Abstract: At approximately 10:30 a.m. on March 28, 1997, Employee #1, a well operator with Halliburton Energy, Bakersfield, CA, was conducting a perforation job at Cal Resources in Ventura, CA. The job was having problems. Gun #1 failed to fire because of an open circuit. Gun #2 failed to fire because of a short in the head. Gun #3, reusing gun #1, was successful. Gun #4 demonstrated low order firing. While gun #4 was being dismantled, it was found to still be under pressure. Employee #1 attempted to bleed off the pressure by loosening the CCL/head assembly. All pressure was thought to have been released from the gun, but it was found to contain more pressure and fluid. Employee #1 was exposed to the vapor and fluid release, and he became dizzy and suffered a headache almost immediately. He also became numb at some point, and then nauseous. Employee #1 continued working for approximately 10 minutes, before becoming incapacitated. He required medical attention and was transported to Mercy Healthcare of Ventura County, where he was treated for exposure to carbon monoxide.