Canadian Cancer Society logo
You are here: 

Sun and ultraviolet radiation (UVR) exposure

Sunlight supports life on earth. It is important for our physical and emotional well-being. Sunlight contains ultraviolet (UV) rays. These invisible rays of energy can damage the skin and eyes. Children, the elderly and people with fair skin are at a higher risk for UV damage. The main source of UV radiation (UVR) is the sun, but indoor tanning equipment, such as tanning beds and sun lamps, are also sources. Exposure to UVR is the most important risk factor for developing skin cancer.

Types of UVR

The 3 types of UVR are based on the length (wavelength) of UV rays:

  • UVA
  • UVB
  • UVC

UVR exposure

The amount of UVR a person receives from the sun depends on many factors, such as the time of day and the season.

The UV index

The UV index informs Canadians about the strength of the sun’s UV rays. The UV index predicts the sun’s intensity using a scale that ranges from 0 to 11+.

Health effects of UVR exposure

Sun damage builds up over time. Each time the skin is exposed to UVR and becomes tanned or burned, individual skin cells and DNA are damaged. In addition to damaging the skin, UVR can also cause cataracts and may affect the immune system.

Indoor tanning

Just like the sun, indoor tanning equipment (such as tanning beds or sun lamps) gives off UV rays that cause skin damage. Indoor tanning devices can give off UVR at levels up to 5 times stronger than the midday summer sun.

Sunlight and vitamin D

You get vitamin D by exposing the skin to sunlight and through your diet and vitamin supplements.

Reducing your risk

Take steps to protect yourself and your family from the sun. Check your skin regularly and report any changes to your doctor.


Now I know that I will help someone with cancer even after I’m gone. It’s a footprint I want to leave behind me.

Read Barbara's story

How can you stop cancer before it starts?

It's My Life! icon

Discover how your lifestyle choices can affect cancer risk and how you can take action with our interactive tool – It’s My Life!

Learn more