TFTC #61 The Z133 Just Got a Whole Lot More Accessible
Sherrilltree Jun 2nd 2026If you work in trees, you've probably heard someone reference "the Z." Maybe in a tailgate safety meeting, maybe from a crew lead after a close call, maybe from an instructor during your latest climb class. But if you've never actually read the full standard cover to cover, you're not alone. As of today, that's a lot easier to fix.
What Is ANSI Z133?
ANSI Z133 is the American National Standard for Arboricultural Operations: Safety Requirements. It's the safety standard written by arborists, for arborists, and it covers the work we actually do: pruning, removals, rigging, aerial operations, and the equipment used in all of it. The standard is developed by a consensus committee through the International Society of Arboriculture (ISA) and has been revised multiple times since its first edition in 1972.
Why Standards Matter
Tree care is one of the most dangerous occupations in the United States, and it's not even a close comparison. According to the Bureau of Labor Statistics, tree care workers face a fatality rate roughly 30 times higher than the national average for all workers. To put that in perspective, that rate is approximately five to eight times higher than the on-the-job fatality rates for police officers and firefighters. Tree workers make up less than one-twentieth of one percent of the U.S. workforce, yet they account for a vastly disproportionate share of workplace deaths.
Standards like the Z133 exist because the industry has collectively agreed on a baseline for how this work should be done safely. The Z is the product of real-world experience. Knowing the Z133 helps you identify hazards before they become incidents. It helps you set up job sites correctly, choose and inspect the right equipment, and establish safe work zones. And if you're running a crew or a business, it gives you a defensible framework for your safety program.
The Z133-2026: Now Free and Digital
The newest edition of the standard, Z133-2026, is now available as a free digital download through the ISA web store. Both English and Spanish versions are available. You don't need to be an ISA member to access it; you just need to create a free MyISA account.
There's no cost for the digital version or for the account.
Download the free digital Z133-2026 from the ISA Web Store
English Version: https://wwv.isa-arbor.com/store/product/4731
Spanish Version: https://wwv.isa-arbor.com/store/product/4731
If you prefer a physical copy, printed booklets are also available for purchase through ISA and other professional organizations.
If you prefer a physical copy, printed booklets are also available for purchase through ISA and other professional organizations.
Read It. Reference It. Share It With Your Crew.
Whether you're a seasoned climber, a new hire learning the ropes, or the person writing the safety manual for your company, ANSI Z133 is the foundational document for how our industry defines safe practice. Now that cost is no longer a barrier, there's no reason not to have it in your back pocket, or at least bookmarked on your phone.