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Outdoor UV (sun)

Approximately 90 percent of all non-melanoma skin cancers can be attributed to UV exposure.


In Canada, the incidence of skin cancers is increasing with BC having the highest melanoma rates in Canada. People can and should protect their skin with shade, clothing and/or sun screen.

Evidence suggests that:

  • people who experience sunburns have a greater risk of developing skin cancer from exposure to the sun
  • childhood and adolescence exposure increases the risk of skin cancer later in life
  • one type of skin cancer increases the risk of developing other types
  • increasing risk of skin cancer is seen with increasing chronic sun exposure
  • research has suggested that non-Hodgkin’s lymphoma is significantly associated with exposure to UV radiation
  • a variety of serious non-cancerous skin diseases result from UV exposure
  • UV exposure is one cause of cataracts and corneal injuries can occur from UV exposure
  • projections for future ozone reduction resulting in increased ambient UV levels means that an exposure will be even more consequential over time
  • people of all ages need to protect themselves from UV

The best protection from skin cancer is to minimize exposure to the sun without reducing regular exercise.

What is the UV Index?

(from ICNIRP...)

The Global Solar UV Index (UVI) is a simple numerical indicator of the maximum solar Ultraviolet (UV) radiation received on the earth’s surface during the day. It was introduced jointly by the World Health Organization (WHO), the United Nations Environment Programme (UNEP), the World Meteorological Organization (WMO), and the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The UV Index can either be calculated using computer models that account for factors such as ozone and the amount of cloud cover that affect solar daily UV radiation or derived from measurements. The UV irradiation is weighted by the sunburn response of human skin (280 to 400 nm wavelength range). Values of the UV Index range from zero to over 20. The higher the UV Index, the greater is the intensity of UV radiation that is damaging to skin and eyes.

The UV Index is an important public awareness tool for informing people about the amount of harmful UV radiation during the day at a specified location. Weather forecasts in newspapers, on TV and radio often present the forecast local UVI alongside the local weather. Since the UVI is designed to be easily understood, it is usually the maximum UV radiation present or forecast on a given day that is reported, although UV radiation levels will vary through the day. Under clear skies, peak UV levels occur in the middle hours of the day, from around 10am to around 2pm (or if there is day-light saving, 11am to 3pm) (but heavy cloud-cover may modify this). Through the year, peak UV levels occur around the summer solstice.

The UV Index is grouped into 5 different categories and each category has a color code so that people can visualize the level of UV hazard and take suitable precautions. The values 0-2 are classified as Low (green); 3-5 as Moderate (yellow); 6-7 as High (orange); 8-10 as Very High (red); 11+ as Extreme (violet). Each level is accompanied by recommended ways to protect the skin and eyes. The main ways to achieve sun protection are to wear protective clothing including a broad-brimmed hat and sunglasses with side panels, and to seek shade. Additionally, broad-spectrum (i.e. protecting both from UVA and UVB) sunscreen of at least sun protection factor (SPF)15+ should be applied and reapplied after sweating, swimming or after any activity that could wipe off the sunscreen. Babies and young children especially, should be protected from intense sun.

UV IndexExposure CategorySun Protection Actions

0 - 2


  • Minimal sun protection required for normal activity.
  • Wear sunglasses on bright days. If outside for more than one hour, cover up and use sunscreen.
  • Reflection off snow can nearly double UV strength, so wear sunglasses and apply sunscreen on your face.

3 - 5


  • Take precaution by covering up, and wearing a hat, sunglasses and sunscreen, especially if you will be outside for 30 minutes or more. 
  • Look for shade near midday when the sun is strongest.

6 - 7


  • Protection required - UV damages the skin and can cause sunburn. 
  • Reduce time in the sun between 11 am and 4 pm and take full precaution by seeking shade, covering up exposed skin, wearing a hat and sunglasses, and applying sunscreen.

8 - 10


  • Extra precaution required - unprotected skin will be damaged and can burn quickly.
  • Avoid the sun between 11 am and 4 pm and seek shade, cover up, and wear a hat, sunglasses and sunscreen.



  • Values of 11 or more are very rare in Canada. However, the UV Index can reach 14 or higher in the tropics and southern US.
  • Take full precaution. Unprotected skin will be damaged and can burn in minutes. Avoid the sun between 11 am and 4 pm, cover up, and wear a hat, sunglasses and sunscreen.
  • Don’t forget that white sand and other bright surfaces reflect UV and increase UV exposure.
SOURCE: Outdoor UV (sun) ( )
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