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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How to Request a Letter of Interpretation

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Date Title Standard Number
What constitutes an emergency response or incidental release of anhydrous ammonia 1910.38, 1910.119, 1910.120, 1910.120(q), 1910.1200
Emergency action plan procedures when employees discover an unknown biohazard. 1910.38
Initial and annual refresher HAZWOPER training requirements for employees exposed to health hazards or hazardous substances at TSD facilities. 1910.38, 1910.120(a)(1)(iv), 1910.120(e), 1910.120(p), 1910.120(p)(7), 1910.120(p)(8)(iii)
PSM compliance for ammonia refrigeration systems. 1910.38, 1910.119, 1910.119(d)(3)(i), 1910.119(d)(3)(ii), 1910.119(e)(3), 1910.119(j)(6)(i), 1910.119(j)(6)(ii), 1910.119(k)(2), 1910.119(l)(2)(i), 1910.119(l)(4), 1910.119(l)(5), 1910.119(m)(3), 1910.119(o)(1), 1910.120, 1910.134, 1910.147, 1910.147(c)(4)(ii)
Application of OSHA standards to escape and protection of employees from threats associated with terrorist actions. 1910.120(q), 1910.38
Requirements for emergency response and planning under the Process Safety Management Standard. 1910.38(a), 1910.38(c)(3), 1910.119(n), 1910.120(a), 1910.120(q), 1910.120(q)(1), 1910.120(q)(6)(ii), 1910.120(q)(6)(iii)
Requirements for electrical wiring in supply and disposal function warehouses containing hazardous materials. 1910.38, 1910.106(d), 1910.106(e)(7), 1910.106(e)(7)(i)
The airflow rate required for a spray painting area. 1910.94(c), 1910.107, 1910.38, 1910.39
Training provisions of OSHA's HAZWOPER standard. 1910.38, 1910.120
Corrugated storage and plastic returnable packaging storage. 1910 - Table of Contents, 1910.38, 1910.176
Employee Emergency Plans and Fire Prevention standard;Portable Fire Extinguishers standard; Electrical Power Generation, Transmission and Distribution standard. 1910.22, 1910.38, 1910.157, 1910.180, 1910.269
The application of the OSHA HAZWOPER standard to employers of transfer facilities. 1910.38, 1910.120, 1910.120(a)(2)(iii), 1910.120(p), 1910.120(p)(8), 1910.120(p)(1)
NFPA, Life Safety Code and Means of Egress. 1910 Subpart E, 1910.35, 1910.38
Hierarchy of air contaminant controls; respirators for emergencies. 1910.134(a)(1), 1910.134(d), 1910.38(a), 1910.120(q)(1), 1926.65(q)(1)
The hazardous waste operations and emergency response regulation. 1910.38, 1910.120
Alarm systems for employee evacuation and/or response. 1910.38, 1910.165, 1910.120, 1910.1200
Emergency drainage systems for flammable/combustible liquids in industrial plants. 1910.106(e)(3)(iv), 1910.38, 1910.39
Clarifications of Interpretations and Citation Policy 1910.38, 1910.157
Interface of 1910.120 and other standards. 1910.120, 1910.38(a)
Training and HAZWOPER. 1910.120, 1910.120(q)(1), 1910.120(q)(6)(ii), 1910.120(q)(6)(iii), 1910.38