Procedures for IDLH Atmospheres

Atmospheres considered immediately dangerous to life or health (IDLH) have special requirements due to their threat level. Even short-term exposure to an IDLH atmosphere can result in death, so it is imperative that these requirements be upheld as follows:

• At least one employee should be stationed outside the IDLH atmosphere in case something goes wrong within.
• Visual, voice, or signal line communication must be maintained between the employee in the IDLH atmosphere and the employee outside the IDLH atmosphere.
• The employee outside the IDLH atmosphere must be trained and equipped to provide rescue if needed.
• If the outside employee must enter the IDLH atmosphere to perform rescue, the employer (or someone the employer officially designates) must first be notified.

The following requirements also apply to IDLH atmospheres:

• If the employer is notified that an employee is entering an IDLH atmosphere to perform rescue, the employer (or official designee) must provide necessary assistance.
• Both the employee inside the IDLH atmosphere and the employee outside the IDLH atmosphere must be equipped with a positive pressure SCBA or an SAR with an auxiliary air tank.
• The employee outside the IDLH must also be equipped with retrieval equipment for removing the employee inside the IDLH in case of an emergency.
• If retrieval equipment would make rescue more dangerous, an alternative but equivalently useful means of rescue may be used.
• If the IDLH atmosphere is part of an interior structural fire, two employees, each wearing positive pressure SCBAs, must enter the IDLH atmosphere; and two employees must be stationed outside the IDLH atmosphere to perform rescue procedures if needed. All four employees must have sufficient communication devices.

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