July 28, 1982

Patricia P. Breslin, Ph.D.
Acting Director, Technical Support
USDOL - OSHA
200 Constitution Avenue, N.W.
Washington, D.C. 20210

RE: Your letter of July 13, 1982, requesting information on powered air purifying respirators approved for abrasive blasting

Dear Dr. Breslin:

Continuous flow supplied air respirators and powered air purifying respirators have many test criteria in common. Both types of respirators must meet the same minimum air flow requirements and the same maximum noise level requirements. General construction requirements for breathing tubes, helmets, and hoods are also the same.

The basic difference between supplied air respirators designed for protection against abrasive blasting and other supplied air respirators is the requirement for "additional devices designed to protect the wearer's head and neck against impact and abrasion from rebounding abrasive material, and with shielding material such as plastic, glass, woven wire, sheet metal, or other suitable material to protect window(s) of facepieces, hoods and helmets" (30 CFR 11; 11.110(a)(6)). This requirement has been used as an additional requirement to those in Subpart K for a powered air purifier approved for abrasive blasting.

If I can be of any further assistance, please feel free to contact me.

Sincerely yours,

James A. Oppold, Ph.D., PE, CSP
Director Division of Safety Research NIOSH



July 13, 1982

Dr. James Oppold
Director
Division of Safety Research NIOSH
944 Chestnut Ridge Road
Morgantown, West Virginia 26505

Dear Dr. Oppold:

We have received several inquiries from our compliance staff in the field concerning the acceptance of MSHA-NIOSH approved powered air-purifying respirators (PAPR's) for abrasive blasting.

Under our standard on ventilation for abrasive blasting operations, the abrasive blasting respirator is defined as 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, 29 CFR 1910.94(a)(1)(ii). We understand that NIOSH has tested and approved several powered air-purifying respirators for abrasive blasting under testing schedule 21C for particulate respirators rather than schedule 19C for continuous flow supplied air respirators. Upon reviewing Subpart K of 30 CFR 11 where all particulate respirators are approved under schedule 21C, we could not find any testing requirements for abrasive blasting PAPR's.

We would appreciate it if NIOSH could provide us with clarification concerning PAPR's for abrasive blasting and whether they have been tested in accordance with the requirements prescribed for continuous flow supplied air respirators (Subpart J of 30 CFR 11). If not, would the requirements prescribed in Subpart K of 30 CFR 11 (schedule 21C) for PAPR's provide the same degree of respiratory and personal protection as a continuous flow supplied air respirator?

Sincerely,



Patricia P. Breslin, Ph.D.
Acting Director, Technical Support