Skip to main content icon/video/no-internet
icon backReturn to Entries

Sunburn

Sunburn is characterized by skin redness, swelling, tenderness, and blistering in response to sunlight exposure. Given the number of athletes who play outdoor sports, prevention of the negative short- and long-term health effects of sunburn is important.

Sunlight

Sunlight is divided into visible light, infrared radiation, and ultraviolet radiation (UVR). UVR is categorized further into UVA (320- to 400-nanometer [nm] wavelength), UVB (290320 nm), and UVC (<290 nm) radiation. UVB radiation can lead to the acute skin changes seen in sunburn. It has the ability to directly damage DNA, causing genetic mutations and cancer. UVA radiation is associated with skin wrinkling and may also contribute to some skin cancers. UVC does not contribute to sunburns.

Environmental factors play a role in determining UVR exposure. The stratosphere contains ozone, which absorbs all UVC, high amounts of UVB, and a small amount of UVA radiation. Ozone concentrations vary with temperature, weather, altitude, and latitude. UVB radiation increases by 3% per degree of latitude, and UVR intensity has been found to increase by 4% for every 300 meters (m) of elevation. Midday sunlight passes through less of the atmosphere than at any other point in the day, leading to more UVR exposure during midday hours. Clouds, fog, and haze can decrease UVR by 10% to 90% but never fully block it out. Snow and sand can reflect up to 90% of UVR. Even under water, UVR can penetrate to a depth of 1 m.

Skin Changes

The epidermis forms the protective, outermost layer of the skin. The deepest layer of the epidermis is constantly repopulated by new keratinocytes (cells composed of keratin), which migrate superficially, replacing the older keratinocytes and turning over the entire epidermal layer in approximately 28 days. Melanocytes (cells that produce melanin) are located in the deepest layer of the epidermis. The melanin is stored in melanosomes, which can be transferred to the keratinocytes. Skin color is influenced by the number and size of melanosomes, the type of melanin they contain, and the rate at which melanin is broken down.

Sunburn occurs as the skin tries to protect itself by absorbing UVR. UVA radiation is partially absorbed by melanin, which produces a darkening of the skin as the melanin is transferred to the keratinocytes. The resulting tan appears immediately after exposure and lasts for a few hours but does not protect the skin against future damage from sun exposure. UVB radiation is responsible for the redness, swelling, tenderness, and blistering that appears 6 to 12 hours after exposure and peaks in effect around 24 hours. These changes are caused by the release of inflammatory mediators, leading to dilation of the blood vessels and increased vascular permeability. In response to the damage, melanocytes accelerate the production of melanin and its transfer to keratinocytes. This results in a darkening of the skin that appears 2 to 3 days after sunlight exposure, persists for days to weeks, and reduces the skin's sensitivity to UVR by two- to threefold.

Risk Factors

Athletes with more melanin, and darker skin, are at lower risk for sunburn, while fair-skinned athletes are more likely to sunburn. But UVR still penetrates the skin and causes damage in people with dark skin. People living at higher altitudes or locations with predominantly sunny climates have an increased risk due to more exposure to sunlight. Sweating has also been found to increase the photosensitivity of the skin and to increase the risk of sunburn.

...

  • Loading...
locked icon

Sign in to access this content

Get a 30 day FREE TRIAL

  • Watch videos from a variety of sources bringing classroom topics to life
  • Read modern, diverse business cases
  • Explore hundreds of books and reference titles

Read next

More like this

Sage Recommends

We found other relevant content for you on other Sage platforms.

close

Have you created a personal profile? Login or create a profile so that you can save clips, playlists and searches

close
close
close Signed In to profile You are signed in as:
close
Logged in Institution Institution