When an oil-well service company employee went to check the fluid level in an oil storage tank, he climbed in without a confined space permit, a monitor or any protective equipment. At the time, liquid nitrogen was being inserted under pressure into the well to force the oil into the tank. Unknown to the worker, the liquid nitrogen had turned into a deadly vapor in the tank.

He became dizzy and passed out, falling off the ladder to the bottom of the tank, where he drowned. His supervisor, noticing the employee was missing, climbed into the tank to look for him, succumbed to the same poisonous vapors and also died.