OSHA term · Glossary
Self-Contained Breathing Apparatus (SCBA)
Verified vs OSHA sources · 2026-10-05
An atmosphere-supplying respirator in which the wearer carries their own breathing-air supply in a cylinder, rather than filtering the surrounding air. Because it does not depend on ambient air quality, an SCBA is the highest level of respiratory protection and is required for the most hazardous atmospheres. A full-facepiece pressure-demand SCBA has the maximum assigned protection factor of 10,000. For IDLH atmospheres, OSHA (29 CFR 1910.134(d)(2)) permits only a full-facepiece pressure-demand SCBA certified for at least a 30-minute service life, or a combination supplied-air respirator with an auxiliary self-contained air supply.
Also known as: SCBA, self-contained breathing apparatus, air pack
On this page
Self-Contained Breathing Apparatus (SCBA) at a glance
- Atmosphere-supplying: the wearer carries a compressed-air cylinder — protection does not depend on ambient air quality.
- Highest assigned protection factor: 10,000 (full-facepiece, pressure-demand mode).
- Required for IDLH atmospheres and where contaminant identity/concentration is unknown (treated as IDLH).
- For IDLH: full-facepiece pressure-demand SCBA rated ≥ 30 minutes, or a combination SAR with auxiliary SCBA (1910.134(d)(2)).
- Pressure-demand (positive pressure) keeps the facepiece pressure above ambient so leakage flows OUT, not in.
- Demand-mode SCBA (negative pressure on inhalation) has a much lower APF of only 50 and is not permitted for IDLH.
- IDLH entry requires standby/rescue provisions: an attendant outside, communications, and rescue capability (1910.134(g)(3)).
In plain English
A respirator with its own tank of breathing air on the wearer's back — the kind firefighters use. Because the worker breathes carried air instead of filtering the surrounding air, it works even where the air is poisonous or has too little oxygen. It gives the strongest protection of any respirator and is the only air-purifying-independent option allowed in atmospheres that are immediately dangerous to life or health (IDLH).
What the rule says
“The employer shall provide the following respirators for employee use in IDLH atmospheres: (A) A full facepiece pressure demand SCBA certified by NIOSH for a minimum service life of thirty minutes, or (B) A combination full facepiece pressure demand supplied-air respirator (SAR) with auxiliary self-contained air supply.”
In context
An enforcement, recordkeeping, or general-duty concept under the Occupational Safety and Health Act and 29 CFR. These terms define how OSHA inspects, cites, and penalizes employers.
Where this is written in OSHA's rules
- 29 CFR 1910.134(d)(2)Read on eCFR / OSHA.gov
- 29 CFR 1910.134(d)(2)(i)Read on eCFR / OSHA.gov
Example
A hazmat team must enter a chemical storage building after an unidentified release. Because the contaminant and its concentration are unknown, the atmosphere is treated as IDLH — no air-purifying respirator is permitted, since a cartridge cannot be trusted against an unknown hazard or low oxygen. Each entrant wears a full-facepiece pressure-demand SCBA (APF 10,000) rated for 30+ minutes. Per 1910.134(g)(3)(i), at least one trained standby employee — more if conditions warrant — remains outside the IDLH atmosphere with equivalent respiratory protection and rescue equipment, maintaining communication with the entrants. The two-outside rule of (g)(4)(ii) is specific to interior structural firefighting, not to hazmat entry.
Why it matters
In IDLH and oxygen-deficient atmospheres, an air-purifying respirator can kill: a filter or cartridge cannot add oxygen and cannot be trusted against an unknown or overwhelming contaminant. The SCBA's self-contained air supply is what makes entry survivable, which is why OSHA restricts IDLH work to pressure-demand SCBAs (or combination SAR/SCBA) and layers on standby and rescue requirements. Misjudging an atmosphere as non-IDLH and using a cartridge respirator instead of an SCBA is a classic fatal confined-space error.
SCBA (self-contained) vs. SAR (supplied-air)
Both are atmosphere-supplying respirators, but the air source differs. An SCBA carries its air with the wearer in a cylinder, giving full mobility and independence but a limited duration (e.g., 30 or 60 minutes). A SUPPLIED-AIR RESPIRATOR (SAR, or airline respirator) delivers air through a hose from a stationary source (compressor or cylinder bank), allowing long-duration work but tethering the worker to the airline and its length limits. For IDLH atmospheres, OSHA requires either a pressure-demand SCBA or a SAR combined with an auxiliary (escape) SCBA — a plain SAR alone is not permitted for IDLH, because a hose failure would leave the worker with no air.
SCBA Modes & IDLH Requirements
| Item | Detail |
|---|---|
| Type | Atmosphere-supplying (carried air cylinder) |
| Pressure-demand APF | 10,000 (positive pressure — leakage flows outward) |
| Demand-mode APF | 50 (negative pressure — not allowed for IDLH) |
| IDLH requirement | Full-facepiece pressure-demand SCBA ≥ 30-min, or SAR + auxiliary SCBA |
| Standby/rescue | Attendant(s) outside + communications + rescue capability (1910.134(g)(3)) |
| Best for | IDLH, oxygen-deficient, and unknown atmospheres |
Self-Contained Breathing Apparatus (SCBA): frequently asked questions
- When is an SCBA required instead of an air-purifying respirator?
