Abstract: On November 20, 2009, Employee #1, #2 and #3 were performing a pallet inventory check inside a 65,000 square foot cold storage room, using a S30 Hyster forklift. The cold room is a closed environment with recirculated air. It has two doors that are opposite of each other and each door is equipped with a pleated drive through plastic curtain. After working in the cold room for approximately 45 to 60 minutes, the three employees became ill. Employee #1 and #3 manifested clinical signs of carbon monoxide exposure, and Employee #2 became unconscious, with gurgling. Employee #1 and #2 were air lifted to Fresno Community Regional Medical Center, while Employee #3 was taken to Sierra View Hospital. The supervisor was in the cold room at the beginning of the inventory check and noted that the forklift was operating properly. Upon reentry into the cold room, the supervisor noted that the south exterior door was closed, which is in conflict with the employer's directives. The forklift appeared to be in good repair and was maintained on a regular schedule by PEPE Materials Handling, a Hyster franchisor. A PEPE forklift technician, using an exhaust analyzer, determined that the carbon monoxide output was 8, which is above the allowable exhaust emissions of 2, that is established in 8CCR 5145(c) for a 100 to 140 cubic-inch internal combustion engine. The combination of carbon monoxide emissions, in conjunction with the closed doors, was identified as the cause of exposure. Employee #1 was hospitalized for treatment, while Employee #2 and #3 were treated, and then were released.