A caught-between hazard (also called caught-in or caught-between) is any workplace situation where a person’s body can be squeezed, crushed, or trapped between two or more objects, at least one of which is moving. It is one of OSHA’s “Fatal Four” hazard categories in construction, and in 2024, struck, caught, or compressed incidents involving powered equipment alone accounted for 213 workplace deaths in the United States. These hazards show up anywhere machines operate, trenches are dug, or heavy vehicles move through tight spaces.
How OSHA Defines the Hazard
OSHA groups these events under the broader label “caught-in or -between.” The category covers three related scenarios: being caught inside a piece of equipment, being compressed between two objects, and being buried or engulfed by collapsing material. In every case, the core danger is the same: part of a worker’s body ends up in a space that is closing or has already closed, with no way to escape the force.
Common Caught-Between Scenarios
These hazards take different forms depending on the worksite. Recognizing them is the first step toward avoiding them.
Rotating Machinery and Nip Points
Nip points (sometimes called pinch points) form wherever two parts rotate together or where a moving part passes a stationary one. Belts approaching pulleys, chains wrapping around gears, and rollers feeding material all create gaps that can grab a finger, hand, or arm and pull it inward. Bandsaws, drill presses, belt sanders, lathes, and grinders all pose this risk. The danger increases anytime guards are removed or bypassed.
Trench and Excavation Cave-Ins
A trench collapse is one of the most lethal caught-between events. When the walls of an unprotected trench give way, the soil can crush or suffocate a worker in seconds. OSHA requires protective systems for any trench 5 feet deep or more. Options include sloping the walls back, installing a trench box or shield, or using shoring to brace the sides. Excavations deeper than 20 feet must be designed by a professional engineer. In 2024, collapse and engulfment incidents killed 80 workers nationwide.
Vehicles and Heavy Equipment
Workers get pinned when a forklift, dump truck, or piece of heavy equipment rolls or backs into them against a wall, rack, column, or another vehicle. These incidents often happen in loading docks, warehouses, and construction sites where workers on foot share space with moving machines. Limited visibility, lack of spotters, and missing backup alarms all contribute.
Unguarded Points of Operation
The point of operation is where a machine actually performs work: where a press stamps metal, where a blade cuts wood, where a die punches holes. If a worker’s hand can reach into that zone during the operating cycle, a caught-between hazard exists. OSHA’s general machine guarding standard requires that every such point be guarded so no part of the operator’s body can enter the danger zone while the machine is running. Methods include barrier guards, two-hand controls that keep both hands away from the cut, and electronic safety devices that stop the machine if a body part breaks a sensor beam.
What Makes These Injuries So Severe
Caught-between incidents tend to produce crushing injuries, amputations, and fatalities at a higher rate than many other hazard types. The forces involved, whether from a hydraulic press, a collapsing trench wall, or a vehicle weighing several tons, far exceed what the human body can withstand. Even a slow-moving conveyor belt can generate enough torque to pull in and trap a limb before a worker can react. Speed of recognition rarely matters because the mechanical advantage is overwhelmingly on the side of the machine or material.
Key Prevention Measures
Machine Guarding
Guards must be attached directly to the machine whenever possible. If that isn’t feasible, they need to be anchored securely nearby. OSHA requires that revolving drums, barrels, and containers be enclosed with interlocked guards, meaning the container physically cannot spin unless the guard is in place. Fixed guards that permanently cover the hazard are the most reliable, followed by interlocked guards that shut the machine down when opened, and adjustable guards that the operator can position for different tasks.
Lockout/Tagout
Before anyone services, cleans, or unjams a machine, all energy sources need to be shut off and locked in the off position. This is known as lockout/tagout. It covers electrical, hydraulic, pneumatic, mechanical, and even stored energy like compressed springs. Every worker authorized to perform this procedure must be trained to recognize the types of energy present and know how to isolate them. Other employees in the area must understand that they are prohibited from restarting equipment that has been locked or tagged out. Skipping lockout/tagout during “quick” fixes is one of the most common paths to a caught-between fatality.
Trench Protection
For excavation work, the non-negotiable rule is straightforward: never enter an unprotected trench 5 feet or deeper. Employers must provide one of the approved protective systems (sloping, shoring, or shielding) along with a safe way to get in and out, typically a ladder, stairway, or ramp within 25 feet of every worker.
Clothing and Personal Items
Loose clothing, dangling jewelry, long hair, and even gloves can catch on a rotating part and pull a worker into a nip point. Standard shop rules require tying back hair, securing loose sleeves and shirt tails, removing rings, bracelets, and necklaces, and in buffing or polishing operations, never wearing gloves because the spinning wheel can grab the fabric and drag a hand in.
Industries With the Highest Risk
Construction consistently leads in caught-between fatalities because of the combination of trenching, heavy equipment, and temporary structures. Manufacturing is a close second due to the density of powered machinery with nip points and points of operation. Agriculture, warehousing, and oil and gas extraction round out the high-risk sectors. In agriculture, power take-off shafts on tractors are a notorious source of entanglement. In warehousing, the interplay of forklifts and pedestrian workers in confined aisles creates persistent pinning risks.
Regardless of industry, caught-between hazards share a common thread: they exist wherever moving objects can trap a person. Identifying those points before work begins, installing proper guards and protective systems, and following energy-control procedures when machines are being maintained are the measures that prevent these injuries from happening.