It’s that time of year again where sunny days are few and far between for many parts of America. Winter strikes down victim after victim with seasonal affective disorder, leaving thousands of people desperate for a glimpse of sunshine. Other people may spend their winters fighting a vitamin D deficiency. During these dark months of the year, many people don’t see the sunshine and don’t protect themselves against it. In fact, on sunny days in snow-filled cities, many people try to absorb as much sunlight as they can by standing outside unprotected. These behaviors spark the debate: is it more important to wear sunscreen in the winter or to soak up the vitamin D from the sun? It has been proven that sun damage can occur during nearly any type of weather. Protecting oneself on cloudy, windy, or cool days is just as important as protecting oneself on hot, sunny days. It is often forgotten that sunburn is caused by ultraviolet radiation (UV) and not temperature. In fact, sunburn on a cold day is often overlooked and classified as the nonexistent ‘windburn’. The sun may not feel strong at this time of year, but the clouds and snow actually reflect 80% of the sun’s UV light. Knowing this, however, does not mean that people are less desperate to produce the much-needed vitamin D. It only begs the question: is it better to avoid vitamin D deficiency or is it better to risk sun exposure. Surprisingly, it is perfectly possible to protect oneself in both ways. The body can only produce a limited amount of vitamin D at a time. Prolonged exposure does not create a reservoir of vitamin D that can be released as needed, as the body only produces what it needs for the time being. The amount of vitamin D that the body can produce is done much quicker than imagined. The exposure from walking from the parking lot to the store or hanging laundry on the clothesline is enough to fulfill the body’s vitamin D capacity. While meeting the vitamin D quota takes very little time in the sun, studies have found that sunscreen does not interfere with vitamin D production. Knowing this, it is more important than ever to slop sunscreen on before leaving the house every day. Every person is at risk of skin cancer caused by sun damage whether they tan or burn, have dark skin or fair skin, or live in a warm climate or cold climate. Most weather apps include a UV index, allowing users to gauge how harmful the sun’s rays are on any given day. The UV index is a simple way to describe the daily danger of the sun’s intensity. Areas with an index of one or two do not typically require sun protection, whereas any index greater than three can cause harm to one’s skin. For more information about the UV index in your area, download the Environmental Protection Agency’s Sunwise UV Index app available for Android and iOS. NFCR-funded scientists James Basilion, Ph.D. and Daniel Von Hoff, M.D. are currently working on unique research projects that show great potential in treating patients with skin cancer, as well as several other cancer types.