Archive Notice - OSHA Archive

NOTICE: This is an OSHA Archive Document, and may no longer represent OSHA Policy. It is presented here as historical content, for research and review purposes only.

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. This 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. To keep apprised of such developments, you can consult OSHA's website at

July 11, 1994



FROM:               JAMES P. DRAKE
                    Acting Assistant Regional Administrator
                    for Technical Support

SUBJECT:            Respirators and Isocyanates

This memorandum replaces the February 15, 1991, memorandum (copy attached) to Larry Falck, Acting Area Director, Jacksonville Area Office, concerning 1910.134 Interpretations, and clarifies the Agency's policy concerning respirator use for spray operations involving paints containing isocyanates. This action is necessary as the February 15, 1991, memorandum has been inadvertently applied to operations other than spray operations.

Positive pressure air-line respirators are the only NIOSH-approved respirators for employees engaged in spray operations and who are exposed to isocyanates. A full-facepiece respirator is required because of the eye irritant and sensitization characteristics of isocyanates. In situations where an overexposure to isocyanates has not been established and an improper type of respirator is being used a citation under 29 CFR 1910.134(b)(2) shall be issued, provided that the compliance officer documents that an overexposure is possible. Such documentation may be accomplished, for example, either by documenting the existing work practices of the employee during the spray operation or through air monitoring.

[OSHA Instruction CPL 2.103, dated August 26, 1994, Chapter III, paragraph C.3.c. discusses guidance to the field where violations of the respirator standard exist and Chapter III, paragraph C.3.a.(1)], discusses violations of air contaminant standards.

Should you have any questions concerning this matter, please contact Sven Rundman of my staff at (404)347-2281.