In as little as 15 minutes ultraviolet rays from the sun can damage your skin, according to the Centers for Disease Control and Prevention. Danielle Pettit-Majewski, administrator of Washington County Public Health, recommends using a broad spectrum sunscreen to block the ultraviolet A and B rays from the sun. She adds sunscreen should be used on cloudy days as well, because the rays are still in the atmosphere. Use a sunscreen with an SPF of at least 15 and reapply every couple of hours. Sunglasses should also be worn to protect eyes from the sun and reduce the risk of cataracts.