The Sun & Your Skin

 from the NeuroNetwork for Emerging Therapies Mini Symposium Series: Here Comes the Sun


Ultraviolet Light (UV)

diagram of visible light versus ultraviolet light

UVA Radiation:

  • Causes skin tanning
  • Causes oxidative DNA stress

UVB Radiation

  • Causes skin burns
  • Directly damages DNA

DNA damage causes skin cancer

  • 1 out of 5 Americans will develop skin cancer by age 70
  • 5 or more sunburns increase your risk of melanoma
  • The most common skin cancer is basal cell carcinoma (~3.6 million diagnosed each year)
  • The second most common skin cancer is squamous cell carcinoma (~1.8 million diagnosed each year)
  • 186,680 melanomas are estimated to be diagnosed in 2023

When You Are Exposed to the Sun (and UV radiation)

photo of the sun

Sunny Day:

  • UVA 
  • UVB
photo of cloudy sky

Cloudy or Rainy Day:

  • UVA passes through to your skin
  • UVB is partially blocked
photo of a man sitting in front of a window

Through Window Glass:

  • UVA passes through to your skin
  • UVB is blocked

Note: Only car windshields protect against UVA, but it passes through the side and rear windows

photo of skiier on Chamonix Mont Blanc


  • Snow reflects ~85-90%
  • Water reflects ~15-20%
  • Sand reflects ~15%
  • Dark soil reflects ~10-20 %

Protecting Your Skin

Basic Tips:

  • Avoid indoor tanning
  • Seek shade
  • Avoid peak sun (10 AM to 4 PM)
  • Sun Protection

Types of Topical Protection:

Sunblock vs. Sunscreen:

  • Sunblock shields from UVA/UVB with zinc oxide and/or titanium oxide
  • Sunscreen contains chemicals that absorb/scatter UV rays

Broad Spectrum:  Protects against both UVA & UVB

Sun Protective Factor (SPF):

  • Amount of protection from sunburn
  • If you take 10 minutes to burn without sunscreen, it will take you 300 minutes to burn with SPF30 sunscreen

Water Resistance:

  • Water resistant: 40 minutes in the water
  • Very water resistant: 80 minutes in the water

How to Apply

  • Apply 15-20 minutes before going outdoors
  • Spray sunscreens should be rubbed in
  • Apply 1 ounce (2 tablespoons) to every area of your skin
  • Reapply after 1-2 hours in direct sunlight, or after swimming, sweating, or toweling off
  • Don't forget your lips and feet, plus remember to wear sunglasses to protect your eyes

Wearable Sun Protection


  • 4-inch brim with a tight weave
  • "If you can look up and see the sun, the sun can see you!"


  • Tight weave fabrics without holes
  • UV Protective Factor (UPF) is the fraction of sun's rays that penetrate the fabric—UPF 50 allows 1/50th of UV radiation to reach skin


  • 100% UVA or UVB blockers or a UV 400 signature
  • The larger, the better lens—especially wraparound styles
  • Polycarbonate are the most shatterproof 

Other Sun Protection Recommendations


  • Sunscreen 30 SPF or higher and water-resistant

Babies Under 6 Months:

  • Sun protection using clothing & hats, as well as seeking shade
  • Apply sunscreen in small amounts to any unprotected skin

Children Above 6 Months:

  • Look for sunscreen made for children—often contain physical blockers of the sun that are less irritating to the skin

 Sensitive Skin:

  • Sunscreen daily (for everyone)

For more information on skin cancer and sun protection: