42 C.F.R. § 84.139 Head and neck protection; supplied-air respirators; minimum requirements.
Title 42 - Public Health
Type AE, BE, and CE supplied-air respirators shall be designed and constructed to provide protection against impact and abrasion from rebounding abrasive materials to the wearer's head and neck.
Title 42: Public Health
PART 84—APPROVAL OF RESPIRATORY PROTECTIVE DEVICES
Subpart J—Supplied-Air Respirators
§ 84.139 Head and neck protection; supplied-air respirators; minimum requirements.

