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 Standard Number
Clarification of Multiple Business Establishments and Covered Employees 2 1904 - Table of Contents, 1904.30
Clarification of a pre-existing injury or illness and recordable events 3 1904 - Table of Contents, 1904.5, 1904.7
Field extraction procedure for isocyanate air samples 1 1910.1000
Specifying decontamination disinfectants and procedures 1 1910.1030(d)(2)
Classification of Combustible Dusts under the Revised Hazard Communication Standard. [1910.1200; 1910.1200(d)] 2 1910.1200(d), 1910.1200
Application of 29 CFR 1910 Subpart S to design of industrial machinery 3 1910 Subpart S, 1910.303(a), 1910.399
Employer Personal Protective Equipment Workplace Hazard Assessment For Footwear 4 1910.132(d)(1), 1910.132(h)(2), 1910.136(a), 1910.136(b)(1)
Weight of the scaffold in determining whether the 4 to 1 factor is satisfied in construction and general industry standards 3 1926.450, 1926.451(a)(1), 1910.27(a)
Interim Guidance on Enforcement of the revised Hazard Communication Standard 3 1910.1200(j)(1), 1910.1200(h), 1910.1200(h)(3)(iv)
Clarification of "as soon as feasible" when conducting post exposure evaluations 1 1910.1030(f)(3)
Regarding the type of hook that is permitted when a crane is used to hoist personnel during underground construction work 2 1926.1431(g)(1), 1926.800(t)(1)(vii)
Expanded Targeting of Establishments Under the Lead NEP 0
List in SDS section 3 when the classification is based on mixture data 1 1910.1200(d)(3)(i)
APF for the combination pressure-demand, full-facepiece SAR with auxiliary SCBA 2 1910.134, 1910.134(d)(3)(i)(A)
Whether a tower crane boom or counterweight may be used over public streets or occupied buildings 2 1926.1425(c), 1926.1417(p)
Unintended disposal of blood-contaminated hospital linens by laundries 1 1910.1030(d)(4)(iv)
Release of employee exposure and medical records to persons other than the employee 6 1910.1020, 1910.1020(a), 1910.1020(b)(1), 1910.1020(c)(3), 1910.1020(e)(2), 1913.10
Labels on ampoules 5mL or smaller 1 1910.1200(f)(1)
Regarding use of compressed gas cylinders while in a horizontal position 1 1926.350(a)(9)
Overhead Crane operations 1 1910.179