The Fatal Four: The 4 Hazards Behind 60% of Construction Deaths (and How to Spot Them in Seconds)

If you've ever asked what are the Fatal Four in construction, the short answer is the four hazard categories that, according to OSHA, cause approximately 60% of all construction worker deaths. They are falls, struck-by, caught-in/between, and electrocution. Learn to recognize these four on sight and you eliminate the majority of the risk on almost any jobsite.

This guide breaks down each one, why it kills, and how to spot it in seconds before someone gets hurt.

What Are the Fatal Four in Construction?

The Fatal Four are OSHA's term for the four leading causes of death in construction. As of recent OSHA data, these four account for roughly 6 out of every 10 construction fatalities. Cut these out and, by OSHA's own estimate, you'd save hundreds of workers every single year.

Here they are, ranked roughly by how often they kill:

1. Falls — by far the biggest killer, responsible for around a third of all construction deaths.
2. Struck-by — workers hit by vehicles, falling objects, or swinging loads.
3. Caught-in or caught-between — trench collapses, equipment, unguarded machinery.
4. Electrocution — contact with power lines, live wires, or faulty equipment.

Let's walk through each one and, more importantly, how to catch it.

1. Falls: The Number One Killer

Falls cause more construction deaths than any other hazard. Most happen from roofs, ladders, scaffolds, and unprotected edges or floor openings. The frustrating part is that nearly all of them are preventable with basic fall protection.

Spot it fast:

• Any worker more than 6 feet up without a harness, guardrail, or safety net
• Unprotected leading edges, floor holes, or skylights
• Ladders set at the wrong angle or not tied off
• Scaffolds missing planks, guardrails, or proper footing

Rule of thumb: if a worker could fall 6 feet or more in construction, fall protection is required. No exceptions for "just a quick job."

When you do a job hazard analysis before the shift, falls should be the first hazard you map for any elevated work.

2. Struck-By: The Hazard You Don't See Coming

Struck-by injuries happen when a worker is hit by a moving or falling object. Think a load swinging off a crane, a tool dropped from above, a nail from a misfired gun, or a backing dump truck.

Spot it fast:

• Workers standing under suspended loads or active lifts
• Loose tools or materials near edges and on scaffolds
• Vehicles and heavy equipment operating near workers on foot
• Missing or unworn high-visibility clothing in traffic zones
• No spotter when equipment is backing up

Keep workers out of the line of fire, secure everything stored at height, and never let foot traffic mix with moving equipment without a spotter or barrier.

3. Caught-In or Caught-Between: The Crushing Hazards

These are the hazards that crush, pin, or bury. The most lethal version is a trench or excavation collapse — a cubic yard of soil weighs as much as a small car. Unguarded machinery and getting pinned between equipment and a wall are also common.

Spot it fast:

• Trenches 5 feet or deeper with no protective system (sloping, shoring, or a trench box)
• Spoil piles dumped right at the edge of an excavation
• Workers in a trench with no safe exit within 25 feet
• Rotating or moving machine parts without guards
• Workers positioned between equipment and a fixed object

For any excavation, a competent person must inspect it before workers enter — and again after rain or any change in conditions.

4. Electrocution: The Silent Killer

Electrocution often comes from contact with overhead power lines, damaged cords and tools, or live wires during work that should have been de-energized. It kills fast and frequently.

Spot it fast:

• Equipment, ladders, or scaffolds operating near overhead power lines
• Frayed cords, damaged tools, or missing ground prongs
• No GFCI protection on outdoor or wet-location circuits
• Work on circuits that weren't locked out and tagged out
• Wet conditions around electrical equipment

Maintain safe clearance from power lines, inspect cords daily, use GFCIs, and never assume a circuit is dead — verify it.

How to Catch the Fatal Four in Seconds

The Fatal Four share a trait: they're usually visible before the incident. The guardrail is missing. The trench has no box. The cord is frayed. The trick is having a trained eye on the work area at the right moment — which is exactly where most crews fall short, because the foreman can't be everywhere at once.

That's the gap an AI hazard scan fills. Point your phone at a work area and you get an instant read on the conditions in front of you, including the Fatal Four, with a severity rating and a specific fix for each issue.

Frequently Asked Questions

What are the Fatal Four in construction?

The Fatal Four are the four leading causes of construction deaths identified by OSHA: falls, struck-by incidents, caught-in/between hazards, and electrocution. Together they account for approximately 60% of all construction fatalities.

Which of the Fatal Four causes the most deaths?

Falls are consistently the deadliest, responsible for roughly a third of all construction worker deaths in recent OSHA data — more than the other three combined in most years.

How can I prevent the Fatal Four on my site?

Proactive hazard spotting is the key: enforce fall protection above 6 feet, keep workers out of the line of fire, protect every trench 5 feet or deeper, and treat all circuits as live until verified dead. Daily inspections and a quick job hazard analysis before each task catch most of these before they cause harm.

Are the Fatal Four the same as OSHA's most cited violations?

They overlap heavily. Fall protection is both the deadliest hazard and OSHA's most frequently cited standard, and you can read more about the cost side in our guide to OSHA penalties in 2026.

Catch hazards before they cost you

The Fatal Four are visible before they turn fatal — if someone's looking. Site Safety AI lets any worker point an iPhone at a work area and get an instant, AI-powered read on falls, struck-by, caught-in, and electrical hazards, each with a severity rating and a fix. Your first scan is free. Download Site Safety AI on the App Store and spot the Fatal Four in seconds, not after the fact.