Find out the SPF and PA ratings on sunscreen and the myths girls all make
1 Find out the sunscreen index To know the ability of sunscreen to protect against UV rays, people rely on SPF and PA numbers. SPF SPF (short for Sun Protection Factor) is a measure of the ability to resist UVB rays used in sunscreens, with the lowest being 15 and the highest being 100. According to international norms, 1 SPF is capable of Protect and limit the harmful effects of UV rays on the skin in about 10 minutes . For example: Sunscreen with SPF 15 will protect the stomach within 150 minutes, SPF 50 will be about 500 minutes. In addition, the SPF number also shows the percentage of ability to block harmful effects from UV rays. When placed in perfect conditions, a sunscreen with an SPF of 15 will block about 93.4% of UV damage, SPF 30 about 96.7%, and SPF 50 about 98%. However, this ratio is also relative in a certain period of time. Index PA PA (short for Protection Grade of UVA) is a measure of a sunscreen's ability to filter UVA rays , published b...