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Ultraviolet (UV) Radiation and Skin Cancer

Ultraviolet (UV) radiation is a type of light. Sunlight has UV rays, along with other kinds of rays. Some light bulbs give off UV rays. UV light bulbs are used in tanning machines, some nail dryers, machines used by dermatologists, and more.

Types of UV rays

UV rays come in three types:

  • UVA . These rays go into the skin more deeply than UVB rays. These play a major part in skin aging and wrinkling. They also contribute to the growth of skin cancer. 

  • UVB. These rays are the main cause of sunburn. They tend to damage the skin's outer layers. These rays play a key role in the growth of skin cancer.

  • UVC. These rays don’t reach our skin. The Earth’s atmosphere absorbs UVC rays before they reach the surface.

How UV rays affect the skin

In most cases, UV rays react with a chemical in the skin called melanin. This is the first defense against the sun. Melanin absorbs the dangerous UV rays that can do serious skin damage. But melanin can’t absorb all the UV rays, and some people don’t have much melanin in their skin. Exposure to UV rays is linked to harmful health conditions such as:

  • Sunburn. A sunburn happens when the amount of UV rays exceeds the protection that the skin's melanin can provide. Sunburn is damage to the skin. It causes pain, redness, and blistering.

  • Premature aging of the skin. Premature aging of the skin is also called photoaging. Signs of photoaging include earlier-than-normal freckling, wrinkling, loss of collagen, and widening of small blood vessels in the skin. These changes can happen earlier and more quickly in people who sunbathe regularly. The skin may also develop brown spots (liver spots) in later years.

  • Skin cancer. More than 2 million people are diagnosed with skin cancer in the U.S. each year. Skin cancer is more common as people get older, but skin damage from the sun begins at an early age. Protection should start in childhood to prevent skin cancer later in life.

What is the UV Index?

The UV Index is an official forecast from international weather organizations. It that estimates how much ultraviolet radiation will reach the Earth's surface. This is to help you plan your sun exposure and prevent burns. The UV Index also includes the effects of cloud cover on the forecast UV level. It notes the risk of overexposure to the sun's UV rays on a scale from 0 (low) to 11+ (extreme).

Understanding the UV Index

UV Index values

Exposure categories

0 - 2

Low. Low danger from unprotected exposure to the sun. But if you burn easily, cover up and use sunscreen with at least sun protection factor (SPF) 30.

3 - 5

Moderate. A moderate risk of harm from unprotected exposure to the sun. Wear protective clothing, sunglasses, and hat if you will be outside. Stay in shade around midday. Apply sunscreen with at least SPF 30 every 2 hours.

6-7

High. A high risk of harm from unprotected exposure to the sun. Wear protective clothing, sunglasses, and hat if you will be outside. Apply sunscreen with at least SPF 30 every 2 hours. Reduce your time in the sun from 10 a.m. and 4 p.m.

8-10

Very High. A very high risk of harm from unprotected exposure to the sun. Wear protective clothing, sunglasses, and hat if you will be outside. Apply sunscreen with at least SPF 30 every 2 hours. Seek shade outdoors. Try to avoid the sun between 10 a.m. and 4 p.m.

11 +

Extreme. An extreme risk of harm from unprotected exposure to the sun. Follow all of the above suggestions to protect yourself from the sun. Wear protective clothing, sunglasses, and hat if you will be outside. Apply sunscreen with at least SPF 30 every 2 hours. Seek shade outdoors. Try to avoid the sun between 10 a.m. and 4 p.m.

Staying safe in the sun

For many people, a small amount of exposure to sunlight is fine. But too much can be dangerous. Keep track of the UV Index. Protect your skin with clothing and sunscreen. Take extra care around sand, water and snow, which reflect UV rays and give you more exposure. These steps will help you reduce your risks of cancer, premature aging of the skin, and other harmful effects.