Letters of Interpretation | Occupational Safety and Health Administration

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
05/30/2002	Protection factors for respirators used in pharmaceutical industry: policy change.	1910.134, 1910.134(d)(3)(i)(A)
05/03/2001	Application of 1926.800 to lone employees working underground in a tunnel or shaft connected to a tunnel.	1926.800, 1926.800(c), 1926.800(f)(5), 1926.800(a), 1926.800(g)(2), 1910.134, 1926.103, 1926.800(e), 1926.800(f)(1)
03/08/2001	Use of multi-station electric pump nebulizer and the squeeze bulb Bitrex for QLFT.	1910.134(f), 1910.134 App A
07/18/2000	Selection of air purifying respirators for gases and vapors with poor warning properties (diisocyanates)	1910.134(d)(3)(iii), 1910.134(d)(1)(i)
10/01/1999	Respirators for voluntary use and cleaning respirators during fit testing.	1910.134(c)(2), 1910.134(d)(1)(ii), 1910.134(f)(6), 1910.134(h)(1)
08/27/1999	Appendix A requirements and techniques for fit testing respirators.	1910.134(f), 1910.134 App A
08/13/1999	1910.134(i) does not apply to portable breathing air compressors.	1910.134(i)
05/12/1999	Respirators for silica dust must be selected based on exposure levels.	1910.134(a)(1), 1910.134(a)(2)
04/08/1999	Preemption of respiratory protection standard by DOT's Office of Pipeline Safety regulations.	1910.134
03/12/1999	Complying with the "two-in, two-out" policy for interior structural firefighting.	1910.134(g)(4)
03/08/1999	Medical evaluation not required for the use of escape only respirators.	1910.134(e)
03/05/1999	Medical evaluations must be performed prior to fit testing.	1910.134(e)
02/05/1999	Using a "generic type" certificate of analysis for Grade D breathing air.	1910.134(i)(4)(ii)
01/29/1999	Using combinations of respiratory protection not approved by NIOSH.	1910.134(d)(1)(ii), 1910.94(a)(5)
01/15/1999	When to use quantitative and qualitative fit testing.	1910.134(f), 1910.134 App A
01/15/1999	Comparing medical evaluation requirements in the HAZWOPER, Respiratory protection, and Fire brigades standards.	1910.120(f), 1926.65(f), 1910.134(e), 1910.156(b)(2)
01/04/1999	The grimace step in respiratory protection fit-testing procedures.	1910.134(f), 1910.134 App A
01/04/1999	Respiratory protection: editing the medical questionnaire; medical questionnaire not always required.	1910.134(e)(2), 1910.134 App C
01/02/1999	Clarification of a PLHCP under the Respiratory protection standard.	1910.134(e)
12/23/1998	Clarification of respirator costs, annual training, and "effective" seal checks.	1910.134(c)(4), 1910.134(f)(2), 1910.134(g)(1)(iii), 1910.134(k)