Operational Field Guide for Safety Compliant Standard Tree Removal 

ANSI Z133 Standard Tree Removal is the regulated arboricultural procedure for systematically felling and dismantling trees using certified protective gear (PPE), rigorous hazard evaluations, precise directional cuts, planned escape routes, and established drop-zone perimeters to prevent injury and property damage.

  • Why Safety Matters: Arboriculture is rated among the most hazardous industries in North America due to dangers from falling timber, overhead electrical lines, and high-speed cutting machinery. 

  • Regulatory Compliance: The Washington State Department of Labor & Industries (L&I) enforces these standards through DOSH (Division of Occupational Safety & Health) across all commercial, municipal, and private tree operations to minimize catastrophic injuries and insurance liabilities.

  • Value for Property Owners: These standards provide residential landowners with practical guidelines to DIY small backyard trees safely and identify severe hazards, such as electrical wire proximity or trunk decay that require certified professionals. Understanding ANSI Z133 also empowers property owners to vet hired tree contractors, ensuring crews follow state mandated safety practices, wear certified gear, and protect property from costly damage

Directional notch cuts are crucial for tree felling. Before the felling process, however, it is important to wear the proper gear for the task.

Mandatory Personal Protective Equipment (PPE)

Before entering the tree drop perimeter, every worker and ground crew member must wear approved PPE.

Gear Category Standard Specification Purpose
Head Protection ANSI Z89.1 Type I/II Deflects falling canopy debris and structural branches
Eye & Face Protection ANSI Z87.1 Impact Goggles or Mesh Visor Prevents eye injury from high-velocity wood chips and sawdust
Hearing Protection Ear muffs or plugs rated NRR 25+ Guards against long-term hearing loss from chainsaw motors
Leg Protection Chainsaw chaps (UL Classified/ASTM F1897) Stops chainsaw instantly upon accidental contact
Footwear & Apparel Heavy-duty non-slip boots and high-visibility vest Extra safety measure for proper fieldwork

Essential Safety Equipment & Gear 

PPE serves as the operator's primary physical barrier against severe injury. Under ANSI Z133 standards, all protective gear shown in the diagram must be up to inspection and worn before entering the active work zone. This gear provides a vital defensive aid against direct impacts and acoustic trauma exceeding 85 decibels.

Infographic of a person wearing essential safety equipment for tree removal, including a hard hat with face shield, safety goggles, hearing protection, cut-resistant gloves, steel-toed boots, chainsaw chaps, a first aid kit, and hazard warning signs.

A complete safety setup combines head-to-toe protection along with immediate emergency supplies. Keeping a first aid kit accessible and wearing ballistic-grade leg and eye protection ensures that unforeseen tool kickback or structural wood failures do not result in fatal injuries.

Pre-Work Tree & Site Hazard Assessment 

Perform a 360-degree inspection of the work site before touching a chainsaw.

1. Electrical Proximity 

Identify all overhead utility and power lines. Maintain a minimum approach distance of at least 10 feet for non-qualified workers.

2. Tree Health & Lean

Check trunk base for fungal decay, hollow cavities, carpenter ant infestation, and root damage. Determine the tree's natural lean and heavy side branches.

3. Overhead Canopy Hazards

Scan for "widow makers" (loose, dead hanging limbs) and interlocking branches from neighboring trees.

4. Environmental Conditions

Never fell trees during high wind gusts (exceeding 20 mph), ice loading, or lightning storms.

Infographic of a Pre-Work Tree Removal Hazard Assessment. It outlines four core inspection steps: electrical hazards, structural integrity, canopy risks, and environmental conditions. Full text details are provided in the section above.

Drop Zone & Escape Route Layout ⚠️

Establish clear spatial boundaries to protect crew members during the fall.

The Exclusion Drop Zone

Establish a circular perimeter equal to at least 1.5 to 2 times the total height of the tree. No non-essential personnel are allowed inside this zone during cutting.

Dual 45-Degree Escape Paths

Clear two unobstructed exit routes extending diagonally backward at 45-degree angles opposite the planned direction of fall.

Path Maintenance

Remove all brush, loose tools, and tripping hazards along both escape routes before beginning the notch cut.

An overhead view of a tree trunk with an arrow pointing straight up labeled Felling Direction. Two green arrows point downwards diagonally at 45 degree angles labeled Safe for escape paths.

Directional Felling Execution: Step-by-Step Guide

Step 1: The Face Notch: Directional Cut

Make a directional notch facing the exact direction of fall. The notch depth must reach approximately 1/3 of the trunk's total diameter. Ensure the top and bottom cuts meet cleanly without bypassing.

Step 2: Hinge Wood Retention

Do not cut all the way through the trunk. Preserve the hinge, a solid band of intact wood equivalent to approximately 10% of the trunk's diameter to guide the tree straight to the ground.

Step 3: The Back Cut

Execute a flat, horizontal cut from the opposite side of the notch, positioned slightly higher than the bottom corner of the face notch. Insert felling wedges as you cut to prevent saw pinching.

Step 4: Retreat via Escape Path

As soon as the tree begins its committing fall, shut down the saw and walk immediately down your pre-cleared 45 degree escape path, keeping your eyes on the falling canopy.

Danger / Unsafe Shortcut Warning:

Never cut all the way through the trunk (straight push-cut) or bypass the directional notch. Cutting through hinge wood causes uncontrollable falls, barber-chair splits, and severe equipment kickback.

Technical infographic outlining the 4-step ANSI Z133 directional felling mechanics: drop zones, open-face notch geometry, cutting sequence, and safe retreat paths.

Frequently asked questions

What emergency medical prep is required before starting the saw?

Always keep a trauma first-aid kit nearby packed with severe bleeding supplies, including a tourniquet and clotting gauze. Before cutting, confirm address so anyone on-site can guide 911 dispatchers in an emergency.

When should the chainsaw brake be locked while moving around?

Click the chain brake into the locked position anytime you take more than two steps, walk over brush or uneven ground, or pause cutting to check your surroundings. If the motor is running and you aren't actively cutting wood, the brake must be engaged.

What is a spring pole and why is it dangerous?

A spring pole is a branch pinned tightly under a fallen trunk that can act as a catapult. If you cut it suddenly, it will snap back with enough force to cause severe injury. To disarm it safely, shave small, shallow slices off the inside curve of the bend to slowly release the tension before cutting it all the way through.

Why is drop-starting a chainsaw prohibited?

Drop-starting, or holding the pull cord and dropping the running saw downward with one hand, gives you zero control over the spinning blade and often leads to serious leg or body lacerations. Always start the chainsaw flat on the ground with your foot holding the handle down or clamped securely between your knees with the chain brake locked.

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