1910.134(g)(4): Two In, Two Out for Interior Firefighting
In interior structural fires, the employer must ensure at least two employees enter the IDLH atmosphere and stay in visual or voice contact at all times, at least two employees stay outside, and all interior firefighters use SCBAs. One outside person may also hold another role if able to assist or rescue safely. Rescue before the full team assembles is not prohibited.
Key takeaways
- 1910.134(g)(4) is part of OSHA's general industry standards (29 CFR Part 1910, Subpart I).
- OSHA cited it 19 times in the last 3 years, in 14 inspections, with $57,236 in current penalties.
- Most citations: NY (3), IL (3), OR (3).
- Related part: 1910.134(g) Use of respirators (678 citations).
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1910.134(g)(4) ("Procedures for interior structural firefighting") is one requirement inside 1910.134 Respiratory protection, an OSHA general industry standard (Part 1910, Subpart I). It includes 3 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
(4) Procedures for interior structural firefighting. In addition to the requirements set forth under paragraph (g)(3), in interior structural fires, the employer shall ensure that: 19 citations
(i) At least two employees enter the IDLH atmosphere and remain in visual or voice contact with one another at all times; 7 citations
(ii) At least two employees are located outside the IDLH atmosphere; and 6 citations
(iii) All employees engaged in interior structural firefighting use SCBAs. 3 citations
One of the two individuals located outside the IDLH atmosphere may be assigned to an additional role, such as incident commander in charge of the emergency or safety officer, so long as this individual is able to perform assistance or rescue activities without jeopardizing the safety or health of any firefighter working at the incident.
Nothing in this section is meant to preclude firefighters from performing emergency rescue activities before an entire team has assembled.
Source: eCFR, text current as of 2026-10-15. Read all of 1910.134.
Where and how often it was cited
| Year | Citations |
|---|---|
| 2024 | 10 |
| 2025 | 7 |
| 2026 | 2 |
Top states: NY (3), IL (3), OR (3), NJ (2), MD (2)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| CITY OF CHICAGO - FIRE DEPT. - BATTALION 11 | CHICAGO, IL | $20,000 |
| CITY OF CHICAGO - FIRE DEPARTMENT - BATTALION 9 | CHICAGO, IL | $10,000 |
| LORD CORPORATION | SAEGERTOWN, PA | $9,000 |
| NEWARK FIRE DEPARTMENT | NEWARK, NJ | $7,000 |
| JERSEY CITY FIRE DEPARTMENT, CONSOLIDATED FIRE HOUSE | JERSEY CITY, NJ | $7,000 |
Free toolbox talk
A 5-minute crew talk on 1910.134(g)(4), plus alerts when this rule changes. Free.
OSHA interpretation letters
- Classification of fires; respiratory protection to extinguish fires. (2002-07-08)
- Complying with the "two-in, two-out" policy for interior structural firefighting. (1999-03-12)
- Respiratory protecton standard two-in/two-out policy. (1998-12-15)
- Two-in/two-out rule for interior structural fire fighting. (1998-11-13)
- Two-in/two-out procedure in firefighting/IDLH environments. (1998-04-29)
- The interpretation of the OSHA standards 1910.134 and 1910.156 which address the requirements for workers who are actively conducting operations in atmospheres that are immediately dangerous to life and health. (1995-11-01)
Related parts of this rule
- 1910.134(g) Use of respirators 678 citations
- 1910.134(g)(1) Facepiece seal protection 639 citations
- 1910.134(g)(1)(i) 605 citations
- 1910.134(g)(1)(i)(A) 523 citations
- 1910.134(g)(1)(iii) 28 citations
- 1910.134(g)(1)(i)(B) 23 citations
- 1910.134(g)(3) Procedures for IDLH atmospheres 14 citations
- 1910.134(g)(1)(ii) 6 citations
Get your crew competent
Trainers on Black Belt Safety: Marc Harvey, Dana Reyes
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Frequently asked questions
How many firefighters must be outside?
At least two employees must be located outside the IDLH atmosphere.
What breathing protection is required?
All employees engaged in interior structural firefighting must use SCBAs.
Can an outside person be incident commander?
Yes, one of the two may have an additional role, as long as they can perform assistance or rescue without jeopardizing any firefighter's safety.
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.