Ultraviolet (UV) radiation is a form of electromagnetic radiation, like radio waves, x-rays and light. It is also sometimes called "ultraviolet light". On the electromagnetic spectrum, UV radiation comes between visible light and x-rays. That is, its wavelengths are shorter than the wavelengths of light and longer than those of x-rays. It is divided according to its effects on living tissue into three wavelength bands: UV-A, UV-B and UV-C (see Figure 1).
Sources of UV radiation in the workplace include various kinds of welding arcs and UV lamps. The sun is the main source of UV radiation out of doors. Most UV radiation sources also emit visible light; this is usually brilliant white, but it sometimes has a purplish hue. UV lasers emit UV radiation without producing any visible light.
Operations that use artificial UV sources may expose workers to excessive UV radiation. These include: welding; processes involved in printing; curing of inks, paints, etc.; non-destructive testing (NTD) and material inspection; and UV disinfection in hospitals and laboratories. Outdoor workers may easily be overexposed to UV radiation from the sun during spring and summer. They include workers in construction, open-pit mining, logging, landscaping, road building and maintenance, agriculture and other sectors.