Image: Bing Fang | Written by: Six Magic Mirror | Editor-in-Charge: Ah Yue
Many girls know that sun protection is very important, it is best to protect all year round, but in the process of actually using sunscreen, girls will always encounter such and such problems.
Magic Mirror often receives related consultations in the background, so I use this article to summarize the questions that everyone often asks, hoping to answer the girls' confusion ~ If students have other interesting questions, please do not ask questions in class, please leave a message in the comment area after class
The higher the sunscreen's sun protection factor, the better?
Although the sunscreen of our country has more than 50 times the sunscreen, the more SPF50+ is uniformly marked as SPF50+, but more and more studies have shown that even if the SPF is greater than 50, increasing the sunscreen index will provide more benefits, such as preventing sunburn.
However, the higher the sunscreen coefficient, the higher the concentration of sunscreen added, and the types of sunscreen may be more, which may increase the irritation to the skin and bring other damage, so it is best to choose products with different sun protection coefficients according to the specific situation.
But now buy a sunscreen with a slightly lower sunscreen coefficient is not so easy, the market is not moving is SPF50+, PA++++, sunscreen below this value may be embarrassed to sell, or it seems that our manufacturers are more unsociable.
In fact, if you go to the beach, plateau, snowy mountains or summer outdoor activities, this situation can use SPF50+, PA++++; if you just commute to work or spend most of the day indoors, choose SPF30 up and down, PA++~+++.
We can also judge the ultraviolet situation according to the ultraviolet index (UVI), this indicator often appears in the weather forecast, the higher the value, the greater the damage to the skin, cloudy days, rainy days or winter is not the reason why you do not apply sunscreen, UVI is greater than 2 when you need to do a good job of sun protection measures.
▲Image source: Self-made in the eleventh consultation room
Sunscreen can be applied thinly?
The well-known SPF and PA values are measured in the case of 2mg/cm of sunscreen products. According to the results of the survey, most people in real life apply between 1/3 and 1/2 of this standard amount, which will greatly reduce the sun protection ability of sunscreen products.
But the specific discount is not yet conclusive, there are studies showing the relationship between the amount of sunscreen and the SPF value is powered, such as SPF16 sunscreen products, if the amount of application is half of the standard, that is, 1mg/cm, then the SPF value is only about 4, but there are also studies that show a linear relationship between the amount of application and the value of SPF, logarithmic relationship...
Regardless of the relationship, the whole face according to the amount of 2mg / cm to apply, about the need for a dollar coin size of sunscreen, the density of the product, the size of the face will make the overall need for the total accumulation of floating up and down.
A clever fairy may ask: Then I use SPF50+ sunscreen, even if I don't apply enough, is it possible to have a good effect?
Theoretically, this is the case, so some dermatologists will recommend that people who can't apply enough sunscreen choose high-power sunscreen, but there are gains and losses, as mentioned earlier, high-power sunscreen may mean higher sunscreen levels, resulting in problems such as absorption into the bloodstream through the skin (but if you only apply it once a day, the impact on health is negligible).
The final sunscreen effect is also related to the application method, the correct method is to apply gently, especially the physical sunscreen does not need to be absorbed, so it can be covered on the skin that needs sunscreen.
Studies have shown that if applied with repeated rubbing, the SPF can be reduced by 20%, but if the spray type of sunscreen is used, it needs to be applied evenly after spraying on the skin, so that the sunscreen can be evenly covered on the skin.
Do you still apply sunscreen with products that have a sunscreen effect?
As mentioned earlier, in order to achieve the sun protection effect labeled, you need to apply a amount the size of a dollar coin, so if you use a base makeup product with a sunscreen multiple to replace it, the standard should be almost the same.
It's just that whether it's a big face or a small face of the girl, the magic mirror really hasn't encountered a lot of "face does not change color", can not reach the amount of effect, so even if the base makeup product has sunscreen value, but it is still recommended to apply sunscreen, do not tell me to affect the makeup effect, it is a moment of greed.
Sunscreen reapply every two hours? Concubines can't do it!
If you can't do it, you can't do it, in fact, the magic mirror can't do it, and I haven't seen which dermatologist can apply it every 2 hours. At present, although the common recommendation is to apply sunscreen every 2 to 3 hours, this time interval is based on real-world conditions, such as whether to sweat, swim, rub (touch/scratch the skin with your hands), etc.
Studies have found that repeated applications or divided applications can make up for the initial lack of application. If you can't ensure that you have enough sun protection to apply, you can reapply it later, and there is no specific time requirement, and you can make up for it as needed.
Do I need to remove my makeup when applying sunscreen?
How to clean the sunscreen after applying? Perhaps different dermatologists have different views, this question can refer to the experimental study published by West China Hospital, which compares the effects of non-waterproof sunscreen and waterproof sunscreen after cleaning with water, cleanser and makeup remover respectively.
The conclusion is that the sunscreen that is not waterproof is not clean with water, but it can be cleaned with cleanser and makeup remover oil; the waterproof sunscreen cannot be cleaned with water and cleanser, and it is necessary to use makeup remover oil to clean.
The results of the test may be affected by specific product choices (the specific products in the study: Ludsa's facial cleanser, Maybelline's makeup remover oil, Innisfree's sunscreen), and if the fairies do not remove their makeup after applying sunscreen every day, they can use this as a reference.
