Many people pay attention to sun protection only in summer, this perception is wrong, regardless of spring, summer, autumn and winter to do sun protection measures. Nowadays, people are also becoming aware of the harmful effects of UV rays on the skin. Short-term medium-wave UV radiation can lead to sunburn, and long-term medium-wave UV radiation can easily induce skin cancer. Long-wave UV can damage the collagen and elastic fibers of our skin’s dermis, accelerating photoaging of the skin. Why does skin peeling occur after sun exposure? Peeling after sun exposure is related to the dysfunctional state of the stratum corneum’s barrier function. UV radiation completely inhibits the metabolism of natural moisturizing factor (NMF) in keratinocytes, causing a section of the lower stratum corneum that is completely deficient in NMF intracellularly. It disrupts the normal physiological process of migration of the stratum corneum to the surface and causes premature exfoliation of the stratum corneum. In addition, UV radiation reduces the activity of antioxidant enzymes in the stratum corneum, causing oxidative degeneration of linoleic acid and cholesterol in the stratum corneum, which directly affects the normal barrier function of the stratum corneum. Even if you are not exposed to the sun, long-term lack of sun protection will result in certain dryness of the skin, such as roughness, dullness, and lack of luster, all of which are caused by stratum corneum dysregulation. Without sun protection, do you really accelerate aging? After a few hours in the sun, the epidermal stratum corneum will change due to UV radiation, and in the following days, rapid division and growth will occur, as if the outermost layer of the epidermis is thickened to four times its original size. This thickened epidermis absorbs some of the UV rays and converts them into mature energy and spreads them to the surrounding cells, thus reducing the UV rays from entering the fragile skin cells for destruction. After 12 hours of exposure to the sun, the UV rays expand the microvessels, resulting in the destruction of blood vessel fibers and the production of erythema. The skin may become edematous after the production of erythema, which directly affects the fibroblasts and for a long time will lead to the formation of permanent destruction of collagen and elastin fibers, resulting in wrinkles and loss of elasticity of the skin before aging. In addition, if long-wave UV rays enter the dermis, it will also lead to the loosening of the reticular tissue, destroying the original water retention capacity of the skin, causing the skin to dry out and then loosen up and form wrinkles and aging phenomena. Sunscreen skin care products, how should you choose? In daily life, it is recommended to combine physical sun protection with chemical sun protection to achieve the best sun protection effect. In terms of physical sun protection, sunshades, sun hats, sunscreen clothing and so on are good choices. Chemical sunscreen can be used to carry out sunscreen products. For the choice of sunscreen products many people think that the higher the sun protection index the better, which is wrong. Generally speaking, when indoors, it is appropriate to use sun protection factor (SPF) in about 10, UVA protection level (PA) + sunscreen skin care products; when outdoors, it is appropriate to use SPF in about 20, PA + + + sunscreen skin care products; at the beach, or other exposure to the sun, it is appropriate to use SPF in about 30, PA + + + sunscreen skin care products. Good sunscreen skin care products on the market today are long-lasting, safe and stable, and can achieve the ideal sunscreen effect.