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Skin Cancer

How Sunscreen Works

yellow and white umbrella in bright sunshineSunscreen can be an important part of protecting your skin from the sun's harmful rays. But how do you know which sunscreens give the greatest protection? We all need protection from the sun’s ultraviolet radiation, also called UV rays. It includes both UVB and UVA rays.  Sunburn is primarily caused by UVB rays. Both types of UV rays can cause skin cancer and early skin aging.

How does sunscreen work?

Let's think of your sunscreen as if it were a beach umbrella. Does it help protect against both UVA and UVB rays? Or does it let some rays through?  No sunscreen fully blocks UV rays. But, by using the right product as directed and in addition to other measures, like wearing protective clothing, you can reduce your risk of skin cancer and early skin aging.

UVA and UVB Protection

To begin providing enough protection, sunscreens should have a sun protection factor, known as SPF, of at least 15. But that is not enough. This will stop some UVB rays, but it may not stop UVA rays. To protect against both types of rays you need something called broad-spectrum protection. So let's increase the protection by adding broad-spectrum to our SPF 15 sunscreen. Now we're protecting against UVA and UVB rays.

Okay, what happens if we increase the SPF to 50, but leave out broad spectrum? The higher SPF gives you more protection against UVB rays. But without broad spectrum, this may not fully protect you against UVA rays.

So what does all this science boil down to?

For greater protection, starting in the summer of 2012, look for sunscreens with an SPF of at least 15 and broad-spectrum on the label.
 

Scripted from How Sunscreen Works, a Federal Drug Administration (FDA) Consumer Update

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Last Reviewed: Jun 27, 2014