We all should wear it when going outside & when you go swimming, especially the little ones. However, for the pools, this can be harmful. When you put sunscreen on before going into the pool, due to the oily nature of the product it contaminates the filter system as it passes through the pool & clouds up the water. It also messes with the chemicals that are put into the pool. This is why most public pools have a sign saying to shower before going into the pool. So make sure to put sunscreen on after you get out of the pool & then rinse off again before getting back into the pool.