Summer will be here in a week and that means sun exposure and taking precautions to avoid burning our skin. Without much thought other than what the SPF number is (sun protection factor) on the sunscreen lotion we use when we apply this to our skin, we think little of what chemicals we are applying.
It’s a confusing system, but SPF 15 blocks 93% of UVB, a SPF 30 blocks 97%, a SPF 50 blocks 98%, a SPF 100 blocks 99%, and if you get red in 20 minutes when your skin is unexposed then a SPF 15 will delay redness by 15x or for about 5 hours. So, a SPF 100 only gives 1% greater protection than SPF 50 to UVB rays with the mistaken idea that you can stay in the sun 50x longer. What most don’t realize is that sunscreens do not block UVA which makes up 95% of ultraviolet radiation, penetrates more deeply into the skin, and causes greater damage. But, I digress. The real problem is what is doing the blocking, and whether it is chemical or mineral.