California Code, Health and Safety Code - HSC § 25916

If any construction, maintenance, or remodeling is conducted in an area of the building area where there is the potential for employees to come into contact with, or release or disturb, asbestos or asbestos-containing construction materials, the owner responsible for the performance of, or contracting for, any construction, maintenance, or remodeling in the area shall post that area with a clear and conspicuous warning notice. The posted warning notice shall read, in print which is readily visible because of its large size and bright color, as specified in either subdivision (a) or (b).