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. The Centers for Disease Control and Prevention says that only about 30 percent of adults regularly use sunscreen and many of them don’t use a sufficient amount. An adult should use enough sunscreen to fill a shot glass to cover arms, legs, neck and face. If you are using insect repellant or other lotions, apply the sunscreen first.

To help consumers select products that best suit their needs, sunscreens are labeled with SPF numbers. SPF stands for "sun protection factor" and refers to the sunscreen's ability to protect against the sun's ultraviolet (UV) radiation. The U.S. Food and Drug Administration (FDA) says the higher the SPF number, the more sunburn protection the product provides. You should use a sunscreen with an SPF of at least 15, which means you can stay in the sun 15 times as long as without the sunscreen and get the same level of sunburn.

The SPF number refers only to protection from UVB rays, the kind that cause sunburn. Your sunscreen, however, should also protect against UVA rays, which is less likely to cause sunburn but is one cause of aging skin. UVA radiation penetrates the skin more deeply than UVB radiation and produces free radicals that attack the collagen (connective tissue) of the deeper skin layers and the blood vessels. In addition, the free radicals damage DNA and interfere with the body's immune response. 

How do sunscreens work?

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

Sunscreens work by absorbing and reflecting UV rays, preventing them from penetrating the 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 of age and all adults should wear sunscreen. Lighter skinned people, particularly those with red or blond hair, are at greatest risk for 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, because clouds block only about 20 percent of UV rays.

  • 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 as many UVA and UVB rays as possible. Sunglasses that wrap around your eyes are best, because they block UV rays from the sides.

  • Apply sufficient amount of sunscreen with an SPF of at least 15 and one that offers protection from both UVA and UVB rays. Use at least an ounce of sunscreen each time you apply it. Reapply every couple hours, or more frequently if you are swimming or sweating.

  • 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

Up to a million Americans are diagnosed with skin cancer each year, and experts say that number is on the rise.

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, but they aren't deadly.

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 the body.

The American Cancer Society and other experts urge people to regularly examine their skin for new moles or moles that change their shape or color.

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.

Connect with MLH

New Appointments

 Well Ahead Newsletter


Copyright 2014 Main Line Health

Printed from:

The information provided in this Web site is for informational purposes only. It is not a substitute for medical advice. All medical information presented should be discussed with your healthcare professional. See additional Terms of Use at For more information, call 1.866.CALL.MLH.