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 http://www.osha.gov.

November 15, 1985

 
MEMORANDUM FOR: REGIONAL ADMINISTRATORS
 
THRU: JOHN B. MILES, Director
Directorate of Field Operations
 
FROM: STEPHEN J. MALLINGER, Acting Director
Directorate of Technical Support
 
SUBJECT: Use of Bureau of Mines Approved Gas Mask Canisters
 

We have received several inquiries concerning the use of Bureau of Mines approved gas mask canisters. These canisters were approved under the Bureau of Mines Schedule 14F for protection against many highly toxic substances such as hydrogen sulfide, hydrogen cyanide and phosphine. All these canisters were approved for concentrations far above their respective immediately dangerous to life or health (IDLH) values and none of these compounds has adequate odor warning properties for the respirator wearer to detect excessive facepiece leakage or sorbent breakthrough.

Although the Mine Safety and Health Administration (MSHA) and the National Institute for Occupational Safety and Health (NIOSH) have extended the expiration date for the Bureau of Mines approved gas mask canisters, NIOSH indicated that they could not conduct quality control testing on these canisters to assure that the performance meets the certification requirements.

In view of the above facts, it is concluded that the Bureau of Mines approved gas mask canisters for protection against hydrogen sulfide, hydrogen cyanide and phosphine may not provide adequate margin of safety to the respirator wearers. Their use for other than emergency escape is not acceptable.