You have probably already seen, from your weather application, the indication “UV” with a number behind it. This is the “UV index” which varies depending on where you are, the season, the time of day. How to protect your skin based on what it indicates? A dermatologist, Doctor Catherine Gaucher from the National Union of Dermatologists-Venerologists, answers this question.
What is the UV index?
First, let’s define the UV index. According to the World Health Organization, it is a “measurement of the intensity of ultraviolet radiation”. “Index values start from zero and increase – the higher the index, the greater the potential for skin and eye damage, and the less time it takes for the harmful effect to appear. The UV index is an important tool to alert people to the need to protect themselves from the sun.”
The dermatologist further specifies that there is several risk levels: low, moderate, high and very high. In the middle of winter in Paris, the risk is low, but if you are at the equator, the risk is very high (the UV index peaks at 15).
How to protect yourself from UV rays?
The way we protect ourselves varies depending on the intensity of UV rays. But Doctor Gaucher specifies that when faced with an index of 15, we are never completely protected. “Even if you use a cream with SPF 100+, that doesn’t mean you are 100% protected.. The number 100 or 50+ which is indicated on creams is not a percentage of sun protection. “It’s a figure calculated by laboratory tests whose effectiveness depends on each person’s skin,” she explains. It’s true “if and only if you have used enough sunscreen”, specifies the dermatologist. The tests are carried out with a fixed quantity of cream per cm2. This quantity corresponds to the equivalent of the last phalanx of the index finger in cream spread on a surface of skin equivalent to the palm of the hand. No more… “If you spread over a larger surface area, you halve the protection factor value of your cream.” She points out that we rarely use that much to avoid the sticky feeling of the cream. “In other words, since we don’t use enough, the effectiveness of the cream is significantly reduced,” she emphasizes.
Which cream for which UV index?
To give guidelines, the dermatologist specifies that between April and October, in Paris, the UV index is between 3 and 5. If you are exposed for more than 30 minutes, you must use a medium protection sunscreen. (at minimum) with SPF 30. In the middle of summer in the south of France, the UV index is around 6/7. There, you have to wear 50 whatever your skin. And reapply it every two hours, especially if you bathe. When the UV index is 1 or 2, she believes that the most important thing is to protect her retina, which is also very sensitive, by wearing sunglasses.
There is a time of day to which you must pay particular attention: the zenith. In other words, we do not recommend exposing yourself two hours before and after the sun is at its highest point. In France, this corresponds to the time slot between 12 p.m. and 4 p.m. in summer.
Finally, to protect your skin from the effects of the sun from an “anti-aging” perspective, she recommends wearing protection 30 all year round. UV rays are the first enemies of skin aging. “Besides, with just one sunburn, the part of skin that has burned can take 10 years at a time,” she concludes.
Read also :
⋙ Is the sun stick as effective as the cream? Dermatologists respond
⋙ Sun cream: protect your face with this sun serum at 11.55 euros which can be used as a makeup base
⋙ Sun cream, monoi, after-sun: how can I recycle my summer products at the start of the school year?