1926.651(g)(1): Testing Excavation Atmospheres
Where oxygen deficiency (less than 19.5 percent oxygen) or a hazardous atmosphere exists or could reasonably be expected, employers must test the air before employees enter excavations greater than 4 feet (1.22 m) deep. Employers must protect workers with respiratory protection or ventilation, prevent exposure to flammable gas in excess of 20 percent of the lower flammable limit, and retest as often as needed when controls are used.
Key takeaways
- 1926.651(g)(1) is part of OSHA's construction standards (29 CFR Part 1926, Subpart P).
- OSHA cited it 16 times in the last 3 years, in 15 inspections, with $38,807 in current penalties.
- Most citations: PA (3), AR (2), AZ (2).
- Related part: 1926.651(g) Hazardous atmospheres (19 citations).
- Free 5-minute toolbox talk for your crew below.
In this article
What this rule covers
29 CFR 1926.651(g)(1) ("Testing and controls") is one requirement inside 1926.651 Specific excavation requirements, an OSHA construction standard (Part 1926, Subpart P). It includes 4 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
(1) Testing and controls. In addition to the requirements set forth in subparts D and E of this part (29 CFR 1926.50-1926.107) to prevent exposure to harmful levels of atmospheric contaminants and to assure acceptable atmospheric conditions, the following requirements shall apply: 16 citations
(i) Where oxygen deficiency (atmospheres containing less than 19.5 percent oxygen) or a hazardous atmosphere exists or could reasonably be expected to exist, such as in excavations in landfill areas or excavations in areas where hazardous substances are stored nearby, the atmospheres in the excavation shall be tested before employees enter excavations greater than 4 feet (1.22 m) in depth. Open (g)(1)(i) 13 citations
(ii) Adequate precautions shall be taken to prevent employee exposure to atmospheres containing less than 19.5 percent oxygen and other hazardous atmospheres. These precautions include providing proper respiratory protection or ventilation in accordance with subparts D and E of this part respectively. 2 citations
(iii) Adequate precaution shall be taken such as providing ventilation, to prevent employee exposure to an atmosphere containing a concentration of a flammable gas in excess of 20 percent of the lower flammable limit of the gas. Open (g)(1)(iii)
(iv) When controls are used that are intended to reduce the level of atmospheric contaminants to acceptable levels, testing shall be conducted as often as necessary to ensure that the atmosphere remains safe. 1 citations
Source: eCFR, text current as of 2026-10-15. Read all of 1926.651.
Where and how often it was cited
| Year | Citations |
|---|---|
| 2024 | 8 |
| 2025 | 6 |
| 2026 | 2 |
Top states: PA (3), AR (2), AZ (2), TX (2), NJ (2)
Largest penalties
| Employer | Location | Penalty for this rule |
|---|---|---|
| 159103 - S. J. LOUIS CONSTRUCTION, INC. | ROXBORO, NC | $9,930 |
| 159654 - UNITED OF CAROLINAS, INC. | CHARLOTTE, NC | $4,965 |
| HORSESHOE CONSTRUCTION, INC. | ANDREWS, TX | $4,840 |
| LUIS ROLDAN | JONESBORO, AR | $4,839 |
| TRETO CONSTRUCTION, LLC | CASPER, WY | $3,457 |
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A 5-minute crew talk on 1926.651(g)(1), plus alerts when this rule changes. Free.
OSHA interpretation letters
Related parts of this rule
- 1926.651(g) Hazardous atmospheres 19 citations
- 1926.651(g)(1)(i) 13 citations
- 1926.651(g)(2)(i) 3 citations
- 1926.651(g)(2) Emergency rescue equipment 3 citations
- 1926.651(g)(2)(ii)
- 1926.651(g)(1)(iii)
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Frequently asked questions
When must the air in an excavation be tested?
Before employees enter excavations greater than 4 feet deep where oxygen deficiency or a hazardous atmosphere exists or could reasonably be expected to exist.
What counts as oxygen deficient?
Atmospheres containing less than 19.5 percent oxygen.
What is the flammable gas limit?
Precautions must prevent exposure to flammable gas in excess of 20 percent of the lower flammable limit.
About this page
Sources
- 29 CFR 1926.651 (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.