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Tunnel ventilation at atmospheric and compressed pressure
Summary A state labor official asked how two tunnel ventilation provisions applied. OSHA said the 200-cubic-foot-per-minute-per-worker rule covered atmospheric-pressure tunnel work, not compressed-air work. It read the compressed-air provision as requiring at least 30 cubic feet per minute per person.
Document
Federal opinion letter
Agency
Occupational Safety and Health Administration (OSHA)
Document number
1975-11-11
Date issued
November 11, 1975
Status
Active
Status last verified October 10, 2026
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About this page: The full text below is the official document from Occupational Safety and Health Administration (OSHA). Ezel adds the plain-English summary and tracks the document's status. The official source linked on this page is authoritative for any reliance.
November 11, 1975
Mr. Charles A. Della
Assistant Commissioner
Department of Licensing and Regulation
[Recipient address omitted]
Dear Mr. Della:
In response to your letter of October 21, 1975 concerning 29 CFR 1926.800(c)(2)(v) and 29 CFR 1926.803(i)(1) we concur with the interpretations indicated in your letter.
- [29 CFR 1926.800(k)(2)]: Requires the supply of fresh air to be not less than 200 cubic feet per minute for each employee in a tunnel work area where operations are conducted at atmospheric pressure. This standard does not apply to compressed air work.
- 29 CFR 1926.803(i)(1): The sentence "Ventilating air shall be not less than 30 cubic feet minute." Means not less than 30 cubic feet minute man during compressed air work.
Sincerely yours,
DAVID H. RHONE
Assistant Regional Director
Occupational Safety and Health Administration
[Corrected 05/28/2004]
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