The operator must provide eye and face protectors for the use of persons engaged in or observing activities where damage to the eye is possible, such as welding, grinding, machining, chipping, handling hazardous materials, or burning or cutting acetylene. These eye and face protectors must be:
(a) Properly marked and in compliance with the requirements of 29 CFR 1910.133; and
(b) Maintained in good condition or replaced when necessary.