According to the Centers for Disease Control and Prevention (CDC), the sun’s ultraviolet (UV) rays can damage skin in as little as 15 minutes.   
During July’s UV Safety Awareness Month, HSHS St. Francis Hospital, following guidance from the American Academy of Dermatology (AAD), reminds everyone to protect their skin while enjoying the outdoors. 
UV radiation is a form of electromagnetic radiation that comes from the sun and man-made sources like tanning beds. There are three types of UV rays:

  • UVA rays can cause skin cells to age and may cause long-term skin damage such as wrinkles, liver spots and leathery skin
  • UVB rays can directly damage the DNA in skin cells and are the main rays that cause sunburn. UBV rays are the most harmful to skin, contributing to skin cancer and premature aging.  
  • UVC rays are high in the atmosphere and do not touch the ground, therefore these rays do not pose as much of a health risk.

The strength of UV rays that reach the ground depends on a several factors, such as:

  • Time of day: UV rays are strongest between 10 a.m. and 4 p.m.
  • Clouds: UV rays can penetrate clouds, so applying sunscreen even on cloudy days is recommended.
  • Reflection off surfaces: UV rays can bounce off surfaces like water, snow, sand and pavement, leading to an increase in UV exposure.
  • Distance from the equator: UV exposure goes down as you get father from the equator.
  • Season: UV rays are stronger during spring and summer months, unless you are close to the equator, which poses year-round sun danger.

Protection from the sun’s rays, especially with the use of sunscreen, is the most effective way to reduce harmful sun exposure. All sunscreens contain protection against UVB rays, but not all provide protection from damaging UVA rays. 

Besides using sunscreen regularly, HSHS experts suggest speaking with your provider about any medications are you taking; some medications can make you more sensitive to UV rays. You can also protect yourself from harmful UV rays by limiting time in direct sunlight, using an umbrella for shade, wearing a wide-brimmed hat and sunglasses and wearing long sleeves and pants.  

For more information about UV rays, visit the Ultraviolet Radiation page of the CDC’s website. To learn about types of sunscreen, how often to apply it and more, visit the American Academy of Dermatology’s Sunscreen Resource Center

Media Contact

Melissa Athmer

Manager, Marketing & Communications
HSHS Illinois
Office: (618) 234-2120, Ext. 32258

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