All About Sunscreen

Summertime. Beach time. Long hours in the sun. Before you head out to the white hot sand, you'll want to pick up some sunscreen. But should you buy SPF 15? SPF 30? How about 45?

Should you get a sun block? A sunscreen? Something that's waterproof?

If you're confused by the numbers and types of sunscreen, welcome to the club. Many Americans, it seems, are so confused by sunscreens that they don't even use them. An adult should use enough sunscreen to fill a shot glass to cover arms, legs, neck, and face. If you are also using insect repellant or other lotions, apply the sunscreen first.

To help you select products that best suit your needs, sunscreens are labeled with SPF numbers. SPF stands for "sun protection factor" and refers to the sunscreen's ability to protect against sunburn. Use a sunscreen with an SPF of at least 30. The actual SPF number refers to how much longer skin with sunscreen takes to burn, compared to unprotected skin.

The sun's ultraviolet rays can be broken down into two types: UVA and UVB. UVA rays are not absorbed by the ozone. They penetrate deep into your skin and are heavily responsible for premature aging. UVB rays are partially absorbed by the ozone layer and mostly affect the surface of your skin, causing sunburn.

The SPF number refers primarily to protection from UVB rays. However, your sunscreen should protect against both UVA and UVB rays. UVA radiation penetrates your skin more deeply than UVB radiation and produces free radicals that attack the collagen (connective tissue) of your deeper skin layers, as well as your blood vessels. In addition, free radicals can damage your DNA and interfere with your body's immune response. Sunscreen that protects against UVA and UVB rays is referred to as "broad spectrum."

The Food and Drug Administration has recently implemented revised regulation standards in testing the efficacy of sunscreens. A sunscreen must meet certain criteria to be labeled "broad spectrum." New regulations also clarify water resistance and require sunscreen companies to label the time you can expect SPF protection while swimming or sweating. 

How do sunscreens work?

When UV rays strike your skin, they cause changes, including mutations in your DNA. These mutations affect how well your DNA controls cell division, and can lead to cancer, experts say. The longer your skin is exposed to the sun, the greater your risk of developing skin problems.

Sunscreens work by absorbing and reflecting UV rays, and preventing them from penetrating your skin. There are two general types of sunscreens: physical sunscreens, such as zinc or titanium oxide, which contain particles that scatter and reflect sunlight from the skin; and chemical sunscreens, which absorb the UV rays.

All children over 6 months and all adults should wear sunscreen. If you have a child under 6 months, you should not expose him or her to the sun. Lighter skinned people, particularly those with red or blond hair, are at greatest risk of burning.

Remember, sunscreen use alone will not prevent all of the possible harmful effects of the sun.

Tips for avoiding the sun

  • Stay out of the sun, particularly from 10 a.m. to 4 p.m., when the sunlight -- and the UV rays -- are strongest. Look for shade, but be aware that a beach umbrella or shade tree can't block all UV rays. And a bright beach or snow-covered ground causes the UV rays to bounce around.

  • You are still at risk on cloudy days, so you should still apply sunscreen.

  • If you must be out in the sun, cover up with a loose-fitting, long-sleeved shirt and pants to protect your skin. Wear a hat with a four-inch brim to protect your face, head, neck, and ears.

  • Wear sunglasses that block both UVA and UVB rays. Sunglasses that wrap around your eyes are best, because they block UV rays from the sides.

  • Apply a sufficient amount of sunscreen with an SPF of at least 30, and one that offers protection from both UVA and UVB rays (broad spectrum). Apply sunscreen 15 to 20 minutes before sun exposure. Use at least one ounce (enough to fill a shot glass) of sunscreen each time you apply it. Reapply every couple hours, or more frequently if you are swimming or sweating. Don't forget to apply protection to your lips with a balm or a lipstick that contains sunscreen with an SPF of 30 or higher.

  • Remember that water doesn't block UV rays. Even if you spend most of your day in the water, you still need sunscreen.

  • Children need protection from the sun, too. Give your child a wide-brimmed hat and don't forget the sunscreen, if your child is older than 6 months.

Warning signs of skin cancer

Skin cancer comes in three types: basal cell carcinoma, squamous cell carcinoma, and melanoma. The first two types are the most common forms of skin cancer and are easily treated. If left untreated, however, they can cause disfigurement. 

Although melanoma is less common, it is serious. If caught early, it is almost always curable. Melanoma is much more likely than the other two forms of skin cancer to spread to other organs in your body.

The risk factors for melanoma include moles, particularly a type called an atypical mole; fair skin; family history of melanoma; people whose immune system has been suppressed; large doses of UV radiation through sun exposure; and severe, blistering sunburns, especially during childhood.