How To Practice The Most Effective Sun Protection?
2. Why Does Sunlight Cause Aging?
3. How Do Ultraviolet Rays Harm Our Skin And Body?
4. How To Protect The Skin From The UV?
5. What Is The Meaning of SPF on Sunscreen?
6. How Does Sunscreen Block UV Rays?
7. Inorganic Sunscreen
8. Organic Sunscreen
9. How Should I Choose A Sunscreen?
10. How To Use Sunscreen?
11. Sunscreen Must Be Combined With Antioxidant
12. Do I Have To Remove Makeup When Using Sunscreen
13. What If I Can’t Remember All These Suncreen Tips And Sun-Screening Agents
Why You Need Sun Protection?
The purpose of sun protection is to delay aging. The process from birth to natural death is an aging process. Aging is a comprehensive phenomenon of the entire human body, and skin changes are only one aspect of it.
The classic photoaging case is the face of the driver who has been driving a truck for 28 years. Half of his face by the window of the car has been exposed to the sun for a long time, which not only produces deep wrinkles, but also severe skin hyperplasia.
Skin aging is a series of comprehensive phenomena, including wrinkles, darkening, dullness, sagging, shriveling, freckles, and so on.
The causes of aging can be divided into intrinsic causes and extrinsic causes.
The intrinsic cause is because the number of cell divisions is limited. When the number of cell divisions reaches the limit, the cell will die. But intrinsic aging is not the main factor leading to aging. The more important aging factor is extrinsic factors, which is the harm of the environment to the human body.
Among the many extrinsic causes, ultraviolet rays have the greatest impact on skin aging. Sun protection is not only to prevent the skin from being tanned but to delay aging as much as possible.
Aging is a comprehensive manifestation of the body. It does not only affect the beauty of the skin but also damages other organs and functions of the body.
Why Does Sunlight Cause Aging?
The light visible to the naked eye can be divided into seven kinds of light visible the naked eye: red, orange, yellow, green, blue, indigo, and purple. In this spectrum, light invisible to the naked eye other than red light is called infrared rays, and light invisible to the naked eye other than purple light is called ultraviolet rays.
Sun protection is to prevent ultraviolet rays from harming the human body.
Ultraviolet rays can be divided into 3 types according to wavelength:
UVC, the wavelength is between 100nm～280nm.
UVB, the wavelength is between 280nm～320nm.
UVA, the wavelength is between 320nm and 400nm, where 320-340nm is the UVA-II, and 340-400nm is the UVA-I.
The ozonosphere above the earth can block UVC, and only UVB and UVA can reach the ground. We mainly prevent is the damage of UVB and UVA.
UVB can cause sunburn and skin sensitivity. The penetration of UVB is weak, usually, clothes, hats, woods, etc. can block UVB.
UVA can cause tanning, decrease in collagen, skin aging, and even skin cancer. UVA has strong penetrating power, ordinary clothes, hats, and glasses cannot completely block the invasion of UVA, and the carcinogenicity of UVA is the strongest of the three types of ultraviolet rays.
How Do Ultraviolet Rays Harm Our Skin And Body?
Ultraviolet rays will activate matrix metalloproteinases in the skin, which will degrade a large amount of collagen and elastin in the skin, causing collagen fibers to lose their elasticity and become loose and weak, and eventually, wrinkles are formed.
There are UVA and UVB in ultraviolet rays. UVB will disturb the order of DNA in cells, while UVA will promote the formation of free radicals, thereby destroying the integrity of the DNA chain. Both of these attacks will make the skin helpless, lose its ability to repair and save itself, and accelerate aging.
UVB is a more direct threat to skin cell genes. It will disrupt the order of DNA in cells and destroy the integrity of the DNA double helix structure. Makes DNA unable to replicate, unable to produce new healthy cells and collagen.
UVA has stronger penetrating power than UVB. Part of UVA can also reach the dermis, deform collagen and cause skin aging. UVA can also induce the formation of free radicals, damage healthy cells, and produce inflammatory reactions, which can cause DNA double helix structure breakage in severe cases.
