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
Clarification of the terms "hole" versus "unprotected sides or edges." 1926.500, 1926.501(b)(1), 1926.501(b)(4), 1926.32(f)
Fall protection for various lift-devices; restraint, positioning, fall arrest and rescue requirements; maintenance vs. construction examples. 1926.451(g)(1)(vii), 1926.451(g)(4), 1926.453(b)(2)(v), 1926.500, 1926.502(d), 1926.502(d)(20)
Trench shield must extend 18" above excavation walls when below grade. 1926.652(b), 1926.650, 1926.651(j)(2)
Anchoring 2-point suspension scaffolds;criteria for testing anchorages. 1910.66, 1910.28(g)(11), 1926.451(d)(18)
Fall protection requirements for residential construction (STD 3-0.1A). 1926.500, 1926.501, 1926.502, 1926.503
Alloy steel chain slings must not be loaded beyond working load limit. 1926.251(b)(4), 1926.251(a)(2), 1926.550(a)(19)
Tie, guy, and bracing requirements for scaffold systems. 1926.451(a)(1), 1926.451(a)(6), 1926.451(c)(1)(ii), 1926.451(c)(1)(iii), 1926.451(c)(3)
Foundation requirements for scaffolds; competent person qualifications for assessing foundations. 1926.451(c)(1)(iii), 1926.451(c)(2), 1926.451(c)(2)(i), 1926.451(f)(3), 1926.451(f)(7), 1926.450
Acceptable use of warning lines as fall protection for roofers and other trades. 1926.501(b)(10), 1926.501(b)(2), 1926.501(b)(12), 1926.501(b)(13), 1926.502(b)
Scissor lifts are not aerial lifts, are considered scaffolds. 1926.451, 1926.453
Recordability of treatment for hydrofluoric acid burns. 1904.12(c), 1904.12(e)
Trolley equipped bridge cranes are exempted from load indicating device requirement. 1917.46(a)(1)(viii)(A)
Selection of air purifying respirators for gases and vapors with poor warning properties (diisocyanates) 1910.134(d)(3)(iii), 1910.134(d)(1)(i)
Work-related injuries and illnesses that occur in home-based worksites are recordable. 1904.2, 1904.12
Open roof hatches should be protected; grab bars not required at hatch exits. 1910.27(c)(7), 1910.23
Soda acid and inverted foam extinguishers are not approved portable refighting equipment. 1926.150(c)(1)(ix), 1926.150(c)(1)(x)
Evaluation of proposed modifications to the Bureau of Prisons' Lockout/Tagout (LOTO) procedures. 1910.147, 1910.147(e)(3), 1910.333, 1910.333(a)(1), 1910.333(b)(2), 1910.333(b)(2)(v)(C)
Double-walled tanks do not reduce the minimum separation distances for flammable and combustible liquids. 1910.106(f)(3)(i)
"Approval" of flexible corrugated plastic covers and generic circuit breaker panel switch lockouts. 1910.305(b)(2), 1910.147(c)(5), 1910.303(g)(2)(ii)
Numerous injury and illness recordkeeping questions. 1904 - Table of Contents