What Do SPF Ratings Really Mean?


Spring has officially arrived, which means the weather is showing signs of improvement and many of us are spending time outdoors enjoying the increasing presence of sunshine.  We all need a little Vitamin D fix after a long winter, but as you surely already know, overexposure to sunshine is dangerous to the health of our skin.

With an overwhelming number of sunscreens available, how does one choose which product to use?  It truly is a daunting task, especially if you don’t understand the information on the product labeling.  Many people simply choose based on price, or how the product smells or on some other non-scientific criteria.  This article should help tear away some of the mystery behind sunscreens and hopefully arm you with the knowledge needed to make a sound choice next time you are shopping for sunscreen.

SPF Ratings

Generally speaking, it takes 15-20 minutes for our skin to start burning without protection from Sunscreen.  A sunscreen with an SPF15 rating should theoretically protect the skin 15 times longer (225-300 minutes or 3.75-5 hours).  But … that DOES NOT mean your fully protected during that time.  An SPF15 sunscreen blocks only about 93% of the suns dangerous rays.  And here is where things get a little confusing.  If an SPF15 product blocks 93% of the sun’s rays, it would be logical to assume an SPF30 product would be twice as effective, but that’s not how it works.  A product rated SPF30 actually blocks out 97% of those rays and an SPF50 shields against 98%.  And no sunscreen can block 100% of UV Rays.

While SPF ratings are helpful for reference, keep in mind that no sunscreen, regardless of strength, should be expected to remain effective longer than two hours.  Experts recommend reapplication at least once every two hours.  This is partly because sunscreen can rub or wash off our skin during activity, especially activities such as swimming, rigorous exercise, etc.  It is also recommended that sunscreen be applied generously.  Most experts recommend one ounce be used to cover the face and body.  The first application of the day should be done at least 15 minutes before going outside if possible.

Broad Spectrum Protection        

It is important to know that not all sunscreens are created equal.  In other words, you could have two products rated SPF15 that don’t offer the same level of protection.  This is because some products are rated for Broad Spectrum protection while others aren’t.  The important difference is that Broad Spectrum sunscreens are designed to protect against both UVA and UVB exposure, while those not rated Broad Spectrum likely offer only UVB protection.  While UVB Rays are most responsible for sunburns, it is equally as important to be protected against UVA exposure.  Left unblocked, UVA Rays penetrate deep into the skin, where they can cause many of the signs associated with aging such as wrinkles and age spots.  More importantly, both UVA and UVB exposure can lead to skin cancer.  Regardless of the SPF rating on the sunscreen you choose, by all means make sure it is rated for Broad Spectrum protection.

Don’t forget, no sunscreen will block out 100% of the suns damaging UV rays.  With that in mind, here are a few additional steps you can and should take to protect your skin from the sun, especially on long days of prolonged exposure.

  • Seek Shade Make a point of taking advantage of as much time out of direct exposure to the sun as you can.  It will go a long way towards giving your skin a much deserved break.
  • Protective Clothing Many outdoor clothing manufacturers offer garments rated for SPF protection.  Consider using these garments in addition to applying sunscreen, rather than in place of sunscreen. Hats and sunglasses should also be worn.
  • Use Caution Near Water/ Snow The sun’s rays reflect off snow and water.  Keep this in mind and think about using a more powerful sunscreen than normal and applying it more often.

Hopefully the information above will come in handy next time you are shopping for sunscreen.  Have fun out there this summer, just remember to protect your skin as much as possible.  You will be glad you did.  For more information, please feel free to visit our website or give us call.