SPF 101

When it comes to sun protection, it’s easy to feel burned out with so much information flooding your way. But there are critical basics you might've missed.

• The rays. UVC are actually the most harmful of ultraviolet radiation, but thankfully, they get absorbed by the ozone layer. UVA rays, which deeply penetrate the skin, are responsible for premature aging (i.e., photoaging) like wrinkles and age spots. This means that while your skin doesn’t show any signs of sunburn, it’s still undergoing damage. According to Health 24, UVA rays also "cause cataracts and blindness." In addition to aggravating the effects of UVB rays, research suggests UVA rays might also cause certain skin cancers. Powerful producers of sunburn, UVB rays cause squamous cell and basal carcinomas and melanoma.
• Defining SPF. SPF, or the Sun Protection Factor, informs the consumer how long she is protected from UVB rays (but, keep in mind that SPF has nothing to do with UVA protection). For the average person, sunscreen with SPF 15 allows her to be outdoors for 150 minutes before experiencing reddened skin. But this value isn’t proportional: SPF 15 protects against 93 percent of UVB rays, whereas SPF 30 defends against 97 percent.
• What SPF do I need? According to Revolution Health, dermatologist and former president of the American Academy of Dermatology (AAD) Stephen P. Stone, M.D., recommends using SPF 15 when you’re running errands or walking to and from the car — activities called incidental exposure. However, if you’re spending a long time outside — playing sports, enjoying a picnic — choose sunscreen with SPF 30.

  What’s more, if you’ve got fair skin or red hair, Dr. Stone suggests using SPF 50, which translates into about 99 percent protection, according to the Skin Cancer Foundation. Also, in addition to individuals who are already extra sensitive to the sun, if you’re taking medication that increases your risk of sunburn or have a history of skin cancer, SPF 50 is also the best choice for you.

• Broad spectrum protection. This sunscreen terminology indicates that a product protects against UVA rays. Look for ingredients like avobenzone (this ingredient can irritate some skin types), titanium dioxide or zinc oxide.
• Has it expired? To find out, search your sunscreen for the expiration date. If there isn't one, dermatologists recommend throwing away your sunscreen after two to three years. However, Rebecca Campen, M.D., assistant professor of dermatology at Harvard Medical School in her article for the Denver Post, suggests trashing your sunscreen after one year.
• Storing sunscreen. So your sunscreen doesn’t lose its effectiveness too quickly, make sure it’s tightly sealed and kept in a cool, dry place.

What shrinks SPF’s strength

Do you think applying a high SPF sunscreen (like 30 or 50) means you’re safe for the rest of the day? Unfortunately, this kind of thinking provides a false sense of security and puts you in danger of sun damage. Learn more about this and other factors that reduce the SPF of your sunscreen.

• You’re sweating and/or swimming. Just because a product says it’s water-resistant or waterproof doesn’t mean you’re safe all day long. Also, there are important distinctions between these two terms: water-resistant retains its SPF 40 minutes after your swim, whereas waterproof means you’re protected for 80 minutes, according to the American Melanoma Foundation. If you’re exercising outdoors or participating in any other physical activity, choose this type of sunscreen.
• You don’t apply enough. Research shows that people apply just 10 percent of the recommended amount of sunscreen, according to the New York Times. You should apply one ounce of sunscreen to all exposed areas, which is equivalent to filling a shot glass.

  Still using an eight ounce bottle after several weeks? Then you aren’t applying enough, according to Elizabeth Hale, M.D., of the Skin Cancer Foundation.

  Always, apply sunscreen to all exposed areas, including your ears, hands and feet. For your lips, invest in a lip balm with SPF 15 or higher. Put on sunscreen 15 to 30 minutes before going outdoors.

• You don’t reapply. Some sunscreens might also say "all day protection." Don’t be fooled into thinking you can apply your sunscreen once a day. No product provides all day protection without needing to be reapplied, writes Vincent Iannelli, M.D., for About. Reapply your sunscreen every two hours; however, if you’re sweating or swimming, you should reapply more often as the sunscreen washes away or rubs off your skin.
• Other factors include skin type (lighter-skinned individuals need higher SPF), weather and rubbing the sunscreen off with your towel.

Our product picks

When choosing sunscreen with broad spectrum protection, look for any of these ingredients on the label, according to the AAD: "oxybenzone, octyl methoxycinnamate, cinoxate, sulisobenzone, octyl salicylate, menthyl anthranilate, titanium dioxide, zinc oxide, avobenzone (Parsol 1789), ecamsule (Mexoryl SX)."

Also, the organization now has a seal of approval for sunscreen; look for the AAD SEAL OF RECOGNITION™. The Skin Cancer Foundation also has a Seal of Recommendation. For products that bear this seal, try DDF Moisturizing Photo-Age Sunscreen SPF 30 or M.D. Forte Aftercare Environmental Protector SPF 30.

See also:

Pro-Tanning Campaign HYPE: Healthy Tanning

Sunscreen and Children: What Every Parent Must Know

Is Your Sunscreen Safe?