SPF15 is for 2 hours of sunscreen ~ so you need to wipe every 2 hours ~ to wipe it 20 minutes before going out ~~ , but if it is a general daily life, use SPF15 to use SPF15. (It is recommended that you use waterproof ~ relatively easy to use) SPF30 can be sunscreen for 4 hours, for outdoor activities ~ like swimming ...
How to choose sunscreen
Is to choose a suitable sunscreen before the summer comes, so that the delicate skin is free of sunlight. So, how to choose sunscreen? 1. It is recommended to do an accurate skin test before buying sunscreen. Oily skin should choose water -based sunscreen products with strong penetration; dry skin should choose frost -like sunscreens; neutral skin generally does not strictly regulate, and lotion sunscreen is suitable for various skin use. 2. Calculate the SPF value. Generally speaking, the higher the SPF index, the greater the protection given. In general, people with ordinary skin colors should be based on SPF8 to 12; fair skin is recommended to choose SPF30 sunscreen; for people with allergies, the SPF value should be selected from 12 to 20. 3, understand the applicable population of different sunscreens. Different sunscreen products have different applications. The best way is to try on the inside of your wrist before buying. If the skin is red, swollen, painful, and itching within 10 minutes, it means that you have an allergic reaction to this product, you can try to try a product that is one times lower than this sunscreen index. If there is a response, it is best to give up the brand's sunscreen.
The view of the sunscreen index SPF
SPF value is the main content of each bottle of sunscreen. The true meaning of the SPF value seems to be too formal and it is difficult to understand. The scientific sunscreen index refers to the ratio of energy required to generate minimum erythema on the skin with sunscreen protection and the energy required to generate the same degree on the same degree on the skin that is not added with any protection. Time multiple.
For the yellow race, it is calculated like this: Generally, the skin of the yellow race can resist the sunlight for 15 minutes without being burned. Dim sunscreen time. Objectively speaking, the height of the sun protection index reflects the size of the ultraviolet protection capacity of sunscreen products. The higher the SPF index, the greater the protection given, but the growth of the SPF value is not proportional to the ability of the screen to block ultraviolet rays.
Generally speaking, the sunscreen index of the lowest sunscreen is SPF2 to 6, the middle sunscreen is SPF6 to 8, the high sunscreen is SPF8 to 12, the SPF value is within 12 to 20 range For high -strengthening sunscreen products, products with SPF values between 20 and 30 are ultra -high -strength sunscreen products. However, because there are many people who like to expose sun -exposed in the sun abroad, the design sun protection product index is relatively high, and some even reach SPF80.
The see the sunscreen index PA
Science has confirmed that UVA -1 is a murderer who causes skin aging. "To indicate defense strength. The correct saying is of UVA -1. Its degree is marked with three intensity of , , . The more " ", the better the effect of UVA.
In careful observation of sunscreens sold on the market, you will find that many sunscreens are not only SPF values, and some also clearly marked the PA value. Because SPF is targeted at UVB ultraviolet rays, that is to say, it can only defend 1 % of the total ultraviolet of the ground, but it is powerless to the real sunny killer UVA. Therefore, the sunscreen of UVA will play a more effective role, and the products marked with PA have such functions to reach the bottom of the leather in the shortest time to prevent ultraviolet damage to elastic fibers and cause skin aging.
Generally, the strength of the PA is represented by , and one more indicates that the effective protection time is prolonged. Specifically:
PA effective protection time is about 4 hours.
PA The effective protection time is about 8 hours.
pa super strong protection.
This: How to choose the right SPF value 1. People with general types of skin should be 8-12; 2. For those who are sensitive to light, the SPF value should be 12-20; 3. Sensitive skin should choose sunscreen products or physical sunscreen containing titanium dioxide. 4. For office workers who are in contact with the sun on the way to get off work, the SPF value is below 15, mainly sunscreen on the face; 5. When playing in the wild and swimming in the sea, the SPF value of the sunscreen is above 30. It is best to use waterproof sunscreen skin and skin care products when swimming.
Many sunscreens on the market are marked with SPF values. Miss promotion will tell you that the higher this value, the stronger the sun protection effect. So what does SPF mean? SPF is the English abbreviation of the sunscreen factor (SUN
Factor), indicating that the sunscreen efficiency can be exerted by sunscreen supplies. It is determined based on the lowest erythema dose of the skin. The skin becomes red after sun exposure. Medicine is called "erythema disease", which is the most slightly reaction made by the skin to the sun. The minimum erythema dose is the shortest day of the skin when the skin appears in erythema. After using sunscreen, the lowest erythema dose of the skin will increase, so the sunscreen coefficient SPF of the sunscreen supplies is: SPF = minimum erythema dose (after sunscreen)/minimum erythema dose (before sunscreen) The minimum erythema dose of someone's skin is 15 minutes, so after using SPF to 4 sunscreen, theoretically stay in the sun for 4 times (60 minutes), and the skin will be reddish; if you choose sunscreen with SPF 8 to 8 Frost, you can stay in the sun for 8 times (that is, 120 minutes). SPF is the index of sunscreen effects that are widely used in the world. It is generally determined by human skin tests or other methods abroad. At present, my country has not yet established standards for determining SPF values. This experiment uses another internationally evaluating sunscreen effect -spectrum method. It evaluates the sunscreen effect of sunscreen by determining the absorption of the sample sample absorption and reflecting ultraviolet capacity (OD). 1. When buying sunscreen, pay attention to the SPF value, which is to prevent UVB rays. The higher the SPF value, the better the skin is "breathing". Some people will be allergic. It is enough to use the SPF value in Guangzhou as long as 15 to 25. When choosing sunscreen products, pay attention to prevent UVA rays. Preventing this ray indicator is represented by PA, the more sunscreen effect, the better. 2, when did you apply sunscreen: Arrange it 15 minutes before going out, and after 15 minutes after the sunscreen oil is wiped. 3, all parts of the body should be wiped, especially in places with strong ultraviolet rays. 4. Apply sunscreen on the back of the hand and sprinkle with water.
