When working in a confined space, ensuring a safe atmosphere is crucial. Here are some key points regarding fresh air and ventilation in confined spaces:

1. Continuous Forced-Air Ventilation: Before entry into a confined space, continuous forced-air ventilation should be initiated and maintained to ensure a safe atmosphere. This ventilation must be directed to ventilate the immediate area where employees are present and continue until all employees have exited the space [1].

2. Clean Air Supply: The air supply for the ventilation must come from a clean source and should not introduce additional hazards into the confined space [1].

3. Atmospheric Testing: Before entry, the atmosphere within the confined space should be tested to ensure it is safe. If a hazardous atmosphere is detected, employees must leave the space immediately, and measures should be taken to address the hazard before re-entry [2].

4. Ventilation and Purging: If a hazardous atmosphere is identified, the space must be ventilated or purged before entry. If ventilation alone is insufficient, personal protective equipment may be necessary [3].

5. Emergency Procedures: Employers must have emergency procedures in place, including evacuation plans if the atmosphere becomes hazardous. Workers should be trained in these procedures and in the use of any necessary equipment [3].

6. Monitoring and Alerts: If mechanical ventilation is used, it should include a method to alert workers of a system failure, allowing them time to evacuate safely [3].

By following these guidelines, you can help ensure a safe working environment in confined spaces.