Industry Safety

ANSI Z133 Secretariat 

International Society of Arboriculture (ISA) 

Mission Statement 

Through research, technology, and education, the International Society of Arboriculture (ISA) promotes the professional practice of arboriculture and fosters a greater worldwide awareness of the benefits of trees. 

Brief History of ANSI Z133 

This standard was developed for the arboriculture industry under the procedures of the American National Standards Institute by the Accredited Standards Committee on Safety Requirements for Arboricultural Operations, Z133. The secretariat of the Z133 Committee is held by the International Society of Arboriculture. The Accredited Standards Committee Z133 was organized on 4 April 1968, in response to efforts by Mrs. Ethel M. Hugg of Johnstown, New York. Mrs. Hugg’s son had died while trimming trees, and this tragic incident caused her to write to federal and state authorities and to various other organizations in an attempt to have measures initiated that would make tree trimming safer. The initial standard was unanimously adopted by the committee on 14 July 1971, and was approved as an American National Standard on 20 December 1972. The Z133 Committee continues to monitor arboriculture safety performance, providing interpretation and clarification of the intent of the requirements in the standard and for any adjustments or revisions of the standard. 

Suggestions for improvement of the current (2017 Revised) standard are welcome. All official comments must be made online using the online comment form.

For general comments or questions, e-mail the International Society of Arboriculture at Z133@isa-arbor.com.