Staying Safe in the grain bin

Among the myriad regulations designed to keep farmworkers out of danger is an extensive list of Occupational Safety and Health Administration (OSHA) requirements for running and/or working around grain bins and silos, the enormous structures in which harvested grain is stored.

So, what is it about stored grain that requires such an abundance of caution?

Explosion

Harvested grain is extremely dusty, and grain dust in a confined space can create a hazard. If the confined dust becomes airborne inside the storage facility and meets a source of heat — a static charge, a bearing burning out in an elevator’s machinery — the dust can ignite, producing a chain reaction of explosions that can damage or even blow the storage vessel apart and injure or kill anyone unfortunate enough to be too close.

Fire

If mold begins to grow in stored grain, it can envelop the grain kernels, binding them together into an ever-growing mass. Mold spores feeding on the grain’s starches and oils produce water, carbon-dioxide, and heat, creating a hot spot in the center of the mass. If insects have infested the grain, this heating process can accelerate. As long as oxygen can’t get to this heated mass, it may remain inert. But that can quickly change if the grain is disturbed, as it is when it’s unloaded from storage.

Engulfment

Shifting grain can behave like quicksand, sucking in and entrapping farm workers and suffocating them — literally drowning them in grain. It the leading cause of confined-space death in agriculture. According to research compiled in the Purdue Agricultural Confined Spaces Incident Database (PACSID), between 1962 and 2023, there were nearly 1,400 documented cases of engulfment. Approximately 58 percent of documented cases were fatal.

Engulfment most often happens when a worker without safety equipment enters the top of a storage structure to solve a problem like a clog. Meanwhile, below, another worker starts a grain auger to empty the vessel. The entire mass of grain begins to shift, making it extremely difficult for the worker at the top of the silo to get out. In less than 30 seconds, without help, the worker may be completely buried.
Engulfment can also occur when the process of emptying the silo has been stopped and started several times, causing a “grain bridge” to form. This condition, in which mold or freezing has caused the top layer of grain to form a deceptively hard, thick crust. But the bridge is likely to collapse, dropping a worker into the loose grain below where they can suffocate.
Workers can also be imperiled when damp or moldy grain has formed steep columns against a bin wall. When a worker tries to dislodge the grain, they can be buried in a grain avalanche.

For more information about farm safety, visit our farm safety tips and resources. Learn more about best safety practices for working in and around grain bins, and find more sources for information, in Grinnell Mutual’s downloadable “Worker Entry into Grain Storage Bins” loss control bulletin.

You can also see a trailer of the independent film “Silo,” an affecting story about a frightening grain bin experience, and learn how to get a DVD or host a screening in your community.

Sources: Kansas State University Department of Grain Science; Oklahoma State University Extension Service

The information included here was obtained from sources believed to be reliable, however Grinnell Mutual Reinsurance Company, SI, and its employees make no guarantee of results and assume no liability in connection with any training, materials, suggestions, or information provided. It is the user’s responsibility to confirm compliance with any applicable local, state, or federal regulations. Information obtained from or via Grinnell Mutual Reinsurance Company, SI, should not be used as the basis for legal advice and should be confirmed with alternative sources.

2/2025