If we do not protect ourselves from the UV, we will age faster. Although after millions of years of evolution, the human body has long evolved a body protection mechanism against photoaging, which is melanin.
Melanin is a self-protection mechanism of the human body, which is used to absorb ultraviolet rays to prevent ultraviolet rays from harming the skin. This is why the greater the exposure to light, the more melanin is produced and the darker the skin.
But now that many people pursue whitening, they will find ways to remove melanin, which is equivalent to removing their protective umbrella. If you do not strengthen sun protection in this case, you are prone to skin cancer.
According to a report by SkinCancer.com, Americans over 70 years old have a 20% chance of getting skin cancer, and ultraviolet rays are the most important factor.
How To Protect The Skin From The UV?
Ultraviolet rays attack the skin in various ways, and the UV block must be comprehensive, and can not let go of any wavelength of ultraviolet rays, especially the strong penetrating and destructive UVA.
It is often difficult to achieve broad-spectrum sun protection with a single sun protection method, and sun protection requires multiple measures.
If you stay indoors most of your working hours, just use blackout curtains to block most ultraviolet rays. On the way to work, you can use only parasols, sun protection clothing, sun hats, etc.
But if you stay outdoors for a long time, you need not only umbrellas and sun hats, but also sunscreen.
Parasols, hats, masks, and glass cannot block all ultraviolet rays. The main function of sunscreen is to block ultraviolet rays that cannot be blocked by parasols. Therefore, sun protection is a very systematic project. The order of importance is “not exposed to the sun> less exposed to the sun > parasol, sun hat > sunscreen”.
The ultraviolet rays that directly hit the human body are blocked by the parasol, but the sunlight that hits the ground will be reflected on your face. And the whiter the material, the stronger the reflectivity of sunlight, for example, the reflectivity of snow to ultraviolet rays is as high as 80%.
What Is The Meaning of SPF on Sunscreen?
A sunscreen has different protection ability against UVA and UVB, so the protection index of UVA and UVB should be labeled separately.
SPF is used to represent the protection score for UVB. The higher the value of SPF, the stronger the protection against UVB, and the longer the duration. This is universal.
For example, if your skin reddens after 1 minute in the sun without sunscreen. After applying SPF30 sunscreen, the skin will be red after 30 minutes in the sun.
The scoring standards for UVA are somewhat different in different regions.
The EU uses the Protection Factor of UVA (PFA) to indicate the ability of sunscreen products to protect against UVA. The EU requires that only the PFA value of sunscreen products is greater than 1/3 of the SPF value before the UVA protection label can appear on the package. For example, for a sunscreen with SPF 50, the PFA value must be greater than 17.
For example, if the PFA of a sunscreen product is 10, after using it in the open air for 10 minutes, it is theoretically equivalent to 1 minute without sunscreen.
Asia is represented by PA and +. From PA+ to PA++++, the more +, the stronger the protection against UVA. The relationship between PFA value and PA is shown in the figure.
The US version of sunscreen products does not indicate the ability of UVA protection, only whether it can protect against UVA. If the UVA absorption value of a sunscreen accounts for more than 10% of the total UV absorption value, and SPF>15, the broad spectrum can be marked on the product. But you don’t know how strong the UVA protection is.
SPF ≥ 15 in fall and winter.
SPF ≥ 30 in spring and summer.
Stay outdoors for a long time, hot sun exposure SPF ≥ 50.
A higher SPF value will not cause stress on the skin, and the safety of sunscreen is only related to the safety of sun-screening agents. Sunscreens with high safety and high SPF put less pressure on the skin than sunscreens with low safety and low SPF.
How Does Sunscreen Block UV Rays?
What works in sunscreen is the sunscreen agent. Sunscreen can be divided into inorganic sunscreen and organic sunscreen. They can reflect or absorb different wavelengths of ultraviolet rays.
Each sun-screening agent can only filter out specific wavelengths of ultraviolet rays. For example, in the picture above, the sun-screening agent can absorb ultraviolet rays with a wavelength of 330nm~370nm. The curve reaches a peak near 357nm, which means that the sun-screening agent absorbs UV rays around 357nm most efficiently.
