1910.134(d)(3): Respirators for Non-IDLH Atmospheres
Employers must provide a respirator that is adequate to protect the worker's health under routine and reasonably foreseeable emergency situations in atmospheres that are not IDLH. Employers must use the assigned protection factors in Table 1 to pick a respirator that meets or exceeds the needed protection, including for combination respirators.
Key takeaways
- 1910.134(d)(3) is part of OSHA's general industry standards (29 CFR Part 1910, Subpart I).
- OSHA cited it 86 times in the last 3 years, in 84 inspections, with $187,400 in current penalties.
- 1 death is linked to inspections that cited this rule.
- Most citations: OR (8), NY (7), TN (7).
- Related part: 1910.134(d) Selection of respirators (573 citations).
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In this article
What this rule covers
29 CFR 1910.134(d)(3) ("Respirators for atmospheres that are not IDLH") is one requirement inside 1910.134 Respiratory protection, an OSHA general industry standard (Part 1910, Subpart I). It includes 11 sub-paragraphs. The official text below is copied word for word from the Electronic Code of Federal Regulations (eCFR). The numbers, injury cases and training on this page show how OSHA enforces it on real job sites.
Official text
(3) Respirators for atmospheres that are not IDLH. 86 citations
(i) The employer shall provide a respirator that is adequate 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. Open (d)(3)(i) 28 citations
(A) Assigned Protection Factors (APFs). Employers must use the assigned protection factors listed in Table 1 to select a respirator that meets or exceeds the required level of employee protection. When using a combination respirator (e.g., airline respirators with an air-purifying filter), employers must ensure that the assigned protection factor is appropriate to the mode of operation in which the respirator is being used. Open (d)(3)(i)(a) 3 citations
| Type of respirator 1 2 | Quarter mask | Half mask | Full facepiece | Helmet/hood | Loose-fitting facepiece |
|---|---|---|---|---|---|
| 1. Air-Purifying Respirator | 5 | 3 10 | 50 | ||
| 2. Powered Air-Purifying Respirator (PAPR) | 50 | 1,000 | 4 25/1,000 | 25 | |
| 3. Supplied-Air Respirator (SAR) or Airline Respirator | |||||
| • Demand mode | 10 | 50 | |||
| • Continuous flow mode | 50 | 1,000 | 4 25/1,000 | 25 | |
| • Pressure-demand or other positive-pressure mode | 50 | 1,000 | |||
| 4. Self-Contained Breathing Apparatus (SCBA) | |||||
| • Demand mode | 10 | 50 | 50 | ||
| • Pressure-demand or other positive-pressure mode (e.g., open/closed circuit) | 10,000 | 10,000 | |||
| Notes: | |||||
| 1 Employers may select respirators assigned for use in higher workplace concentrations of a hazardous substance for use at lower concentrations of that substance, or when required respirator use is independent of concentration. | |||||
| 2 The assigned protection factors in Table 1 are only effective when the employer implements a continuing, effective respirator program as required by this section (29 CFR 1910.134), including training, fit testing, maintenance, and use requirements. | |||||
| 3 This APF category includes filtering facepieces, and half masks with elastomeric facepieces. | |||||
| 4 The employer must have evidence provided by the respirator manufacturer that testing of these respirators demonstrates performance at a level of protection of 1,000 or greater to receive an APF of 1,000. This level of performance can best be demonstrated by performing a WPF or SWPF study or equivalent testing. Absent such testing, all other PAPRs and SARs with helmets/hoods are to be treated as loose-fitting facepiece respirators, and receive an APF of 25. | |||||
| 5 These APFs do not apply to respirators used solely for escape. For escape respirators used in association with specific substances covered by 29 CFR 1910 subpart Z, employers must refer to the appropriate substance-specific standards in that subpart. Escape respirators for other IDLH atmospheres are specified by 29 CFR 1910.134 (d)(2)(ii). | |||||
(B) Maximum Use Concentration (MUC). Open (d)(3)(i)(b) 16 citations
(1) The employer must select a respirator for employee use that maintains the employee's exposure to the hazardous substance, when measured outside the respirator, at or below the MUC.
(2) Employers must not apply MUCs to conditions that are immediately dangerous to life or health (IDLH); instead, they must use respirators listed for IDLH conditions in paragraph (d)(2) of this standard.
(3) When the calculated MUC exceeds the IDLH level for a hazardous substance, or the performance limits of the cartridge or canister, then employers must set the maximum MUC at that lower limit.
(ii) The respirator selected shall be appropriate for the chemical state and physical form of the contaminant. 4 citations
(iii) For protection against gases and vapors, the employer shall provide: Open (d)(3)(iii) 53 citations
(A) An atmosphere-supplying respirator, or
(B) An air-purifying respirator, provided that: Open (d)(3)(iii)(b) 52 citations
(1) The respirator is equipped with an end-of-service-life indicator (ESLI) certified by NIOSH for the contaminant; or
(2) If there is no ESLI appropriate for conditions in the employer's workplace, the employer implements 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 shall 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.
