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    Consumer Health: What is a sunburn?

an overhead photo of a man's sunburned lower legs and feet in flip-flops, on the beach

July is UV Safety Month, which makes this a good time to learn about sunburn and why it's important to avoid one by protecting your skin from the harmful effects of ultraviolet, or UV, radiation from sunlight.

Sunburn is inflamed, painful skin that feels hot to the touch. It's caused by too much exposure to UV light. That UV light may be from the sun or artificial sources, such as sunlamps and tanning beds. UVA is the wavelength of light that can penetrate to the deep layers of skin and lead to skin damage over time. UVB is the wavelength of light that penetrates the skin more superficially and causes sunburn.

UV light damages skin cells. The immune system reacts by increasing blood flow to the affected areas, which causes the inflamed skin known as sunburn.

Any exposed part of your body, including your earlobes, scalp and lips, can burn. Even covered areas can burn if, for example, your clothing has a loose weave that allows UV light through. Your eyes, which are extremely sensitive to the sun's UV light, also can burn. You can get sunburn on cool or cloudy days. Surfaces such as snow, sand and water also can reflect UV rays and burn skin.

Sunburn signs and symptoms usually appear within a few hours after sun exposure. But it may take a day or more to know how severe the sunburn is. If the damage is severe, medical attention may be required.

Intense, repeated UV light exposure that results in sunburn increases the risk of other skin damage, such as wrinkles and age spots. It also raises the risk of skin cancers such as melanomaThis slideshow includes images of several conditions caused by sun damage.

Here are four ways you can protect yourself from UV radiation damage:

  • Time of day
    Avoid sun exposure in the middle of the day — between 10 a.m. and 4 p.m. — when the UV rays are strongest. In addition, be mindful that clouds offer little protection, and UV rays can bounce off surfaces such as water, sand, snow or pavement, leading to increased UV exposure.
  • Sunscreen
    Use a broad-spectrum sunscreen with a sun protection factor, or SPF, of at least 30 — even on cloudy days. Apply sunscreen generously, and reapply every two hours — or more often if you're swimming or perspiring. Use a generous amount of sunscreen on all exposed skin, including your lips, the tips of your ears, and the backs of your hands and neck. And if you're using leftover sunscreen from year to year, be sure to check the expiration dateLearn more about choosing the best sunscreen.
  • Sunglasses
    UV radiation also can burn your eyes. Sunburned eyes can feel painful or gritty. Too much UV light can damage the retina, lens and cornea. Sun damage to the lens can lead to clouding of the lens, or cataracts. Exposure to UV light also can increase your risk of developing ocular melanoma. Sunburn of the cornea also is called snow blindness. Look for sunglasses that block both types of UV radiation — UVA and UVB rays. Learn more about choosing the best sunglasses.
  • Protective clothing
    Sunscreens don't provide complete protection from UV rays. You also should protect your skin with dark, tightly woven clothing that covers your arms and legs, and a broad-brimmed hat that provides more protection than a baseball cap or visor. Some companies also sell photoprotective clothing, with a UV protection factor, or UPF, rating similar to the SPF rating of sunscreens. Learn more about UPF clothing.

Exercising and enjoying time outdoors are important for good health. This time of year means fun in the sun for many people. Knowing how to protect your skin will allow you to do so safely.

Connect with others talking about sun safety in the Skin Health Support Group on Mayo Clinic Connect, an online patient community moderated by Mayo Clinic.

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