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 https://www.osha.gov.

April 21, 1986

Mr. Derek Mullins
Compliance Industrial Hygiene
The Industrial Commission of Arizona
P.O. Box 19070
Phoenix, Arizona 85005-9070

Dear Mr. Mullins:

This is in response to your letter of March 24, concerning the use of nonapproved M-17 gas masks.

The M-17 gas mask is used for the protection of army personnel against chemical warfare. The Mine Safety Appliance Company (MSA) was the principal manufacturer of the mask under contract with the Department of Defense. From my conversation with a technical representative of MSA, I learned that the production of the M-17 was terminated in the early seventies. Since the Defense Department owns the mold, MSA no longer stocks spare parts for this mask. Furthermore, this mask was made in accordance with specifications for military use. It may not pass the certification tests currently administered jointly by the Mine Safety and Health Administration (MSHA) and[by] the National Institute for Occupational Safety and Health (NIOSH) under the provisions of [42 CFR 84]. MSA does not recommend the use of this mask by civilians.

[This document was edited on 03/22/99 to strike information that no longer reflects current OSHA policy.]

Since the M-17 is not approved by MSHA and NIOSH, this respirator may not be used by workers other than enlisted military personnel. There are many approved gas masks available with modern design, improved construction materials, and with different types of canisters for protection against a wide variety of air contaminants. There is no reason for OSHA to accept the M-17 under a variance situation on the basis of unavailability. Furthermore, the currently available M-17 masks were manufactured at least ten years ago. The facepiece may have deteriorated and the sorbent probably has lost effectiveness over such a long storage time. Besides, users can no longer obtain spare parts and fresh canisters from MSA. Although the M-17 may be purchased at an attractive price as compared to the currently approved gas masks, the level of protection provided by this mask is questionable.

We hope we have addressed your concerns.


Ching-tsen Bien
Supervisory Industrial Hygienist
Office of Science and
Technology Assessment