Raising Safety Standards for Working at Height

The term “working at height” refers to work performed above another level, including ladder, scaffolding, roofs, or near an edge or opening. The common denominator for working at height is the potential to fall to another level if proper safety precautions aren’t in place.

Someone is working at height if they are working:

- Above the ground or another level
- Near an edge or ledge
- Near an opening or on a fragile surface

Falls from height result in a greater risk for serious injuries and fatalities.

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Understanding Working at Height Hazards

Recognizing conditions that make working at height dangerous can help you prevent workplace falls. Whether you’re developing a fall protection plan or performing a hazard assessment, identifying hazards can help you mitigate them.

#1. LEADING EDGES AND SHARP EDGES

Understanding the difference between leading and sharp edges can mean the difference between life and death. Each presents unique hazards and requires the right equipment to keep workers safe.

- Sharp Edge – An edge that is not rounded that can cut and/or completely sever most types of lifelines. The smaller the edge radius of the edge, the sharper it is.
- Leading Edge – ANSI A10.32-2012 defines a leading edge as the “unprotected side or edge during periods when it is actively or continuously under construction.” Leading-edge hazards occur when a fall protection system is anchored at foot level behind the worker. When that worker moves away from the anchor point, there is a potential to fall over the edge.

Sharp edges endanger workers when lifelines become frayed, cut, or severed entirely. These equipment conditions can cause falls to a level below, resulting in serious injuries. Leading edges can pose additional risks, including:

- Increased Fall Distances – With leading-edge work, employees are often attached at foot level, which means they will fall further than if they were anchored at shoulder height or overhead. In these situations, employers need to take fall clearance into account and provide PFAS designed for leading-edge applications.
- Lock-up Speed – Self-retracting lifelines anchored at foot level may not react to a fall over a leading edge until the worker’s D-ring passes over the leading edge. That means they may have fallen five feet or more before the self-retracting lifeline engages to arrest the fall.
- Increased Fall Arrest Forces – The further a worker falls before fall-arrest systems engage, the greater the impact on their body. Employers should provide PFAS that are rated for leading and sharp edge work and contain energy-absorbing devices.
- Increased Potential for Swing Fall Hazards – Even in a harness, hanging off an edge is dangerous. The danger increases significantly if a worker is swinging, and the lifeline is stretched over a sharp edge. The motion can fray or cut the line, leading to a fall.

#2. FALL CLEARANCE

Fall clearance is the minimum distance needed between a person’s feet and the level below to prevent them from hitting the ground or striking any other object. In the event of a fall, there must be sufficient clearance to allow for fall arrest. Calculating fall clearance is critical for safety when working at height.

To prevent impact in working at height situations, add the appropriate factors together to determine the fall clearance required. This calculation will provide the safe required distance below the anchorage connection point.

Here is a simple equation for determining the required distance:

Required Distance = Lanyard Length + Deceleration Distance + Work Height + Safety Factor

- Lanyard Length – The length of the lanyard or retractable device connected to the harness anchorage point.
- Deceleration Distance – The distance between the start of the fall to when the fall arrest system engages. OSHA limits this distance to 3.5 feet or less.
- Work Height – The height where the work is taking place.
- Safety Factor – Additional safety distance below the worker.

The height and weight of the worker should also be considered when determining fall clearance.

Click on the image on the right to enlarge the fall clearance tool from 3M®.

#3. DROPPED OBJECTS

While PFAS can protect workers from fall impacts and save lives, they cannot protect people on the ground from objects dropped when working at height. Though falls top OSHA’s Fatal Four, “struck by an object” comes in second with an estimated 10% of workplace deaths resulting from falling, swinging, or misplaced objects. Employers can mitigate these risks by investing in fall protection for tools.

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