What do SPF and PA mean on sunscreen? How to choose SPF and PA?

We always see such numerical indicators on sunscreen: SPF and PA. So, what do SPF and PA mean in sunscreen?

What does SPF mean in sunscreen?

SPF refers to the sun protection factor, or sun protection factor. SPF is the abbreviation of Sun Protection Factor, which indicates the sun protection effect of sunscreen products. It is determined based on the minimum erythema dose to the skin. It targets the UVB band, and the number following it represents how many times the duration of sunburn can be extended.

How much SPF is suitable for sunscreen

SPF targets UVB, and the number behind it represents how many times the sunburn time can be extended.

For example, the skin of Asians will normally get tanned and sunburned after 15 minutes in the sun.

Using SPF15 UV protection products can provide about 225 minutes (15 minutes x SPF15) of sun protection time.

30+ means 30 times of 15 minutes, 15*30=450 minutes, which is 7 and a half hours. SPF50 sunscreen represents 15×50=750 minutes.

30+ is about 8 hours, so 30+ is enough for most parts of China. For daily care, shopping, or window shopping, you can choose sunscreen products with SPF 5-8.

When going out for fun, you can choose sunscreen products with SPF10-15. Use a waterproof sunscreen of SPF 20-30 when swimming or sunbathing.

What does the PA value of sunscreen mean?

For some time, sun protection has only focused on UVB protection, because the energy of UVB is greater than that of UVA. However, recent studies have shown that UVA can penetrate into the dermis of the skin, causing greater damage to the skin. Therefore, most sunscreen products in recent years have added UVA protection index reference. Currently, there is no consistent evaluation standard for the UVA protection effect of products, and there are also differences in the labeling of UVA sun protection capabilities in different countries. Among them, PA is the most commonly used.

PA is the abbreviation of Protection Grade of UVA, and the “+” indicates the product’s ability to protect against UVA. The more “+” signs there are, the better the protection effect is, and it is less likely to get tanned or photoaged.

PA＋：Effective

PA++: Quite effective

PA+++: Very effective.

China has adopted this method to express the sun protection ability of UVA ultraviolet rays. Currently, most qualified sunscreen products on the market are marked with two sun protection indicators: SPF and PA.

How to choose SPF and PA

Generally speaking, if it is cloudy or you are indoors, you can choose SPF15, PA+ products.

When doing outdoor sports or being exposed to strong sunlight for a short period of time, such as when commuting to get off work, it is necessary to choose products with SPF30, PA++.

When exercising outdoors for long periods of time in the summer or in plateau areas, it is best to choose a sunscreen with the strongest possible sun protection, such as SPF30+, PA+++, and apply it every 1 or 2 hours to effectively protect the skin and limbs from damage by ultraviolet rays.