- An SCBA (or a combination supplied-air respirator with auxiliary SCBA) is required whenever the atmosphere is immediately dangerous to life or health (IDLH), oxygen-deficient, or of unknown composition — because air-purifying respirators (cartridges/filters) cannot add oxygen and cannot be relied upon against unknown or overwhelming contaminants. For IDLH atmospheres, 29 CFR 1910.134(d)(2) specifically requires a full-facepiece pressure-demand SCBA rated for at least 30 minutes, or a combination SAR with an auxiliary self-contained air supply.
- What is the assigned protection factor of an SCBA?
- A full-facepiece SCBA operated in pressure-demand (positive-pressure) mode has an assigned protection factor of 10,000 — the highest APF in OSHA's Table 1. Operated in demand mode (negative pressure on inhalation), a full-facepiece SCBA has an APF of only 50, and demand-mode SCBAs are not permitted for IDLH atmospheres. This is why IDLH work specifically requires the pressure-demand configuration.
- What is the difference between an SCBA and a supplied-air respirator?
- An SCBA carries its breathing-air cylinder with the wearer, providing independence and mobility but a limited air duration. A supplied-air respirator (SAR/airline) supplies air through a hose from a remote source, allowing long-duration work but tethering the worker to the airline. For IDLH atmospheres, a plain SAR is not sufficient — OSHA requires either a pressure-demand SCBA or a SAR paired with an auxiliary (escape) SCBA so the worker can still escape if the air supply fails.
Related terms
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More OSHA terms
The action an employer takes to fix a cited violation or eliminate a hazard OSHA identified during an inspection. The citation sets an abatement date, the deadline to correct the hazard, and within 10 calendar days after that date the employer must certify to OSHA that the violation was abated. Failure to abate accrues additional penalties of up to $16,550 per day.
Area DirectorThe senior OSHA official in charge of a specific OSHA Area Office — the local unit that runs inspections and enforcement in its geographic territory. The Area Director has the authority to issue citations, propose penalties, hold informal conferences with employers, and approve settlement agreements. When a Compliance Safety and Health Officer (CSHO) completes an inspection, it's the Area Director who ultimately issues the citation.
Bureau of Labor Statistics (BLS)The federal statistical agency within the U.S. Department of Labor that collects, analyzes, and publishes data on workplace injuries, illnesses, and fatalities. BLS conducts the annual Survey of Occupational Injuries and Illnesses (SOII) — compiled from employer OSHA 300 logs — and the Census of Fatal Occupational Injuries (CFOI). SOII data drives OSHA's Site-Specific Targeting (SST) program: establishments whose DART rates significantly exceed their BLS industry average are placed on the SST inspection list.
Competent PersonUnder OSHA's construction standards, a person who is capable of identifying existing and predictable hazards in the surroundings or working conditions, and who has the authorization to take prompt corrective measures to eliminate them. The role requires both knowledge and the authority to act, and is mandated by name in many specific standards — excavations, scaffolds, fall protection, asbestos, and more.
CitationThe formal written notice OSHA issues to an employer after an inspection, describing each alleged violation, the standard cited, the proposed penalty, and the date by which the hazard must be corrected (abated). OSHA must issue a citation with reasonable promptness and no later than six months after the violation occurred.
Closing ConferenceThe meeting at the end of an OSHA inspection where the compliance officer confers with the employer and informally advises them of any apparent violations found. Importantly, the closing conference discusses what was observed and the employer's rights — but it does NOT state final citations or penalties, which come later in the written Citation and Notification of Penalty.
Compliance Officer (CSHO)An OSHA Compliance Safety and Health Officer — the inspector who conducts workplace inspections. A CSHO presents credentials (a photo ID and a serial number), holds the opening conference, performs the walkaround, collects evidence, interviews employees, and recommends citations. CSHOs are either safety specialists or industrial hygienists.
ContestAn employer's formal challenge to an OSHA citation, penalty, or abatement date. To contest, the employer must file a written Notice of Contest with the OSHA Area Director within 15 working days of receiving the Citation and Notification of Penalty. Filing sends the case to the independent Occupational Safety and Health Review Commission (OSHRC); missing the deadline makes the citation a final, un-appealable order.
Sources & verification
- 29 CFR 1910.134(d)(2) (eCFR / OSHA.gov)
- 29 CFR 1910.134(d)(2)(i) (eCFR / OSHA.gov)
- OSHA — 29 CFR 1910.134 (Respiratory Protection)
- OSHA — Respiratory Protection (Safety and Health Topics)
Reviewed by HazComFast against eCFR, OSHA.gov, NIOSH, and the Federal Register. Last reviewed 2026-10-05. This glossary is general information, not legal advice; OSHA State-Plan states (e.g. California, Michigan) may adopt stricter requirements.
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