Ultraviolet (UV) radiation is a type of natural energy from the sun. Scientists know that prolonged exposure to UV rays increases a person’s risk of getting skin cancer.

Sunlight is essential for human health. When it hits a person’s skin, it triggers a reaction that makes vitamin D. Vitamin D helps with calcium absorption and bone growth.

However, UV rays can damage the skin. According to the Centers for Disease Control and Prevention (CDC), most skin cancers are the result of overexposure to UV rays from the sun, tanning beds, or sun lamps.

This article explains UV radiation and how it can damage the skin. It also highlights steps people can take to reduce their risk and explains what symptoms to look out for.

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UV radiation is a type of energy from the sun. According to the United States Environmental Protection Agency, there are three types of UV rays:

  • Ultraviolet A, or UVA: This type makes up most of the UV radiation on Earth. These rays cause skin aging and can damage a person’s eyes.
  • Ultraviolet B, or UVB: These rays cause sunburn and can damage skin cells’ DNA. UVB rays are responsible for most skin cancers.
  • Ultraviolet C, or UVC: The earth’s atmosphere blocks these rays. However, scientists can recreate them. Their uses include UV sanitizing light bulbs and arc welding torches.

Prolonged UV exposure can cause cancer. The damage builds up over time.

According to the American Cancer Society (ACS), UV rays can damage skin cells’ DNA. Damaged DNA can make cells grow and reproduce uncontrollably, leading to cancer.

Skin cancers start in the top layers of the skin. The names of various types of skin cancer reflect the cells they affect. These include:

  • squamous cell carcinoma
  • basal cell carcinoma
  • melanoma

Basal cell carcinoma is the most common type of skin cancer. It usually occurs on a person’s arms, head, or neck — parts of the body that many people expose to sunlight. However, basal cell carcinoma can form anywhere on the body.

Squamous cell carcinomas also develop on areas of exposed skin. The face, neck, arms, chest, rim of the ear, and back are common sites.

Melanomas begin in cells called melanocytes. When UV rays hit a person’s skin, they stimulate these cells to make melanin. Melanin is the skin’s pigment, and increased amounts darken or tan the skin.

Sunburn is usually the first symptom of UV damage. Even mild sunburn can lead to premature aging and skin cancer. Tanned skin is also evidence of sun damage.

People with fair skin may be at greater risk of sunburn, but it can affect anyone.

Sunburn increases a person’s risk of getting skin cancer. Even one severe sunburn during childhood or adolescence doubles a person’s chances of developing melanoma later in life.

Repeated sunburns carry increased risks.

People can also get sunburned by using tanning beds or other indoor tanning aids that involve UV rays.

Learn how to treat and prevent sunburn here.

According to the National Cancer Institute (NCI), skin cancer is the most common type of cancer.

Basal and squamous cell carcinomas make up most cases. Both of these cancers are highly treatable if doctors detect and treat them early, as they tend not to spread to other parts of the body.

Melanoma is a rarer form of skin cancer and is more likely to spread than other types.

Skin cancers usually start as unusual markings or changes in the appearance or texture of the skin. The ACS recommends that anyone with unusual moles, lumps, or sores on their skin get checked for skin cancer.

The American Academy of Dermatology recommends that people check their skin every month for symptoms of skin cancer, such as:

  • moles that change shape or look different from others
  • scaly patches
  • sores that do not heal or sores that heal but then come back
  • dome-shaped growths
  • raised, itchy patches of skin
  • areas that appear fragile and tend to bleed easily
  • dark streaks under a finger or toenail

People with fair skin that burns easily are most at risk of skin cancer, but it can happen to anyone. UV exposure, either from sunlight or from indoor tanning aids, increases a person’s risk.

Age also plays a part. Skin cancer rates tend to be higher in older people.

People who work outdoors or spend a lot of time outside have regular exposure to UV rays, which increases their risk of developing skin cancer.

The CDC reports that certain groups are less likely to use sunscreen than others, which may make them more susceptible to skin cancer. Sunscreen use is lowest among men, non-Hispanic Black people, people with less sun-sensitive skin, and people with lower incomes.

Anyone can get sunburned, regardless of skin tone.

According to a 2016 study, People of Color are less likely to develop skin cancer, but when they do, it is usually diagnosed at a later stage, making treatment more difficult.

Learn more about how sunburn affects dark skin here.

UV rays can damage the skin, even on cloudy days. Surfaces such as water, snow, sand, and cement can also reflect rays. UV rays are usually strongest in the middle of the day, between 10 a.m. and 4 p.m.

The CDC recommends taking simple steps every day to protect the skin:

  • Wear sunscreen on exposed skin every day. Broad-spectrum sunscreens block UVA and UVB rays and have a sun protection factor (SPF) rating. The higher the SPF rating, the more protection they give. However, sunscreens do not block all UV rays.
  • Seek shade rather than full sun.
  • Cover up with loose-fitting long-sleeved shirts, long pants, or skirts. Sunglasses help protect the delicate skin around the eyes and reduce the risk of cataracts. A wide-brimmed hat can protect a person’s head, neck, face, and ears.
  • Avoid indoor tanning.

Learn how to choose and use sunscreen here.

Not all skin cancers look alike. However, a new mole or a sore that will not heal can be a symptom of skin cancer. If someone is concerned about skin changes, they should consult a dermatologist.

The NCI recommends following the ABCDE rule when checking unusual blemishes or moles for symptoms of melanoma:

  • A for asymmetry: The shape of one half is not the same as the other half.
  • B for border: The border is ragged, notched, or blurred. The pigment may spread and be noticeable in the surrounding skin.
  • C for color: The coloring differs from one area to the next, with shades of black, brown, and tan. Some areas may also appear white, gray, red, pink, or blue.
  • D for diameter: The marking has changed size — it is particularly of concern if it has gotten bigger. Most melanomas are larger than 6 millimeters or 1/4 inch wide, which is about the width of a pencil eraser. However, they can be smaller than this.
  • E for evolving: The marking changes shape, size, or color over a couple of weeks or months.

Learn about how effective skin cancer apps are for early detection.

Protecting the skin from UV rays is a daily challenge, but doing so reduces the risk of skin cancer.

Most people with basal or squamous cell carcinomas respond well to treatment, and deaths are rare. However, these cancers can recur.

Melanoma causes more deaths, as this type of cancer is more likely to spread to other parts of the body.

According to the ACS, if doctors diagnose melanoma at an early stage, the 5-year survival rate is 99%. This means that 99 out of 100 people will still be alive 5 years after diagnosis. However, if it spreads to other organs, this rate drops to 30%.

UV rays can damage the skin and may lead to skin cancer.

Sunburn increases the risk of developing skin cancer, but prolonged exposure without burning also damages the skin.

People can reduce their risk by wearing sunscreen, covering their skin, seeking shade, and avoiding the sun during the hottest part of the day.