The risk of suffocation in stored grain bins was highlighted by a review of nine case histories of farmers who either fell through crusted surfaces on the top of stored grain or suffocated in grain as it was emptied from a storage bin. When grain is stored wet, it is possible for the grain to cake or crust at the surface. This is called bridging. Walking on this bridge to break up the material has cost the lives of workers who have become engulfed in the grain as it breaks loose. Another common accident occurs when a farmer attempts to free caked material from below the level of grain stored. As grain is stored for longer periods of time, it gives off carbon-dioxide (124389) at increasing rates. Even if a farmer were not completely buried by the falling grain, he may still suffocate due to the lack of oxygen in the area above him. Steps to prevent these tragedies were listed and included breaking up the surface crusts from outside the bin, contacting the state extension specialist to determine the availability of additional equipment for your bin, staying above the material at all times if you must enter the bin, never standing on top of stored material, wearing safety belts or harnesses equipped with properly fastened life lines, stopping the flow of grain before entering the bin, and turning on ventilating equipment before entering the bin.