The absorption of ultraviolet rays by skin is related to its wavelength. The shorter the wavelength, the smaller the depth of penetration into the skin and the weaker the pigmentation after irradiation; The longer the wavelength, the deeper the penetration into the skin and the stronger the pigmentation after irradiation. Due to photochemical reaction, photon flow with higher energy level can cause denaturation of nucleoprotein and some enzymes in cells.
Therefore, after being irradiated by ultraviolet rays, it takes 6-8 hours for cell changes and symptoms to appear, including skin dryness and pain, epidermal atrophy, and even blistering and shedding. Because ultraviolet rays have weak penetrating power to tissues, they do little harm to deep subcutaneous tissues. However, severe ultraviolet rays can cause systemic reactions, such as fatigue, low fever and drowsiness.
Because some people's skin is allergic to ultraviolet rays, solar dermatitis (also known as sunburn) occurs after illumination, and the exposed parts of the skin are itchy, tingling, desquamation, and may break and scab.
The actual observation shows that in the plateau area at an altitude of 3500 meters (the ultraviolet ray is usually 3-4 times that of the plain area), the bare skin is exposed to ultraviolet ray for 20-40 minutes around noon, and the skin has a burning feeling and peeling feeling; After 40-80 minutes, papular blisters will appear on the skin, leading to various lesions.
Extended data:
How can you repair the skin after exposure?
1. First of all, after the skin is exposed to the sun, some tiny blood vessels will expand, which is also the reason why the skin will be red. At this time, to keep the skin cool, it is best to avoid the sun at once and go to a cool place. After the skin surface temperature drops, you can continue to use cold water or spray to cool down, which can have a good soothing effect on the skin.
2. Then within six hours after exposure, apply some skin care products such as repair cream, because even if the skin cools down after exposure, the ultraviolet radiation may have hurt the deep skin. For lighting, you can use aloe vera gel or after-sun repair products containing natural calming and soothing ingredients, such as lavender, chamomile, licorice, seaweed, witch hazel, oats and calendula.
3, then remember one thing after doing it, that is, hydrating. Just as people need to drink water when they are thirsty, they also need to "drink water" after their skin is exposed. When the skin is exposed, the moisture of skin cells will be evaporated, and a large number of epidermal cells will die, and then gradually fall off.
If you don't replenish water within 24 hours after sun exposure, your skin will become dry, prone to fine lines and even dry skin. Therefore, the skin should be deeply hydrated after exposure, and the facial skin can be covered with a hydrating mask.
4. Then, you need to supplement the skin with nutrition, especially collagen. People who are exposed to the sun for a long time will look older than their peers. This is because substances in the skin, such as collagen, are lost faster than usual during the sun exposure. Therefore, after the sun is finished, it is necessary not only to replenish water, but also to maintain the skin, use various skin care essences, supplement nutrition and collagen for the skin, and restore the skin to a good state before the sun.
It's best to remember that if little red dot appears after the skin is exposed to the sun, and the itching is serious, don't be careless at this time. This is probably a symptom of sun skin. At this time, you should seek medical attention in time. Moreover, if the sunburn is serious, such as large-scale peeling or even blisters, it is best to go to the hospital in time.
At the same time, when nursing yourself, don't wash the sunburned parts with hot water, and don't scratch the itchy parts, which will aggravate the sunburn of the skin.
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People's Daily Online-Guangdong Channel >> Invisible damage of ultraviolet rays: skin exposure and diseases.
People's Network-Jiangsu Channel >> Health >> What should I do after my skin is exposed to the sun? How to repair after exposure