Welcome to brain Stuff production of I Heart Radio. Hey brain Stuff, Lauren Vogelbaum. Here, as I record this, it is August, which here in the Northern Hemisphere means hours
of outdoor time under the blazing summer sun. But even though many of us do wear sunscreen to help prevent sunburned skin cancer and the kind of skin damage that the beauty industry calls premature aging, recent research has found that we're not applying that sunscreen as thickly as we should, cutting its effectiveness by about Sunscreen is rated for its sun protection factor or SPF, with SPF thirty able to
block of ultra violet rays. The higher the SPF, the greater the protection, although even SPF one hundred doesn't block a hundred percent of UV light. The problem, according to this recent research out of University College London, is that few of us use enough sunscreen to an enjoy those high levels of protection. Lead author Anthony Young explained to us via email that to calculate SPF ratings in the lab, sunscreen is applied at a thickness of two milligrams of
product for each square centimeter of skin. He said, an average woman has about one point seven square meters or eighteen point three square feet of skin. For a whole body sunscreen, she will need about thirty three grams or one point one fluid ounces. With three whole body applications a day, that's about a hundred grams or three point
four fluid ounces. For reference, a fluid ounce is roughly equivalent to a shot glass of sunscreen, and a large tube of sunscreen holds just eight fluid ounces of product, so a person spending a full day in the sun should use about half a tube all by themselves. Are you using that much sunscreen? Probably not. Young and his colleagues estimate that our real life application of sunscreen is closer to about point seven five milligrams perse. Weare centimeter
less than forty of the recommended thickness. As a result, we're not getting anything close to the protection promised on a bottle of SPF thirty. The good news from young study is that you can get away with using less product with spfs of fifty or higher. They found that even the real world application rate of point and seven five milligrams of sunscreen per square centimeter if using SPF fifty,
provided considerable DNA protection compared to untreated skin. So does that mean that you should run out and buy the most expensive SPF onere or spread your regular SPF thirty is thick as cream cheese on a bagel. We also spoke with Ivy Lee, a board certified dermatologist based in Pasadena, California, who explained that you could, but that the best daily
sun protection strategy is to keep it realistic. Police said, I tell my patients to go for the highest SPF possible that feels good on the skin for daily use. How do you know you're really applying two milligrams per square centimeter? No one knows. We don't want to induce anxiety over this. We want to build healthy habits. Skin cancer is the most common type of cancer in the United States, and exposure to ultra violet or UV light is a risk factor for all types of cancer, including melanoma.
More than nine thousand, three hundred Americans die from melanoma every year. Unprotected exposure to UV light damages the DNA and skin cells, leaving them more susceptible to skin cancer. DNA damage can result from either a few severe sunburns or a lifetime of cumulative sun exposure. Incredibly, the American Academy of Dermatology reports that getting just five or more blistering sunburns between the ages of fifteen and twenty will
increase your overall melanoma risk. By and Lie says that although skin cancer is less prevalent in people of color, exposure to UV light can also cause premature aging. Daily sunscreen use will slow the appearance of wrinkles and age spots for all skin tones. Healthy sun protection habits include avoiding sun exposure during the peak hours between ten am to two pm, wearing a wide brimmed hat and sunglasses when outside in full sun, and of course, applying sunscreen
on all exposed skin even in overcast conditions. For full coverage, Lee recommends starting the day with a cream or lotion type sunscreen, preferably fifteen to thirty minutes before you step outside. Instead of measuring out a full shot glass of product, Lee tells her clients to think of applying sunscreen like a massage, working it fully into the skin without missing a spot. Since body sizes vary and products spread differently,
there's no preset amount that works for everyone. Lie suggests reserving spray or powder type sunscreens for fast reapplication on the go. The ideal is to reapply every two hours, but Lisa's a more realistic plan is to reapply around lunch time if you're going to be out all day. If you're heading out on water, sand, or snow, more frequent applications are required because UV rays reflect off of those surfaces. According to Lee, it's a myth that you can't burn the palms of your hands or the soles
of your feet. Also, tablets and other handheld devices reflect UV light to so pick a shady spot if you're going to spend some time in the sun scrolling. Today's episode was written by Dave Ruse and produced by Tyler Clang. For more on this and lots of other topics, visit how stuff works dot com. Brain Stuff is production of iHeart Radio. For more podcasts my heart Radio, visit the iHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.