance transported Employee #1 and Employee #2 to the hospital. After evacuation from the cooler, the east side cooler door was shut. At that time, the cooler temperature was about 70-72 degrees Fahrenheit. Workers went to do crop field work or went to work at the packing facility. The fire department arrived at the cooler at approximately 3:45 p.m. and tested the cooler air with a Trackit PM Carbon Monoxide meter. Carbon monoxide air levels were approximately 917 ppm. After examination of Employees #1 and #2, the ER physician requested that all workers who worked in the cooler be examined. In total, 33 workers were seen at the emergency room for assessment of carbon monoxide exposure. Employees #1, #2, and #3 were hospitalized.