(iv) For protection against particulates, the employer shall provide: Open (d)(3)(iv) 1 citations
(A) An atmosphere-supplying respirator; or
(B) 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 Open (d)(3)(iv)(b)
(C) 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.
Table I—Assigned Protection Factors [Reserved]
| Altitude (ft.) | Oxygen deficient Atmospheres (% 02) for which the employer may rely on atmosphere-supplying respirators |
|---|---|
| Less than 3,001 | 16.0-19.5 |
| 3,001-4,000 | 16.4-19.5 |
| 4,001-5,000 | 17.1-19.5 |
| 5,001-6,000 | 17.8-19.5 |
| 6,001-7,000 | 18.5-19.5 |
| 7,001-8,000 1 | 19.3-19.5. |
| 1 Above 8,000 feet the exception does not apply. Oxygen-enriched breathing air must be supplied above 14,000 feet. | |
Source: eCFR, text current as of 2026-10-15. Read all of 1910.134.
Injuries linked to this rule
1 death is linked to inspections where OSHA cited 1910.134(d)(3).
At approximately 9:34 a.m. on January 10, 2025, an employee was directed to enter a 23,737-gallon rail tank car containing residues of PCBs and transformer oil to obtain wipe samples of the interior surfaces. The rail tank car was a permit-required confined space. The employee…
Where and how often it was cited
| Year | Citations |
|---|---|
| 2024 | 32 |
| 2025 | 29 |
| 2026 | 25 |
Top states: OR (8), NY (7), TN (7), MD (6), WI (5)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| CLEAN HARBORS ENVIRONMENTAL SERVICES INC. | TWINSBURG, OH | $16,550 |
| CAVCO INDUSTRIES INC. | AUSTIN, TX | $13,828 |
| QUVA PHARMA, INC | BLOOMSBURY, NJ | $13,828 |
| TACTICAL CLEANING ACQUISITION, LLC | HARWOOD, TX | $13,240 |
| ROCK-IT NATURAL STONE | WISTER, OK | $12,500 |
Free toolbox talk
A 5-minute crew talk on 1910.134(d)(3), plus alerts when this rule changes. Free.
OSHA interpretation letters
- Use of powered-air purifying respirators (PAPR) for welding operations and assigned protection factor (2021-04-15)
- Hooded versus tight-fitting respirators when complying with the Asbestos Standard (2017-07-18)
- APF for the combination pressure-demand, full-facepiece SAR with auxiliary SCBA (2013-11-04)
- Protection factors for respirators used in pharmaceutical industry: policy change. (2002-05-30)
- Selection of air purifying respirators for gases and vapors with poor warning properties (diisocyanates) (2000-07-18)
- The use of particulate filters and respirators. (1997-05-05)
- Use of Chemical Cartridge Respirators for Protection Against Mercury Vapor (1985-11-15)
Related parts of this rule
- 1910.134(d) Selection of respirators 573 citations
- 1910.134(d)(1) General requirements 477 citations
- 1910.134(d)(1)(iii) 312 citations
- 1910.134(d)(1)(i) 88 citations
- 1910.134(d)(1)(ii) 74 citations
- 1910.134(d)(3)(iii) 53 citations
- 1910.134(d)(3)(iii)(B) 52 citations
- 1910.134(d)(3)(i) 28 citations
- 1910.134(d)(3)(i)(B) Maximum Use Concentration (MUC) 16 citations
- 1910.134(d)(2) Respirators for IDLH atmospheres 10 citations
- 1910.134(d)(2)(i) 9 citations
- 1910.134(d)(3)(i)(A) Assigned Protection Factors (APFs) 3 citations
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Frequently asked questions
What does non-IDLH mean here?
Atmospheres that are not immediately dangerous to life or health; this paragraph covers respirators for those conditions.
How do employers choose the level of protection?
They must use the assigned protection factors (APFs) in Table 1 to select a respirator that meets or exceeds the required level of protection.
Do APFs work on their own?
No. Table 1 notes that APFs are only effective when the employer runs a continuing, effective respirator program including training, fit testing, maintenance and use.
About this page
Sources
- 29 CFR 1910.134 (eCFR), text current as of 2026-10-15
- U.S. Department of Labor enforcement data: OSHA inspections, citations and accident records, copied nightly; data as of 2026-10-20
3-year window. Federal OSHA only; state-plan rules are not counted. Plain-language text is a summary, not legal advice; the official text controls. Black Belt Safety is not part of OSHA or the Department of Labor.