1910.146(c)(5)(ii)(C): Pre-Entry Atmosphere Testing
Before an employee enters the space, employers must test the internal atmosphere with a calibrated direct-reading instrument for oxygen, then flammable gases and vapors, then potential toxic air contaminants, in that order. Any employee who enters, or their authorized representative, must be given the chance to observe the testing.
Key takeaways
- 1910.146(c)(5)(ii)(C) is part of OSHA's general industry standards (29 CFR Part 1910, Subpart J).
- OSHA cited it 24 times in the last 3 years, in 24 inspections, with $104,811 in current penalties.
- 1 death is linked to inspections that cited this rule.
- Most citations: NY (5), TX (3), TN (2).
- Related part: 1910.146(c) General requirements (1,090 citations).
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1910.146(c)(5)(ii)(C) is one requirement inside 1910.146 Permit-required confined spaces, an OSHA general industry standard (Part 1910, Subpart J). 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
(C) Before an employee enters the space, the internal atmosphere shall be tested, with a calibrated direct-reading instrument, for oxygen content, for flammable gases and vapors, and for potential toxic air contaminants, in that order. Any employee who enters the space, or that employee's authorized representative, shall be provided an opportunity to observe the pre-entry testing required by this paragraph. 24 citations
Source: eCFR, text current as of 2026-10-15. Read all of 1910.146.
Injuries linked to this rule
1 death is linked to inspections where OSHA cited 1910.146(c)(5)(ii)(C).
At 10:20 a.m. on August 1, 2024, an employee was working inside a transformer. The employee entered a permitted confined space filled with nitrogen and asphyxiated due to overexposure to nitrogen. The employee was killed.
Where and how often it was cited
| Year | Citations |
|---|---|
| 2023 | 3 |
| 2024 | 5 |
| 2025 | 11 |
| 2026 | 5 |
Top states: NY (5), TX (3), TN (2), NC (2), AK (1)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| MEYERROSE & COMPANY, INC. | KEARNY, NJ | $16,552 |
| HITACHI ENERGY USA, INC. | CRYSTAL SPRINGS, MS | $16,550 |
| MAJESTIC STEEL USA, INC. | HOUSTON, TX | $16,131 |
| ATHENS FOODS, INC. | BROOK PARK, OH | $11,916 |
| BUILDING MATERIALS MANUFACTURING LLC | WIND GAP, PA | $10,000 |
Free toolbox talk
A 5-minute crew talk on 1910.146(c)(5)(ii)(C), plus alerts when this rule changes. Free.
OSHA interpretation letters
None exist. OSHA has not published a letter of interpretation for 1910.146(c)(5)(ii)(C).
Related parts of this rule
- 1910.146(c) General requirements 1,090 citations
- 1910.146(c)(2) 359 citations
- 1910.146(c)(1) 293 citations
- 1910.146(c)(4) 253 citations
- 1910.146(c)(5) 63 citations
- 1910.146(c)(5)(ii) 59 citations
- 1910.146(c)(7) 50 citations
- 1910.146(c)(3) 40 citations
- 1910.146(c)(7)(iii) 33 citations
- 1910.146(c)(8) 19 citations
- 1910.146(c)(9) 11 citations
- 1910.146(c)(5)(ii)(H) 10 citations
Get your crew competent
Trainers on Black Belt Safety: Marc Harvey, Dana Reyes
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Frequently asked questions
What order are tests done in?
Oxygen content, flammable gases and vapors, then potential toxic air contaminants.
What instrument is used?
A calibrated direct-reading instrument.
Can the entrant watch the testing?
Yes, the entrant or their authorized representative must be given the opportunity to observe.
About this page
Sources
- 29 CFR 1910.146 (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.