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

There are 3 types of UV rays:

• 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. It causes the skin to become thick and leathery over time. 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 sit out in the sun regularly. The skin may also develop brown spots (liver spots) in later years.

• Skin cancer. Millions of 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.

• Cataracts and other eye problems. UV radiation exposure increases the risk of cataracts. With this condition, the lens of the eye becomes cloudy and it becomes hard to see. If not treated, cataracts can lead to blindness over time. Other changes that can decrease vision are also possible.

What is the UV Index?

The UV Index is an official forecast from the National Weather Service. It estimates how much ultraviolet radiation will reach the Earth's surface for most ZIP codes across the U.S. This information can help you plan outdoor events and plan your level of sun exposure. It also gives you tips on how to help prevent sunburns. 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). The World Health Organization (WHO) uses a system of colors that correspond to UVI level.

Understanding the UV Index

UV Index values	Color	Amount of risk
0 - 2	Green	Low. Low danger from unprotected sun exposure. But if you burn easily, cover up and use sunscreen with a sun protection factor (SPF) of at least 30.
3 - 5	Yellow	Moderate. A moderate risk of harm from unprotected sun exposure. Wear protective clothing, sunglasses, and a hat if you will be outside. Stay in shade around midday. Apply sunscreen with at least SPF 30 every 2 hours.
6-7	Orange	High. A high risk of harm from unprotected sun exposure. Wear protective clothing, sunglasses, and a 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	Red	Very High. A very high risk of harm from unprotected sun exposure. Wear protective clothing, sunglasses, and a 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 +	Purple	Extreme. An extreme risk of harm from unprotected sun exposure. Follow all of the above suggestions to protect yourself from the sun. Wear protective clothing, sunglasses, and a 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. They all 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.