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Ultraviolet Rays From the Sun

Overview

The sunlight that reaches the earth has ultraviolet A and ultraviolet B (UVA and UVB) rays. These ultraviolet rays are the main causes of damage to the skin from the sun. UVA and UVB rays affect the skin's sensitivity to sun exposure in different ways.

UVA

  • Can pass through window glass
  • Is not affected by a change in altitude or weather
  • Is present all day and every day of the year
  • Penetrates deep into skin layers
  • Is 20 times more abundant than UVB rays
  • Causes long-term skin damage

UVB

  • Cannot pass through window glass
  • Causes sunburn
  • Causes tanning
  • Helps the body make vitamin D
  • Is more intense:
    • During the middle of the day
    • In the summer
    • At high altitudes and near the equator
  • Can cause skin cancer and cataracts

Most sunburn and skin cancer can be prevented. Use the following tips to protect your skin.

Avoid exposure to the sun

  • Try to spend less time in the sun from 10 in the morning to 4 in the afternoon. Find shade if you need to be outdoors.
  • Wear clothing that blocks the sun. This can be a wide-brimmed hat that covers your neck, ears, eyes, and scalp. It can also include loose-fitting, tightly-woven clothes that cover your arms and legs.
  • Wear sunglasses that block UV rays.

Use sunscreen

  • Always wear sunscreen on exposed skin. Make sure to use a broad-spectrum sunscreen that has a sun protection factor (SPF) of 30 or higher. Use it every day, even when it is cloudy.
  • Apply sunscreen at least 30 minutes before you go out in the sun. Put on more every 2 to 3 hours while you are in the sun and after you sweat a lot or swim.
  • Take extra care to protect your skin when you're near water, at higher elevations, or in tropical climates.
  • Use a broad-spectrum lip balm or cream that has SPF of 30 to protect your lips from getting sunburned.

Credits

Current as of: September 20, 2021

Author: Healthwise Staff
Medical Review:
William H. Blahd Jr. MD, FACEP - Emergency Medicine
Adam Husney MD - Family Medicine
Kathleen Romito MD - Family Medicine
E. Gregory Thompson MD - Internal Medicine

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