SPF is about Time, PA is about Strength
Hey everyone! The days of intense sunlight continues, are you making sure you have protection against sunburns?
In Japan, no matter which drugstore you enter, there is a myriad of sunscreens that line the shelves. As a newcomer in sunscreen protection, I had difficulties in choosing a suitable one to use. Whether to go with the most stylish design, or with a well-known brand… I guess each of us has our own way of picking.
Q) What do you look for when you choose a sunscreen?
Even though SPF value is highly looked out for, PA levels are not looked at that often.
From the study in Japan about what the most important point people look out for when buying a sunscreen, “SPF value”, “gentle on the skin” and “ ease of applying” came out on top. Seems that the majority certainly knows the effect of UV on their skins! However, it is intriguing that even though PA values are also displayed, it doesn’t seem that a lot of people look out for it.
Sunscreens and UV Care Cosmetics have values such as “SPF50” and “PA++” on them. There are many who think that the bigger the values, the better. We may know roughly what they mean, but do we really know what they mean?
SPF and Time
SPF, as we all know, is “Sun Protection Factor”, a protection standard against reddening of the skin. We see SPF30 and SPF50 most of the time, and SPF50+ is the best we can get in Japan.
As we mentioned previously, the SPF value shows how long the sunscreen can delay sunburns. The effectiveness of the delay can be calculated through the formula:
Time taken to get sunburn without sunscreen (in minutes) x SPF value
So take for example someone who gets sunburnt in 20 minutes out in the sun. When applying a SPF10 sunscreen, it will take 20 min x 10= 200 minutes for him to get sunburnt. So remember, though surprising, even low SPF values can have rather good protection. Of course, these days you are likely to find sunscreens with a minimum of SPF30 instead!
Left lady: “Even with low SPF values, protection is still substantial!”
Right: “Because SPF measures ‘how long’ of a protection we can get”
Bottom: “Even with high SPF, sweat and sebum can cause the sunscreen to thin and become uneven, so be sure to reapply them after 2-3 hours!”
Sunscreens of higher value such as SPF70 and SPF100 are sold overseas, but does that mean Japanese sunscreens are not effective? Not so. In Japan, we take into account the amount of burden our skins have to take on, so SPF50+ is shown. It is also recommended that we reapply sunscreens.
PA and Strength
PA refers to the “Protection Grade of UVA”, a protection standard against skin spots and wrinkles. The number of +’s show the strength, and is currently divided into four different levels, from + to ++++, .
The PA system is a system decided by the Japan Cosmetic Industry Association for Japan, and may seem foreign to people outside of Japan. However, you may compare it with the PPD system (Persistent Pigment Darkening) by dividing the measurements into four levels. (This system is used more in Euroe
PA, PPD comparison table
Just by looking at the numbers, even with PA+++, there is quite a wide gap between PPD8 and PPD16. Such a rough comparison may be one of the reasons why many do not like the PA system.
To understand PPD protection, we can understand its protection strength through the following percentage formula:
(1 – 1/PPD) x 100
The percentage is the amount of UVA protection the sunscreen provides.
Actually, until 2012, PA+++ was the highest value, meaning there were only 3 different levels. However, in recent years people have heightened concerns about UVA protection. Following that in 2013, PA++++ was introduced and products started to include it.
Though it’s may be easy to neglect protection against skin spots and wrinkles because the effects are not immediate, be sure to check PA values too! I hope everyone looks out for them when choosing the sunscreen products! ^^
Now that you have a better understanding of what SPF and PA represents, you can ensure that you have the most effective sunscreen protection for yourself. Shopping for sunscreens will be more fun too! Let me know what sunscreens are your favourites!
How are SPF and PA values decided?
Actually, the amount of sunscreen used in laboratory tests is about 1 cm2, or 2 mg. The calculated amount needed to apply to the whole face is about 80mg, or the size of a 500yen coin. Unfortunately, that amount is not effective enough to provide adequate protection if we don’t apply thickly. Therefore, let’s be aware that a casual application of sunscreen is not enough to provide the amount of UV protection stated on the package.