The answer is that it does affect. Depending on whether the fabric is very dense or not dense, that is to say manufactured with more or less dense materials, more or less radiation can pass through the clothes, and therefore more or less radiation can reach the skin. And this is very important especially for the most sensitive skins. It is important to keep in mind what kind of clothes we wear, not just long sleeves or short sleeves, which obviously also influences the radiation received.
In countries that, like Asians, are not very fond of sunbathing, they pay close attention to this issue and develop very light fabrics, but with greater protection from solar radiation. In addition to the type of fabric and the weft, the color of the clothes, their weight and the ability to absorb moisture also affect how the solar radiation is absorbed. For example, if the normal clothes that we use in summer have a capacity of protection against the sun similar to a factor of solar protection (what in English knows like UPF) of 6, this special clothes to avoid the radiation can get to have a sun protection factor of 30, and that means that only 3% of the ultraviolet rays will pass.
Speaking of solar radiation, another issue that tends to worry a lot are sun creams. I usually have many questions on this subject, because there is a lot of ignorance about what cream to use or how to apply it. The first thing to know is what the sun protection index means (or the SPF acronym that we see in the markets that refer to the English name "Solar Protection Factor"). This index reflects the time it would take to burn. For example, a protection index 15 means that it protects fifteen times, that is, with that cream you would burn fifteen times later than without any protection. But of course this number is variable among people. There are some with very clear skin that can burn in five minutes and other people with darker skin that can take half an hour. To know how each index affects each specific person, you must know how long it takes to burn your own skin. So these indices are always relative.
You have to know that there is no hundred percent protection. Even the highest rates offer only partial protection. It is also important that sunscreens protect for ultraviolet A and B. And this is so because the two radiations can lead to different types of cancer. And then in terms of administration, we must be careful, some penetrate better into the skin than others, some are lost with sweat or bath … and that means that they have to be applied again more or less frequently.
Another aspect that greatly influences the radiation that is received is the time at which it is exposed to the sun. The time determines how vertical the sun is relative to the position of the person to whom its rays are coming. The closer to the vertical, the more energy these rays have and they are more dangerous. That's why the noon hour is the most damaging. In the hours of the morning or the afternoon, the sun is more inclined on the Earth and the angle of the rays on the skin is greater reason why it arrives with smaller energy. That is why it is recommended that to go to the beach or to go for a walk, those hours in the morning or the end of the afternoon are better. Although it is also important to know that you do not have to be always in the dark. It is like everything, in excess it is bad but the sun is necessary because it gives us vitamins and causes the release of hormones that make us feel good.
And another question about which there is a great disinformation are the tanning booths. It is proven that they increase the risk of skin cancer. There are statistical studies that indicate that they can increase up to 75% the risk of developing cancer in individuals between 18 and 25 years. In the cabins, as with the sun, the type of skin is very important. A person who has clear skin, in the same way that he burns when he sunbathes, can also burn more easily in one of these cabins although time is controlled. It is also shown that these cabins not only induce mutations in DNA but also age the skin. That is, there is a whole series of complications associated with the use of booths. Dermatologists do not recommend them, unless it is for very specific pathologies that need phototherapy such as psoriasis, but in general simply for being brown … it is not the healthiest way.
Marisol Soengas is director of the Melanoma Research Group of the National Center for Oncological Research (CNIO).
Question done via email by J. Manuel Duque.
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