**Understanding Sunscreen: Myths, Facts, and How to Protect Your Skin**
Skin cancer is among the most common forms of cancer in the United States, and protecting your skin from the sun’s harmful rays is crucial in reducing your risk. Despite the prevalence of skin cancer, many Americans still have misconceptions about sunscreen and sun protection. Dr. Adam Friedman, a professor and chair of dermatology at the George Washington School of Medicine and Health Sciences, emphasizes that there are many aspects of sun exposure and sunscreen use that people often misunderstand.
### What Does SPF Really Mean?
One of the biggest misconceptions concerns the meaning and scope of the Sun Protection Factor, or SPF, which is the most prominent number on sunscreen packaging. Many people assume that a higher SPF provides total protection against all types of harmful sun rays. However, Dr. Friedman clarifies that SPF only measures protection against UVB rays—the type of ultraviolet light responsible for causing sunburn.
UVB rays are indeed dangerous; they are the primary cause of sunburns and play a significant role in developing skin cancers. However, they are not the only threat. Ultraviolet A (UVA) rays, which are not measured by SPF ratings, penetrate deeper into the skin. While UVA rays do not cause visible burning, they are strongly associated with premature skin aging, such as wrinkles and loss of skin elasticity, because they damage collagen and elastin fibers in the skin. UVA exposure is also linked to skin cancer, though its effects are less immediately noticeable compared to UVB rays.
### The Hidden Dangers of UVA Rays
One of the challenges with UVA rays is that their harmful effects are not always obvious—they don’t result in the immediate redness or burning sensation that UVB rays cause. As Dr. Friedman puts it, UVA is a “silent killer.” Not only can UVA rays penetrate deeper into the skin, but they can also reach you when you least expect it. For example, regular glass windows, including those in cars and buildings, can effectively filter out most UVB rays but allow UVA rays to pass through. This means you can be exposed to UVA rays even while indoors, if you are near a window, or while driving a car.
Moreover, UVA rays can penetrate through clouds, so even on overcast days, you are still at risk. Many people mistakenly believe that cloudy weather means it’s safe to skip sunscreen, but in reality, up to 80% of UVA rays can reach your skin through clouds. This makes daily protection important, regardless of the weather.
### Choosing the Right Sunscreen
When selecting a sunscreen, Dr. Friedman and organizations like the American Academy of Dermatology recommend using a product with an SPF of at least 30. This provides strong protection from UVB rays. However, Dr. Friedman goes further, advising people to opt for higher SPFs when possible. He explains that most people do not apply sunscreen as liberally or as often as recommended, so a higher SPF can offer a buffer of extra protection if you are using less than the ideal amount.
Equally important is choosing a sunscreen labeled “broad-spectrum.” This designation means the sunscreen protects against both UVA and UVB rays. Without broad-spectrum protection, you may be shielding your skin from burns while still leaving yourself vulnerable to the deeper skin damage and cancer risk associated with UVA exposure.
### How to Apply and Reapply Sunscreen
Proper application is critical for sunscreen to be effective. Most people do not apply a sufficient amount to achieve the level of protection indicated on the label. Dr. Friedman recommends applying sunscreen generously to all exposed skin, not just the face and arms. Often-overlooked areas include the ears, the back of the neck, the tops of the feet, and the scalp (especially for people with thinning hair or bald spots). For best coverage, apply sunscreen about 15 minutes before going outdoors.
Reapplication is another area where many people fall short. Sunscreen can wear off due to sweating, swimming, or rubbing against clothing and towels. The technical recommendation is to reapply sunscreen every two hours, or more frequently if you are swimming or sweating heavily.
Dr. Friedman acknowledges that in reality, few people remember or take the time to reapply so frequently. He encourages people to do their best, noting that even imperfect efforts are better than none. If you spend most of your day indoors and away from windows, a single morning application may be sufficient. However, if you plan to be outdoors or