Ultraviolet radiation with wavelengths ranging from about 280 nm to 315 nm
The ultraviolet (UV) rays have wavelengths ranging from about 10 nm to about 400 nm. They are that portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. UV radiation is of three types according to wavelength: ultraviolet A (UVA), ultraviolet B (UVB), and ultraviolet C (UVC).
UVB is an ultraviolet radiation with wavelengths ranging from about 280 nm to 315 nm.1 UVB rays have shorter wavelengths than UVA. And unlike UVA that are not absorbed by the ozone layer, UVB are mostly filtered and absorbed by the atmosphere. UVB rays are more harmful than UVA since they have greater amount of energy. Nevertheless, UVB rays are less able to penetrate the skin compared with UVA rays. UVB rays can penetrate the superficial layers of the skin but not the deeper layers. They are therefore associated with delayed skin burn and skin tanning. Similar to UVA, UVB rays are also able to cause skin ageing. Exposure to UVB may also lead to skin cancer formation especially in fair-skinned.
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1 Space Environment Technologies. (n.d.) "ISO 21348 Definitions of Solar Irradiance Spectral Categories" (PDF)". Retrieved from [].