According to the recommendations of the American Skin Cancer Foundation, sunscreen should be reapplied every two hours, or after swimming, sweating or drying towels. The reason is that the protective effect of sunscreen will weaken with time, and the influence of external environment will also reduce its protective effect. So wearing sunscreen in the morning can't take care of it for a day.

In addition to applying sunscreen every two hours, there are other ways to enhance the sunscreen effect, such as wearing a sunscreen, a sunscreen cap and sunglasses, avoiding exposure to strong sunlight and choosing a sunscreen with a high SPF value.