Abstract: Employees were making preparations to pull the casing from a well that was to be abandoned. Employee #1 cleaned out a valve and thought it was clear, but, in fact, there was an obstruction. He then checked for gas pressure and, when no gas escaped, he mistakenly assumed there was no pressure. He opened the valve wider, which cleared the obstruction, and natural gas rushed out of the well. Employee #1 was trapped in the cellar for about 10 minutes until the flow could be stopped. Natural gas, which is predominantly methane, has refrigerant properties. The substantial reduction in pressure as the gas escaped from the well caused a significant decrease in the temperature of the gas. Employee #1 died from frostbite/cold injury.