As the weather heats up, sun protection is gradually becoming a concern for the majority of women. So what exactly are UV rays? How do I protect myself from the sun? UVB is a part of sunlight, including UVA, UVB and UVC three kinds of rays, they have different effects on the skin. uva, also known as tanning section, it is the most important cause of premature aging of the skin, can reach the human dermis, although it does not cause acute inflammation of the skin, but it can penetrate the epidermis to the bottom layer of the skin and latent, over time will cause premature aging of the skin, epidermal roughness, wrinkles and spots, muscle sagging, sagging. UVB, also known as the sun red segment, penetrates up to the epidermis of the human body and is the main band of sunburned skin, which can cause skin redness and pain in mild cases and blistering and peeling in severe cases. UVC, also known as germicidal segment, transmits only to the stratum corneum of the skin, and most of it is retained by the atmosphere and does not cause harm to human skin. There are two main methods of sun protection. One is through umbrellas, sun hats and other methods, and one is to apply sunscreen cosmetics. In fact, UVA can pass through ordinary glass, and sunshades can only isolate UVB that can give a burning sensation, while UVA can penetrate without difficulty. Therefore, it is best to combine both methods to protect yourself from the sun. SPF is the Sun Protection Factor, which is a multiple of the time it takes for a cosmetic product to prolong the redness of the skin caused by the sun. Generally, it is appropriate to choose an SPF value of 12-20. If you work in the field, travel and seaside, you should use products with SPF value of 20 or more. Some people think that the higher the sun protection index, the more sun protection can improve the effect, which is wrong. The sunscreen index is too high cosmetics easy to block pores, is not conducive to sweating, causing excessive burden on the skin, so rub on will feel discomfort, and is not suitable for daily use. The correct approach is to use supplies with different sun protection indices for different occasions and for different requirements. UVB is not only the culprit of skin tanning and sunburn, UVB is also a “killer” that can not be ignored, which can make the skin allergic, spots, so choose both UVA and UVB sunscreen is the best sunscreen. Sunscreens are not applied once to maintain a day, because sunscreen will fail after 3 to 4 hours in the sun. In addition, skin sweat or encounter moisture, etc., will accelerate the failure of sunscreen cream, in order to improve the effect of sunscreen, can be applied again after 3 ~ 4 hours, such as a long time in the sun, should be rubbed every hour. If you apply sunscreen cream and then apply foundation or apply thin powder, the effect of sunscreen is better. Sunscreens should be applied after skin care products because moisturizers are fat soluble and if covered with sunscreens will dilute or dissolve the sunscreen ingredients, rendering the sunscreen useless. We don’t only need to use sunscreens when the sun is strong. In fact, the sun’s ultraviolet rays are present even on cloudy days and in cloudy weather, so it is important to protect yourself from the sun at all times. In seasons other than summer, UV rays can also take away skin moisture and damage skin tissue, so sun protection is a year-round task. Some people think that sun protection is only for older people. In fact, younger skin is more susceptible to UV damage than older skin, but the accumulated damage only shows up when you are older, such as discoloration and wrinkles, so sun protection is a concern from early childhood.