Protecting yourself from the sun’s rays


In the summer, it’s so nice to enjoy beautiful sunny days. Yet these hours of enjoyment carry a hidden danger: the sun’s rays. Are you familiar with the basic principles of sun protection so as to avoid the harmful effects of the sun?

Se protéger contre les rayons du soleil

Harmful effects of the sun

The sun is a star that humans have admired for thousands and thousands of years, and is accorded countless virtues. Medically, it enables the human body to produce the vitamin D necessary to maintain bone health. While cautious daily exposure to the sun may be beneficial, too much exposure — too often and for too long — carries several risks. Too much sun can have immediate effects (sunburn or sun stroke, for example), but can also be pernicious, leading to skin cancer. This is the most common type of cancer in Canada, with more than 80,000 people diagnosed each year. Less frequently, overexposure to the sun can cause eye problems, bad skin reactions related to the intake of certain medications, premature ageing of the skin, or immunosuppression, a weakening of the body’s ability to fight certain viruses. As well, some people may be hypersensitive (allergic) to the sun.

Tips for protecting yourself from the sun

When going out in the sun, the key is to use common sense, by learning to approach it with caution —   and by using a few tricks! Here are the most important:

  • Choose your time of exposure: before 11 a.m. and after 4 p.m., the sun is less strong
  • Seek out shade, by looking for a covered area or using a parasol
  • Wear a large-brimmed hat
  • Wear sunglasses that offer UVA and UVB protection (look for a label indicating 100% UV protection)
  • Apply a sunscreen with a protection factor of 30 or higher. Don’t forget your lips.
  • Protect babies under a year old with a physical screen (light clothing, a parasol, etc.)

Choosing the right sunscreen

There are many quality products on the market. Good protection requires a sunscreen that works against both UVA and UVB rays, because these two types of solar rays are equally dangerous. Several ingredients used in sunscreens are effective against UVA rays or UVB rays or both. Yet certain ingredients should be avoided because of their allergic potential. Below is a table to help you choose the right sunscreen according to its ingredients.

Table 1: Ingredients to look for in sunscreen

Ingredients to look for

Ingredients to look for

Avobenzone (Parsol 1789)


Homosalate, octisalate


Mexoryl SX and XL

Tinosorb S and M

Titanium dioxide

Zinc oxide

Another important aspect to consider when choosing a sunscreen is the SPF, that is, the sun protection factor. The SPF only indicates the protection against UVB rays, it does not apply to UVA rays. The higher the SPF, the better the sunscreen protects against UVB. An SPF of at least 30 is recommended. That means that the sunscreen blocks 97% of the UVB rays reaching the skin. The following table shows the effectiveness of different SPFs.

Table 2: Percentage of UVB rays blocked according to SPF


Percentage of UVB rays blocked












98 %





Choosing a sunscreen with an SPF of 30 or higher is especially important if you have light skin, if you are taking photosensitizing medication, or if you have a disease that makes you particularly sensitive to the sun (e.g., lupus). Young children can also benefit from a sunscreen with an SPF greater than 30. This advice is equally valid for people who work outdoors. For those who have already had a skin cancer, a sunscreen of at least SPF 60 should be preferred to ensure adequate protection in case of poorer application. Finally, an aerosol sunscreen is recommended for acne-prone skin.

Proper use of sunscreen

Even the best sunscreen will be of no use if you forget to put it on. As well, its protection is greatly diminished if not used correctly.

  • Apply sunscreen in sufficient quantity. For adults, follow the rule of two tablespoons: that’s the minimum quantity recommended for the entire body — legs, arms and face included. If you spread on only half the recommended quantity, you reduce your protection by as much.
  • For lips, purchase a lip balm with an SPF of at least 30.
  • Apply sunscreen 15 to 20 minutes before going outside.
  • Reapply sunscreen about every two hours or after swimming or intense physical activity (regardless of the SPF). Always apply to dry skin.
  • Wear sunscreen at all times (beware of light clouds that do not really block the sun’s UV rays).
  • Verify the expiry date of the product you’re using and replace it if it has been open for more than a year.
  • For babies less than six months old, apply sunscreen on parts of the body that are not covered by clothing (face, neck, ears, hands).

When you expose yourself to the sun’s rays, you have to slather on sunscreen at all times. Having a tan is by no means cause for exception, because the protection offered is equivalent to an SPF of no more than 4. Even though your skin may not get as red, the sun’s rays are still getting through. Moreover, self-tanning lotions do not offer any protection against the sun.

It is also false to believe that being in the water protects you from the sun’s rays. Water reflects up to 50% of the sun’s rays and will not save you from a good sunburn if you stay in for a few hours. There are several sunscreens on the market that stay on even in water. The label “water resistant” means that protection is maintained for 40 minutes in the water, while a sunscreen labelled “waterproof” gives you 80 minutes of protection in the water. It is also important to know that clothing wet from swimming or sweat loses its protection against the sun.

Summer is short, so enjoy it, while exercising caution in the sun! If you need advice on choosing the right sunscreen, do not hesitate to consult your pharmacist.

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