There are only two types of the inorganic sun-screening agent on the earth, namely titanium dioxide and zinc oxide.
Their advantage is that they are very stable and form a protective film on your face, whose main function is to reflect or absorb ultraviolet rays. These two sun-screening agents will not produce adverse reactions on your skin and will not cause skin irritation, so they are very suitable for sensitive skin, pregnant women, or infants who need to apply sunscreen.
However, due to the development of modern technology, the production technology of zinc oxide and titanium dioxide is no longer the level of a hundred years ago. Modern technology can make nano-level zinc oxide. Sunscreen particles of this size may penetrate the skin and cause toxic side effects.
The disadvantage of titanium dioxide and zinc oxide is that to achieve a higher level of protection, the added amount should be relatively high. One of the big drawbacks of adding too high an amount is that they tend to have a significant white cast, which is when the sunscreen leaves a white layer on your skin. Unless some companies will add some colorants to harmonize the color of inorganic sunscreens.
Inorganic sun-screening agents have high technical requirements, and it is difficult to achieve a high sun protection factor only by relying on inorganic sun-screening agents.
Although zinc oxide is a broad-spectrum sun-screening agent, its absorption rate of ultraviolet rays is not high.
Titanium dioxide has obvious loopholes in the UVA wavelength, and it needs to be added in sufficient amounts and technical support to achieve a high sun protection factor.
Sunscreens with more inorganic sun-screening agents have a bad skin feel.
Zinc oxide is often added to baby skincare products because it has a certain antibacterial function, so acne patients are also recommended to use inorganic sunscreen, which can inhibit Propionibacterium acnes and Staphylococcus aureus on your face.
Organic sunscreen has a good skin feel, a wide range of protection wavelengths, a variety of types, and easy selection. There will be no white cast when wearing organic sunscreen. Isolate ultraviolet rays by absorbing ultraviolet rays.
The disadvantage of organic sunscreen is that it easily penetrates the skin and causes toxic side effects. Sensitive skin, pregnant women, infants, and young children using organic sunscreen can easily cause skin sensitivity.
Common organic sun-screening agents are as follows:
The data in this table comes from go.drugbank.com
Avobenzone (BMDBM): UVA sunscreen with the widest protection wavelength, the most effective, and the highest usage rate.
Avobenzone can absorb UVA 320nm～400nm wavelength, can absorb some UVA-I, but the effect of absorbing UVA-II is weak, and the peak of UVA absorption is at 357nm.
However, avobenzone is very unstable and will gradually decompose after being irradiated by ultraviolet rays, thus losing the sun protection effect.
Avobenzone will accelerate its decomposition when it encounters zinc oxide or octinoxate. Avobenzone needs to be used with octocrylene, oxybenzone, Tinosorb S, and other sun-screening agents to improve the stability of avobenzone. Or use some techniques to stabilize avobenzone.
Octinoxate (OMC): Currently the most widely used UVB sunscreen.
Octinoxate can absorb ultraviolet rays in the wavelength range of 280nm to 320nm, with the highest absorption rate at 311nm. It has minimal irritation to the skin and is relatively safe.
Octinoxate and avobenzone will decompose each other, the two should not be used together.
Oxybenzone (B-3): Oxybenzone is the most controversial sunscreen.
Oxybenzone can stabilize avobenzone, but its molecular weight is very small, and it is easily absorbed by the skin, causing skin sensitivity. Sensitive skin, pregnant women, and babies should not use sunscreens containing oxybenzone.
Oxybenzone is my sunscreen blacklist ingredient.
Uvinul A Plus (DHHB): A common alternative to avobenzone UVA sunscreen, Uvinul A Plus can absorb 310nm-390nm ultraviolet rays.
DHHB has strong stability, but its protective ability is weaker than avobenzone.
Its color is a little yellow, and the amount added is not high, otherwise, the whole face will appear yellow. The US FDA has not approved the use of DHHB, but Australia has approved the use of DHHB in sunscreens.
