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Understand SPF and PA correctly and apply sunscreen properly

Overview

If you read the importance of sunscreen (LINK), you will now know why you should apply sunscreen.

If you realize the importance of applying, then you need to know how to use it properly. Many users apply sunscreen without knowing that they are putting it on in the wrong way. 

The amount of sunscreen to be applied is very important in terms of effectiveness and for your skin.

Let's find out what SPF and PA are and how to apply sunscreen properly through this post.

What is SPF?

SPF is an abbreviation for "Sun Protection Factor" and quantifies the degree of UV-B blocking. If you are curious about UV-A and UV-B, refer to the above link.

SPF = MED for skin with sunscreen / MED for skin without sunscreen
* MED stands for Minimal Erythma Dosage, which refers to the minimum amount of ultraviolet radiation taken to develop erythema

Simply put, applying sunscreen with SPF15 when the amount of UV rays is 1, reduces the number of UV rays exposed to the skin by one-fifteenth.

Usually, 1SPF has a cut-off duration of 15 minutes.
The summary is as follows.
SPF8 x 15 minutes = 120 minutes (2 hours)
SPF15 x 15 minutes = 225 minutes (3.75 hours)
SPF 30 x 15 minutes = 450 minutes (7.5 hours)
SPF 50 x 15 minutes = 750 minutes (12.5 hours)

And each SPF has the following UV-B blocking force.
SPF15 = 93.3% UV-B blocking power
SPF30 = 96.6% UV-B blocking power
SPF40 = 97.5% UV-B blocking power
SPF50 = 98% UV-B blocking power
SPF100 = 99% UV-B blocking power

Sometimes you may have seen SPF50+ (50 Plus) products. This means that the SPF is higher than SPF50. This type of marking is intended to eliminate customer concerns about the product. 

To achieve higher SPF, it is natural to use stronger chemical ingredients or higher dosages. Of course, the stronger the chemical, the more likely it is to irritate the skin.

As mentioned above, SPF50 has 98% blocking power. The market's marketing strategy is to collectively call it 50+ (50 plus) rather than displaying high numbers such as 70 and 100 so that customers would feel safer about the product.

What is PA?

PA stands for "Protection grade of UVA" and indicates the degree to which UV-A is blocked.

The categories are as follows.
PA+ = PPD 2~4
PA++ = PPD 4~8
PA+++ = PPD 8~16
PA++++ = PPD 16+

PA is a rating system used by converting UVAPF and is mainly used in Asia, and the formula is as follows.
UVAPF = MPPD for skin with sunscreen / MPPD for skin without sunscreen
* MPPD is the minimum amount of ultraviolet radiation that the skin causes blackening in time.
* * MPPD = Minimal persistent pigment darkening

How to read PA or PPD is relatively simple.
It can be seen as a figure indicating how many times the blocking power is compared to when nothing is applied.

For example, PA+ says PPD 2~4, which means it has 2~4 times more blocking power than when nothing is applied. Therefore, PA+++ has 8 to 16 times more blocking power than when nothing is applied.

Usually, it is recommended to use PA+ when you do indoor activities and to use at least PA++ for outdoor activities.

How do I apply it properly?

In order to achieve an efficacious level of what's written(SPF, PA/PPD) on your product, you have to apply the sunscreen a lot more than you think.

According to the Ministry of Food and Drug Safety, 2.0 mg of sunscreen is applied per square meter (1 cm^2) before measuring SPF.

In other words, no matter how PA++++ and SPF are 100, it's actually hard to see the effect if you apply as little as you normally do.

However, it is very difficult to determine how much a square meter and two milligrams are. In that case, use the two-finger rule. Squeeze as much as the index and middle finger and apply it to the face.



If it's still hard to understand, I recommend applying the sunscreen until you feel "Isn't this too much?" Usually, that's the amount that you should at least be applying to your face.

It is also strongly recommended to apply several times, not just once. This is very important content, so I will explain it in detail in other posts.


When is the moment that sunblock is not required

There are often people who use both sunblock and foundation makeup among those who do makeup. Of course, the more you apply, the better the UV protection will be, and if your skin is not sensitive, there is no big problem.

However, many base foundations and cushion products that come out these days contain a certain amount of SPF and PA.

In addition to the cushion with the SPF40 function, there is no need to apply SPF40 sunscreen.

Therefore, it is recommended that you check whether your makeup products, such as cushions and base foundations, have SPF and PA functions and determine whether should you use sunscreen.

Source



Location: South Korea

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