How often is it recommended to apply sunscreen for optimal protection?

For optimal protection, it is recommended to apply sunscreen every two hours. This frequency is crucial because sunscreen can wear off due to various factors such as sweating, swimming, and towel drying. When exposed to the sun, reapplying every two hours helps maintain an effective barrier against harmful UV rays, which can cause skin damage, premature aging, and increase the risk of skin cancer.

While applying sunscreen once a day or three times a day may seem sufficient, these recommendations do not take into account those activities that can diminish its effectiveness throughout the day. Applying sunscreen only when outdoors is also inadequate since UV rays can penetrate clouds and cause damage even on overcast days. Therefore, the two-hour guideline is established to ensure continuous protection throughout periods of sun exposure.