Fluorescent Tube (UV-C Germicidal Lamp) is another application of UV light, which is commonly known as UVC lamp or germicidal lamp. It emits ultraviolet light of peak wavelength 253.7nm (or 254nm), which is a pathogen killing wave used in medical or industrial sterilization. Germicidal UV lamp use strong rays which can effectively destroy DNA, RNA and cells of pathogens (bacteria, viruses, and protozoa) through direct illumination. To further enhance sterilization effect, UVC lamp could be modified quartz or high boron glass tube which could emit 188nm UVD light, which can oxidize atmospheric oxygen to create ozone (O₃) molecule, which diffused in air to kill germs. As prolonged inhalation of ozone may cause unpleasant feelings, some applied germicidal lamp added titanium to glass to hinder ozone emission and makes them workable in manned environment but without direct radiation to human or plants as well as plastics structure. Users always need to take note that short-wave UV light is harmful to humans, so they could only be used by professions or in well designed and certified apparatus under proper operations.

Similar to other UV lamp, germicidal lamp is a mercury discharge lamp which emits ultra violet light source or wavelength 253.7nm (UVC) and 188nm (UVD). Ultra violet of germicidal lamp do not require any powder, and as UVC and UVD have low transmission rate against normal glass, special material such as quartz or high boron glass needed to be used. Germicidal lamp is available in different lamp shape, which can be T5, T8, PL-S and PL-L lamps, as well as special 4pins T5 tube or U shape tubes. They work with most electronic ballast in the market and some small wattages can work with magnetic ballast. Solid state mercury (amalgam) could be used to improve safety, stability and environmentally friendliness of the product.

Ultra violet lamp is light on base on low-pressure mercury vapor discharge mechanism, which it is mandatory to work with an external device, which can be either magnetic ballast or electronic ballast. When power is connected, high temperature is created at the inner filament at both end of the tube. The high temperature vaporize mercury inside the tube to form a complete circuit inside the tube, which ionized mercury will emit ultra violet when hitting on the UV powder coated on the glass tube.