The importance of sunscreen

A picture is worth a thousand words and sometimes when we visually process something, it sticks with us in memory.

This is a photo from an article in NEJM where a truck driver, exposed to sun on the left side of the face over many years shows dramatic asymmetric dermatoheliosis.  The aging difference is not in years, but in decades!  So make sure to wear your broadspectrum sunscreen!

Here is a good checklist for sifting through the hundreds of sunscreens available on the market. 

  • Use a sunscreen of at least an SPF 30 or greater if one is going to have prolonged sun exposure.  Don’t just count on the sun protection which is in your make up.  Studies show that most people apply half as much sunscreen as they need.
  • Use a sunscreen which blocks both UVA and UVB, a broad-spectrum sunscreen. Padimate A, Padimate O and the cinnamates are common chemicals used to block UVB. Benzophenones, Anthranilates and Avobenzone (Parsol 1789) are common chemicals that block UVA light. I like the Avobenzone found in chemical sunscreens.
  • Physical sunscreens (titanium dioxide, zinc oxide, icthmol, etc.) block both UVB and UVA. Micro sized titanium dioxide and zinc oxide preparations allow these chemicals to be less noticeable on application.  I am a big fan of physical blocks and wear Neutrogena baby SPF 60 quite often.
  • Apply sunscreen at least one hour before exposure.
  • Waterproof sunscreens should be applied at least one hour before water exposure.
  • Reapply sunscreen at least every two hours.
  • SPF (sun protection factor) gives one a rough estimate of how long one can stay in the sun without burning. For example an SPF 15 sunscreen will protect someone who burns in 10 minutes 15 times additional protection or 150 minutes.
  • SPF only applies to UVB protection.
  • Reapplying a sunscreen does NOT extent the period of protection. Taking the above example a sunscreen with an SPF of 15 will not give 300 minutes of protection if reapplied, it will only assure you of getting 150 minutes of sun protection.
  • A water-resistant sunscreen will remain unchanged after 40 minutes of water exposure.
  • A water-proof sunscreen will remain unchanged after 80 minutes of water exposure.
  • It takes one ounce of sunscreen to cover the body. Thus an 8 ounce bottle of sunscreen will be used up in four days of total body application. (How old is your bottle of sunscreen at home?)
  • DEET-containing sunscreens may reduce the SPF in the sunscreen by 30%.
  • Wear UVA and UVB protective eye glasses, sunglasses or goggles to protect the eyes from sun damage and cataract formation.
  • Sombrta makes sun protective lightweight clothing (SPF 30+)