April 15, 1999

Mr. Larry L. Janssen, CIH
Technical Service Specialist
3M Occupational Health & Environmental Safety Division
3M Building 260-3B-09
St. Paul, MN 55144-1000

Dear Mr Janssen:

This is a response to your letter dated December 29, 1998, and addressed to the Occupational Safety and Health Administration's (OSHA's) Directorate of Compliance Programs. I apologize for the delay of this response. You requested clarification of OSHA's definition of "abrasive-blasting respirators" in light of the changes made to the ventilation standards (29 CFR 1910.94 and 1926.57) in the January 8, 1998 Federal Register.

As you mentioned, the original definition of abrasive-blasting respirators read: "A continuous flow air-line respirator constructed so that it will cover the wearer's head, neck and shoulders to protect him from rebounding abrasive." When the definition was revised, the phrase "continuous flow air-line" was removed because the old definition could potentially contradict a later paragraph in the standard, namely (a)(5)(i).

Both ventilation standards state in paragraph (a)(5)(i) that "Employers must use only respirators approved by NIOSH under 42 CFR part 84 to protect employees from dusts produced during abrasive-blasting operations." NIOSH has approved more than just "continuous flow air-line respirators" for abrasive-blasting; many of these approved respirators could be excluded by the old definition. The revised definition allows the use of respirators which have been approved for abrasive blasting, but were technically prohibited by our standards because they were not "continuous flow air-line respirators."

Other types of respirators which NIOSH has approved for abrasive-blasting include several powered-air purifying respirators and some pressure demand respirators. The last combination you suggested in your letter (a canvas shroud added to a negative pressure, full facepiece air-purifying respirator) does not satisfy the approval requirement and is still not permitted under the revised definition.

I hope this clarifies OSHA's intention with this revision to the abrasive blasting standard. If you have any further questions, you may contact OSHA's Office of Health Compliance Assistance at (202) 693-2190.

Sincerely,

Richard E. Fairfax
Director
Directorate of Compliance Programs