UVA/UVB/UVC is divided into UVA/UVB/UVC, and almost all of the UVC reaches the atmosphere is absorbed and refracted, so it is not harmful to people. UVB is directly shot on the ground, UVA can reflect, then you think about the physical physics learned in junior high school and high school. Essence UVA is a wave. When refracted, it will weaken, so you can use SPF15 and 20 when you are indoors, because it is not all shot indoors, and it is also absorbed or refracted by indoor objects. Repeated refraction is repeatedly refracted. It will be greatly weakened. rnrn紫外线的强度并不是都一样，这里我又要说地理了，冬季的时候地球发生偏转，而且离太阳较远，所以紫外线就比较弱，而SPF只是防护时间，但It is also necessary to look at the intensity of ultraviolet rays.
The summer scorching sun, that is, outdoor. People with common sense know that it must be used more than 30 times more than 2 hours of outdoor activities. The increase in temperature has caused sunscreen products to lose protection due to high fever, so it should be supplemented once every 2 hours. If it is only a few tens of minutes of work and class time, a lot of time is indoors, you can choose 20. If you choose 30 , you can protect it for one day. Why did I have mentioned the first point?
Hello, I know that my medicine makeup and skin consultant is very happy to help you. Dear, choose sun protection from the SPF value, refer to the following experience: SPF is designed according to the role of sunscreen agent on UVB. Although the high SPF value means that the protection time for UVB is longer, but and and and and. It does not mean that it has the same effect on UVA. UVA is the main cause of dermal glue fiber damage, skin aging, and wrinkles. Even if the SPF value is higher, it cannot guarantee safety. Correct usage: SPF5-8 sunscreen supplies can be selected for daily care or shopping. SPF10-15 sunscreen supplies can be used when going out. Waterproof sunscreen supplies with SPF20-30 when swimming or making sunbathing. 1.2 1. The sunscreen multiple (SPF) of sunscreen (SPF) according to the intensity of ultraviolet rays. In summer, the ultraviolet rays are relatively strong. You must choose sunscreen with higher sunscreen multiples (recommended SPF> 30); sunscreen with lower multiples in winter (SPF10-15 is recommended). 2. The sunscreen should be selected according to the amount of outdoor activities. If it is an outdoor worker, or for a long time for outdoor activities, it is recommended to use sunscreen with higher sunscreen multiple (SPF> 30); otherwise, you can choose a sunscreen with a lower multiple (SPF10-15). 3. S selection sunscreen according to the sensitivity of the skin. If the skin is sensitive, you need to choose a physical sunscreen. In addition, children, pregnant women and elderly are also best to choose physical sunscreen. 4. If you go to swim outdoors, you need to choose waterproof sunscreen. Every time you go ashore, you need to re -apply. If Note · Several misunderstandings during the use of sunscreen: SPF value, the better, the better the sunscreen can be used before applying, the thicker the better (how thick the sunscreen is applied?) 1: Skin care order during skin care The sunscreen can be used before applying makeup, which can better ensure that it is close to the skin cells that need to be protected. Correct usage: After cleansing in the morning, spray the toner and apply the moisturizing lotion, you can apply sunscreen. 2: The sunscreen should be coated with a lot of thickness The sunscreen must be effective to achieve a certain thickness. Too thick will cause burden on the skin. Correct usage: If you want to achieve the sun protection effect, apply 2-2.5 grams at a time, and you should apply 1-1.5 grams at a time. The amount of sunscreen is more than the cream, at least one yuan coin size. 3: How to use the differently used cream with different SPF values SPF is designed according to the role of sunscreen. Although the high SPF value means that the protection time for UVB is longer, it does not mean that it does not mean that it does not mean It has the same effect on UVA. UVA is the main cause of dermal glue fiber damage, skin aging, and wrinkles. Even if the SPF value is higher, it cannot guarantee safety. Correct usage: SPF5-8 sunscreen supplies can be selected for daily care or shopping. SPF10-15 sunscreen supplies can be used when going out. Waterproof sunscreen supplies with SPF20-30 when swimming or making sunbathing. Inned skin problems Welcome to know the platform of the medicine skin and skin expert platform, or go to the official website of the cosmeceutical website for online consultation
If you are only 25 years old and not exposed to the sun, you can use 15 usual. Do not use 30 that too high, it is easy to cause skin aging 2 ··· It is the same as cosmetics. The face is somewhat exciting
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