Tinosorb S (BEMT): It can absorb UVA and UVB at the same time. Tinosorb S has a large molecular weight, is not easily absorbed by the skin, and has high mildness.
The protection wavelength of Tinosorb S is very wide. The peak of ultraviolet absorption is at 342nm, but UVA with absorption wavelength greater than 370nm is poor.
Tinosorb S has a high absorption efficiency, and a small amount of it will have a good effect on improving the sun protection ability.
It can also stabilize avobenzone effectively without being damaged by other ingredients. The EU and Japan allow the use of Tinosorb S in sunscreens, but the US FDA has not approved its use.
Tinosorb M (MBBT): Tinosorb M can absorb and reflect ultraviolet rays. The protection wavelength is very wide, both UVB and UVA can be blocked, and it can also prevent blue light.
For UVA-I, especially for the 380-400nm band that many sunscreens cannot block, Tinosorb M can still absorb some ultraviolet rays. The use of Tinosorb M and Tinosorb S together can make up for the shortcomings of Tinosorb S’s low absorption rate after 370nm.
The molecular weight is large and very mild.
The EU and Japan allow the use of Tinosorb M in sunscreens, but the US FDA has not yet approved its use.
Mexoryl SX; can protect against UVA and UVB, the peak of ultraviolet absorption is at 345nm. The molecular weight is large, it is not easily absorbed by the skin, and the safety is high.
Mexoryl XL: It can effectively block UVA and UVB. There are absorption peaks at 303nm in the UVB and 344nm in the UVA.
Strong stability, water-resistant, and sweatproof.
The molecular weight is large, it is not easily absorbed by the skin, and the safety is high.
Mexoryl XL is usually used together with Mexoryl SX because they can form a more powerful UV filter system.
Octocrylene (OCR): It can effectively absorb UVA and UVB at the same time, and can block ultraviolet rays in the 290nm-340nm wavelength.
Octocrylene can absorb part of UVB and part of UVA. But regardless of UVA or UVB, its filtering wavelength is not complete, and other sun-screening agents are needed to improve sun protection.
The high absorption rate, non-toxic, non-teratogenic, good stability
Octocrylene has a fatal disadvantage. When it is exposed to the sun, it will release free radicals. Therefore, the use of sunscreens containing this ingredient requires anti-oxidant products.
Polysilicone-15 (Parsol SLX): Its advantage is that it feels smooth on the skin, but its disadvantage is that it absorbs ultraviolet rays in the 290nm-340nm band, mainly concentrated in UVB.
Octisalate: UVB sun-screening agent, the absorption wavelength is 295nm-315nm.
Octisalate has a low absorption rate, so it is not used as a primary sunscreen, but only used to enhance the effectiveness of other sunscreens.
Compared with other sunscreens, octisalate is safer, less toxic, and cheaper.
Homosalate: UVB sun-screening agent, can absorb ultraviolet rays in the 295nm – 315nm wavelength.
However, studies have shown that Homosalate has a weak effect on hormones and produces toxic metabolites.
The US FDA is very conservative. Many new sunscreens have not been approved so that many American sunscreens are still using oxybenzone. Novices choose sunscreen as much as possible to choose the Japanese version or the European version or see if there is oxybenzone in the ingredient list.
How Should I Choose A Sunscreen?
Choose organic sunscreen or inorganic sunscreen?
Sensitive skin, pregnant women, and babies mainly rely on parasols and sun hats for sun protection and use inorganic sunscreens to block the leaked ultraviolet rays. If sensitive skin is looking for a skin feel and wants a more natural look on the face, try to choose the milder ingredients in organic sunscreen.
For healthy skin, choose sunscreens that contain both inorganic sun-screening agents and organic sun-screening agents. Both UVA and UVB must be blocked, and the wavelength should be as wide as possible.
