Here's several:
In the 19th century, surgeons wore white gowns, but in the 20th century surgeons began to wear cyan or green surgical gowns, for several reasons.
First, in the brightly-lit operating room, green reflected less light than white and caused less strain on the eyes of the medical team.
Second, cyan is the complementary color of red, so red blood on a cyan gown looks black or gray, and not red, and is not as vivid.
Also, since red and green are complementary colors, shifting your sight to green after staring at red for long periods of time does not cause green after-images, as shifting from red to white will do.
Lastly, since green is considered one of the most restful and soothing colors, it causes less anxiety to patients.
