1910.134(d)(3)(i): Choosing an Adequate Respirator
Employers must provide a respirator that is adequate to protect the employee's health and meet all other OSHA requirements, in routine work and reasonably foreseeable emergencies. They must use the assigned protection factors in Table 1 to choose a respirator that meets or exceeds the needed protection, and for combination respirators the factor must fit the mode in which it is used.
Key takeaways
- 1910.134(d)(3)(i) is part of OSHA's general industry standards (29 CFR Part 1910, Subpart I).
- OSHA cited it 28 times in the last 3 years, in 28 inspections, with $104,608 in current penalties.
- 1 death is linked to inspections that cited this rule.
- Most citations: TN (4), NY (4), MD (3).
- 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)(i) is one requirement inside 1910.134 Respiratory protection, an OSHA general industry standard (Part 1910, Subpart I). It includes 2 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
(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. 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.
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)(i).
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 | 11 |
| 2025 | 12 |
| 2026 | 5 |
Top states: TN (4), NY (4), MD (3), NV (2), OH (2)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| CLEAN HARBORS ENVIRONMENTAL SERVICES INC. | TWINSBURG, OH | $16,550 |
| ROCK-IT NATURAL STONE | WISTER, OK | $12,500 |
| DUBOIS CHEMICALS, INC | SHARONVILLE, OH | $9,678 |
| MID-CONTINENTAL RESTORATION CO., INC. | OKLAHOMA CITY, OK | $9,344 |
| GA TELESIS LANDING GEAR SERVICES, LLC | MIAMI, FL | $9,268 |
Free toolbox talk
A 5-minute crew talk on 1910.134(d)(3)(i), 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)
- 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)
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)(3) Respirators for atmospheres that are not IDLH 86 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)(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 respirator must the employer provide?
One adequate to protect the employee's health under routine and reasonably foreseeable emergency situations.
How are respirators selected?
Using the assigned protection factors in Table 1 to choose one that meets or exceeds the required level of protection.
Do assigned protection factors always apply?
The factors in Table 1 are only effective when the employer runs a continuing, effective respirator program, including training, fit testing, maintenance and use requirements.
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.