Ultraviolet (UV) light is a component of the electromagnetic spectrum that falls in the region between visible light and X-Rays. This invisible radiation includes the wavelength range of 100 nm to 400 nm.
UV light can be further subdivided and categorized into four separate regions:
- 100 to 200 nm:
Far UV – these wavelengths only propagate in a vacuum
- 200 to 280 nm:
UV-C – useful for disinfection and sensing
- 280 nm to 315 nm:
UV-B – useful for disinfection, curing, tanning, and medical applications
- 315 nm to 400 nm:
UV-A (or “near UV”) – useful for disinfection, medical applications, printing, curing, lithography, and sensing
Most Natural UV light is generated by the sun with about ten percent of sunlight being UV and only 3 to 4 percent penetrating the atmosphere to reach the ground. Of the UV radiation that reaches the earth, 95 percent is UV-A and five percent is UV-B.
No measurable UV-C from the sun reaches the earth’s surface.
Because of the spectral sensitivity of DNA, the UV-C region demonstrates significant germicidal properties.