Which of the following criteria identifies a permit-required confined space?

A permit-required confined space is defined by specific characteristics that create conditions necessitating special precautions prior to entry. The primary criterion that identifies such a space is the presence of a potential hazardous atmosphere. This includes situations where harmful gases or vapors could accumulate, leading to life-threatening conditions for any individual entering the space.

Recognizing that a confined space can contain a hazardous atmosphere is essential for ensuring the safety of workers, which is why specific permits are required before work can commence. This ensures that adequate safety measures, including monitoring and protective equipment, are in place to mitigate any risks associated with potentially harmful substances in the environment.

Other criteria, such as having sufficient oxygen, determining access control, and assessing suitability for long-term occupation, do not define a permit-required confined space. For instance, a space can have sufficient oxygen but still present other hazards that require a permit for entry, and unrestricted access does not contribute to the potential risks associated with working in such environments.