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Confined Space Definitions


Authorized Attendant

Properly trained worker who is positioned outside a confined space. This person monitors the entrants within a confined space and the external surroundings.

Authorized Entrants

Properly trained workers with the authorization to enter confined spaces.

Confined Space

Any enclosed space with limited means of entry or egress, which is not designed for continuous occupation.


Physical act of entering a confined space. An entry occurs when a worker’s face breaks the plane of the confined space opening.

Hazardous Atmosphere

Atmosphere that is oxygen enriched, oxygen deficient, combustible, toxic, or otherwise immediately dangerous to life or health.


Operations that could provide a source of ignition, such as riveting, welding, cutting, burning, or heating.

Permit-Required Confined Space

Confined space that contains actually or potentially hazardous atmospheres, or the potential for engulfment by particulate matter or liquid.

Person Authorizing Entry

Worker who is properly trained in administrative, technical, and managerial aspects of confined space entry. This person authorizes entry and has the authority to terminate entry when conditions become unfavorable.


May 2011
Revised November 2014