What is a Sunburn? Causes & Science of Sunburns

sunburn prevention

Almost all of us have experienced sunburn at one point or another—typically, because we fail to use the proper sun protection methods. While many of us are capable of riding out the three or four days that our skin is red, itchy, and painful, the initial symptoms of a sunburn are just the start of the damage.

Sunburns are more dangerous than many people realize and can have drastic consequences.

The statistics are frightening: Suffering one or more blistering sunburns during childhood more than doubles your chances of developing potentially-deadly melanoma later in life. Recent research shows that one in five Americans will develop skin cancer by the age of 70.

In addition to cancerous growths, sun damage can cause aesthetic damages as well. Research has repeatedly shown that up to 90 percent of sagging, wrinkling, and dark spots is a result of how much sun exposure you’ve sustained. One study in particular found that UV exposure is responsible for 80 percent of visible facial aging signs.

What really happens when your skin is exposed to the sun’s rays? A sunburn is your skin’s response to the sun’s UV radiation—when your skin is sunburned, it’s an indication that severe damage has been done. Let’s take a look at exactly what happens to your skin when it gets burned.

What is a sunburn?

So what’s the science behind sunburns? The sun puts off both UVB and UVA rays. UVB rays are shorter and are responsible for the development of skin cancer. UVA rays are longer and penetrate deeper into the skin; this type of radiation is responsible for wrinkles, sagging, and other sings of aging.

When your skin is exposed to UV radiation, the body triggers a defense mechanism. Our skin contains cells called melanocytes, which are tasked with producing a pigment called melanin. Melanin absorbs UV light, then dissipates it as heat; think of melanin as the body’s natural sunscreen. When your skin senses sun damage, the body sends melanin into surrounding cells in an effort to shield them from further harm.

People with darker skin have more melanin at their disposal, while those with pale skin are quicker to burn. A sunburn is the skin’s response to severe UV damage, but it’s not only red skin that you should be wary of; any change in the color of your skin is an sign of sun damage—even that golden tan you crave. Whether you’ve tanned or gotten a severe red burn, UV radiation has damaged the DNA in your skin cells. Any type of damage can lead to skin cancer, so it’s important to wear sun protection at all times.

When UV radiation strikes the skin, it can damage the DNA in your cells. Once a cell has received too much radiation, it sacrifices itself to prevent damage in surrounding cells. When your body senses damage it launches a counterattack, sending surpluses of blood to the area to help improve healing; it’s during this time that inflammation flares, which can cause skin sensitivity and pain.

This is the case for mild sunburns—if you experience a severe sunburn, the consequences are worse. If you’ve been overexposed to UV radiation, the skin may blister; these little pockets of skin form protective bubbles over the tissue and fill with liquid.

uvb cause sunburn

What are the symptoms of a sunburn?

A severe sunburn causes a host of symptoms, which are indicative of your body’s efforts to repair the damage caused by the burn. Common sunburn symptoms and signs include:

  • Blisters
  • Red, warm skin at the site of the burn
  • Itching

After exposure to UV radiation, your skin may turn red in as little as 30 minutes; the burn will continue to develop for 24 to 72 hours following, and it’s during this time that pain is typically most severe.

Sunburned skin is hot to the touch, may itch, and certainly painful. The immediate effects of a sunburn are unpleasant to say the least, but sunburned skin is more likely to incur skin damage; excessive sun exposure can also increase the risk of skin cancer.

Why does my skin peel after a sunburn?

If your skin begins peeling after a sunburn, it’s because your body is attempting to get rid of damaged cells that could become cancerous. When the body registers severe damage, all those cells are sacrificed—essentially, your skin cells die off in mass to be replaced by new, healthy skin cells.

Am I Always at Risk for Sunburn?

Any time you head outside, your skin is exposed to UV radiation. However, there are certain days and time of day that have an increased risk of sunburn. To understand your risk of sunburn on a given day, take a look at the UV Index Scale. This tool can predict how quickly your skin will burn if you don’t use proper protection. Every day, the National Weather Service measures ultraviolet levels, then converts their findings into a scale that indicates exposure risk.

uv index
  • 2 or less: If the UV index rating is less than two, there’s minimal risk for sunburn for the average person. The average person’s skin will begin to burn after 60 minutes if unprotected.
  • 3 to 5: If the UV index rating falls between 3 and 5, risk for sunburn is raised to moderate. The average person’s skin will begin to burn after 30 to 45 minutes if unprotected.
  • 6 to 7: If the UV index rating reads 6 or 7, you’re at high risk of harm from unprotected sun exposure. It can take anywhere from 15 to 25 minutes to develop a sunburn if unprotected.
  • 8 to 10: If the UV index rating falls between 8 and 10, you’re at very high risk of harm from unprotect sun exposure. If your skin is unprotected, you can burn within 15 minutes.
  • 11+: If the UV index rating is 11 or higher, you’re in extreme danger of sunburn. If you’re unprotected, skin damage can occur within 10 minutes.

Note of caution: Regardless of the UV index reading, you should always wear appropriate sun protection when heading outdoors, whether it’s the middle of summer or dead of winter.

How do I prevent sunburn?

The best way to prevent a sunburn is to limit your sun exposure. The following methods can help keep your skin safe from UV rays:

Steer clear of midday sun

The sun is its strongest during the hours between 10 a.m. and 4 p.m. Try to stay indoors as much as possible and stick to shady areas if you must be outside.

Wear protective clothing

Keep your skin safe from the sun’s damaging rays with protective clothing, including wide-brimmed hats, sunglasses, and clothing made from sun protective fabric.

Apply (and reapply) sunscreen

Always wear broad spectrum sunscreen, whatever the weather outside. Simple rule of thumb: Don’t leave the house until you’ve applied appropriate SPF. Broad spectrum solutions are FDA-approved to protect against both UVA and UVB rays, offering you the best available protection. If you don’t like the feeling of sticky creams, opt for brush-on powder sunscreen that’s quick to apply and easy to reapply. If you wear foundation with sunscreen, make sure you’re taking care to reapply a new layer of foundation every two hours.

How does a sunburn lead to skin cancer?

According to WebMD, skin cancer is often caused by overexposure to the sun’s rays over a set of years, but sun damage can occur even if you don’t develop a painful, itchy burn.

When UV rays hit your skin, DNA damage occurs. This triggers the body’s inflammatory response, which funnels blood to the area. In most cases, this makes the skin appear red—in some cases, it doesn’t. Don’t let a lack of redness lead you to believe that your skin isn’t being damaged. Any time spent unprotected outside can increase your risk of skin cancer.

Skin cancer develops primarily on areas of skin that are consistently exposed to the sun, including the scalp, face, lips, ears, neck, chest, arms and hands, and it’s important to be on the lookout for indications of cancerous growth.

Use the ABCDE system to keep a watchful eye on any irregular spots or marks that develop or grow. The chart below shows normal skin spots versus those indicative of melanoma.

how to spot melanoma

If you notice any irregularities in your moles or skin hue, make an appointment with an accredited dermatologist for testing. The sooner you have a spot looked at, the better.

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