Introduction: Magnitude of problem

The hazards of flowing grain are not obvious or well known and incidences result in fatality nearly half the time. Entrapment can occur in many situations and normally happens very quickly. Unloading operations, grain bridges and grain masses on side walls are three main causes of entrapment in grain containers. Basically, farmers or workers are exposed to this danger each time they move grain. Grain storage is an important function in agribusiness since grain prices tend to be higher later in the marketing year than at harvest. Grain storage is important to maintain flexibility in where and when grain is sold, support an efficient harvest, since grain does not have to be delivered to an off-farm location, and can provide grain gradually throughout the year for livestock feed.

We have seen an increase in incidences over the recent years with 2010 being a record breaking year for fatalities. There were nearly 10,000 commercial grain storage units (elevators, mills, ethanol factories, trucks/wagons, shipping, etc.) in 1999 and millions of farmer-owned units in the United States, alone. In 1996 there were approximately 92,000 employees working in grain elevators, 68,000 employees working in grain mills and, as of 2007, there were 2.2 million farms employing about 1,920,000 people (1). As you can see, grain engulfment dangers have the ability to impact at least two million people. Keep in mind this estimate is probably low based on illegal immigration and child/family labor which is common in farming operations.

In a study of deaths from asphyxiation and poisoning at work in the United States from 1984 through 1986 we saw a total of 42 deaths from engulfment (8). Specifically, 12 occurred in elevators or grain bins, 8 in storage bins, 5 in rail cars, 4 in sand hoppers, 2 in dump trucks and 11 in other locations (8). Remember, this only includes the working population, but highlights the variable locations where sphyxiation from engulfment can occur.

Considerations in the magnitude of this problem should be given to the vast span in age and gender that may be exposed to grain engulfment risks. In youth, agricultural work (particularly on family farms) contributed to an estimated 300 deaths and 23,500 serious, non-fatal injuries in the US in 1985 (9). These fatalities were caused by a number of exposures including loading grain, tractor rollovers, and handling large animals among others.

While exposures to asphyxiation are not the number one cause of death to youth on farms, one study highlights the risks that may pose a higher danger (10).

Please see: Table 1 - Causes of farm accidents in children

Exposures related to the injury problem/known risk factors

Three known risk factors of grain storage are that 1) people do not realize how fast grain can move, 2) how much force flowing grain has on the human body and 3) or they are unaware of the presence of dangerous gases. Three likely situations exposing people to the physical threat include unloading operations, grain bridges and grain masses on sidewalls.

Unloading operations:
Grain can move very fast; a 10 inch auger can remove 85 cubic feet of grain in one minute (2). This equates to moving the amount of grain equivalent to a human body in 3.3 seconds. Obviously, when a person is on the top of the grain surface it would take them longer than 3.3 seconds to move through the pile to the auger affording more than 3.3 seconds to rescue the trapped. When grain is being unloaded, the auger is typically near the bottom, center of the bin. The flow of the grain moves in the center causing a funnel shape on the top of the grain surface. If anyone were in the grain bin during unloading operations, they would be sucked into the middle and sink.

grain bridge.jpg

Grain bridges:
Grain bridges may occur when grain is put in the bin wet. When grain is wet it tends to mold and stick together causing problems when attempting to unload the bin. A grain bridge basically gives the farmer a false impression of the surface of the grain. Once inside the bin it seems as though the grain was not emptying at all, when in fact the grain that was removed created a void beneath the grain bridge. The farmer may attempt to break up the grain mass. Once the auger is started, the grain bridge may break placing the farmer in a similar situation as discussed above under Unloading Operations. This particular issue can also occur quite easily in grain wagons or transportation situations.

grain bridge.jpg

Grain masses on sidewalls:
Similar to grain bridges, when grain gets wet or moldy it could also stick to the side of the bin. Injuries happen in this situation when the grain is taller than the person in which it has the capability to cover you when it releases from the wall. Surprisingly, if a person is covered by just one foot of corn they would be exposed to 300 pounds of pressure (2).

grain on sidewall.jpg

Time and Pressure:
A person becomes trapped once their knees are covered and cannot escape without assistance. This is because grain exerts so much pressure and friction around your legs that you can simply not get out. Basically, your starting point is 6 to 10 inches in the grain just by standing in the bin so it doesn't take long to become trapped. Grain acts just like a boa constrictor; each time you move the grain shifts and compounds around your body making it even more difficult to move. Additionally, if the grain is flowing while you are trapped, the floor you are standing on is constantly being removed beneath your feet creating further challenges. Because of these factors it is understood that you can become trapped within 6 seconds and can be fully submersed within 25 seconds (2).

