Designations of UV wavelength ranges, originally for distinction of physiological effects of UV, and establishment of safe exposure limits. The generally accepted ranges are:
VUV: 100-200 nm
UVC: 200-280 nm
UVB: 280-315 nm
UVA: 315-400 nm
UVA is commonly referred to as long UV wavelengths; while UVC is considered short UV wavelengths. VUV stands for „vacuum UV.“ Measurement of specific ranges may be defined by the responsivity of a radiometer. It should be made clear, when referring to these ranges, exactly what wavelengths they represent. Specific manufacturers of radiometers will use uniquely specified ranges.