The Ultraviolet (UV) part of the solar spectrum has numerous beneficial effects on human biology, but too much can be very harmful; the UV region covers wavelength ranges between 100-280 nm (UVC), 280-315 nm (UVB) and 315-400 nm (UVA). Virtually all of the UVC portion and about 90% of the UVB portion coming from the sun are absorbed by the earth’s atmosphere.
UV radiation helps the production of Vitamin D but at the same time causes skin burns and can cause cancer, melanoma and cataracts; UV radiation measured with a response similar to that of human skin is referred to as Erythematous and is used to calculate the Global UV Radiation Index (UVI) for public health information.
For some types of applications it is only necessary to measure the total UV irradiation, which consists of the combination of UVA and UVB; usually the UVA component that reaches the earth’s surface is 15 to 20 times higher than the UVB one.
Total UV radiation is usually monitored in weather and climatological stations as an extension of solar radiation monitoring by pyranometers; it is also used to verify the UV output of light sources or sun simulators for research in the field of solar energy.
The measurement of the UVA and UVB components, on the other hand, is used to monitor and investigate the effects of UV solar radiation on plants and animals; in the field of tests on materials it is instead important to verify the effects of deterioration to external UV exposure.
UVE radiation is instead monitored for its effects on human biology and for human applications, where it is essential that the measurement is similar to the erythematous response of human skin; the data is used to calculate the UV Index for public health information and usually disclosed with weather forecasts; UV radiation is also measured during the development of cosmetics, sun creams and skin protective materials.
