Escape respirators have a SINGLE function:
to allow a person working in a normally safe environment sufficient time to escape from suddenly occurring respiratory hazards.
Given this function, selection does not rely on assigned protection factors. Instead, these respirators are selected based on:
- a consideration of the time needed to escape, and
- the likelihood of IDLH or oxygen deficiency conditions.
Escape respirators can be separated into two (2) categories:
- air-purifying respirators (APR) and
- self-contained breathing apparatus (SCBA)
Air-Purifying Respirators (APR) for Escape
Air-purifying respirators remove contaminants from the air by sorbent and/or filter media, but because they do NOT provide breathing air, these respirators can NOT be used in an oxygen-deficient atmosphere.
Escape capabilities of air-purifying respirators can be summarized as follows:
- Air-purifying respirators with particulate filters or chemical cartridges are approved for escape from atmospheres containing SPECIFIC CONTAMINANTS in concentrations that are NOT immediately dangerous to life or health (IDLH), which includes oxygen-deficient atmospheres less than 19.5% by volume. This includes half and full facepiece respirators that are routinely used in many work environments.
- Mouthpiece-type cartridge respirators (TC-23C) are approved for escape ONLY.
- Air-purifying respirators with canisters (TC-14G) include the escape gas mask (canister) respirator, the gas mask (canister) respirator, and the filter self-rescuer.
The “escape gas mask” consists of a half-mask or a mouthpiece respirator. The mouthpiece respirator can be used for SHORT PERIODS of time to escape from LOW
CONCENTRATIONS of organic vapor or acid gas. The “escape gas mask”, which utilizes a half-mask, filters contaminants from the air. These respirators may also be used to escape from low concentrations of organic vapor or acid gas, but NOT from oxygen-deficient atmospheres. Escape gas mask respirators equipped with full facepieces can also be used for escape from IDLH conditions but NOT from oxygen-deficient atmospheres. These respirators may be used for escape from contaminant concentrations above the IDLH value provided that the maximum use concentration (MUC) for the canister is NOT exceeded and adequate oxygen (≥19.5%) is present.
Note that NOT all “gas masks” provide protection against carbon monoxide (CO). Check the certification to determine if the respirator is specifically certified for use against levels of CO that exceed the exposure limit.
“Gas masks” with full facepieces are also acceptable for routine use in non-IDLH atmospheres. Gas masks with mouthpieces are for escape ONLY.
No air-purifying device is suitable for escape from a POTENTIALLY oxygen-deficient atmosphere.
The filter self-rescuer unit is the mouthpiece device, which is designed to protect specifically against atmospheres with not more than 1% carbon monoxide. The filter self-rescuer is normally used in mining.
Self-Contained Breathing Apparatus (SCBA)
A self-contained breathing apparatus (SCBA) provides breathing air to the user for escape from oxygen-deficient environments.
Escape SCBA devices are commonly used with full facepieces or hoods and, depending on the supply of air, are usually rated as 3 to 60-minute units.
Self-contained self-rescuer (SCSR) devices have been approved by MSHA/NIOSH for escape from mines, but these devices may also have application in other similar environments. SCSRs are mouthpiece respirators that provide a source of oxygen enriched air for up to 60 minutes.
SCSRs are normally stored in mines and used for emergency escape from mine disasters.
ALL SCBA devices can be used in oxygen-deficient atmospheres.
When selecting escape apparatus, careful consideration must be given to potential eye irritation. This consideration is important for determining whether a gas mask or
SCBA equipped with a full facepiece should be selected rather than a device equipped with a half-mask or mouthpiece.
The majority of gas masks or escape gas masks can be used in situations involving gases, vapors, or particulates. For escape from particulate-contaminated
environments, an air-purifying element must be selected that will provide protection against the given type of particulate. In addition to contaminants and concentration levels, the time to escape the hazard must be considered. For example, escape SCBA can have rated service lives of 3 to 60 minutes.
NIOSH intends to review the selection criteria for escape respirators and will provide additional guidance in future revisions of the RSL.
Source: https://www.cdc.gov/niosh/docs/2005-100/pdfs/05-100.pdf