Summer is here and sunscreen has become a topic of concern. Some people have asked: There is zinc oxide ointment in hospitals, and I heard that zinc oxide is a physical sunscreen, so is it possible to use zinc oxide ointment as a sunscreen? Others asked: What kind of sunscreen is good to buy? My skin is allergic, and I get red when I’m in the sun, so what should I do? I’m here to answer all of your questions. A, ultraviolet and photoaging UVB is divided into three categories according to the wavelength range UVA, UVB and UVC, UVC is called a short-wave ultraviolet, and our sunscreen behavior is not relevant, not discussed here; UVB is called medium-wave ultraviolet, wavelength range 320-280nm, penetrating power is weak, only the role of the skin shallow, is considered the main factor of sunburn; UVA is called long-wave ultraviolet. Wavelength range 400-320nm, strong penetrating power, can pass through the glass, directly on the skin and subcutaneous tissue, damage collagen and elastin, resulting in skin slackening, wrinkles, pigmentation and other aging phenomena, so that UVA and aging close relationship (UVA caused by skin aging is called photoaging). Second, sunscreen ingredients Sunscreen ingredients are divided into two categories, one is called chemical UV absorbers, the other is called physical UV shielding agents. The sunscreen principle of chemical UV absorbers is to protect the skin by continuously absorbing UV light. Octisalate (octyl salicylate) protection band 290-320nm, Octinoxate (OMC) protection band 290-320nm, Octocrylene (Octocrylene), water-soluble broad-spectrum UV absorber, which can absorb both UVA and UVB, is the FDA-approved Class I sunscreen. It is a Class I sunscreen approved by the U.S. FDA; Avobenzone is one of the few ingredients that can have defensive properties in the 380-400nm band, MexorylSX and MexorylXL sunscreen band 290-390nm, which are newer UVA sunscreens and one of the safest and most effective UVA sunscreens available today, approved by the U.S. FDA It is one of the safest and most effective UVA sunscreens available today and is FDA approved. The above protective ingredients cannot be used alone, but at least two ingredients must be used at the same time to achieve the purpose of UVA and UVB protection at the same time, which is the perfect protection. Physical UV shielding agent mechanism of action is to reduce UV damage to the skin through scattering, is a physical sunscreen, mostly inorganic powder, such as titanium dioxide, zinc oxide, iron oxide, talc, etc., of which titanium dioxide and zinc oxide have been listed by the U.S. FDA as approved for use in the list of sunscreen agents. Titanium dioxide and zinc oxide are the two main ingredients, both of which are hardly absorbed by the skin and are highly safe, but the disadvantage is that they will turn white when applied to the skin, and too much use will clog skin pores and cause acne and dermatitis. Nowadays, micronized zinc oxide technology and flat zinc oxide technology have emerged. Micronized zinc oxide technology means that ordinary zinc oxide is made into micron-sized particles, which reduces the heaviness of zinc oxide and does not turn white when applied on the face, and at the same time can resist UV rays like zinc oxide, but there are several studies that show that the smaller the particles of micronized zinc oxide, the more likely it is to be absorbed by the capillaries and enter the The smaller the particle size, the more likely it is to be absorbed by capillaries and enter the bloodstream, thus indirectly affecting human cells and possibly even generating toxicity, making its safety controversial. Flat zinc oxide technology is the treatment of zinc oxide into a flat sheet, can avoid the sunscreen powder overlap to together, greatly reducing the gap of the sunscreen film; can be evenly coated distribution, more delicate texture, higher transparency, can reduce the whitening phenomenon, sunscreen ability increased by 1.6 times, is the industry’s leading physical sunscreen technology. Third, the sunscreen formula To achieve a better sunscreen effect, compounding the use of sunscreen ingredients is more common. The combination not only overcomes the shortcomings of a single sunscreen ingredient in the broad spectrum and sunscreen effect, but also gives better play to the synergistic and complementary effects between multiple sunscreen ingredients, while reducing the possible irritation of the product on the skin. The best quality sunscreen products contain not only the best performing sunscreen ingredients, but also other ingredients to make the product suitable for different skin needs. Sunscreen products for sensitive skin usually add soft skin-friendly synthetic esters and silicones to give the product a warm and comfortable texture; add fatty acids, glutathione and lecithin