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.

October 16, 1998

John M. Dobby, CIH, CSP
Boelter & Yates
1300 Higgins Road, Suite 301
Park Ridge, IL 60068-5772

Dear Mr. Dobby:

Thank you for your letter of September 4, concerning Appendices C, D1, D2, and E of the Occupational Safety and Health Administration's (OSHA) Permit-Required Confined Spaces (PRCS) standard 29 CFR 1910.146 and your suggestion to revise the appendices.

We agree with you that the values reflected in these illustrations differ from the values for the ceiling or threshold quantities found in Subpart Z of 29 CFR 1910. The intent of these appendices is to illustrate the content of the respective standard paragraphs to which they apply.

Your letter stated that these values could be misinterpreted. Based on the lack of other comments on the issue, we believe that the vast majority of readers of the standard understand that these illustrations are just that, illustrative, and not meant to reflect the mandatory values of other standards.

OSHA, at the present time, does not have any Federal Register notices planned which can address positive and negative aspects of your recommendations. However, a copy of your letter will be forwarded to the Directorate of Safety Standards Programs for their files on this standard.

If you have further questions relating to this letter please contact Mr. Don Kallstrom of the Office of General Industry Compliance Assistance, (202) 693-1850, or the Directorate of Safety Standards Programs at (202) 219-7216.


Richard Fairfax, Acting Director
Directorate of Compliance Programs