Section 39.579. Masks

(a) Masks shall be composed of vulcanized rubber, fiber, metal or equivalent material, which withstand sterilization, formed so as to protect the face of the operator above the mouth. Masks shall be supplied with a headband or headgear of any suitable design and material to retain the mask in proper position. Masks made of woven wire shall have openings not greater than 0.0295 inch (0.75 mm) fiber or equivalent material, which withstands sterilization. They shall bear a permanent and distinctive marking by which the manufacturer, dealer or distributor may be readily identified. No part shall be composed of quick-burning material.

(b) For use in electric arc welding the masks shall be constructed so as to be at least three inches from the eyes of the wearer and shall be of nonconductive material.

(c) Windows shall be made to conform to the specifications and tests in § 39.575 (relating to windows of masks).