Rescue is also very challenging due to the risk factors mentioned above. For instance, when a 165 pound person becomes submersed it takes about 900 pounds of pressure to remove them due to the weight and pressure the grain puts on their body (2). Not only are you challenged with the sheer force needed to remove someone, you are working against the clock and are placed in awkward pulling positions. Due to these factors you need to consider the force that is being placed on the victim which may cause further injury or even ripping them in half.

Biological threats:
When stored grain has a high moisture content it may stick together contributing to some of the physical threats mentioned above, such as bridging or sticking to the wall. Additionally, when grain is moist, it may form mold or spoil which gives off dangerous gases, specifically carbon dioxide (3). These gases can be invisible and suffocate someone exposed to the confined spaces of a grain bin.

Trends in related injuries and fatalities

While most people would expect grain bin injuries to only occur in the fall during harvest, this is not the case. If you recall, the importance of having grain storage capabilities is to store grain to capitalize on better prices later in the marketing year, provide flexibility in where and when grain is sold, provide harvesting efficiencies and feed livestock throughout the year. The following graph exemplifies how the risk of grain engulfment is year-round (3).

Please see: Table 5, Number of Monthly Suffocations, 1984-1999

Although we cannot pin-point a risky time of year, we are seeing an increase in grain entrapments in the recent past. In fact, 2010 has been the most deadly year yet, killing 25 people and injuring 21 (6). This resulted in a 36% increase in fatalities caused by grain engulfment since 2009. Of the 46 incidences 13 occurred in grain facilities while the remainder occurred on farms (6). It is expected that these numbers are grossly under reported and could be 30% higher nationwide (6). Also notice, through the 1980's and 1990's we saw fatalities totaling anywhere from 3 to 8 per year (7).

Please see: US Grain Entrapments

Due to these alarming statistics that are trending upward, the Occupational Safety and Health Agency published a warning to all grain operators. This warning highlighted the regulations in addition to the agency's authority through assessing penalties. Three examples included a $1.5M, a $1.6M and a $721K fine for entrapment deaths or injuries (5). Finally, they called out their intent to refer any fatality incident to the Department of Justice for criminal prosecution. This exemplifies a potential decline in compliance or/and an increase in regulatory enforcement.

Cost of injury problem

As discussed above, noncompliance with the grain handling standards may be very expensive (i.e. $1.6M) (5). But beyond monetary fines, any injury/fatality cost the company time, morale, production and worker's compensation. For farmers, an injury/fatality may result in a loss of crops and assets or the necessity for a career change.

One of the largest costs related to engulfment include the cost of life. How can we put a monetary value on this? What is the cost of a child's life, an emergency responder's life, a businessman's (farmer) life?

In recent years, the market for more grain, like corn, is on the rise. Since ethanol became a an energy commodity, corn growers drive to get the biggest bang out of their buck and store more grain onsite to do so (12). The map below highlights the U.S. ethanol sector and how it has grown over the last decade. Again, with this grain commodity having a higher demand, we see more storage units to handle the market. Because of this, we see more grain work being done, thus, increasing the number of exposures in the Corn Belt.


In the past, we saw very little enforcement on grain storage operators; however, in the last year we started to see more regulatory activity due to alarming trends. Not only is OSHA urging grain operators to become safer, they are threatening them to make it right: "If any employee dies in a grain storage facility, in addition to any civil penalties proposed, OSHA will consider referring the incident to the Department of Justice for criminal prosecution pursuant the criminal provisions of the Occupational Safety and Health Act of 1970." (5) This statement highlights the agency's serious response to the current mortality data related to engulfment. Interestingly, I think this may also highlight the lack of enforcement in the past as they are now becoming more aware of the severity of grain operations.

