OSHA's requirements for confined space entry are detailed in the 29 CFR 1910 standards. Key requirements include:

1. Permit-Required Confined Spaces: Employers must identify and evaluate confined spaces to determine if they are permit-required. A permit-required confined space has one or more of the following characteristics: a hazardous atmosphere, potential for engulfment, an internal configuration that could trap or asphyxiate, or any other recognized serious safety or health hazard [1].

2. Atmospheric Testing: Before entry, the internal atmosphere must be tested for oxygen content, flammable gases and vapors, and potential toxic air contaminants. Continuous monitoring is required to ensure safe conditions [2].

3. Ventilation: Continuous forced air ventilation must be used to eliminate any hazardous atmosphere before and during entry [2].

4. Entry Permits: A written entry permit must be issued before entry, detailing the hazards, measures taken to isolate the space, acceptable entry conditions, and the personnel involved in the entry [3].

5. Training and Roles: Employers must provide training to all employees involved in confined space entry operations, including authorized entrants, attendants, and entry supervisors. Each role has specific duties and responsibilities [4].

6. Emergency and Rescue Procedures: Employers must develop and implement procedures for summoning rescue and emergency services, and for rescuing entrants from permit spaces. This includes ensuring that rescue services are available and that they are capable of performing rescues [4].

7. Reclassification of Spaces: A permit-required confined space can be reclassified as a non-permit space if all hazards are eliminated without entry into the space [5].

These requirements are designed to protect workers from the hazards associated with confined spaces and ensure safe entry and exit procedures.