We have known since childhood that “everything grows by the sun”, and the survival of people, animals and plants cannot survive without the sun, but we do not know that the sun is a “double-edged sword”. 90% of skin aging is caused by the sun’s ultraviolet rays The cause of skin aging, in addition to endogenous aging, that is, the aging of the body’s own cells, the main factor is exogenous aging, which is the greatest impact of ultraviolet radiation in the sun. Therefore, the exogenous aging of skin is called “photoaging”. It is true that the process of endogenous aging is inevitable, we can only follow the natural metabolic law of the body’s skin, maintain a good life and rest time, and then supplemented with skin sunscreen, health products and nourishing products, so as to achieve the purpose of slowing down skin aging. Sunlight in addition to visible light, infrared light, there is about 1% of ultraviolet (UV). According to the wavelength and its biological effect, generally divided into three wavelengths: long-wave dark spot ultraviolet (UVA, wavelength 320 ~ 400nm), medium-wave red spot ultraviolet (UVB, wavelength 280 ~ 320nm), short-wave sterilization ultraviolet (UVC wavelength 200 ~ 280nm), the shorter the wavelength the greater the harm to the skin. UVC with a wavelength of 280nm or less is usually absorbed by the ozone layer and rarely radiates to the ground, while UVA and UVB are the most important components that cause skin damage. Among them, UVA accounts for about 99%, UVB accounts for about 1%. As you can see, in strong sunlight weather, especially in the summer, it is very important to do a good job of sun protection. The more you go out, the less you need sunscreen 2, only in summer, sunny days need sunscreen 3, before you go out and put on sunscreen can work all day 4, the greater the SPF value the better 5, shopping sites to stock up on a few thin sunscreen at low prices Sunscreen, you need to know 1, the greater the SPF, the worse the permeability, preventing Skin normal secretion whistle. 2, sunscreen 20 minutes before going out, and then again when going out; 2mg/cm2 each time; every 2 hours to wipe. 3, for water sports, it requires SPF, PA value is higher, and need its high fat solubility, to be able to longer resistance to water immersion. The radiation at the seaside is nearly 20 times more than in general, go swimming at the beach to use professional sunscreen oil. 4, the snow will reflect the sun, ultraviolet rays, so the snow also need to strengthen the sunscreen. 5, online shopping for cheap colorful sunscreen is often useless, and even sun protection is not as effective as the average dark T-shirt! Sun protection you need to follow the ABC principle A – avoid, avoid sunlight; B – block, blocking protection, C – cream, sunscreen. So sun protection is not just applying sunscreen and everything will be fine, the focus is to avoid the midday sun. Melasma and post-laser patients need more attention. There was a female patient who came to the clinic. One weekend in summer, she led her 8-year-old son to Nanjing “Water Magic Water Park” to play, and applied sunscreen to her face and neck, her front chest and her child’s whole body several times, while her back and shoulders were completely applied by her son with his small hands a few times. After half a day of fun, she came home at night and began to feel a hot sensation, and the parts exposed during the day were turning red. She looked at her son’s tender skin intact, and then looked at her own face, neck and forehead as well, so she rubbed on the repair cream and moisturizer and rested. But the next day, the red spot turned dark red, and many blisters on it, gently rubbing the red spot around the blisters, to tear off a thin layer of skin. She was so anxious that she didn’t expect it to be so serious, so she rushed to the hospital to seek help from Professor Dan Luo. After examination, she was diagnosed with second-degree sunburn and told her that it was a child’s failure to put sunscreen in place that caused the mother’s back flesh to suffer. She was advised not to tear the blistered skin to prevent infection. She was told to continue using repair creams and moisturizers, not to be irritated, and to apply a wet compress with cool, pure water, and add oral medication to treat it. Sunburn, also known as solar dermatitis, is an acute inflammation of the skin caused by intense sunlight exposure and is an acute phototoxic reaction that occurs on the skin due to excessive exposure to medium-wave ultraviolet light. It is mostly seen in late spring and early summer and can develop in everyone, especially light-skinned people, women and children. The peak onset of sunburn is mostly two or three days after water sports or highland desert activities, and healing is slow, and in some patients the condition may gradually worsen.