▲Image source: Reference[2] Comparison of residues after cleaning of non-waterproof sunscreen
▲Image source: Reference[2] Comparison of residues after cleaning of waterproof sunscreen
Will the sunscreen that was opened last year still be used this year?
First of all, we must see if the bottle of sunscreen has exceeded the shelf life, if it exceeds it, do not use it, if it does not exceed, continue to look down. General products will be marked after the expiration date, for sunscreen, the general agreement is 12 months, that is, marked with the "12M" logo, if it has exceeded the expiration date after opening, then it is not recommended to continue to use.
In addition, if you have previously stored it in a high temperature, directly exposed to the sun, humid environment, or if the texture, taste, and color of the product have changed, you will give up using it in these cases.
The same applies to other skincare products. Magic Mirror believes that the fairies who read this article will not have to use up 1 bottle of sunscreen for 1 year.
Can using sunscreen cause vitamin D deficiency?
No. 80% of the body's vitamin D is synthesized by irradiating the skin with medium-wave ultraviolet light (UVB), and the sunscreen we use will reduce the amount of UVB exposure absorbed by the skin, so there will be fairies who ask this question.
According to current research, the daily use of sunscreen in healthy people does not lead to a lack of vitamin D in the body, which is related to the lack of vitamin D in most people, but even if the correct and adequate use of sunscreen will not lead to vitamin D deficiency.
Because UV-induced vitamin D synthesis is a highly efficient process, bare skin with two arms is enough to synthesize the vitamin D content needed for a day by walking in the sun for 20 minutes.
But for people with dark skin, people with very good sun protection, people in the northern region, office people who rarely go out and the elderly, it is not enough to rely on the sun, it is recommended that you supplement your own vitamin D. In addition, food is also an important source of vitamin D.
▲Image source: soogif
Titanium dioxide in sunscreen can cause cancer, what to do?
There was indeed this news before, and the European Commission listed titanium dioxide as a suspected carcinogen of Category II. The protagonist of this time, titanium dioxide, is the ingredient we often encounter in cosmetics such as sunscreen, foundation, and concealer, titanium dioxide is not only a physical sunscreen, but also used as a whitening agent in cosmetics.
However, the EU notes that this Class II carcinogen refers to titanium dioxide by the inhalation route. According to current research, it is safe to apply titanium dioxide to the skin, and the titanium dioxide contained in the skin care products we apply will not be inhaled into the lungs.
And we ordinary people need to contact the inhaled titanium dioxide in their daily lives, mainly spray-type sunscreen, so when using such products, we must pay attention to avoid spraying directly on the mouth and nose.
I have insisted on sun protection all summer, why is it still tanned?
Some girls rely too much on sunscreen, think that the palace painted with SPF50+, PA++++ sunscreen can be "rampant", on the beach, on the street with a small face, everyone must appreciate the appearance of the palace, the principle is "to apply the strongest sunscreen, the fiercest sun".
Although sunscreen is easy to use, but the high number of sunscreen can not absorb or reflect all the ultraviolet rays, there are still some ultraviolet rays will be absorbed by our skin through the sunscreen, in addition, the visible light in the sun, infrared rays will also cause skin damage, not to mention that the sunscreen applied by the girls may not be enough.
Sun protection does not only refer to applying sunscreen, but also includes the use of umbrellas, hats, sunglasses, clothing and other hard sun protection measures, in addition, you can also avoid going out during the strongest UV rays, go to places with strong ultraviolet rays to "punch in", if you have to do this, try to carry out activities in shady places.
Are sunscreen clothing on the market really sunscreen?
Some of the sunscreen clothes on the market are "hanging sheep's head to sell dog meat", and some are really anti-ultraviolet rays, the key lies in how to choose.
For textiles, there is a special indicator to evaluate its sun protection performance, that is, ultraviolet protection coefficient (UPF), only UPF value > 40, and UVA transmittance, so buy sunscreen clothing to look for this indicator. (Directions to "Dermatologist's Sun Protection Tips")
After the summer, everyone will have a black and white dividing line on their arms, and the explanation that you did not leave is that you do a good job of sun protection, or you may have worn a summer long sleeve.
Although our daily clothes are not marked, but there are also levels of sun protection capacity, if you do not want to buy "sunscreen clothing", you can also choose ordinary clothing, ordinary clothes are usually woven tighter, the fabric is thicker, the color is darker, the fabric of lycra or polyester material is loose, thin, light in color, and the fabric of cotton and linen material has higher sun protection ability.
The above is the whole content of today's course, in short, I hope that students will pay attention to sunscreen, scientific sunscreen, and leave the class.
Don't forget to pay attention to it after class, the backhand of the students who learn well is a forward, share it with their little sister who is afraid of tanning!
I love the world!
bibliography
[1] Heidi Li,Sophia Colantonio,Andrea Dawson,Xing Lin,Jennifer Beecker. Sunscreen Application, Safety, and Sun Protection: The Evidence [J]. SAGE Publications,2019,23(4).
[2] Wei Chen MD,Mei He MB,Li Xie MM,Li Li PhD, MD. The optimal cleansing method for the removal of sunscreen:Water, cleanser or cleansing oil? [J]. Journal of Cosmetic Dermatology,2020,19(1).
[3] Neale R E,Khan S R,Lucas R M,Waterhouse M,Whiteman D C,Olsen C M. The effect of sunscreen on vitamin D: a review. [J]. The British journal of dermatology,2019,181(5).