SPF Explained

A sunscreen’s SPF rating is incredibly important, but it is not the only guide when you are buying sunscreens. All the SPF number lets you know is how long you can stay in the sun without burning while wearing that product. For example, let’s say you’re like me and you can stay in the sun for about 15 minutes before your skin starts to turn pink. Applying a sunscreen rated SPF 15 will allow you to stay in the sun 15 times longer (three and three-quarters hours: 15 times 15 minutes) without getting pink. In other words, the SPF number, 15 in this case, multiplied by the amount of time you can normally stay in the sun without getting pink, is how long you can stay in the sun after you’ve applied the sunscreen. If you normally can stay in the sun 25 minutes without getting pink, applying an SPF 15 sunscreen would let you stay in the sun six and one-quarter hours (15 times 25 equals 375 minutes) without burning.

It’s vital to know that the SPF rating refers only to protection from UVB radiation. The European Union has adopted a UVA rating system, but it is controversial and has not yet been adopted in other parts of the globe. The FDA is working on one but there is no telling when that will be done, and England and Japan have a separate system all to themselves. What this adds up to is that no one quite agrees on how to measure UVA protection. Currently there is no way to judge the UVA protection in a skin-care product with sunscreen unless you check the ingredient listing. However, only a handful of ingredients can protect skin from the UVA spectrum. So that SPF 15, SPF 30, or SPF 70 sunscreen must absolutely contain the UVA-protecting ingredients of either titanium dioxide, zinc oxide, avobenzone (also called butyl methoxydibenzyl methane), Tinosorb, or ecamsule (Mexoryl), or you will not be getting the best protection. And your skin deserves the best!

Understanding UV

Before you can understand how to deal with the sun, it is helpful to know what exactly you are dealing with. Sun feels great, especially when you’re outdoors and it’s shining. But even on a cloudy day, when you can’t see the sun, the sun’s rays are ever present and ever attacking the skin. Basically, the sun’s infrared rays (IR) do the important work of keeping us warm, and the visible rays provide daylight. At the same time, the sun’s ultraviolet radiation (UVR) is also important, because its effects are serious for skin and eyes.

In essence, the UVR irradiation present in sunlight is an environmental human carcinogen on par with smoking and pollution. Unprotected exposure to the sun, or to sun lamps that duplicate the sun’s effect on skin, is nothing less than toxic. Research on this topic is abundant and clear, particularly when it comes to the appearance of wrinkles, skin discolorations, dryness, flaky skin, immune system impairment, and skin cancer.

UVR is divided into three different bands: UVA, UVB, and UVC. Virtually all UVC radiation is filtered out by the atmosphere so that none actually reaches the earth’s surface (although ozone depletion has some researchers worried about this one, too). In direct contrast to UVC, UVA rays reach the earth in significant amounts. UVB reaches the earth, too, though some of this radiation is filtered by the ozone. It is a testament to UVB’s destructive effect on skin that even small amounts not blocked by the ozone layer can cause significant damage.

UVB radiation, the rays of the sun that cause sunburn, has a considerable capacity to cause instant skin damage. UVB damages the skin’s genetic structure, causing mutations and abnormal growth patterns.

UVA are the silent rays of the sun. You don’t feel them, but they are omnipresent and cause the skin’s tanning response. As attractive as a tan looks, the free-radical damage that takes place at the same time and is generated by the UVA rays is insidious and relentless.

Even though UVB rays are much stronger than UVA radiation, UVA radiation is the larger danger for skin. That’s because the earth is bombarded with about 100 times as much UVA as UVB radiation. So while UVA may be weaker compared to UVB, the amount present in the atmosphere still creates a potent impact on the skin.

What this adds up to is a huge headache for your skin. Looking younger without protecting yourself from the sun is simply impossible. UVA and UVB combined can cause skin cancer, cataracts, and other eye damage, and suppresses the body’s (and skin’s) immune system, stopping it from working properly. Unprotected or prolonged sun exposure, even with protection, causes the outer layer of skin to become thick, wrinkled, and discolored, while the lower layers of skin are slowly destroyed, causing thinning and more severe wrinkling. Capillaries near the surface of skin can become thinner, break, and become visible, especially on the cheeks, nose, and chin.

Pollution’s effect on the ozone layer of the atmosphere, located many miles above the earth’s surface, is serious business for many reasons, but this discussion is about what that means for skin. When intact, the ozone layer filters out much of the sun’s UVB radiation, though it has relatively little effect on UVA. It is the sunburning UVB rays that increase when the ozone layer is eroded, which means more serious burns for those who dare to go outside without protection.

By the way, UVB rays can’t get through glass, so there’s no risk of sunburn when you sit in a car or next to a window, but that’s the good news. The bad news is that UVA rays can get through windows. Normal glass doesn’t protect skin from UVA damage, so sitting in a car or next to a window that lets daylight through offers no UVA protection whatsoever. (Sunglasses are very important, but I discuss that later in this chapter.)

(Sources: Future Oncology, December 2008, pages 841–856; Journal of Pathology, January 2007, 241–251; Journal of Investigative Dermatology, January 2002, pages 117–125; Clinical Experimental Dermatology, October 2001, pages 573–577; Journal of the American Academy of Dermatology, July 2001, pages 610–618; Experimental Gerontology, May 2000, pages 307–316.)

Are expensive sunscreens more effective? Sunscreens are regulated as over-the-counter drugs by the FDA, so price is not an indicator in any way, shape, or form about efficacy. Research has shown that in order for sunscreens to be truly effective they must be applied liberally every day and reapplied as needed. Because of this fact, expensive sunscreens may actually be a problem for skin because how liberally is someone going to apply a $35, $50, $75, or higher per-ounce sunscreen? And remember, sunscreen needs to be applied 365 days a year—most people aren't aware that sun damage begins the moment their skin sees daylight, spring, summer, winter or fall. Over time, cumulative exposure generates a lot of skin damage!