Damage to skin occurs from over-exposure to ultraviolet radiation in rays from the sun. The two most significant groups of rays are ultraviolet B (UVB) and ultraviolet A (UVA). Both types can cause or contribute to skin cancer and may cause eye damage and harm he body's immune system. UVB rays are those that cause sunburn. UVA rays are the main cause of skin aging from sun damage.
Ultraviolet damage is cumulative so each sunburn increases the harm already done to your skin. The first 18 years of life are when most of the damage is done. Protection from the sun, including proper application of sunscreens, must begin during childhood and continue throughout a person's lifetime to prevent the unwanted damaging effects of ultraviolet light. Without proper protection, one of every seven Canadians will develop skin cancer.
A sunscreen absorbs the sun's ultraviolet rays and protects the skin from UVB. Better sunscreens also block most of the UVA.
The protection offered by a sunscreen is measured by its sun protection factor (SPF). This system shows how long you can stay in the sun before burning. The higher the SPF number on the package, the more sun protection your skin receives. For instance, if you would burn in 10 minutes without protection, by applying a sunscreen with an SPF 15 you will burn in 150 minutes (10 minutes X SPF 15 = 150, see table 2). Additional applications will not extend this time. For this reason, seeking shade and covering up as much as possible is a wise choice.
All sunscreens on the Canadian market must be identified with an SPF value indicating the product's degree of protection. Even if the sunscreen package claims you will receive six or eight hours of protection, the SPF is your most important guide because it is based on your sunburn and tanning history. Sunscreens that contain a product called PABA absorb UVB but not UVA radiation. They bind closely to skin even after showering, swimming or sweating. However, PABA has been associated with skin irritations and sensitivity.
As well, people sensitive to certain drugs may have a reaction to sunscreens containing PABA and should avoid sunscreens that contain this product. Examples of medications that may provoke this reaction include sulpha drugs, artificial sweeteners and some oral hypoglycemics and diuretics. Talk to your pharmacist or doctor about your sunscreen choices if you are using one of these medications. Table 1 provides a list of PABA and non-PABA sunscreens with SPF of 15 or greater.
Sunscreens that contain salicylates rather than PABA do not absorb UV rays as effectively and higher concentrations are required. Their benefit is lost from the skin by swimming, showering and sweating. Their major advantage, however, is their small likelihood of causing allergic reactions.
A sunblock provides a physical barrier to the sun. These products are most familiar as the white cream on the nose of an athlete but they are also available in a less visible form. They protect high-risk areas like the nose, lips, ears, shoulders and backs of hands.
There are other products available that provide UV protection for specialized needs. Your pharmacist can help you choose if one of these would meet your needs.
Some medications can trigger what is called a photosensitive reaction. This means that the medication causes the body to react in some way to exposure to light, especially sun. Your pharmacist or doctor can tell you if a particular medication you are taking can cause this effect. If so, you should avoid sunscreens that are scented or contain PABA.
Some simple advice applies to everyone who will be in the sun.
To ensure proper sun protection, use 25-30 mL to cover the entire body and reapply after sweating, or after spending more than 80 minutes in the water.
Sunscreens with an SPF of 30 or even 45 are better choices if you have extremely sun-sensitive skin or work in the sun all day.
Water-resistant products must maintain their effectiveness for at least 40 minutes in water. Waterproof products must do so for at least 80 minutes.
If you have dry skin you will benefit from a cream or lotion-based sunscreen as it helps moisturize skin as well as offering protection. If you have oily skin or acne, an alcohol-based, non-fragrant solution or gel would be a better choice. It is important to avoid alcohol-based products over areas of inflamed skin or eczema.
The sun is most intense when directly overhead and short shadows are cast. When the shadow is shorter than your child, it is time to go indoors or find some shade. If the shadow is longer than the child, it is safe to play outside.
Sunlight may cause cold sores to flare up. An adequate lip sunscreen may block the effect of solar radiation and prevent recurrence of cold sores.
Both UVA and UVB can penetrate clouds and pollution thus demonstrating the need for sunscreen protection on cloudy days as well.
There is controversy on this issue. Sunscreens block absorption of the UVB that the body needs so it can produce vitamin D. Production of Vitamin D decreases dramatically with age and regular use of sunscreens may slow the process even more. If you are in this age bracket, to overcome this risk you can:
The UV index measures the intensity of ultraviolet radiation expected to be in the atmosphere on a given day. The scale ranges from zero to 10. The greater the index (reported daily on radio and television) the less time it will take for sunburn to develop (see Tables 3 and 4).
If you fall into any of the following groups, you should always use a UVB and UVA sunscreen of SPF 15 or higher. You:
The Canadian Dermatology Association recommends protecting the skin from the sun every day from spring through fall. You should also use protection in winter if you participate in an outdoor sport. Sunscreens with SPF 15 or greater are labelled with the Canadian Dermatology Association logo to guide you in your choice. The Canadian Dermatology Association has developed guidelines for suncare protection to include sunblock formulations of zinc and titanium.
It is never too late to benefit from protection against the damaging effects of the sun's ultraviolet rays. Use a sunscreen or sunblock whenever you are in the sun.