Studies show that daily use of sunscreen can significantly lower your risk of skin cancer and skin aging. You should apply sunscreen daily, 15-20 minutes before going outside and enough to actually be effective. An interesting fact is that majority of people when they apply sunscreen do not apply enough of it and do not re-apply it often enough. The average person in a bathing suit needs a full ounce to completely cover all exposed areas, and every 2 hours. In fact, dermatologists actually recommend using sunscreen daily regardless of the season or weather or cloud coverage. Whether you will be inside or outside, you also come in contact with UV light through windows and UV light can also pass through clouds.