Germicidal lamp

A germicidal lamp is a special type of lamp which produces ultraviolet light (UVC). This short-wave ultraviolet light disrupts DNA base pairing causing thymine-thymine dimers leading to death of bacteria on exposed surfaces. It can also be used to produce ozone for water disinfection.

There are two common types available:

Low pressure lamps

Low-pressure lamps are very similar to a fluorescent lamp, with a wavelength of 253.7 nm (1182.5 THz).

The most common form of germicidal lamp looks similar to an ordinary fluorescent lamp but the tube contains no fluorescent phosphor. In addition, rather than being made of ordinary borosilicate glass, the tube is made of fused quartz. These two changes combine to allow the 253.7 nm ultraviolet light produced by the mercury arc to pass out of the lamp unmodified (whereas, in common fluorescent lamps, it causes the phosphor to fluoresce, producing visible light). Germicidal lamps still produce a small amount of visible light due to other mercury radiation bands.