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CHNSkin basics
Is it enough to look only at the SPF number on a sunscreen?
When you see numbers such as SPF 30 or 50+ in a store, it is confusing whether higher is better and how much is enough for daily life. You also start to wonder whether you can choose by the number alone.
Sunscreen labels become easier to read once you know a few standards. This article sets out what the numbers mean and how to use the product, which is as important as the numbers.
What do SPF and PA each indicate?
SPF is an index that mainly indicates how much a product blocks ultraviolet B (UVB), which makes the skin red. The higher the number, the higher the level of protection, but a high number does not mean that the effect lasts that much longer in actual use.
Ultraviolet A (UVA) reaches deep into the skin and can affect aging, so a separate label is checked. In Korea, the PA label (the number of '+' signs) indicates the level of UVA protection.
| Label | What it indicates | Points to note |
|---|---|---|
| SPF | Level of UVB protection | Even with a high number, a sufficient amount and reapplying are needed |
| PA | Level of UVA protection (number of '+' signs) | The more '+' signs, the higher the level of UVA protection |
| Product form | Cream, lotion, gel, stick, etc. | Choose according to the area of application and your skin condition |
What should I check besides the number?
It is important to apply a sufficient amount evenly. If the amount is too small, the level of protection shown on the label may not be reached. It is common practice to reapply when you are out for a long time or after sweating.
If your skin is sensitive or you have just had a procedure, choose a mild product with simple ingredients, and if stinging, redness, or itching after applying it persists or gets worse, stop using it and contact the clinic.
Does it differ between daily life and outdoor activities?
The amount of ultraviolet light you are exposed to differs between days spent mostly indoors and days with a lot of outdoor activity. On days with a lot of exposure, one approach is to combine a product with a high level of protection with physical protection such as hats and parasols.
However, which product suits your skin depends on your skin type and condition, so it is hard to directly compare or recommend products. If you have concerns, discuss them at a consultation, where your skin condition can be checked.
Frequently asked questions
Q. With SPF 100, am I fine for the whole day?
A. Even with a high number, the level of protection can decrease with sweat, friction, and the passage of time, so it is common practice to reapply. Along with the number, how you use it matters.
Q. How do I reapply over makeup?
A. The method differs by product form, so it is hard to give one answer for everyone. Choose a method that does not irritate your skin, and if there is discomfort, reduce use and consult the clinic.
Q. Do I need to apply it on cloudy days too?
A. Ultraviolet light is present on cloudy days as well. It is safer to use it consistently regardless of the weather.
