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Optical Radiation

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Optische Strahlung

What is UV radiation?

Ultraviolet (UV) radiation comprising the wavelength range from 100 nm to 400 nm is the most energetic part of optical radiation. It adjoins directly to the range of ionising radiation. In the short wavelength range UV radiation can have similar effects as ionising radiation. According to different biological effects UV radiation is subdivided into three wavelength ranges: UV-A radiation (400 – 315 nm), UV-B radiation (315 – 280 nm) and UV-C radiation (280 – 100 nm). UV radiation is not visible for humans and cannot be perceived by other sense organs. Depending on wavelength and intensity UV radiation can produce numerous health effects mainly to eye and skin.

Sun, UV radiation and ozone

As sunlight passes through the earth’s atmosphere, its intensity and spectral distribution are subject to changes caused by absorption, reflection and scattering. Most of the so-called "solar UV radiation", i.e. ultraviolet radiation from the sun, is absorbed by ozone in the stratosphere and troposphere. This filter function heavily depends on the UV wavelength.

Logo des UV-Schutz-Bündnis

Alliance for UV Protection

The Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) initiated an interdisciplinary Alliance for UV Protection of experts from science and medicine. This Alliance involves among others the Federal Centre for Health Education (Bundeszentrale für gesundheitliche Aufklärung, BZgA) as well as professionals in radiation protection, cancer research and medicine from various organisations. Some of them have been advocating precautionary measures concerning the health risks of UV exposure for many years. The experts united in this UV Alliance jointly emphasize the prudent use of sun exposure.



UV index forecasts are issued every 3 days each year from April to September by BfS, in cooperation with the Federal Environment Agency (Umweltbundesamt), Germany's National Meteorological Service (Deutscher Wetterdienst, DWD) and other associated institutions. The UV index is the internationally standardised measure of the daily peak value of erythemal UV radiation expected to reach the Earth’s surface. The higher the UVI value, the less time it takes for sunburn to occur on unprotected skin.

Die Sonne hat für das Leben auf der Erde fundamentale Bedeutung.

What is Solar Radiation?

The sun is essential for life on earth. Many vital processes on the earth’s surface, such as climate and life itself, are fuelled by radiation energy from the sun. About 99.98 per cent of the overall energy accountable for the global climate originate from the sun

Fraum Im Solarium mit Fragezeichen

Sunbed Check

The Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) advises that anybody who, despite the health risks involved, would like to use a sunbed should make a quality check on their own as a matter of principle. The “sunbed check” below provides a checklist suitable for this purpose.

Joint recommendation on UV radiation and vitamin D

The Federal Office for Radiation Protection (BfS) together with the Alliance for UV Protection initiated an interdisciplinary scientific expert discussion on the harmonization of the hitherto conflicting recommendations regarding UV exposure for endogenous vitamin D synthesis. The scientific discussion led to the following joint recommendation:

UV index worldwide

Typical UVI values in various countries worldwide, calculated with the radiation transfer programme STAR at the 21st of each month.

© Bundesamt für Strahlenschutz