Elisa Shackelton: Is your sunscreen still good?

With warmer days upon us and spring break just around the corner, you may be getting antsy to get outside and expose more of yourself to the sun, but we all know that the sun can damage our skin and increase the risk of serious consequences, including skin cancer. Although it's not the only safeguard we need to take, sunscreen is one of the easiest ways to protect our skin and is a good first line of defense, so make sure you have a good supply of sunscreen before you start spending extended hours out in the sun.

Throughout time, the ingredients in sunscreen can deteriorate, so last year's bottle may not be effective this year. An expiration date should be printed somewhere on the bottle. If your product doesn't have an expiration date, it's best to buy a new bottle after about a year, or if the product seems to have changed consistency, has a strange odor or has changed color. The active ingredients in sunscreen have a shelf life of about two years, but you can't be sure how long the sunscreen sat in a warehouse or on the shelf before you purchased it.

Sunscreen provides either physical or chemical protection from UV light. Physical sunscreens form an opaque film that reflects or scatters UV light before it can penetrate the skin. These sunscreens contain ingredients, such as zinc oxide and titanium dioxide, which protect against both UVA and UVB rays. Original formulations of physical sunscreens remained white when applied to the skin. Newer formulations blend more with your skin tone and are less noticeable.

Chemical sunscreens absorb UV rays before they can cause any damage. They contain one or more ingredients, such as avobenzone or oxybenzone, which absorb UVA or UVB rays. For broad protection, chemical sunscreens often contain more than one ingredient to protect against both UVA and UVB rays. A newer over-the-counter sunscreen contains mexoryl (Anthelios SX) and offers protection against UVA and UVB radiation.

What reduces effectiveness?

How much protection your sunscreen offers depends on many factors, including how likely your skin is to burn (your skin type), the amount and type of sunscreen used, how often the sunscreen is applied and how intense the UV rays are. In addition, many factors can make sunscreen less effective. These include:

• High humidity

• Sweating

• Drying or rubbing your skin with a towel

• Swimming, showers or other contact with water

Look for sunscreens that are water-resistant, which offers some protection against washing off in water or when perspiring heavily. Sunscreens can no longer be labeled "waterproof" because all sunscreens wash off to some extent. Other terms that can no longer be used on sunscreen product labels include "sun block" (no product actually blocks all UV rays) and "all-day" (no sunscreen lasts all day). Make sure any product you use actually contains sunscreen - many tanning oils and lotions don't.

Also, most people use sunscreen too sparingly. A liberal application is 1 ounce - the amount in a shot glass - to cover all exposed parts of the body, so if you have a 4-ounce bottle, you'll be using about one-fourth of it for one full-body application. Be sure to rub the sunscreen in well, too. To maximize protection, apply sunscreen liberally 30 minutes before going outdoors and reapply every two hours, or as needed. And don't count on your skin to tell you when you've had too much sun. It may take up to 24 hours for a sun burn to develop fully.

For more information, contact Elisa at the CSU Moffat County Extension Office, 539 Barclay, 824-9180.

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