In fact, there are two kinds of ultraviolet rays that are easy to harm the skin, UVA and UVB. Generally speaking, the SPF value in sunscreen refers to the ability of sunscreen to protect UVB. UVB can cause sunburn, but UVA can also cause skin aging and damage deep cells of skin. Therefore, in order to avoid all ultraviolet rays on the skin, you should choose a sunscreen that can prevent UVA and UVB at the same time. Myth 2: You only need to apply sunscreen once a day. Every time you apply sunscreen, let your skin have half an hour to absorb it before going out, but that doesn't mean that these sunscreen absorbed by your skin can protect you from ultraviolet rays all day. You should apply sunscreen at least every two hours, especially after swimming, even if you use waterproof sunscreen. Children's skin is more vulnerable to the sun, so they need extra protection. Experts believe that excessive sun exposure in childhood will greatly increase the possibility of skin cancer in the future. Myth 3: Don't worry about exposure on cloudy days. This is a misunderstanding that many people will fall into. In fact, most of the ultraviolet rays in the sun can penetrate the thin clouds. If the clouds are thick, they can only provide a certain degree of protection. Myth 4: All sunglasses will protect your eyes from harmful light. Not all sunglasses can protect eyes from ultraviolet rays. Some sunglasses designed for fashion are purely for display, so make sure your sunglasses have this effect. Myth 5: Low SPF sunscreen is also useful. If the SPF of sunscreen is lower than 15, it will not have much sunscreen effect. Pay attention to the regular use of sunscreen with SPF exceeding 15. Sunscreen also has a shelf life. Pay attention to check the expiration date on the bottle. Most sunscreens have a shelf life of 2 to 3 years. Myth 6: You can get a healthy body color without sun protection. It is impossible to be healthy without sunscreen. Black skin color is a warning that the sun is hurting your skin. UVA ultraviolet rays can cause skin aging and wrinkles, while UVB ultraviolet rays can cause deeper sunburn. Myth 7: Wearing a T-shirt while swimming can protect your skin from sunburn. Although wet T-shirts can provide some protection for your skin, wet clothes absorb ultraviolet rays more easily than dry clothes. If you are going to swim in a T-shirt, please be sure to bring a dry dress so that you can change it at any time. Myth 8: You don't need sun protection on a cold mountain top. In fact, the higher the altitude, the stronger the sunshine, so although you may feel cooler at the top of the mountain, your skin will get sunburned faster. It is best to wear long-sleeved clothes to cover your skin, a hat and sunglasses, sunscreen on your face, and protective cream on your lips, nose and ears.