Low pressure lamps mainly emit radiation with a wave- length of 253.7 nm, which is appropriate for the bacteri- cidal treatment of air and water. They are typically used for sterilising drinking water, upgrading grey water in industrial settings, and reducing bacteria in fish farms. They are also employed in air conditioning and cooling systems and will disinfect surfaces as well as air.
Another important wavelength is 184.9 nm. This will pro- duce ozone in air that contains oxygen. Used in water, the wavelength will trigger chemical reactions. For ex- ample, it will reduce COD to achieve water of highest purity, or will remove odours from air. Lamps of this type are available at wattages of 4 to more then 400 W.