B.C. youth were officially banned from using indoor tanning booths Monday as part of a provincial regulation to curb early skin cancer development.

Tanning businesses are now required to display a sign informing of the ban and could be fined $345 if caught breaking the rules. “By eliminating exposure to this known carcinogen at a young age we can help prevent cancer,” the Canadian Cancer Society’s Barbara Kaminsky said in a statement.

Anyone 17-and-under in B.C. who wishes to use a tanning booth must now have a doctor’s prescription.

Officials said indoor tanning before 35 can increase melanoma risk — the most deadly type of skin cancer — by 75%.