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
Clarification of the respiratory protection medical evaluation. 1910.134(e)(2)
Respiratory protecton standard two-in/two-out policy. 1910.134(g)(4)
Enforcement policy for abrasive-blasting respiratory protection under the Lead in Construction Interim Final Rule. 1926.62(f), 1910.134
Respiratory protection for anhydrous ammonia storage installations. 1910.111, 1910.134
Employee declination of medical evaluation; religious exemptions for respirator use. 1910.134
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)
Assessing hazards to select eye and respiratory protection. 1910.132(d), 1910.133, 1910.134(d)
Decontamination of SCBA second stage regulators. 1910.134(h)(1)(iii)
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
Respiratory Protection Standard: Interim Enforcement Policy. 1910.134, 1926.103
Medical evaluation requirements under the respiratory protection standard 1910.134(c), 1910.134(e)
Two-in/two-out procedure in firefighting/IDLH environments. 1910.134(g)(4), 1975.3(d)
Conditions where OSHA might accept a product that is not approved by NIOSH. 1910.134
NIOSH approved respirator during the period of an employee's escape from a chemical release of phosgene. 1910.134(d)(1)(ii)
SCBA cylinder interchangeability. 1910.134(d)(1)(ii), 1910.156(f)(1)(iv), 1910.120(q)(3)(x)
Permissible Exposure Limits for Nuisance dust. 1910 - Table of Contents, 1910.134, 1910.1000