756 Respiratory Protection

Respirators for IDLH Atmospheres

In environments where the concentration of airborne contaminants is Immediately Dangerous to Life or Health (IDLH), respirators with high levels of protection are required.

All oxygen-deficient atmospheres must be considered IDLH. Exception: If the employer demonstrates that, under all foreseeable conditions, the oxygen concentration can be maintained within the ranges specified in Table II of the standard (i.e., for the altitudes set out in the table), then any atmosphere-supplying respirator may be used.

The following are some types of respirators commonly used in IDLH environments:

• Combination Airline Respirators with Escape SCBA: These types of respirators combine an airline respirator, which supplies breathable air from an external source, with an escape SCBA.
• Combination Airline Respirators with Escape SCBA and Full-Facepiece: Similar to the previous type, this respirator combines an airline respirator and an escape SCBA. However, it also includes a full-facepiece, providing additional protection for the eyes, face, and respiratory system.
• Demand/Pressure-Demand Airline Respirators: These respirators provide a continuous supply of clean air from an external source through a hose or airline. They have a demand or pressure-demand valve that supplies air only when the wearer inhales, reducing the consumption of supplied air. They may be equipped with a full-facepiece or a half-mask respirator.

It's important to note that the specific type of respirator required for IDLH environments may vary depending on the specific hazards and regulatory requirements of the particular situation. Proper selection, fit testing, training, and regular maintenance are crucial for ensuring the effectiveness and safety of respirators used in IDLH environments.

Respirators for Non-IDLH Atmospheres

The employer must provide a respirator adequate enough to protect the health of the employee and ensure compliance with all other OSHA statutory and regulatory requirements, under routine and reasonably foreseeable emergency situations.

The respirator selected must be appropriate for the chemical state and physical form of the contaminant.

For protection against gases and vapors, the employer must provide an atmosphere-supplying respirator, or an air-purifying respirator, provided that:

• the respirator is equipped with an end-of-service-life indicator (ESLI) certified by NIOSH for the contaminant; or
• If there is no ESLI appropriate for conditions in the employer's workplace, the employer must implement a change schedule for canisters and cartridges that is based on objective information or data that will ensure that canisters and cartridges are changed before the end of their service life. The employer must describe in the respirator program the information and data relied upon and the basis for the canister and cartridge change schedule and the basis for reliance on the data.

For protection against particulates, the employer must provide:

• an atmosphere-supplying respirator; or
• an air-purifying respirator equipped with a filter certified by NIOSH under 30 CFR part 11 as a high efficiency particulate air (HEPA) filter, or an air-purifying respirator equipped with a filter certified for particulates by NIOSH under 42 CFR part 84; or
• for contaminants consisting primarily of particles with mass median aerodynamic diameters (MMAD) of at least 2 micrometers, an air-purifying respirator equipped with any filter certified for particulates by NIOSH.

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