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UVI – Index of Ultraviolet Radiation Risk

The Ultraviolet Radiation Index – UVI – is an accepted world-wide measure to indicate the risk level for exposure to UV radiation that reaches us from the sun, at different hours in different regions.  The index aims at helping the public protect itself from radiation.

 

Solar radiation reaching earth (Nasa imagery)

Solar radiation reaching earth (Nasa imagery)

 

The Israel Meteorological Service, like its colleagues throughout the world, issues a daily forecast of the UVI for each hour throughout the daylight hours, from 7:00 to 17:00 hrs.  The forecast applies to different regions of the country and is published on the Israel Meteorological Service's Website and other communications media.

 

The thinning out of the ozone layer, as well as seasonal and climatic changes, may influence the UV radiation level that reaches the earth's surface at any given time, and the Meteorological Service takes this into account in its calculations.  The UVI comprises numerical values indicating the risk level from exposure to the sun's radiation, according to the wavelengths of the expected radiation at one time or another, on a scale of five levels.  The numerical value expresses the risk level according to the intensity of the radiation at any hour during the daylight hours.

                          

Risk levels according to the UVI:

1-2: Low – low risk of UV radiation for the 'average person'

3-5: Intermediate – intermediate risk of damage resulting from unprotected exposure to the sun

6-7: High – high risk of damage resulting from unprotected exposure to the sun

8-10: Very High – very high risk of damage resulting from unprotected exposure to the sun

11 and above: Extreme – extremely high risk of damage resulting from unprotected exposure to the sun

 

Each of the numerical values in the index is accompanied by recommendations for protection from the sun, and serves as a useful tool to plan activities in the sun safely.

If the UVI forecast for a certain geographical region is higher than usual, a special UV warning may be issued for that region.

Details of the risk level and the daily UVI forecast in Israel may be found on the Israel Meteorological Service's Website.

 

References

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