Falls from height: why they happen and why they kill

Falls from height are one of the oldest and most predictable ways to die at work. A roofer steps backward off an edge while measuring. An electrician leans out from a ladder to reach a fixture. A labourer lifts a plywood sheet that was covering a floor opening and steps into the hole. A maintenance worker crosses a warehouse roof and puts a foot through a skylight. Each of these falls takes less than two seconds, and each was preventable with equipment and methods that have existed for decades.

This course is about preventing falls from height and protecting workers when a fall cannot be ruled out. It explains how fall hazards are assessed, how guardrails, covers, nets, travel restraint and fall arrest systems work, how to choose anchors and calculate clearance, how to plan rescue, and how the law and standards apply in your country. It builds on HSE-103 Hazard Recognition and Risk Assessment, and it picks up where HSE-106 left off: that course covered slips, trips and same-level falls and introduced ladders, while this one covers falls to a lower level.

This is an awareness course. In Ontario, for example, workers on construction projects who use fall protection must complete a Working at Heights program approved by the Chief Prevention Officer and delivered by an approved provider, and that training is valid for three years. Every province also requires employers to train workers on the specific fall protection systems and procedures at their site. Designing anchors and horizontal lifelines, writing rescue procedures and inspecting equipment each require a competent person or, for some systems, a professional engineer.

What counts as a fall from height?

A fall from height, or a fall to a lower level, is any fall in which the worker ends up below the surface they started on. It includes falls from roofs, floors, mezzanines, platforms, ladders, scaffolds, vehicles, trailers, loading docks, equipment, machinery and stacked material, and falls into holes, pits, shafts, excavations and openings. It also includes falls through fragile surfaces such as skylights, roof panels, ceiling tiles and rotten decking.

The law sets trigger heights above which fall protection is required. Lesson 2 compares them. But trigger heights describe when the law demands specific equipment, not when a fall becomes dangerous. Workers die every year from falls of 2 or 3 m, and some from much less, especially when they land on their head, on concrete, on rebar or into machinery. Many regulations therefore require protection at any height where the surface below would cause more serious injury than a flat floor, for example open machinery, water, a hazardous substance or projecting objects.

The physics of a fall

Falls are dangerous because gravity accelerates the body quickly and the body has very little time to react. Ignoring air resistance, which is small over the heights involved in most work falls, a falling body gains speed at about 9.8 m/s² (32.2 ft/s²). The time to fall a height \( h \) and the speed at impact are:

Human reaction time to an unexpected event is typically somewhere between 0.2 and 0.5 seconds, and a surprised worker usually takes longer than that to do anything useful. In the time it takes to recognize that you are falling, you have already fallen about a metre. There is no time to grab anything, and the arms rarely protect the head.

The damage depends on how quickly the body stops. A worker who lands on concrete stops in a few centimetres, so the forces on the skull, spine and organs are enormous. The same physics explains how fall arrest equipment works: an energy absorber or a self-retracting device lengthens the stopping distance to around a metre, which cuts the force on the body to a level a healthy person can survive. Lesson 7 returns to this idea.

How often falls happen

Falls are a leading cause of serious injury and death in Canadian workplaces, and they dominate construction fatality statistics. The Association of Workers' Compensation Boards of Canada reports fatalities and lost-time claims by event, and falls to a lower level appear in every year's data among the leading causes of traumatic death in construction. Ontario's Ministry of Labour has repeatedly identified falls from heights as the leading cause of critical injuries and deaths on construction projects, and falls are a perennial focus of provincial inspection blitzes. The figures vary from year to year and between provinces, so check the current reports from your workers' compensation board for exact numbers.

Behind the fatalities are many more serious injuries: fractured skulls, spinal cord injuries, broken pelvises, heels and wrists, and internal injuries. Survivors of serious falls often never return to their old work. For employers, a single fall can mean prosecution, large fines, higher compensation premiums, project delays and the loss of experienced workers.

Where and why falls happen

Falls cluster around a few situations:

• unprotected edges of roofs, floors, mezzanines, balconies, loading docks and platforms;
• openings in floors and roofs, including stairwells, shafts, hatches, skylights and holes left for ducts and services;
• fragile surfaces that look solid, such as skylights, plastic roof panels, corroded metal roofing and ceilings;
• ladders and step stools used for the wrong task, set up badly or climbed while carrying materials;
• scaffolds and work platforms with missing guardrails, planks or ties;
• vehicles, trailers and equipment, where workers climb onto loads, cabs and machinery;
• leading edges, where a floor or roof is still being built and the edge moves as work progresses.

Investigations into fatal falls show recurring causes. Fall protection was not provided at all. It was provided but not used, because it slowed the job, was uncomfortable, or the worker thought the task would take only a minute. It was used incorrectly: the lanyard was tied to something that failed, the clearance was too short, the harness was badly fitted, or the worker unhooked to move past an obstruction. Covers were not secured or not marked. Guardrails were removed for a delivery and not replaced. No one had planned how to rescue a worker who fell and was left hanging.

The human side

Falls rarely happen because workers want to take risks. They happen because of ordinary pressures and assumptions:

• the job is expected to take only a few minutes;
• the worker has done it many times before without falling;
• the anchor is in the wrong place, so tying off would mean climbing down and moving it;
• the harness is in the truck, or is shared and does not fit;
• the schedule is tight and everyone is behind;
• no one has told the worker exactly where the edge or the opening is.

Good fall protection is planned before anyone goes up, so that the safe way is also the practical way. That means guardrails that are already in place, anchors located where the work is, equipment that fits, and supervisors who stop work when protection is missing.

What fall protection tries to achieve

Every fall protection measure in this course does one of three things:

• it prevents the worker from reaching an edge or opening at all, for example guardrails, covers, travel restraint and working from the ground;
• it limits how far a worker can fall, for example fall restricting systems and some positioning systems;
• it stops a fall that has already started, safely and without the worker hitting anything, for example fall arrest systems and safety nets.

Preventing a fall is always better than arresting one. A fall arrest system that works perfectly still exposes the worker to forces, possible swing into structures, suspension in a harness and the risks of rescue. Lesson 3 explains the hierarchy of controls that puts these options in order.

Related courses

Ladders and scaffolds are covered in detail in HSE-213 Ladder and Scaffold Safety. Elevating work platforms, scissor lifts and boom lifts are covered in HSE-217. Same-level slips and trips are covered in HSE-106, and personal protective equipment in general in HSE-104. This course points to those courses rather than repeating them.

Short exposures, big consequences

Many fatal falls happen during tasks that last only minutes: checking a gauge, retrieving a dropped tool, taking a measurement, adjusting a ladder or covering an opening at the end of the day. Because these tasks are short, they are often left out of planning. The physics does not care how long the task takes. A fall during a two-minute task is exactly as fast and as hard as a fall during a two-day job, which is why fall protection planning must cover every task at height, however brief.