A method for producing a sterile cryogenic fluid is disclosed. A warm gas stream is sterilized by filtration and fed to a heat exchanger resulting in a cryogenic sterile fluid being formed. The waste gas stream from the heat exchanger is fed to a second filtration unit and the warm sterile waste gas stream is fed to a second heat exchanger to produce more cryogenic sterile fluid, resulting in a more efficient use of gases employed in the sterilization process.
