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What Does SPF Stand For And What Does It Mean?

Topics: Cancer Prevention, Skin Cancer

July 13, 2020

what is spf?

Even though summer is halfway over, August is Summer Sun Safety Month. This means there is still time to be conscious about practicing sun safety. One major way you can do this is by slathering on some sunscreen and repeat it often anytime you're outside.

Choosing a sunscreen can be a daunting task. With so many combinations of numbers and specializations, it's no wonder a lot of people skip wearing sunscreen altogether. To clear up some confusion, let's talk more about what SPF is as well as its importance when using the right sunscreen for your skin.

What is SPF?

SPF stands for sunburn protection factor.

That number you see behind it on the bottle? That's a relative measure of how long the UV rays of the sun would take to redden (burn) your skin with sunscreen versus how long it would take without. So, for example, if you wore an SPF 30 sunscreen (as directed), it would take you 30 times longer to burn than if you weren't wearing any sunscreen at all. 

There are other factors that go into how quickly you burn. Someone with blonde hair, blue eyes, and porcelain skin is going to burn long before their friend with dark hair, brown eyes, and olive skin. However, both should use a sunscreen with higher numbers to protect their skin. 

Is SPF Enough?

It depends. An important thing to understand is that the sun produces two types of ultraviolet rays that affect the skin: UVA and UVB. These rays can cause premature aging and increase your risk of developing melanoma or non-melanoma skin cancers. Most skin cancers are caused by exposure to UVB rays, while UVA rays are known to play a major part in skin aging and wrinkling.

You may be wondering what this has to do with SPF. The thing about SPF is that it only measures UVB protection, which is great if your main concern is reducing your risk of skin cancer. However, if you're also concerned about premature aging, it's important that you look for a sunscreen that states "broad spectrum" on the label. A broad-spectrum sunscreen provides both UVA and UVB ray protection.

SPF Numbers: Is Higher Better?

The American Academy of Dermatology recommends using a sunscreen that is SPF 30 or higher. Keep in mind, however, that although higher SPFs do mean more protection, the difference in that protection becomes smaller.

  • SPF 15 = 93% UVB protection
  • SPF 30 = 97% UVB protection
  • SPF 50 = 98% UVB protection
  • SPF 100 = 99% UVB protection

The FDA requires any sunscreen SPF 15 or lower carry a warning label stating that it only protects against sunburn, not skin cancer or skin aging. It's always a good idea to choose a sunscreen SPF 30 or higher. Our Arizona cancer specialists put together a checklist for choosing your sunscreen.

No sunscreen can filter out 100% of the sun's UVB rays. This is why it's a good idea to include other sun safety practices, such as seeking shade, wearing protective clothing, and staying indoors from 10 am to 4 pm when UV rays in Arizona are the strongest.

Slather and Repeat

Apply your sunscreen 20 minutes before going outside. To ensure continued protection reapply every 90 minutes. If you will be actively sweating or in the water, be sure to find a sunscreen that is also water-resistant and reapply each time you get out of the water.

Pay attention to all areas of bare skin, including your neck, face, ears, legs, and tops of your feet. For your lips, choose a lip balm that's at least SPF 15 and reapply it frequently throughout the day. For more information on protecting your skin from both sunburns and skin cancer, visit our blog on sun safety.

In many cases, people who get sunburned don't use enough sunscreen, don't reapply it, or use a product that is past its expiration date. Remember, your skin is exposed to UV rays every time you go outside – even on cloudy days, on the snow, and in the water – so practice sun safety by slathering on some broad-spectrum, SPF sunscreen.

Other Products That Offer SPF

As the importance of SPF for skin care has become more common and a larger topic of discussion, many companies have begun offering SPF in their products. Today, you find SPF in your makeup and moisturizers.

These products make SPF a part of your daily care routine. However, you don't want to rely solely on these products. First, you need to make sure the product has at least an SPF 30.

Second, you're only using these products on your face and neck, so you need to be sure to protect the rest of your exposed skin.

Third, if you're spending time outdoors, you need to reapply the SPF every 90 minutes to ensure coverage. 

When Summer Fades

You know the summer season has arrived when you visit the pharmacy or grocery store to find a prominent shelf filled with sunscreen. The rest of the year, sunscreen is tucked away on a couple of shelves hidden at the back of the store.

This does all of us a great disservice. It leads you to believe that sunscreen isn't as important during other times of the year.

This isn't the case!

Each and every time you leave your home you should be wearing sunscreen with an SPF 30 or greater on any portion of exposed skin. This includes driving to work each day. You can get color on your exposed arms while driving back and forth to work. 

As we celebrate Summer Sun Safety Month in August, it's important to learn the basics of protecting our skin from the sun's harmful rays.

Understanding the difference between UVA and UVB rays helps you make better choices with sunscreens that contain broad-spectrum coverage. It's also essential that we care for our skin and use a sunscreen with a minimum of SPF 30 throughout the year. 

Originally published August 2018. Updated July 2020.

Arizona Oncology - The US Oncology Network