A shortwave UV lamp can be made using a fluorescent lamp tube with no phosphor coating. These lamps emit ultraviolet light with two peaks in the UVC band at 253.7 nm and 185 nm due to the mercury within the lamp. 85% to 90% of the UV produced by these lamps is at 253.7 nm. The glass tube passes the 253 nm radiation but blocks mostly the 185 nm wavelength. Such tubes have two or three times the UVC power of a regular fluorescent lamp tube.

These low-pressure lamps have a typical efficiency of approximately thirty to forty percent, meaning that for every 100 watts of electricity consumed by the lamp, they will produce approximately 30–40 watts of total UV output. These germicidal lamps are used extensively for disinfection of surfaces in laboratories and food processing industries, and for disinfecting water supplies.

Germicidal lamp keeps 100% killing rate to many common germs under experimental environment.