“High Visibility Safety Apparel and Headwear” is referred to in Title 8, but calls for the incorporation of the ANSI standard (American National Standards Institute (ANSI)/ International Safety Equipment Association (ISEA) 107-2004, High Visibility Safety Apparel and Headwear. The ANSI standard has 3 classes of this type of clothing.
Unless Title 8 calls for the use of this particular type of clothing for a job function, the use of such clothing is optional or voluntary, such as in Title 8 Section §1598. Traffic Control for Public Streets and Highways or §1599 Flaggers. These two sections appear to be the only sections that deal with the High Vis clothing. These sections are under the Construction Safety Orders. A thorough study of these Orders should be performed prior to conducting any operations governed by them.
While this is not required for all operations, risk managers would be best advised to require it for any operation where visibility is reduced or there is a lot of congestion and identifying the key person is challenging. Think emergency operations.