A 94-year-old man died in a grain bin incident in Iowa on Monday, officials said.

The Fremont County Sheriff's office said Robert Wayne Smith was unloading soybeans in Tabor, Iowa while running a grain vacuum before he was found dead.

Smith's son was outside moving a semi-truck that they were loading and returned to find him under the beans.

Smith was pronounced dead at the scene. His body was sent to the State Medical Examiner's office to determine the cause of death.

Tabor is a small town in southwestern Iowa near the state's border with Nebraska, nearly 40 miles southeast of Omaha.

Grain bins have long posed health risks

The Occupational Safety and Health Administration warns grain bins pose many dangers including the risk of suffocation or engulfment. The agency has previously issued a hazard alert informing the public of the risks of grain bins and silos.

According to the insurance group Nationwide, there were 29 grain entrapments reported in 2021, which resulted in 11 deaths. The agency said over 300 grain entrapments have been recorded in the decade ending in 2023 and estimates that an additional 30% of cases go unreported.

It takes just four seconds for an adult to sink knee-deep in flowing grain, Nationwide said. OSHA said flowing grain can act like "quicksand," causing people to sink in just seconds. In 20 seconds, an adult could become fully engulfed, Nationwide said.

OSHA added there is a potential for unsafe oxygen levels and hazardous gases present in storage bins, adding further risk.

Anyone working in grain bins is at risk of being trapped or buried by grain, but young workers are especially vulnerable, OSHA said.

Additionally, workers who try to rescue co-workers trapped in grain bins are at risk of being hurt themselves because it requires a great deal of force, "much more than is needed to rescue someone from underwater," meaning a person's strength is not enough to pull another person out.