1926.1204(c)(4): Purging and Ventilating Permit Spaces
Employers must purge, inert, flush or ventilate a permit space as needed to eliminate or control atmospheric hazards. If the atmosphere cannot be reduced below 10 percent LFL, entry is allowed only if the space is inerted to make the whole atmosphere non-combustible, employees use PPE for other atmospheric hazards, and all physical hazards are eliminated or isolated.
Key takeaways
- 1926.1204(c)(4) is part of OSHA's construction standards (29 CFR Part 1926, Subpart AA).
- OSHA cited it 4 times in the last 3 years, in 4 inspections, with $16,550 in current penalties.
- 1 death is linked to inspections that cited this rule.
- Related part: 1926.1204(c) (27 citations).
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1926.1204(c)(4) is one requirement inside 1926.1204 Permit-required confined space program, an OSHA construction standard (Part 1926, Subpart AA). 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) Purging, inerting, flushing, or ventilating the permit space as necessary to eliminate or control atmospheric hazards; 4 citations
When an employer is unable to reduce the atmosphere below 10 percent LFL, the employer may only enter if the employer inerts the space so as to render the entire atmosphere in the space non-combustible, and the employees use PPE to address any other atmospheric hazards (such as oxygen deficiency), and the employer eliminates or isolates all physical hazards in the space.
Source: eCFR, text current as of 2026-10-15. Read all of 1926.1204.
Injuries linked to this rule
1 death is linked to inspections where OSHA cited 1926.1204(c)(4).
At 5:00 p.m. on July 13, 2024, Employee #1 entered a manhole to tape piping in preparation for pouring concrete inverts. Shortly after entry, a coworker, stationed topside, observed that Employee #1 appeared pale and was sweating profusely. When asked, Employee #1 indicated difficulty breathing.…
Where and how often it was cited
Free toolbox talk
A 5-minute crew talk on 1926.1204(c)(4), plus alerts when this rule changes. Free.
OSHA interpretation letters
None exist. OSHA has not published a letter of interpretation for 1926.1204(c)(4).
Related parts of this rule
- 1926.1204(c) 27 citations
- 1926.1204(c)(2) 2 citations
- 1926.1204(c)(3) 2 citations
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Frequently asked questions
What methods can control atmospheric hazards in a permit space?
Purging, inerting, flushing, or ventilating the space as necessary.
What if the atmosphere cannot be brought below 10 percent LFL?
Entry is allowed only if the space is inerted to be non-combustible, PPE is used for other atmospheric hazards, and all physical hazards are eliminated or isolated.
Does inerting create other hazards?
The rule notes PPE must address other atmospheric hazards, such as oxygen deficiency.
About this page
Sources
- 29 CFR 1926.1204 (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.