Lastly, people are unaware of the risks related to working with grain. There is however a perceived risk for all farming activities (from substance exposures to risk of injuries). The chart below was taken from a study on Occupational Health and Safety Risks and Potential Health Consequences Perceived by US Workers in 1985 (11). This study highlights workers perceptions of the health and safety risks around them while they work, but does not specify if they understand the exact risks or if their perceptions are accurate. Because of these variables, we are not seeing progress in the reduction of severe engulfment incidences.

See Table 2: Perceived exposure to health-endagering substances, work conditions, or risks of injuries of currently employed persons in their present jobs, by occupation, United States, 1985

Prevention and Control:

Due to grain storage being a relevant and a necessary function, OSHA regulates these types of commercial operations. Since OSHA began regulating grain storage facilities in 1987, explosions from grain dust have been reduced by 42%, the number of injured workers was reduced by 60%, the number of workers killed was reduced by 70% and the average number of annual grain suffocations decreased by 44% (3). The standard focuses on controlling grain fires, grain dust explosions and the hazards associated with entry into bins, silos and tanks. OSHA does not however, regulate farmer-owned entities in the same fashion.

The Grain Handling Facilities Standard (29 CFR 1910.272) focuses on the following areas when workers enter storage bins (4):

  • Employs Lock Out Tag Out practices - de-energization of augers and equipment
  • Prohibits manual flow methods - forbids workers walking on/down grain to make it flow
  • Prohibits entry into bridging/sidewall conditions - forbids workers enter bins where bridging/side-wall masses are occurring
  • Tests the air within a bin for oxygen content/hazardous gases prior to entry
  • Provides continuous ventilation until any unsafe atmospheric conditions are eliminated; if conditions cannot be improved, workers must wear appropriate respirators
  • Issues a permit each time a worker enters a bin, unless employer is present during the entire entry operation. Permit must certify above precautions have been implemented prior to workers entering the bin
  • Verifies communications are maintained between observer and worker and observer is equipped to provide assistance/perform rescue outside of bin
  • Provides body harness with lifeline when entering bin from a level at or above stored grain - ensures lifeline is positioned and of sufficient length to prevent workers from sinking further than waste-deep in grain
  • Provides workers with rescue equipment, such as winch systems specifically suited for bin rescues, such as coffer dams (which come in plastic, wood or metal)
  • Coffer Dam1.jpg Coffer Dam2.jpg Coffer Dam3.jpg

    Rescue Considerations:
    If you are the individual that finds the victim there are at least three things to accomplish. Number one - shut the auger off to stop the flow of grain. In fact, you may choose to follow Lock Out Tag Out practices during the rescue to minimize a potential for the auger to start up while you are rescuing the victim. Number two - turn ventilation fans on to supply fresh air to the victim and rescuers and Number three - call for help or backup support, including 911 for medical support (i.e. first aid, ambulance).

    When rescuing a victim, there are a few options to consider based on the extent of entrapment. If the victim is fully submersed and being suffocated your actions are to remove the grain from the victim as quickly and efficiently as possible. This includes cutting holes on opposite sides of the bin so the grain flows away from the victim. The holes should be cut just below the victim or at the bottom of the bins. This activity may be completed by your local, trained, fire department or emergency response teams. If the victim is waste deep and able to breath, there are tools that can be utilized (i.e. coffer dams) to save the victim and the bin.

