Ultraviolet radiation is divided into three parts, according to the region of the wave spectrum in which it is found:
Radiation GRAPE: extends from 320 to 400 nanometers (nm);
Radiation UV-B: occupies the range of 280-320 nanometers (nm);
Radiation UV-C: ranges from the 280 range to shorter wavelengths.
Of these three ultraviolet radiations, only UV-B poses a risk to human health. UV-A radiation is not absorbed by the atmosphere and its measurement is important, whereas UV-C is totally absorbed by the Earth's atmosphere and therefore does not participate in measurements made on the Earth's surface.
The UV-B radiation is the most studied of all, it is absorbed in the stratosphere by ozone, but a small amount that reaches the Earth is already a concern, as the excess of this radiation causes skin cancer.
The measurement of UV-B radiation is important because it allows the study of the ozone layer and its destruction as well. This measure makes it possible to disclose the so-called “UV-B index” and define quantitatively whether the sun is strong or weak. This index has a scale from 0 to 16, an example: in the city of São Paulo in winter, the index is 5, and in summer it is 12.
By Líria Alves
Graduated in Chemistry
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sunscreen in action
Source: Brazil School - https://brasilescola.uol.com.br/quimica/tipos-radiacao-ultravioleta.htm
