What does spf50+pa+++ mean? Understand the sun protection index and use it correctly so as not to get darker

The weather is getting hotter and the sun is getting stronger, so many girls are preparing to stock up on sunscreen. But what does spf50+pa+++ on sunscreen mean? When is it appropriate to use spf50+pa+++ products?

What does SPF50+PA+++ mean?

SPF50+PA+++ indicates the sun protection index of the product. The first SPF50+ means that under laboratory conditions, the product can absorb more than 98% of medium-wave ultraviolet rays (the calculation formula is (50-1)/50*100%=98%).

PA+++ means that the time it takes for the skin to get tanned is delayed by more than 8 times.

Note: The meaning of SPF and PA values ​​at different levels

SPF20 = (20-1)/20*100% = 95%, which means that 5% of the ultraviolet rays will still reach the skin;

SPF 30 = (30-1)/30*100% ≈ 96.67%, which means that about 3.33% of UVB rays can reach the skin.

It can be seen that the protection gap between products with different SPF values ​​is not large.

PA + (PFA value 2-3): Delays tanning time by 2 to 4 times.

PA++ (PFA value 4-7): Delays tanning time by 4 to 8 times.

PA + + + (PFA value 8 or above): Delays tanning time by more than 8 times.

Unlike SPF, if the PA value has an additional + sign, the protection ability will increase exponentially, so the more + signs in the PA value, the better.

When is it appropriate to use SPF50+PA+++

Products with a sun protection index of SPF50+PA+++ are more suitable for long-term outdoor activities in the summer. In addition, in areas with strong ultraviolet rays such as plateaus or beaches, it is necessary to choose sunscreen skin care products with SPF50+PA value of three + or above. It is not suitable to use products with strong protection such as SPF50+PA+++ on a daily basis, because such products will feel more greasy, and they contain more chemical ingredients and are more permeable to the skin.