UV Rays & How the Sun Can Damage Your Skin

Exposure to ultraviolet (UV) radiation, either from the sun or tanning beds, is a leading cause of skin cancer. For the majority of people, exposure to UV radiation comes mainly from sunlight. 

With the classification of UV radiation as a human carcinogen by the World Health Organization, it is important to understand how exposure to UV radiation increases skin cancer risk and what you can do to minimize that risk.


Source: http://www.wikihow.com/Understand-the-Effects-of-Different-UV-Rays

What is UV Radiation?

Sunlight is made up of three types of harmful rays: 

  1. Ultraviolet C (UVC)
  2. Ultraviolet B (UVB) 
  3. Ultraviolet A (UVA)
Diagram of ultraviolet radiation from the sun. Creative Commons license.

Diagram of ultraviolet radiation from the sun. Creative Commons license.

UVC rays have the shortest wavelength. While it is the most powerful and potentially harmful,  UVC rays are absorbed in the ozone. They don’t make it to the surface of the planet in large enough doses to have an impact on our skin.

UVA and UVB are a different story, though. Both make it through the atmosphere intact, and both can be harmful to your skin, including increasing your risk of developing skin cancer.

UVB Rays

UVB rays have a shorter wavelength and don’t penetrate as deeply into your skin, but can cause more direct tissue damage. 

Overexposure to UVB rays causes sunburns and damages the epidermis—the visible top layer of the skin. It can also damage and alter the DNA of skin cells,  increasing the risk of skin cancer. 

UVB intensity varies geographically and may be more or less intense depending on the season and time of day.

UVA Rays

UVA rays have the longest range and are not absorbed by the ozone layer. UVA is what gives people a tan (excepting those with lighter skin, who simply burn). It also causes premature aging and suppresses the immune system. UVA also alters the DNA of skin cells in the dermis, making it more difficult for your body to fight off cancer-causing changes.

Understanding the Role of Skin 

Your skin is the largest organ of the human body. Along with being the largest organ, skin is a protective casing that covers your entire body. The amount of skin on the body of the average human adult stretches more than 20 square feet and weighs roughly eight pounds!)

A diagram of epidermal hair follicle development, as affected by the thickness of the epidermal layers. Creative Commons license.

A diagram of epidermal hair follicle development, as affected by the thickness of the epidermal layers. Creative Commons license.

Skin does a long list of critical jobs that keep you alive. Along with keeping your insides on the inside, your skin 

  • Shields your fragile internal organs from inhospitable environments
  • Helps regulate your body temperature by keeping you warm or cool 
  • It contains the nerve cells that create your sense of touch
  • It keeps out microbes like bacteria that might make you sick
  • It blocks harmful ultraviolet (UV) radiation from the sun

Unfortunately, protecting your internal organs from UV rays comes at a cost. Anyone who has forgotten to put on sunscreen and spent a little too long outside knows the symptoms that appear when damage has occurred: your skin becomes tight, painful, and burnt.

But while sunburns are painful and unsightly, they are far from the most dangerous aspect of UV radiation. After the sunburn fades, severe UV radiation damage and/or long-term sun exposure can alter our DNA and cause us to develop skin cancer.

Effects of UV Exposure

UVA and UVB rays affect the skin in different ways. 

UVA radiation penetrates more deeply into the skin than UVB radiation and is responsible for the skin changes attributed to premature aging, such as wrinkles. Recent research indicates that UVA radiation plays more of a role in the development of skin cancer than previously thought.

UVB radiation affects the upper layers of skin and is primarily responsible for changes to the surface of the skin, such as the reddening and darkening of the skin associated with sunburns and suntans. UVB radiation also stimulates vitamin D production in the body, but prolonged exposure provides more damage than reward.

Both types of UV rays damage the DNA of skin cells. This damage can lead to the skin cell mutations that cause skin cancer. In addition to skin cancer, UV radiation exposure can also cause premature aging, immune suppression, and irreversible eye damage.

Reducing UV Exposure

You cannot completely avoid UV rays, but you can significantly reduce your exposure. 

Sunscreen is one of the most useful tools in combating UV radiation. Choosing the right sunscreen is essential. You want a broad-spectrum sunscreen with an SPF of 15 or higher that protects against UVA and UVB radiation. Apply sunscreen 20 to 30 minutes before sun exposure and reapply your sunscreen every two hours or immediately after getting wet or sweating excessively. 

In addition to sunscreen, you also want to find other ways to protect yourself from the sun. Wear a hat and sunglasses to protect your scalp, ears, and eyes. UVA rays can penetrate glass and clouds, so it is still important to wear sunscreen indoors and on cloudy days. If possible, avoid prolonged time outdoors during peak hours of sunlight, particularly in the summer.

In Summary

Unfortunately, any exposure to ultraviolet radiation—whether from the sun or from a tanning bed—will damage the skin and increase the risk of skin cancer. The good news: there are several effective ways to protect your skin from the sun and mitigate the risk of developing skin cancer.

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