to simulate the skin’s natural repair barrier, improve the sebaceous film of sensitive skin, improve hydration, moisturizing ingredients can also have a synergistic effect with UV absorbers; add a small amount of antioxidants and calming ingredients to reduce skin sensitivity to the product. The small amount of antioxidants and calming ingredients reduces skin sensitivity to the product. “No-add” sunscreen products use moisturizing ingredients polyol to produce antiseptic effects, effectively eliminating the use of preservatives and making the product safer and less irritating. There are products that add film-forming polymers to form a solid protective film, both to maintain the protective effect, but also to reduce chemical sunscreen penetration into the skin to produce side effects, but also to produce a waterproof effect; with nylon powder or mineral powder adsorption oil can improve the product’s sunscreen staying power, making it more suitable for oily skin in the spring and summer. Fourth, sunscreen misconceptions physical sunscreen than chemical sunscreen good this statement is really some absolute, now sunscreen products are purely physical sunscreen, the main focus is safe, but can not be separated from the “oil, thick, white”, if oily skin absolutely can not be used; some are a combination of physical and chemical sunscreen, adapt to a wider range; there are separate The actual sunscreen product is chemical, both light and comfortable, and full frequency protection. In short, to take into account the composition and skin feel, suitable for their own is good. The higher the multiplier, the more stimulating it is to measure the irritation of the sunscreen products on the skin, mainly depending on the ingredients chosen, good safety sunscreen ingredients, with the appropriate moisturizing ingredients, and the necessary calming and soothing ingredients, such products are high times, the chances of stimulating the skin are not high. On the contrary, the choice of cheap poor safety sunscreen ingredients, even if it is low multiples, will also stimulate the skin. The whiter the product, the better the effect of sunscreen products color is mainly determined by the physical sunscreen ingredients, the more physical sunscreen ingredients, the whiteness of the product will increase accordingly, but the sunscreen effect is determined by the sunscreen multiplier, product usage and other factors together, the same color case, the physical sunscreen multiplier is generally lower than the chemical sunscreen ingredients products, but the measurement of sunscreen effect is a comprehensive The process of evaluation, not simply by the color can make the right judgment. Nanoparticles are not safe when it comes to safe sunscreens, the first choice is definitely the main physical sunscreen ingredients, then the color white is the biggest factor affecting the development of zinc oxide, for example, precisely because zinc oxide particles are very large will scatter all the light, and therefore appear white, as the particles become smaller and smaller, the white will become lighter and lighter, the wavelength of UVA is 320-400nm, if the zinc oxide particles less than 400 The wavelength of UVA is 320-400nm, if the zinc oxide particles are less than 400nm, it is close to “transparent”, but it loses its sunscreen effect. The patented Z-cote product also does not say nano-sized (nano-level) products, even the flat zinc oxide technology mentioned earlier, it is difficult to transdermal absorption, so since the so-called “nano-particles” do not exist, it does not matter whether it is safe or not. No special seaside products in the seaside and other locations for water activities when the use of sunscreen products, in addition to SPF times enough, but also through the U.S. FDA 80min waterproof test, the logo is “verywaterresistance”, this special test shows that after 80 minutes in the water still retains the label SPF value half of the effectiveness; if the logo is “for waterresistance”, it is to indicate that passed the U.S. FDA 40min test, which represents the product has a certain waterproof effect. Even so, it is necessary to reapply sunscreen products after 2 hours. Sunscreen is only used in summer, as mentioned before, UVA time is the “culprit” of aging, so in order to anti-aging, it is necessary to use sunscreen products 365 days a year without interruption, in clinical work, I have three requirements for melasma patients sunscreen, referred to as “three numbers “In my clinical work, I have three requirements for melasma patients: days (365 days a year without interruption), times (once in the morning and once at noon, because the products used in the morning will fall off or degrade at noon, making the sunscreen effect discounted and must be replenished in time), and degrees (above SPF30, above PA++).