Sunscreen 101: When, what kind and how often

May 25, 2016 Providence Health Team

Spring is here and summer not far behind, and that means many Americans have moved outdoors. Gardening, picnicking, cycling, hiking and lounging by the pool are some of our favorite pastimes. But too often we forget the sunscreen.

Did you know that without sunscreen, the sun's ultraviolet (UV) rays can damage your skin in as little as 15 minutes? Or that sunscreens have SPF ratings from 15 to 100? What does SPF actually mean? Read on.

Why use sunscreen?’

Anyone can get skin cancer. Contrary to popular myth, people with darker skin are susceptible to skin cancer, and UV rays are damaging on cloudy days. An estimated 1 in 5 Americans will develop skin cancer in their lifetime, according to the Skin Cancer Foundation. The foundation says that each year, there are more new cases of skin cancer than the combined incidence of breast, prostate, lung and colon cancer.

The basics of Sunscreen Protection Factor (SPF)

Most sun protection products work by absorbing, reflecting or scattering sunlight. Sunscreens are assigned a sunscreen protection factor (SPF) number, which indicates how well they block UV rays.

There are two kinds of UV rays:

  1. UVA rays penetrate into the thickest layer of the skin. Without sunscreen, these rays can lead to premature skin aging, wrinkling and suppression of the immune system.
  2. UVB rays can burn the top layers of the skin and play a key role in the development of skin cancer.

The American Cancer Society says higher SPF numbers do mean more protection, but it’s important to understand the SPF scale:

  • SPF 15 filters about 93 percent of UV rays.
  • SPF 30 about 97 percent.
  • SPF 50 about 98 percent
  • SPF 100 about 99 percent

While these numbers do matter, many people don’t realize that there’s little to be gained by using sunscreen with an SPF higher than 50, and that no sunscreen protects your skin completely.

What's the best sunscreen?

In picking a sunscreen, the American Academy of Dermatology says to make sure that the product of your choice:

  • Offers “broad spectrum” protection. This means it filters both UVA and UVB rays.
  • Has a rating of SPF 30 or higher
  • Is water resistant. This means the sunscreen stays on wet or sweaty skin for 40 to 80 minutes before it needs to be reapplied.

In general, sunscreen wears off even if you aren’t wet and needs to be reapplied every two hours as long as you’re in the sun. Makeup and lip balms may contain some sunscreen. But if they aren’t rated SPF 15 or higher, you need additional protection.

Finally, always check your sunscreen’s expiration date. Most have a shelf life of no more than three years.

Other sun protection options

You have more than sunscreen to protect your skin from the sun's damaging rays. These tips from the Centers for Disease Control and Prevention are especially helpful when combined with sunscreen:

  • Shade: Use sunscreen or wear protective clothing when you’re outside — even when you’re in the shade.
  • Clothing: Long-sleeve shirts and long pants and skirts can provide protection from UV rays. Clothes made from tightly woven fabric offer the best protection.
  • Hats: Wear a hat with a brim all the way around that shades your face, ears and the back of your neck. A tightly woven fabric, such as canvas, works best.
  • Sunglasses: Sunglasses protect your eyes from UV rays and reduce the risk of cataracts. They also protect the tender skin around your eyes.

If you have additional questions or concerns about using sunscreen, talk to your dermatologist or health care provider. You can find a Providence provider here.

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