Wherever there is danger of injury from flying particles or substances, adequate shields, screens, chip guards, or enclosures shall be provided and they shall be designed and constructed for the purpose of deflecting or confining said flying particles or substances in a manner that will prevent injury to employees. When it is not possible to provide such guards, employees subject to such hazards shall be protected by the use of personal protective equipment.
Cal. Code Regs. Tit. 8, § 3303