When sunscreens contain organic sun-screening agents, try not to choose “Avobenzone + zinc oxide” or “Avobenzone + Octinoxate”. Many people wear sunscreen every day, but one of the reasons why freckles are still serious is that the sunscreen used contains avobenzone, and the sunscreen spray containing octinoxate is additionally used. The sun-screening agents in the sunscreen are decomposed.
What aspects should be considered in the choice of sunscreen?
When choosing a sunscreen, priority should be given to protection, durability, and water resistance. If a sunscreen is not strong in protection, it should be discarded even if it has a good skin feel and high mildness.
Then consider the mildness and safety of the ingredients according to your skin sensitivity.
Finally, according to the skin type, consider the moisturizing power and skin feel of the sunscreen. If alcohol appears in the sunscreen, it may make your skin dry, so you should increase moisturizing work or change to a non-alcoholic sunscreen.
If you are particularly prone to sweating or face contact with water and have healthy skin, choose a waterproof sunscreen.
If you use non-waterproof sunscreen, reapply sunscreen after a lot of sweating or face contact with water. If you wear makeup, you can use sunscreen spray or sunscreen powder to reapply.
The waterproof logo of sunscreen is universal. If the sun protection power does not change after 40 minutes of activity in the water, then the sunscreen is water-resistant. If the sun protection power does not change after 80 minutes of activity in the water, then it is very water-resistant.
How To Use Sunscreen?
If the sunscreen is wrongly selected and used, it will not produce effective sun protection. The prerequisite for sunscreen to take effect is to form a complete protective film, and sunscreen must take a sufficient amount to form a film. If you use the wrong method, such as patting with your hands, or ball up, or putting on makeup before the sunscreen has formed a film or the wrong way of making up, these will destroy the filming of the sunscreen. The sunscreen without film formation has a sunscreen effect close to 0.
The way to ensure that the sunscreen forms a film is to take a sufficient amount of sunscreen and apply it evenly on the face.
If there is a ball up with the skin care products or cosmetics you are using, either change sunscreen or skincare products or cosmetics. Because the sunscreen will be squeezed out if it balls up, and an effective sunscreen film cannot be formed.
After wearing sunscreen evenly, wait 5-10 minutes before applying makeup. Strictly avoid rubbing during the makeup process, rubbing will also destroy the sunscreen film. Makeup by pressing.
Sunscreen Must Be Combined With Antioxidant
As long as you are exposed to the sun, no matter how perfect your sunscreen work is, it cannot completely isolate the ultraviolet rays. The leaked ultraviolet rays will generate free radicals when irradiated on the skin. Free radicals will damage healthy skin cells and cause skin deterioration.
Antioxidant skin care products are to eliminate these free radicals.
Common antioxidants in skin care products include vitamin C, vitamin E, coenzyme Q10, ergothioneine, lipoic acid, tea polyphenols, and idebenone.
If you don’t know about antioxidants, then use vitamin C serum during the day.
Do I Have To Remove Makeup When Using Sunscreen?
If you only wear sunscreen and no makeup, most sunscreens can be washed clean with facial cleansers, unless it is a sunscreen that is very strong film-forming, or water-resistant. The protective film of sunscreen depends on the film-forming agent.
Some film-forming agents are more difficult to wash off. In the ingredient list, you can see hydrogenated polydimethylsiloxane, polymethyl methacrylate, and trimethylsiloxysilicate. These three film-forming agents may require makeup removers.
Or you use a cleanser that can remove makeup. If you use the cleanser after using the makeup remover, it will easily destroy the healthy skin barrier.
What if I Can’t Remember All These Sunscreen Tips And Sun-Screening Agents?
If you can’t remember how to sun protection, please make a note or save this post, and check the tips when you buy sunscreen.
Then, cosdna.com has a list of ingredients for skin care products, and all sun-screening agents will be marked.
This website will indicate whether the sun-screening agents protect against UVA, UVB, or both. The protection against UVA and UVB is also marked. The more black coverage, the more comprehensive the sun-screening agent will protect against ultraviolet rays in this wavelength. Click on the name of this sun-screening agent and there will be a separate introduction.
After you have judged the protective ability of a sunscreen, you will no longer be confused by various reviews.
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