Contact: Fred Blosser (202) 260-8519
April 28, 1993


NIOSH Warns Farmers of Deadly Risk of Grain Suffocation

According to the National Institute for Occupational safety and Health (NIOSH, grain farmers and their families may face deadly hazards this spring when working with grain bins. At least nine farmers recently suffocated to death in stored grain after being buried alive.

"We must act to prevent this tragic loss of life. The harvest should yield life, not take it away," said NIOSH Director, Dr. J. Donald Millar. NIOSH warns workers that the risk of being suffocated in grain may be higher this year than usual. A particularly wet fall coupled with a large 1992 crop means the grain was stored wet and may be stored longer than is typical. Moisture can cause the grain to cake or crust at the surface (frequently termed bridging). Bridged grain is extremely hazardous because it prevents grain flow and hides underlying pockets in the grain. Farmers walking on the bridged surface or attempting to break up the bridged material have fallen through the surface and become engulfed in grain.

Farm workers may also be buried by stored grain while the grain is being emptied from the bottom of the bin. Much like quicksand, the flowing grain can pull the worker completely into the bin. The force created by the unloading grain is so great that once a person is waist deep in the grain, he or she is unlikely to be able to escape, even with the aid of a safety rope. Typical unloading rates will bury a person in less than a minute. Another serious hazard may occur if grain cakes along the bin walls. When workers try to break the caked material loose from below the level of grain, large sections of grain may break off, burying them below.

The risk of suffocation increases if grain spoils, because it give off carbon dioxide, which may displace the oxygen in the bin. Even if a worker is not completely buried, he or she can suffocate because of the lack of oxygen above the grain surface.

The following page describes the deaths of nine workers who lost their lives after either falling through crusted surfaces on the top of stored grain or suffocating in grain as it was emptied from a storage bin. To prevent future deaths, workers must be told of the hazards they face and the methods for preventing injury and death. A 1987 NIOSH "Alert" describes these methods, which are summarized on the following page. NIOSH urgently requests your assistance in disseminating this information to workers at risk.

Preventable Deaths

The following workers have suffocated recently in grain bins. NIOSH hopes that future injuries and deaths will be prevented by alerting farm workers to the circumstances of these deaths.

Steps for Prevention

The following precautions must be taken when working with grain bins.

Break up surface crusts from outside the bin. Surface crusts may be broken through the roof door with a weighted line or a wooden, plastic, or other pole that does not conduct electricity. Conductive poles should not be used, since they may contact power lines near the bin.


Contact your state extension specialist to find out the availability of additional equipment for your bin. Some storage bins can be modified to include equipment capable of mechanically breaking up bridges and clumping. Commercially available equipment and services are also available to assist in breaking crusted grain surfaces from outside of the bin, but the safety of these devices has not yet been determined.


DO NOT ENTER STORAGE BINS! If you MUST enter a bin, take the following precautions:

Stay above the material at all times and never stand on top of stored material. Assume that all stored materials are bridged and unstable. The potential for entrapment and suffocation is constant. Never enter a storage area from the bottom when material is caked to the sides of the bin or is bridged overhead.

Wear safety belts or harnessed equipped with properly fastened life lines that will keep you above the stored material in case of a fall. As similarly equipped standby person should be stationed outside the area. This safety equipment will not protect a worker if he or she falls below the level of stored material.

BEFORE entering the bin: Stop the flow of grain. The bin should not be loaded or unloaded while a worker is inside. All equipment used to fill or empty a bin should be turned off and locked out to prevent other workers from starting the equipment.

The bin should be thoroughly ventilated with unheated air prior to entering the bin and while the worker is in the bin. For information about this or other occupational safety and health concerns, call toll free: 1-800-35-NIOSH.


DHHS (NIOSH) Publication No. 93-116


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