    Rescue 2.jpg
    Rescue 3.jpg
    Rescue 4.jpg

Human Factors: Lack of supervision; risk taking; impulsive behavior; in a hurry; lack of safety culture; lack of lock out tag out compliance
Vehicle: Grain bins; auger systems; grain trucks, trailers and train cars; silos; not using tools appropriately
No knowledge of worker inside grain container
Environment: Being inside a grain-filled bin w/ energized auger; grain bridges; grain masses on sidewalls; gases present

Human Factors: Lack of equipment to protect worker; not wearing PPE; not using safety equipment properly
Vehicle: Worker not connected to safety harness/lifeline; test for dangerous gases not completed; auger is energized
Environment: Entrapment; grain settling creating force; asphyxiation from gases

Human Factors: Lack of resistance to grain force on body; asphyxiation; lengthy rescue; additional people in danger
Vehicle: Difficult access to victim; Lack of trained rescue teams; Lack of rescue equipment in rural areas
Environment: Emergency responders distance; potential to endanger responders

1. Prevent the creation of the hazard in the first place.

a. Do not enter a grain container
b. Keep grain in proper condition
c. Do not walk down the side of grain piles to make it flow
d. Prevent unauthorized entry, especially by children

2. Reduce the amount of the hazard brought into being.
a. If you must enter, use harness/lifeline and two observers
b. Use hand signals to communicate
c. Train employees/farmers/family of hazards (drive awareness)
d. Work from top to bottom when cleaning grain bin walls
e. Provide site tours to local emergency responders
f. Place entrapment warning decals on bins and transport vehicles

3. Prevent the release of the hazard that already exists.
a. Use lock-out tag-out procedures on augers
b. Use tools to verify grain bridge does not exist
c. Use inspection holes and grain markers

4. Modify the rate or spatial distribution of release of the hazard from its source.
a. Engineer safer, more horizontal grain containment systems to minimize the depth a person could become engulfed

5. Separate, in time or space, the hazard and that which is being protected.
a. Cut the bottom of the container out to release grain quickly when victim is engulfed
b. Use of coffer dams when victim is trapped

6. Separate the hazard and that which is protected by interposition of a material barrier.
a. Build a solid bridge inside grain container for employee to safely stand

7. Modify basic relevant qualities of the hazard.
a. Engineer safer methods to enter grain containers
b. Develop a grain removal system that takes grain from the top vs bottom of container to remove quick-sand effect
c. Train all local responders how to respond safely to grain entrapment
d. Provide all local responders with coffer dams and appropriate response tools

8. Make what is to be protected more resistant to damage from the hazard.
a. Develop personal protective equipment resembling chest protector to minimize crushing in conjunction with breathing apparatus

9. Begin to counter the damage already done by the environmental hazard.
a. Use coffer dams when victim is trapped
b. Provide victim a notification system for emergency response needs

10. Stabilize, repair, and rehabilitate the object of damage.
a. Provide medical care for physical injuries
b. Provide counseling for post-traumatic disorders

Of the possible countermeasures identified above, some are more realistic or feasible than others. For instance, some of these methods of hazard removal are already being utilitized in grain operations, such as awareness training, lock out tag out, observer and personal protective gear (harness/lifeline) and coffer dams. Some of the engineering suggestions are less likely to take hold due to the vast number of grain containment systems, who owns them, the lack of regulatory inspection, expense, etc. Some of the items that are not yet deployed may be feasible additions to how grain operators do business. More specifically, provide site tours to local responders in order to highlight site risks, layout and locations of operations. Additionally, I think there is a great opportunity to verify our local responders are trained to handle these type of emergencies and have the appropriate equipment to respond effectively.


Grain storage is prevalent throughout the United States and may continue to rise due to market needs. The potential of grain engulfment depends on multiple variables. We cannot count on incidences occurring in any particular part of the calendar year; they are not seasonally distributed. This risk occurs at commercial and farmer-owned operations and exposes more than two million workers and families to grain engulfment. Engulfment can occur in multiple types of grain operations such as storage bins, elevators and transportation. Engulfment has been increasing over the past decade and impacts all ages/sexes of the population. While OSHA has safety requirements specified in the commercial industry, family farms are exempt from regulation. This may contribute to the injury rates increasing due to additional on-farm storage units in recent years. We have seen an increase in regulatory scrutiny and involvement in this sector based on negative mortality trends. It is unclear if all emergency responders have a clear understanding of engulfment and the steps to take to rescue a victim. It is also unclear if all rural/local responders have the best equipment (like coffer dams) to use in response efforts.


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