The 2009 edition of ANSI Z117 Safety Requirements for Confined Spaces has been published. The standard contains numerous updates. If I had to sum up the changes in one word it would be clarity. Most of the changes are not substantial but clarify the intent of the committee in several important areas.

Beyond OSHA requirements
ANSI Z117 was first published prior to the OSHA 1910.146 Confined Space Standard. OSHA used Z117 in the development of their own standard. The ANSI standard goes beyond OSHA though in a number of key areas.

All ANSI standards are consensus documents. A balanced committee of representatives with expertise in the topic debates the content of the standard until consensus is reached. No one individual or group can unfairly sway the final standard. Public comment is also incorporated into the process. ANSI rules require that the committee address all public comments.

The confined space standard uses a performance-based approach. Guidelines are established on what must be done but latitude is provided concerning how any particular organization accomplishes the objectives. I believe this approach is significantly better than a prescriptive standard that requires things to be done in a specific way.

Z117 is laid out in a two-column format. The left column contains the mandatory elements of the standard. The right column provides explanatory material that can assist the user with interpreting and applying the left column items but does not create additional requirements. A simpler way to look at this concept might be that “shall” statements are in the left column and “should” comments are in the right column. There are also appendicies that contain useful but nonmandatory information.

Better hazard identification
A definition was added for “serious hazard” allowing differentiation between serious hazards and less severe issues considered hazards. A non-permit space may have hazards. Any space that contains serious hazards must be classified as a permit-required space. A serious hazard is one capable of causing death, substantial injury, or of incapacitating the entrant.

One specific clarification is that hazard identification must be completed prior to any entry of the space and must be conducted by a qualified person. This concept has been in place but the wording was more open to interpretation in the previous edition of the standard.

Training: Beyond once and done
Another specific addition to the standard is that both initial and follow up training are required. No fixed timing is specified for ongoing training but the concept that once and done is enough is clearly no longer permitted. The need for supplemental training is driven by gaps in performance, changes in spaces, procedures, equipment, or hazards.

The effectiveness of training must be assessed periodically by a qualified person. One of the best ways to complete this is with job site audits of confined space entry operations. Evaluating actual performance tends to provide the best view of whether knowledge and skills are being appropriately applied.

Training must be provided as often as necessary to insure competence. The frequency will vary depending upon the nature of your entry operations. How often your personnel engage in confined space work will be one of the main influences. Organizations that seldom conduct confined space entries may actually require more refresher training than groups that use their skills frequently. Where entries are routinely made, one of the key issues to watch for is the introduction of shortcuts or other bad habits.

The level of risk should also be part of the determination on the frequency of supplemental training. Where confined space entries involve relatively low risk environments training may not be needed as often as in those operations where hazards are more severe.

Atmospheric hazards are historically the leading cause of death in confined space incidents. The standard places a great deal of emphasis on identification and assessment of atmospheric hazards, atmospheric monitoring, appropriate training for those who conduct the monitoring, and elimination and control measures for atmospheric hazards.

A process, not a program
The essence of the confined space safety process laid out in the standard includes identifying spaces and their hazards; developing a written process for managing entry operations including the use of a permit to authorize entry; training personnel so that they are competent to implement the process; preparing and using appropriate hazard elimination and control processes and techniques; preparing effectively for emergencies; and evaluating the performance of the overall process.

Depending upon the nature of your confined spaces, implementation may not always be easy. Effective use of the standard will help prevent confined space incidents that may lead to deaths and injuries.


Click on the ASSE Resource Center at, click on “Standards,” and click on the description ofANSI/ASSE Z117.1-2009 Safety Requirements for Confined SpacesandANSI/ASSE Z117.1-2009 Standard and the Z117 Comparison Document