Respiratory protection for silica abrasive blasting

March 28, 1985

Mark Nicas, M.S., M.P.H.
Associate Industrial Hygienist
Research and Standards Development Unit
Department of Industrial Relations
[Recipient address omitted]
Dear Mr. Nicas:

This is in response to your letter of March 28, concerning respiratory protection for abrasive blasting with silica sand.

Provision 29 CFR 1910.94(a)(5)(ii)(b) of the ventilation standard requires that "abrasive-blasting respirators" shall be worn by all abrasive-blasting operators when using silica sand in manual blasting operations where the nozzle and blast are not physically separated from the operator in an exhaust ventilated enclosure. This is a work practice provision. That is, whenever the described operation takes place, "abrasive-blasting respirators" must be worn.

The Occupational Safety and Health Administration (OSHA) interprets provision 29 CFR 1910.94(a)(5)(iii)(b) as providing for a limited deviation from this requirement by permitting the use of "dust-filter respirators" as interim protection for an operator while "abrasive-blasting respirators" are temporarily unavailable for use for a justifiable reason. A "dust-filter respirator" may not be used as interim protection, however, if the airborne concentration of crystalline silica exceeds the protection factor allotted the respirator. If the "dust-filter respirator" is not designed to protect the operator's eyes and face from the impact of abrasives, supplementary equipment providing such protection will have to be provided in accordance with 29 CFR 1910.94(a)(5)(v)(b).

Thank you for contacting OSHA. If we can assist you again in the future, we shall be glad to do so.

Sincerely,
John B. Miles, Jr., Director
Directorate of Field Operations

[Requester letter reproduced on OSHA page; omitted here.]