This revised standard provides minimum safety requirements to be followed while entering, exiting, and working in confined spaces at normal atmospheric pressure, but does not pertain to underground mining, tunneling, caisson work or other similar tasks that have established national consensus standards. This is a performance-oriented standard and, as such, is not intended to replace existing specific standards and procedures. Rather, it is intended to support those that meet the performance objectives defined in this standard. (Two appendices, including logic diagram for determination of confined spaces and references)