Sunburn - Causes of sunburn

Sunburn is caused by overexposure to sunlight, which contains ultraviolet radiation (UV rays).

Ultraviolet rays

The sun produces three different types of UV rays. They are:

UVA rays – these are less potent than UVB rays, but penetrate deeper into the skin. They damage the middle layer (dermis), which contains tissues that give the skin its elasticity. Prolonged exposure to UVA rays can age the skin prematurely.
UVB rays – these UV rays are absorbed by the top layer of skin (epidermis). The epidermis releases chemicals that cause the pain, swelling and redness associated with sunburn.
UVC rays – are filtered by the earth's atmosphere, which means that protection against this type of radiation is not required.

UVA and UVB are the two types of ultraviolet rays that cause sunburn.

Sunburn can also be caused by exposure to other sources of UV light, such as tanning beds and phototherapy lamps. These lamps are often used in light therapy to treat conditions such as jaundice in newborn babies (yellowing of the skin).

Exposure to UVA and UVB rays increases your risk of developing skin cancer. Sunburn is a warning sign that you are putting yourself at risk and damaging your skin.

Who's at risk of sunburn?

Everyone who is exposed to UV light is at risk of getting sunburn. However, the less melanin you have, the less protected you are against the effects of UV light.

You are more likely to get sunburn if you:

are in a country that is close to the equator, such as Ecuador in South America or Uganda in Africa
are under six or over 60 years of age
have pale, white skin and blonde or red hair
are at a high altitude – for example, climbing or skiing
spend prolonged periods of time outdoors in a sunny climate, particularly when there are clear skies
are near snow, ice or water where the sun's rays can reflect onto your skin

Young children and babies are more sensitive to the effects of UV rays.

Melanin

Melanin is a pigment that is produced when your skin is exposed to sunlight. It absorbs the UV radiation found in sunlight to help protect your skin. This results in your skin becoming darker, which is a sign that it has been damaged by UV rays.

If you have fair skin or red hair, or if you have not been in the sun much, your melanin levels will be low. This increases your risk of burning more quickly. Melanin stops you burning so easily, but it does not prevent the other harmful effects of UV radiation.