Sun Protection Christina Chung July 24, 2012 With summer in full swing and everyone heading outdoors, it is important to know the ins and outs of keeping your skin healthy and protected from the sun. Applying sunscreen should be part of everyone’s daily regimen, but there are many misperceptions regarding what it does and how to use it. Here are a few of the most important myths debunked. The higher the sun protection factor (SPF), the betterSPF is a measure of UVB protection only and is not an indicator of UVA protection. It is a ratio of how long it would take your skin to burn with sunscreen applied properly over how long it would take it to turn red without protection. So if without sunscreen it takes you 10 minutes to burn, a sunscreen with an SPF 30 would protect you for 300 minutes if applied properly. So at some point, yes, it becomes a meaningless game of numbers. Additionally, you may be unwittingly exposing yourself to the sun’s damaging UVA rays during this period of extended “protection.” Dermatologists recommend reapplying sunscreen every two hours at the very least no matter what the SPF. “Broad-spectrum” sunscreenBoth UVA and UVB rays reach the earth and can cause skin cancer and premature skin aging. Until last year, there was no federal regulation on the definition of “broad-spectrum” and sunscreen manufacturers were not required to test their products for UVA coverage. Hence, the term “broad-spectrum” meant that a product may protect you from all, some or none of the sun’s UVA rays. The new FDA guidelines, slated to go into effect later this year, dictate that a “broad-spectrum” sunscreen needs to demonstrate that it protects you from a standardized (but not complete) portion of UVA spectrum. “Waterproof” sunscreenA sunscreen can only protect you while in the water for a finite time period. In fact, the new FDA regulations do not allow a sunscreen to be labeled as “waterproof” or “sweatproof” as these claims were found to be misleading. Sunscreens will now be labeled as “water-resistant” for a specific time period of either 40 or 80 minutes, which will be indicated on the label, after which point they must be reapplied. These “water-resistant” sunscreens also need to be reapplied immediately after towel drying. Cloudy or rainy daysUp to 80 percent of the sun’s rays go though both clouds and fog, including UVA rays that can cause skin cancer and photo aging. Using daily broad-spectrum sunscreen with an SPF of at least 15 is an absolute must regardless of whether it is sunny or overcast. People with darker skin tonesWhile darker skin burns less frequently, studies are showing that all forms of skin cancer are on the rise among the Black, Latino and Asian populations. More importantly, skin cancer in skin of color often presents at a more advanced stage, which only highlights the importance of daily sunscreen use in these patients. A few last but important tips. Make sure to apply your sunscreen 15-30 minutes before heading out. Use approximately two tablespoons to cover your body. Seek shade between the hours of 10 a.m. and 4 p.m. when the sun’s rays are the strongest. Cover up with clothing, wear a large-brimmed hat, and UV-blocking sunglasses. And don’t forget to reapply – nothing can ruin a perfect summer weekend like a bad sunburn. Dr. Christina Chung is an assistant professor in the Department of Dermatology at Drexel’s College of Medicine. Dr. Chung specializes in general dermatology. Her areas of expertise include the treatment of ethnic skin, cosmetic dermatology and women's health. Dr. Chung sees patients at Drexel Dermatology at 219 N. Broad Street.