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.

January 29, 1999

Mr. Robert I. Leighton
Leighton Associates, Inc.
70-20 Austin St., Suite 115
Forest Hills, NY 11375

Dear Mr. Leighton:

This is in response to your letter dated January 11, addressed to the U.S. Department of Labor, Occupational Safety and Health Administration's (OSHA's) Directorate of Compliance Programs, in which you disagree with OSHA's policy to cite employers when respirators are used in a manner that has not been approved by the National Institute for Occupational Safety and Health (NIOSH). In particular, you have asked why a half-face negative pressure air-purifying respirator cannot be worn underneath a Type CE air-supplied abrasive helmet.

As you already know, our previous letter of February 26, 1996, to David Abrams addressed the same issue. It stated that the combination of a half-face negative pressure air-purifying respirator and a Type CE air-supplied abrasive helmet has not been approved by NIOSH. This is still the case. NIOSH approval for this situation is not, as you suggest, purely academic. There is the potential that the use of these two respirators together could affect the protection factors of each other due to their mutual interference. This interference may not always be obvious. As we stated in the first letter, the only way to determine this for sure would be to submit all respirator components for approval as required by NIOSH. For this reason, we continue to view dual use of respirators as a potential hazard.

We also have an additional concern about employees removing their helmets while still within a contaminated atmosphere. This procedure can expose employees to very high air contaminant levels. It can also contaminate the interior of the helmet and further add to the potential exposure of the employee when the employee re-dons it. The employer must determine why employees are removing their respirators and how this practice can be eliminated safely.

I hope this clarifies OSHA's position on the use of non-approved respirator combinations. If you have any further questions feel free to contact OSHA's Office of Health Compliance Assistance at (202) 693-2190.


Richard E. Fairfax
Directorate of Compliance Programs