Yes that sounds like what I had read! So in effect, if I put some spf 15 on my face every 2 hours while in the sun and am in the sun for 6 hours, it will give me the same burn protection as if I put on some spf30 ONCE and stayed in the sun for 4 hours. Now i recall that you don't need the higher spf number if you re-apply some every 2 hours or so. I am leery of overly strong stuff on my skin- but yes I don't want skin cancer either! So the 15 should work fine for me if I reapply if staying out more than 2 hours.