The selection and use of sunscreen A. Why do you need sunscreen? In short: one is to prevent sunburn, and the other is to prevent tanning. In addition, some photosensitive skin diseases need sunscreen, and some people use it to prevent skin cancer and photoaging. There are ultraviolet rays, visible light and infrared rays in sunlight, and it is the ultraviolet (UV) rays that cause sunburn, while the most important thing that works outside the purple line is UVB and UVA, with UVB acting more strongly. UVB is enhanced with altitude, and desert, ice and snow can greatly increase the reflection of UVB. Second, what are the main manifestations of sunburn? Sunburn can appear 6 hours after exposure to the sun and is most serious 12-24 hours later. The manifestation is erythema at the exposed area, with burning or painful sensation, blistering and edema may appear in serious cases, and a few may have fever, chill, nausea, hypotension, etc. The skin may appear flaking in about 1 week. The skin may appear tanned after sun exposure. According to the situation of sunburn and tanning skin can be divided into 6 types (I~VI), among which type I is most prone to sunburn and will not tan, while type VI is most prone to tanning and will not sunburn. Third, what can be done to prevent sunburn? 1.Avoid traveling in the middle of the day (10:00-14:00) 2.Find the shade of trees or buildings 3.Cloak and hat protection 4.Use sunscreen 4.What sunscreens are available? It can be divided into chemical sunscreen and physical sunscreen. Chemical sunscreen is to absorb UV rays and then emit the energy of UV rays in the form of heat, while physical sunscreen is like a mirror to reflect UV rays out, more suitable for sensitive skin, such as children mostly use physical sunscreen. With the same sunscreen index, both sunscreens are about as effective. Physical sunscreens are milder, but the more they contain, the heavier they are, and they tend to clog pores; while chemical sunscreens are more refreshing, but they tend to cause allergies. On the other hand, the higher the sunscreen factor contains more sunscreen ingredients, not only easy to cause pore blockage, the skin will also feel greasy and uncomfortable, because of the uncomfortable sense of burden caused by the willingness to use reduced, do not like to use every day or did not rub enough, but make the sunscreen effect is greatly reduced. Five, how to use sunscreen? (a) Choose the right SPF index. Sun Protection Index (Sun Protection Factor, SPF), is the ratio of the energy required to produce the smallest erythema on skin protected with sunscreen, and the energy required to produce the same degree of erythema on skin without any protection, simply put, it is the time multiple of skin against UV rays. The higher the SPF value, the greater the skin irritation. SPF 50 sunscreen products provide only 1% to 2% more protection than SPF 30 products. The most you need in summer is a sunscreen with an SPF value of 30 to 40. Oily skin is recommended to use a slightly lower SPF value, and dry skin can use a slightly higher one. 1, the general type of skin people, sunscreen index value to 8-12 appropriate; 2, people sensitive to light, sunscreen index value to 12-20 appropriate; 3, only on the way to and from work exposure to the sun’s office workers, sunscreen index value of 15 or less can be, to the face sunscreen; 4, in the field to play, beach swimming, sunscreen sunscreen index value to 30 or more. When swimming, it is best to use waterproof sunscreen skin care products. 5, children’s skin is very delicate, easy to sunburn, and sunburn time is short, so the general choice of children’s level of SPF50 or more sunscreen, about 500 minutes (10 minutes × SPF50) of sun protection time. Sun protection factor PA is a test index that measures the defense ability of sunscreen products against the sun’s ultraviolet UVA rays, the defense effect is distinguished into three levels, namely PA +, PA + + +, PA + + +, PA + + indicates effective, PA + + indicates quite effective, PA + + + indicates very effective. (B) according to skin type selection Oily skin: choose a water-based, oil-free formula sunscreen with strong penetration, and recognize the OilFree (oil-free) logo on the outer packaging. Never use sunscreen oil, and use caution with physical sunscreen products. You can apply the product on the back of your hand or tiger’s mouth, if the skin can be quickly absorbed, no sticky feeling, whitening feeling, and no oily feeling, it is basically a qualified and refreshing sunscreen. Oily skin skin care before using sunscreen to use the oil control series of skin care products to regulate the skin pores, oil and other states, daily clean skin is particularly important. Acne skin: If the skin is more oily and prone to acne, you should choose a refreshing and penetrating lotion-like products, water-based and oil-free formulations of sunscreen, but when acne is serious and inflammation is present to suspend the use of sunscreen and turn to physical methods of sun protection by shading. The sunscreen must also be used before the acne skin care to control acne skin conditioning, and apply sunscreen to light, thin as the main point, first in the hand spread open, and then hands evenly pressed on the face can be. Dry skin: to use the texture of nourishing, and added hydrating effect and antioxidant sunscreen. Before using sunscreen, you should do a good job of moisturizing and adjusting the oil balance of your skin, and using a moisturizing mask after sun exposure is also important. Sensitive skin: choose sunscreens that are professionally formulated for sensitive skin, pick a plant-based sunscreen or a physical sunscreen that contains titanium dioxide, or a product description that clearly states “allergy tested”, “fragrance-free, preservative-free”, etc. The words Mixing can increase the likelihood of skin irritation. The ingredients of each brand of sunscreen are inconsistent, and if mixed and overlapped on the skin, it may cause the ingredients to interfere or repel each other, reducing the effectiveness of sunscreen and even causing skin allergies. (C) the use of the method must be wiped in advance 30 minutes before leaving home, before leaving home in a supplement, the use of the dose, each cm2 must have at least 1 ~ 2ml of the amount to achieve the best isolation effect. In the day is not when you go out to wipe once sunscreen is foolproof, sweating must be replenished rub. Chemical sunscreens are best reapplied every 4 hours. Six, how to treat sunburn? Cold compresses can be applied, and if necessary, antipyretic and analgesic drugs (NSAIDS) and medium-acting hormone therapy are given, and severe patients are treated symptomatically.