Making Sense of Sunscreen

Learn more about UV rays and how to choose a good sunscreen and use it properly.

Sunscreens promise protection from the sun's ultraviolet (UV) rays, which can cause sunburn and skin cancer. But how effective are they?

Studies have proven that sunscreen lowers the incidence of skin cancer. But sunscreen doesn't give complete protection, and using it doesn't mean you can sit in the sun for long periods without damage.

To protect yourself, it helps to know more about UV rays and sunscreens.

Sun facts
Sunlight contains two types of ultraviolet rays that can reach the earth and cause skin damage: ultraviolet A (UVA) and ultraviolet B (UVB).

  • UVA rays account for the bulk of our sun exposure, so they cause most aging of the skin. They are also linked to some skin cancers.
  • UVB rays directly damage the DNA of the skin cells. They cause most sunburns and most skin cancers.

There are no "safe" UV rays. Both types can cause skin cancer, including melanoma, the most deadly form of skin cancer.

Selecting the right sunscreen
The goal of a sunscreen is to protect the skin from UV rays. When sorting through your choices at the drugstore, focus on the SPF (sun protection factor) number on the labels. Experts recommend using sunscreen with an SPF of 15 or higher.

SPF is an indicator of how well the sunscreen protects against UVB rays. For example, with an SPF 15 sunscreen, you get about one minute of UVB rays for each 15 minutes you spend in the sun. An hour in the sun wearing SPF 15 sunscreen gives you about the same UVB exposure as four minutes without sunscreen.

A good sunscreen should protect against both types of UV rays. Make sure the label says "broad-spectrum" or that it provides both UVA and UVB protection. To provide broad-spectrum protection, most sunscreens will include some of the following:

  • Chemical ingredients: These absorb both UVA and UVB radiation. These may include avobenzone or benzophenones. Some, especially benzophenones, can cause skin reactions.
  • Physical ingredients: These can physically block and reflect away both types of UV radiation. Zinc oxide and titanium dioxide are two of the more common physical compounds found in sunscreens. These are less likely to cause allergic skin reactions than some chemical ingredients.

It's important to remember that no sunscreen provides complete protection. Even if you don't burn, too much time in the sun can still damage and age the skin and increase your risk of skin cancer.

Many moisturizers and other cosmetic products have an SPF. These products may be fine if you only spend a few minutes in the sun each day. But if you work or play outdoors, you need a stronger, water-resistant sunscreen.

How to use sunscreen
To fend off the sun's damaging rays:

  • Use a sunscreen with a SPF of at least 15. Apply it at least 30 minutes before sun exposure to give it time to bind to your skin.
  • Apply sunscreen generously. You should use about one ounce (a palmful) each time you apply it. Coat all skin not covered by clothing. Don't miss easy-to-forget areas, such as tops of the feet and the ears.
  • Reapply sunscreen every two hours when outdoors and after swimming, sweating heavily and toweling off.
  • Use sunscreen every day. UV rays reach the earth even on cloudy days, and UVA rays can pass through glass.
  • Don't rely on sunscreen alone to protect your skin. Cover up when outside. Wear a brimmed hat, UV-protection sunglasses and a long-sleeved shirt, pants or skirt.

Children need extra attention because they often spend a lot of time in the sun and their delicate skin can burn easily.

  • Don't use sunscreen on children younger than 6 months. Babies should be kept out of the sun and covered or shaded when they're outside.
  • Protect children older than 6 months by using sunscreen, dressing them in protective clothes and urging them to play in the shade.