OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

November 11, 1975

Mr. Charles A. Della
Assistant Commissioner
Department of Licensing and Regulation
Div. of Labor & Industry - OSH
203 E. Baltimore Street
Baltimore, Maryland 21202

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.



  1. [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.
  2. 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,

Assistant Regional Director
Occupational Safety and Health Administration

[Corrected 05/28/2004]