The barrier method
Sunscreen forms a barrier between your skin and the sun, slowing down the rate it which the sun's rays enter the deeper layers of the skin. In order for a sunscreen be effective, it must fulfill two criteria: must have a sun protection factor (SPF) built in, and it must have filters to stop both of the ultraviolet rays in sunlight — UVA and UVB — penetrating skin.
The SPF of a Sunscreen is worked out i, a ratio of how much radiation it takes before skin burns. Put simply, it indicates now many times longer you can be exposed the sun than you normally would before burning. So if you normally burn after 15 minutes exposure to sunlight, sunscreen containing an SPF of 8 will allow you to stay out in the sun for 120mins. A higher SPF sunscreen means you can stay out longer, and one that's water-resistant means that it's still effective if you sweat or swim — ideal for water sports. A sunscreen must also offer protection against both UVA and UVB rays in sunlight. Both of these can trigger abnormal cell changes and skin dehydration.
Fact and fiction
Despite increased awareness of skin protection, there are still many myths
about how much protection from the sun an SPF actually gives you. Does a
high SPF last longer than a low SPF? No. The process of determining a sunscreen's
SPF in the laboratory does not take external factors into consideration.
You must reapply sunscreen after swimming, exercising or towelling dry.
Will a higher SPF keep my skin healthier? No. However high the SPF of a sunscreen,
your skin will still suffer from dehydration, and minute alterations may still
take place in skin cells, unless you use an after-sun moisturizer. If I already
have a tan, will I be able to stay out longer before I burn? No. It's not
how tanned You are, but what skin type you have that determines whether You
burn and how long it takes before you do.
Keep it cool
A couple of other things you should bear in mind are how long your sunscreen has left, and how you should store it. Like all skin care products, sunscreen has a limited shelf-life; check the expiry date on the tube before buying (or using) it. Sunscreen also deteriorates if stored incorrectly. Ideally you should store it somewhere dark at less than 25degC — don't leave it out on the deck of a boat or the dashboard of a car, because it won't work when you need it to.
If you're going off the beaten track, buy your sunscreen in advance. Leading brands such as Clarins and others are readily available at chemists in most large cities in the region. You may also want to consider other products such as moisturizers to limit the sun's ageing effects. And if you're going to a malarial area, a new product you'll definitely want to pack is Clarins'After Sun Moisturizer with Anti-Mosquito Formula.
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