Thirty other states have some age restrictions on UV tanning device use, but the California law is the first in the country to set such a high age requirement.
The American Academy of Dermatology is applauding the tougher restriction.
The group noted that research finds people who use indoor tanning are at a 75 percent higher risk for the most dangerous type of skin cancer.
But the indoor tanning association said there is no agreement among researchers that exposure to ultraviolet light, that does not cause burns, leads to melanoma.
