UV causes some sunscreen ingredients to gradually deteriorate on the skin’s surface in response to sun exposure. Sunscreen can also dissipate due to sweating, rubbing, and penetration into the skin. To maintain maximum effect, sunscreen should be re-applied every two hours. A single application before coming to school cannot be expected to adequately protect a child for afternoon physical education.
These products must be applied liberally and, as with paint, two coats are better than one. Thus, Sun Safety for Kids coined the phrase: “Put on a lot. And don’t miss a spot!”