WAC 296-307-63225. Make sure warning signs are posted for areas where noise levels equal or exceed 115 dBA

The employer must make sure warning signs are posted at the entrances or boundaries of all well-defined work areas where employees may be exposed to noise that equals or exceeds 115 dBA (measured using a sound level meter with slow response). Warning signs must clearly indicate that the area is a high noise area and that hearing protectors are required.