Skin Deep: Sun Science

Decoding Sunscreen

Sunscreen is a no-brainer. Unfortunately, understanding the differences among brands is less clear. The FDA is now mandating that sunscreen manufacturers adhere to more stringent labeling requirements and more consistent claims about what a sunscreen can do, and what type of UV protection it offers. For instance, did you know that moisturizer or makeup with SPF doesn’t offer adequate sun protection? Do you know the PPD of your sunscreen and how it can prevent your skin from aging? Do you apply enough sunscreen to your skin? So, what are the new rules of sunscreens?

Broad-spectrum sunscreen is a must.There are different types of ultraviolet [UV] radiation (yes, sun rays are radiation!); “UVA” penetrates deep into the skin and affects cells, causing damage: wrinkles, blotchiness, sagging and roughening. “UVB” rays hit just below the top layer of skin and are the main cause of skin cancer. It is important to know that SPF lotions will only offer protection from UVB rays. When looking for protection, look for a broad spectrum sunscreen, which filters both UVA and UVB radiation and will reduce the risk of skin cancer and premature aging. A new mandate by the FDA is that only sunscreens that have been tested and protect from both UVA and UVB will legally be labeled as broad-spectrum.

SPF? PPD? Physical Sunscreen or Chemical Sunscreen? What’s the difference? Sunscreen works by creating a barrier on the skin that either absorbs the UV rays or reflects them. SPF measures the amount of protection from UVB rays and PPD measures the amount of protection from UVA rays. “Physical” sunscreens (usually thicker, white-colored and containing zinc), which protect your skin from the sun by deflecting or blocking the sun’s rays, tend to be better tolerated by most skin types and also protect almost immediately after application. “Chemical” sunscreens work by absorbing the sun’s rays and, because there’s a delay of protection against UV rays, they need to be applied 20 minutes prior to sun exposure. By contrast, chemical filters tend to be more irritating to skin but can offer more coverage against UVA and UVB rays than physical sunscreens. If you have sensitive skin and have had a reaction to sunscreen before, try a fragrance-free product, like Banana Boat Sensitive Sunscreen SPF 30+ (which is also broad-spectrum).

Confused by SPF? Take a number SPF numbers measure how long a sunscreen will protect you from burning verses how quickly your skin turns red without sunscreen. For instance, if you’re out in the sun without any protection and you start to burn after 30 minutes, had you used an SPF 20 it would have kept you from burning.

Here is the math:
SPF 15 x 30 minutes = 450 minutes (7.5 hours) of protection
SPF 30 x 30 minutes = 900 minutes (15 hours) of protection
SPF 45 x 30 minutes = 1,350 minutes (22.5 hours) of protection

SPF 50 only blocks about 1 percent more UVB ray than a SPF 30 (which blocks 97 percent). Those super-high “+” SPF sunscreens really only offer a slight amount of additional coverage and cost more, but really tend to lead to a false sense of security – and may have a higher risk of irritation to some skins.

Application is key Smooth on a generous amount of broad-spectrum, water-resistant sunscreen to clean, dry skin 20 minutes before going out into the sun. Average sized adults should apply half a teaspoon of sunscreen (about 3 milliliters) to each arm, as well as 3 milliliters to the face and neck area – including ears. Use one full teaspoon (about 6 milliliters) on each leg, and do the same for the front and back of the body. To make it simpler in the math area, that’s about the size of 1 shot glass for one full-body application.

Reapply All the math of SPF goes out the window if you don’t reapply! If you’re outdoors it’s recommended that you reapply sunscreen every two hours, as it can easily wipe or sweat off. Also, remember to reapply after swimming or any water sport. Eventually all sunscreen washes off, so new packaging will no longer bear the terms “waterproof” or “sweatproof.” Instead, allowances will be made for claims of water resistance up to 40 or 80 minutes.

Don’t just rely on sunscreen Sunscreen alone doesn’t provide complete protection from the sun; you’ll need other safeguards. Slide on those sexy sunglasses! When you’re choosing sunglasses, look for UV protection details on product labels. Choose sunglasses that block 99 to 100 percent of both UVA and UVB rays. Skip sunglasses that are labeled “cosmetic” and instead opt for larger rather than smaller lenses – or, better yet, the wraparound variety.

Be wary of Vitamin A Toxicologists are currently disputing the potential cancer-causing effects of Vitamin A in sunscreen; so for now it’s probably best to try to eliminate Vitamin A derivatives (retinol and retinyl palmitate) in your sun products until more studies are published.

Consider SPF clothing Look for clothes that offer UV protection, or wash tightly woven cotton clothing in a UV rinse which can raise the SPF value of clothing from a 5 (which is the SPF value of an average T-shirt) to 30.

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