A 50-year-old male cleaner died when he fell approximately 35 feet through a temporary roof opening and was impaled on a piece of equipment on the factory floor below. He had been cleaning an exhaust fan with a pressure washer on the factory roof. He and two co-workers had removed the fan from its casing creating a temporary roof opening and set the fan beside the roof opening for cleaning. Facing the fan with his back to the opening, the cleaner apparently stepped backwards and fell through the opening.