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
General concerns in the Construction Industry. 1926 - Table of Contents
Clarification of OSHA's Hazard Communication Standard with regards to the carcinogenicity of wood dust 1910.1200
Clarification on OSHA's policy regarding Immediately Dangerous to Life and Health since NIOSH has lowered several IDLH levels. 1910.134(d), 1910.134(d)(2)
MSDSs for chemicals purchased prior to 1985. 1910.1200
8-hour total weight average (TWA) permissible exposure limit (PEL). 1910.1000, 1910.1001, 1910.1017, 1910.1018, 1910.1025, 1910.1027, 1910.1028, 1910.1029, 1910.1043, 1910.1044, 1910.1045, 1910.1047, 1910.1048, 1910.1050, 1910.1051, 1910.1052
Interpretation of the provision of the Permit Required Confined Spaces Standard 1910.146
Clarification of the OSHA reference to welding rods in a March 21, Memorandum to Regional Administrators. 1910.1200
Interpretation of a lifting device and its ability to act as a rescue retrieval system as it applies to OSHA's permit required confined space entry standard. 1910.146
Letter of compliance for a ladder stand-off with handrails device. 1926.1053
The use of solvent aerosol for controlling exposure to asbestos during automotive brake repair. 1910.1001(f)(3)
The appropriate method for assessing hydrogen sulfide peak exposure levels 1910.1000
The Lockout/Tagout Standard. 1910.147
Interpretation of the Process Safety Management of Highly Hazardous Chemicals Standard. 1910.119, 1910.147
Fall Protection Standards. 1926.501(b)(5)
Ironworkers involved in steel erection activities must be protected from falls. 1926.501
Fall Protection. 1926.502(k)
No scaffold shall be erected, moved, dismantled, or altered except under the supervision of competent persons. 1926.20, 1926.451
Requesting OSHA to comment on the Scaffold Industry Association testing procedures to determine fall arrest tie-off locations. 1926 Subpart L
Clarification of the Process Safety Management standard with regard to material and energy balances. 1910.119
Review of a new product, "The Safety Boot". 1926.500, 1926.501, 1926.502, 1926.503