Ultraviolet (UV) rays are thought to be the major risk factor for most skin cancers. Sunlight is the main source of UV rays, which can damage the genes in your skin cells. Tanning lamps and beds are also sources of UV rays. People with high levels of exposure to light from these sources are at greater risk for skin cancer.

Three types of UV rays:

  • Ultraviolet A rays (UVA) cause cells to age and can cause some damage to cells' DNA. They can penetrate deep into the skin and are linked to long-term skin damage, such as wrinkles, but are also thought to play a role in some skin cancers.
  • Ultraviolet B rays (UVB) can cause direct damage to the DNA, and are the main cause of sunburns. They are nearly 1000 times stronger than UVA rays and are also thought to cause most skin cancers.
  • Ultraviolet C rays (UVC) don't get through our atmosphere and therefore are not present in sunlight.

The amount of UV that you're exposed to depends on the strength of the rays, the length of time your skin is exposed and whether your skin is protected with clothing or sunscreen.

If you want a lifetime of healthy skin, reduce your exposure to all types of UV rays – and never use tanning beds.

More about UV rays


Know the UV Index

Environment Canada’s UV Index is a useful tool when it comes to sun protection. It tells you the strength of the sun’s daily UV rays – the higher the number, the stronger the sun’s rays and the more important it is to protect yourself from the sun.

Privacy | Contact us

2017 Canadian Cancer Society. All rights reserved.