I have seen so many people applying sunscreen incorrectly, and thinking they are protected.  I knew a dermatologist, and he told me a lot that most people just are not aware of. I decided to use Natural organic sunscreen just to make sure I was not absorbing toxins or detrimental chemicals.  I did not know that you should initially apply the sunscreen so that it forms a film.  It takes about 30 minutes for the sunscreen to be absorbed, so a common instruction from the manufacturer is to apply it every 2-4 hours; my dermatologist told me that re-applying it every 30 minutes is more effective.