Letters of Interpretation

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. Each 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.

These letters of interpretation and the standards they address may not apply to OSHA State Plans. State Plans are required to have standards and enforcement programs that are at least as effective as OSHA's and may have different or additional requirements. Please see OSHA-approved State Plans for more information.

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Date Title Standard Number
Atmospheric Testing required for confined space entry. 1910.146(d)(5)(ii), 1910.146(d)(5)(iii)
A confined space atmosphere above a PEL is not always a "hazardous atmosphere". 1910.146(b)
Applicability of 1910.146 to fall hazards into pits. 1910.146, 1910.146(b), 1910 Subpart D
Validity of Illustrations in the Confined Space Standard Appendices. 1910.146 App C, 1910.146 App D, 1910.146 App E
Requirements for posting signs for PRCSs. 1910.146(c)(2)
A chest freezer is not considered a PRCS. 1910.146(c)(1)
Response to fires in permit-required confined spaces (PRCS). 1910.146, 1910.156(c)(4)
OSHA's policy concerning repeat violations and requirements for PRCS sign posting. 1910.146(c)(2)
Permit-Required Confined Spaces 1910.146
Permit-Required Confined Spaces Standard. 1910.146
Electronic monitoring system for complying with the confined space standard. 1910.146
OSHA Instruction CPL 2-2.53, Guidelines for First Aid Training Programs. 1910.151(b), 1926.50(c), 1910.266(i)(7), 1910.269(b), 1910.268(c)(3), 1910.142(k)(2), 1926.950(e), 1910.146(k)(2)(iii), 1926.605(d)(1), 1910.410(a)(3), 1915.12(e)(1)(iv)
Introduction of electrical welding equipment into a non-permit confined space. 1910.146, 1910.252, 1910.252(a)(4)(i), 1910.252(b)(4)(i), 1910.252(b)(4)(vii), 1910.252(c)(4), 1910.252(c)(9), 1910.252(c)(10), 1910 Subpart Q
Hard-line communication equipment for use in the PRCS standard. 1910.146
Recording of atmospheric test results. 1910.146
A possible conflict between exposure record retention. 1910.146, 1910.1020
Citations which were issued to Heinz, U.S.A. 1910.119, 1910.146
Permit-Required Confined Spaces and Lockout/Tagout. 1910.146, 1910.147
Voluntary safety and health audits under the Occupational Safety and Health Act 1910.1020, 1910.95, 1910.119, 1910.120, 1910.132, 1910.134, 1910.137, 1910.146, 1910.147, 1910.272, 1910.1025, 1926.20
Entry into a confined space when the lower flammable limit is greater than ten percent. 1910.134, 1910.146