We should all wear sunscreen every single day, no matter where we live. This isn’t new advice, yet many of us don’t apply sunscreen before heading out for the day. We may think of it as a summer or vacation necessity, but not as a year-round habit. While we definitely should use sunscreen to prevent premature aging, wrinkles, and dark spots, not everyone is convinced that melanoma is caused by excessive sun exposure.Melanoma is usually a type of skin cancer that arises from the melanocytes, the cells that contain melanin. Melanin controls the color of our eyes, hair, and skin. Melanocytes also produce moles, which is where melanoma originates. Because melanoma is visible, it can be discovered and treated early. Signs and symptoms of melanoma can include:• A change in a mole: shape or color• A sore that doesn’t heal• A spot or a sore that becomes itchy, tender, painful, or starts to bleed• A flat red sore that appears rough, dry, or scaly• A new spotThe Melanoma Research Foundation reports that over 90% of melanoma is caused by exposure to ultraviolet (UV) rays. The UV can come from the sun, or from sources such as tanning beds. Melanoma rates have increased over 3% a year since 1992, about the time scientists noted that the ozone layer was thinning and advised wearing sunscreen on a daily basis.Melanoma seems to occur more with intense and intermittent sun exposure, as well as sunburn events, rather than with consistent time in the sun. Interestingly, the Cancer Research Center of the UK reports that people who travel for tropical holidays—and get a quick tan—have higher rates of melanoma. So do people of higher socio-economic status, probably because they can afford to take sunny holiday trips. People who are regularly outdoors, such as farmers and fishermen, have lower rates of melanoma.While researchers agree that most melanoma cases are due to sun exposure, there is no real evidence that sunscreen can prevent it. More study is needed. In fact, sunscreen can provide a false sense of security, because sunbathers feel as if they can stay out in the sun longer. Most people don’t apply enough sunscreen and also fail to re-apply it during sun exposure. Tanning beds are certainly a risk. A 2012 meta-analysis of 27 studies showed that using a tanning bed—even once—raised the risk of developing melanoma. The risk jumped if a person used a tanning bed before age 35. The intense exposure to UV rays for a short time, at close range, gives high levels of UV radiation. This is consistent with the known cause of melanoma. The younger the age of exposure, the higher the risk. Because melanoma can occur anywhere on the body, including the soles of the feet, not just areas exposed to the sun, some scientists are still uncertain that sunlight is the only cause. Dr. Scott Menzies, a dermatologist and Professor at the University of Sydney, Sydney Melanoma Diagnostic Centre in Australia, feels that we should all continue to use sunscreen: “Sunscreens are also used wrong all the time. To protect again melanoma and other skin cancers, sunscreen has to be applied properly. Apply a thick layer ½ hour before going out into the sun and reapply every two hours or after swimming or sweating. The higher the sunscreen, the greater the protection, so try to use a SPF of 30 or more."