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
When to use qualitative or quantitative fit testing; storing SCBAs on fire trucks. 1910.134(f), 1910.134(h)(2), 1910.134 App A
Clarification of the medical evaluation provisions of the revised respiratory protection standard. 1910.134(e)
Two-in/two-out rule for interior structural fire fighting. 1910.134(g)(4)
Format for Material Safety Data Sheets (MSDSs). 1910.1200, 1926.59
Exposure limits and symptoms of Hydroquinone, acetic acid, and glutaraldehyde exposure. 1910.1000
Assessing hazards to select eye and respiratory protection. 1910.132(d), 1910.133, 1910.134(d)
Reporting threshold for non-carcinogenic mixtures on MSDSs. 1910.1200(d)
Policy for descent control devices used in construction. 1926.501(a)(2), 1926.502(b), 1926.20(b)(4), 1926.21(b)(2)
Requirements for back-up alarms on construction vehicles. 1926.601(b)(4), 1926.602(a)(9)
Longshoring: requirement, selection, and payment for protective footwear. 1917.94, 1918.104
Decontamination of SCBA second stage regulators. 1910.134(h)(1)(iii)
Apparel requirements for line-clearence tree-trimmers 1910.269
Successor liability for employee exposure and medical records. 1910.1020(c)(7), 1910.1020(h)
Worker exposure to tobacco smoke. 1910.1000
Application of 1910.147 to the change out of a grinding wheel. 1910.147(a)(2)(ii), 1910.147(a)(2)(iii)(A)
Validity of Illustrations in the Confined Space Standard Appendices. 1910.146 App C, 1910.146 App D, 1910.146 App E
Health care professional's discretion regarding medical evaluations and exams. 1910.134(e)
Conduct of respiratory protection medical evaluations by medical technicians. 1910.134, 1910.134(e)(2)(i)
Questions and answers regarding the respiratory protection standard 1910.134
Difference between "grain elevators" and "grain handling facilities" 1910.272(j)