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
Hierarchy of controls for exposure to air contaminants 1910.1000, 1910.107(d)(9)
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)
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)
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)
Mobile crews must have prompt access to nearby toilet facilities. 1926.51(c)(4), 1926.51(c), 1926.51
Tuberculosis testing procedures for the home health care industry. 1910.134
Protection factors for respirators used in pharmaceutical industry: policy change. 1910.134, 1910.134(d)(3)(i)(A)
Training requirements for employees who perform non-electrical work on electrical equipment. 1910.269(a)(2)(i), 1910.269(a)(2)(ii), 1910.269(x)
Coverage of minor machine-servicing activities under the Lockout/Tagout standard. 1910.147(a)(2)(ii), 1910.147(a)(2)(iii)(A)
Ground fault protection requirements for 120-volt and/or 240-volt circuits. 1926.404(b), 1926.404(b)(1)(i), 1926.404(b)(1)(ii)
Review of Roof Mates' Roofer's Rack, Tool Box, Bracket, and stocker. 1926.250
Training requirements for fire brigade members. 1910.156(c)(3)
OSHA Guidance concerning use of clip on products for ladders to facilitate transport of the ladder or other objects. 1926.1053(b)(4), 1926.1053(b)(3), 1910.23
ANSI Z358.1 guidance for complying with 1910.151(c) citation policy for eyewashes and showers. 1910.151(c)
Clarification of 1910.151 (Medical Services and First Aid). 1910.151, 1910.151(b)