Confined-space entry constitutes a serious potential hazard to workers, and as a result, it is subject to strict controls. Confined spaces, which include tanks, ducts, and electrical and telephone vaults, may be severely oxygen-deficient, or may contain flammable or toxic gases and vapors.

An entry permit for confined-space work must be issued and approved by the supervisor and EH&S. Atmospheric testing, lockout procedures, and training are required. Additional ventilation, protective equipment, or other controls may also be necessary.