Skin cancer is caused by exposure to ultraviolet (UVA or UVB), from sunlight. Avoiding direct exposure to sunlight is the most effective way of preventing skin cancer. However, there are times when sun avoidance just isn’t practical.

Sunscreen is the most important product available to help block ultraviolet light. Three important factors to consider with sunscreen use are:

  • the spectrum of UV radiation absorbed
  • amount applied
  • frequency of application


UV Radiation:

The sun gives off three types of ultraviolet (UV) radiation. All UV rays cause skin cancer.


UVA radiation:

Goes deeper into the skin (dermis)

Causes premature ageing and wrinkles

Causes change in the appearance of skin colour (tanning)


UVB radiation:

Affects the skin’s surface (epidermis)

Contributes most to the burning of skin

Causes eye damage


UVC radiation:

Very dangerous but mostly filtered out by the ozone layer


How to Pick the Proper Sunscreen:

  • SPF (Sun Protection Factor) measures the amount of UVB absorption in the sunscreen. (Note: there is no method of reporting the UVA absorption). To determine if a sunscreen protects against UVA and UVB radiation, check the label for:
  • The words broad-spectrum (this means it blocks both UVA and UVB)
  • An SPF of at least 30 (higher numbers give higher rates of protection)


Applying Sunscreen Properly

The most common mistake people make when using sunscreen is not using enough and not reapplying.

  • Apply at least 20 minutes before sun exposure to ensure the product is absorbed by the skin
  • When initially applied, sunscreen should form a film on the skin
  • Reapply every two hours, and/or after swimming or perspiring.
  • Alternate applications of sunscreen with applications of bug sprays
  • Apply sunscreen after moisturizers and before makeup


Daily Sunscreen

Sunscreen should be applied daily and throughout the year. The sun’s rays reflect off surfaces such as snow, sand and concrete.  Whether in the city, at the beach, or in the mountains, your skin needs protection from UV radiation.

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