OSHA's requirements for confined space entry are detailed in the 29 CFR 1910.146 standard, which outlines the necessary precautions and procedures to ensure safety. 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. Written Program: Employers must develop and implement a written permit space program that includes measures to prevent unauthorized entry, identify and evaluate hazards, and establish safe entry operations [2].

3. 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 are maintained [3].

4. Ventilation: Continuous forced air ventilation must be used to eliminate any hazardous atmosphere before entry and must continue until all employees have exited the space [3].

5. Entry Permits: A written entry permit must be issued before entry, detailing the hazards, entry conditions, and the measures taken to ensure safety. The permit must be available to all entrants [4].

6. Training: Employees involved in confined space entry must be trained to understand the hazards, the use of equipment, and the procedures for safe entry and exit [4].

7. Rescue and Emergency Services: Employers must develop and implement procedures for summoning rescue and emergency services, and for rescuing entrants from permit spaces [5].

8. Attendants: At least one attendant must be stationed outside the permit space for the duration of entry operations to monitor the safety of entrants and to initiate rescue procedures if necessary [5].

These requirements are designed to protect workers from the significant risks associated with confined spaces, such as toxic atmospheres, engulfment, and entrapment. Employers must ensure compliance with these standards to maintain a safe working environment.