Understanding Sunscreen

This information explains how to use sunscreen correctly.

The sun gives off ultraviolet light in the form of rays. There are 2 kinds of rays, ultraviolet A (UVA) rays and ultraviolet B (UVB) rays. UVB rays can cause sunburns, while UVA rays can lead to skin damage and aging. Both types of rays can cause skin cancer.

If you use it correctly, sunscreen can help protect you from sunburns, skin aging, and skin cancer.

What does SPF mean?

SPF stands for “sun protection factor” and is a measure of the level of protection from UVB rays. The SPF number of a sunscreen tells you the amount of time that the product will protect you from sunburn. For example, if you begin to burn 10 minutes after being in the sun with no sunscreen, then using a sunscreen with SPF 30 would increase that time to 300 minutes (10 minutes x 30 SPF). However, you need to reapply sunscreen every 2 hours, even if it has a high SPF.

Today, many sunscreens protect against both UVB and UVA rays. These are labeled as “broad-spectrum sunscreens.” See section titled “How do I protect myself against UVA rays?” for more information.

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What SPF should I use?

In general, the higher the SPF, the more UVB rays are blocked. Make sure to use an SPF of at least 30. Remember that no sunscreen can completely protect you from the sun, even for short exposures.

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How do I protect myself against UVA rays?

UVA rays contribute to skin aging and skin cancer, so it’s important to protect yourself against them. The SPF number of a sunscreen indicates only the UVB protection, not the UVA protection. Sunscreens that protect against UVA rays must:

  1. Be labeled as having “broad-spectrum protection.”
  2. Have an SPF of 15 or higher.

These sunscreens must also have this statement included on the label: “If used as directed with other sun  protection measures, this product reduces the risk of skin cancer and early skin aging, as well as helps prevent sunburn.”

Sunscreens with an SPF below 15 or without broad-spectrum protection do not protect against UVA rays. These products carry a label stating that they do not protect against skin cancer. Make sure you use sunscreens that have UVA protection.

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Who needs sunscreen?

Everyone, especially if you have a fair skin tone and burn easily with sun exposure.

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When should I use sunscreen?

You should use sunscreen every day that you are outside, even on cloudy days. About 80% of the rays pass through the clouds.

Apply your sunscreen at least 20 minutes before going outside. Reapply your sunscreen every 2 hours. Also, reapply it immediately after swimming, toweling off, or sweating.

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What is the correct way to put on sunscreen?

Use 1 ounce of sunscreen for each application on your entire body. Apply it at least 20 minutes before going outside.

  1. Spread a thin layer on your skin.
  2. Wait for it to absorb.
  3. Then, apply another thin layer on your skin.
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What is the difference between sunscreen products?

Gels and sprays feel less greasy than lotions, but they may irritate sensitive skin. A water-resistant sunscreen stays on longer. However, it only will protect you in the water for 40 to 80 minutes (check the label), so make sure to reapply it often.

Look for a sunscreen with an SPF of at least 30 and broad-spectrum protection, rather than checking for specific ingredients.

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If I use sunscreen, do I need to do anything else to protect my skin?

If you apply sunscreen correctly, it will help protect you against sunburns and skin cancer, but it does not offer  100% protection. You should also do the following to protect yourself from the sun:

  • Wear protective clothing, such as long-sleeved shirts, wide-brimmed hats, and sunglasses.
  • Stay out of the sun between 10:00 am and 2:00 pm when the sun’s rays are the strongest.
  • Choose a shaded location instead of being out in the sun.

These practices are especially important if you are at risk for sunburn or have a history of skin cancer.

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Are tanning salons or tanning beds safe?

No. Tanning beds give off large doses of UVA rays and smaller doses of UVB rays. Although tanning beds can lead to a tan with little or no burning, the rays they give off cause skin aging and skin cancer.

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Are sunless tanning lotions safe?

Yes, but the “tan” from these lotions does not protect you from sunburn, so make sure you apply sunscreen before going outside.

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If I use sunscreen and stay in the shade, what can I do to get vitamin D?

Vitamin D is important for bone health and may also help prevent some cancers. Sun exposure is one source of vitamin D but you can also get it from your diet. For example, milk and wild salmon are good sources of vitamin D. You may also need to take a supplement in order to get enough vitamin D.

We recommend that you apply sunscreen every day and get vitamin D from your diet. Your doctor can tell you how much vitamin D is right for you.

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