UV radiation
Skin fulfils a number of different functions in the human body. One of them is the protection against external environmental influences, for example against the ultraviolet (UV) radiation.
But what is UV radiation
exactly? Within this capter you will find all important information about UV radiation.
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UV radiation. Sunlight is composed of many different forms of light. Of these, only visible light, heat rays (infrared light) and UV light reach the surface of the Earth. UV light has an impact on our skin. It contains so much energy that it is able to enter the skin, while you can neither see nor feel them. More details about UV radiation... |
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UV radiation in detail Among UV radiation, we have to distinguish between
While UV C rays never reach the Earth as they are withheld by the ozone layer, UV A and UV B rays reach our planet and have an impact on our skin. They contain so much energy that they are able to enter the skin, while you can neither see nor feel them. UV B rays for example enter the upper skin layer (epidermis) where they cause tanning and sunburn. |
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UV A rays can penetrate into a deeper skin layer (dermis). They can cause skin ageing and the so-called “sun allergy”. For the development of skin cancer, both types of rays are responsible, UV B still more than UV A.
UV radiation can be of different intensity. This depends on the season and the daytime. In summer and around noon (between 10 am and 4 pm), it is usually especially strong.
The geographical situation and the altitude play an important role as well. Around the equator, the radiation is more intensive as it hits the Earth vertically. In the mountains and in clear air we get remarkable more UV radiation than in a valley.
Important is as well the surrounding in which we are exposed to the sunlight: snow, water and tarmac strongly reflect the UV light, and this is the reason why sunlight is so intensive on the beach, on the ski slope and when we are swimming in the water.
It’s unfortunately an error to think that a cloudy sky would keep the sunrays at bay. Clouds can weaken the intensity of the rays, but cannot completely stop them. In some exceptional cases they may even intensify the impact of the light.
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The so-called UV index shows the intensity of the sunlight. |
It starts at 1 and ends at 10. The higher the index number, the higher is the intensity. And the higher the UV index is, the more important it is to apply sun protective measures. The UV index is often published together with the weather forecast in radio, television, newspapers and internet. The given number indicates the maximum intensity at noontime.
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As of an UV index of 3 it is recommended to protect one’s skin against the sun by using adequate clothing, sunscreen or simply by avoiding direct sunlight.
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Please check here for the UV index of the place where you live: http://www.epa.gov/sunwise/whereyoulive.html. |
