I'm supposed to wear this cr@p every day. (once a cancer patient, always a cancer patient) and I also lean toward the physical blocks (oxides and clothing). I use the chemical blocks when I know I'm going to be sweating or swimming, just because they do absorb into the skin and work after the solar radiation has penetrated your flesh. (kind of a last-ditch protection in my book)

Wear your sunscreen correctly! Wear protective clothing! Hooray for brimmed HATS! (block 90% of sun you may encounter)