Risk factors inside a grain bin are numerous and include the speed of the flowing grain, the force of the grain on a body and presence of dangerous gases. “Molds, fungi and bacteria may create problems,” Smith said. “Also, gases such as carbon dioxide, nitrous oxide and others may build up in grain bins.

“Time and pressure are important. When a worker becomes trapped to his knees he can’t escape without assistance. And movement may cause him to sink deeper and deeper. As grain keeps moving it quickly forms a cone of depression.”

A person weighing 165 pounds will require 900 pounds of force to lift him out of the grain if he is fully submerged. “Extraction often is necessary from awkward positions and may result in serious injury. Training and safety equipment are necessary.”

Most engulfment cases—68 percent—occur in corrugated metal grain bins. Transportation may result in engulfment and usually involves grain wagons. Some cases occur in semi-trailers and rail cars.

Excess moisture in the grain is a prime contributing factor to grain engulfment, Smith said. Other factors include excess fines and foreign material in the grain, out-of-condition grain, engaged unloading equipment (with workers inside the bin), entering a grain bin, unsupervised children in exempt workplaces, increased on-farm storage, unfamiliarity with extraction procedures, lack of safety features in older storage structures and an inability to install proper safety equipment —harnesses—in older facilities.

Smith said prevention is essential. “Signs are not enough. Owners and managers must make safety a priority. No shortcuts should be allowed.”