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
Applicability of OSHA's ladder standard, 29 CFR Part 1926 Subpart X to a particular situation. 1926.1050, 1926.1053(a)(1), 1926.1053(a)(1)(ii)
Site-Specific Targeting: Clarification. 1903 - Table of Contents
Steel erection standard requirements concerning installation of perimeter safety cable. 1926.502, 1926.760(d), 1926.760(d)(3), 1926.760(a)(2)
Request for guidance on saws operated on "cut-climb/reverse-rotation" mode 1910.213(c)(3), 1910.213(f)(2)
Classification of fires; respiratory protection to extinguish fires. 1910.134(b), 1910.134(g)(4), 1910.155(c)(26), 1910.156(a)(2)
Use of verification tags for lockout. 1910.147, 1910.147(c)(5), 1910.333
Powered industrial truck addition/modification approval and marking requirements 1910.178(a)(4), 1910.178(a)(5)
Application of steel erection standards to precast concrete and lift slab structures. 1926.750(a), 1926.750, 1926.750(b)(1), 1926.750(b)(2)
Requirements for crucibles and other below-the-hook lifting devices. 1910.179
Acceptability of aluminum hard hats. 1910.135(b)
Use of mobile scaffolds with casters in the unlocked position; moving the mobile scaffold without dismounting. 1926.452(w)(2), 1926.452(w)(3), 1926.452(w)(6)(iv), 1926.452(w)(6), 1926.452(w)(6)(i), 1926.451(f)(1), 1926.451(a)(1)
Hierarchy of controls for exposure to air contaminants 1910.1000, 1910.107(d)(9)
Guidance on approval requirments for general circuit breaker panel swich lockouts in General Industry. 1910.305(b)(2), 1910.147(c)(5), 1910.303(g)(2)(ii)
Clarification concerning fall protection and vertical walled trenches with depth of 6 feet or greater and use of controlled access zones. 1926.501(b)(7), 1926.501(b)(7)(i), 1926.501(b)(7)(ii), 1926.501(b)(2), 1926.501(b)(9), 1926.502(k), 1926.651(f)
Scenario of a tool change process applied to Lock Out/Tag Out's service and maintenance exception. 1910.147(a)(2)(ii)
Flexible corrugated plastic covers for temporary use to cover live electric parts in switch and panel boxes. 1926.405(d), 1926.305(d)
Custom-designed lifting accessories must be proof-tested and marked before being deployed for use and after repair or replacement. 1926.251(a)(4)
Re-use of blood tube holders. 1910.1030(d)(2)(vii)(A)
Fit testing and medical monitoring requirements for wearers of filtering facepiece respirators. 1910.134(f)(2), 1910.134(e)(1), 1910.134(g)(1)(iii)
Safety Standards regulating the stability of mobile scaffolds, scissor lifts, and aerial work platforms. 1926.452(w), 1926.453, 1926.452(w)(6), 1926.452(w)(5), 1926.453(b)(2)(viii), 1926.453(a)(1), 1926.453(a)(2)