Electromagnetic radiation with a wavelength ranging from 180 nanometers to 400 nanometers is known as ultra violet radiation.

Ultraviolet Rays are measured and controlled in workplaces where UV radiation hazards exist, such as exposure to sunlight and the welding process.

Depending on the conditions of exposure and the wavelength of radiation, UVR may have both positive and negative effects on human health. While excessive UVR exposure can cause photochemical reactions, DNA lesions, skin and eye damage, and immune system dysfunction, small amounts of UV are beneficial to people, and are even required for the production of vitamin D.