16 08 web touro

Since today is the first day of summer, it is important to understand the relevance of sunscreen, its ingredients, and what the SPF numbers mean.

Simply put, SPF is Sun Protection Factor – the measure of the sunscreen’s ability to protect skin from damaging effects of UVB rays (which are the ones that cause the burn).  If it takes 20 minutes for your skin to start turning red, an SPF of 15, in theory, prevents reddening 15 times longer – so about 5 hours.  SPF 30, 40, 50, likewise would protect even longer.

For most of us, SPF 15 is fine, but those of us who have very fair skin, a family history of skin cancer or medical conditions that increase sensitivity to sunlight should be using an SPF 30 or higher.  And don’t be fooled by the number.  SPF 30 does not protect twice as much as 15.  While SPF 15 filters out 93% of UVB, SPF 30 filters out 97%, which, although better, is only a slight improvement.  However no sunscreen, regardless of SPF factor, really remains effective longer than 2 hours without reapplication.

What type of Sunscreen to use:  This will depend on how much sun exposure you anticipate.  It should protect you from both the UVA and UVB.

  1. If you work outside and spend a lot of time outdoors, you need a water resistant sunscreen that holds together on the skin.  These are also the types that you want to use on hot days or if you are playing sports, as they are less likely to drip if you sweat, and may not be as good for everyday wear as they are stickier, don’t go as well with makeup, and still need to be applied every 2 hours as they are not water-proof.
  2. Some cosmetics, moisturizers and after-shave lotions now have sunscreen already in them, and this would be sufficient for everyday activities with a few minutes here and there in the sun.
  3. Look for those that combine several active chemical and physical ingredients in order to provide the largest protection.  PABA, salicylates and/or cinnamates (octylmethoxycinnamate and cinoxate) protect from UVB; benzophenones (oxybenzone and sulisobenzone) protect from some UVA; avobenzone, ecamsule, titanium dioxide or zinc oxide protect from the remaining UVA.

Who should use sunscreen:  Anyone over the age of 6 months, actually.  Even those of us who work inside near windows as we continue to be exposed to those UVA rays!  Children under 6 months should not be exposed to direct sunlight, since their skin is highly sensitive to the chemical ingredients in sunscreens as well as the sun itself.  The best ways to protect them is with shade and protective clothing.  When you do select a sunscreen for your infant/child, avoid the ones with PABA.  Children’s sunscreens are the best to select as they are less likely to irritate the skin, and protect without being absorbed.

How much to use and how often to apply: About 1 oz (a shot glass full) at a time.  Sunscreen should be applied 30 min prior to exposure to allow the ingredients to fully bind to the skin, and should be reapplied every 2 hours, immediately after swimming/toweling off, or sweating a great deal.

However…No matter how high the SPF, or how often or thickly you put it on, sunscreen will never fully protect you.  In addition to wearing good sunscreen, to protect your skin from damage and decrease your cancer risk, you still need to take other precautions:

  1. Stay in the shade when possible
  2. Wear sunglasses
  3. Stay inside when UV radiation levels are highest (10a-4p)
  4. Wear a broad brimmed hat
  5. Wear sun-protective clothing, preferably with Ultraviolet protection rating (UVP) on the label, or at least clothing that is dark and tightly woven which offers a bit more protection.

Enjoy the sun, but protect yourself!

Dr. Feinberg






Gail Feinberg, DO, FACOFP, M.Ed, is a Professor and Chair Department of Primary Care, College of Osteopathic Medicine, at Touro University California.