OSHA's requirements for confined space entry are detailed in 29 CFR 1910.146, which outlines the necessary practices and procedures to protect employees from the hazards associated with entering permit-required confined spaces. Here are the key requirements:

1. Permit-Required Confined Space Program: Employers must develop and implement a written program for permit-required confined spaces. This program should include measures to prevent unauthorized entry, identify and evaluate hazards, and specify acceptable entry conditions [1].

2. Entry Permit: Before entry, an entry permit must be issued, detailing the space to be entered, the purpose of entry, the date and duration of the permit, authorized entrants, and the hazards involved. It should also outline the measures taken to isolate the space and control hazards [2].

3. Atmospheric Testing: The atmosphere within the space must be tested for oxygen content, flammable gases and vapors, and toxic air contaminants before entry. 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. 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 [2].

6. Rescue and Emergency Services: Employers must develop procedures for summoning rescue and emergency services and ensure that rescue equipment is available and personnel are trained in its use [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. Documentation of this reclassification must be maintained [5].

These requirements are designed to ensure that confined space entry is conducted safely, with appropriate precautions to protect workers from potential hazards.