The number of microorganisms existing in the air (such as viruses, bacteria, yeasts, moulds) is reliably reduced by UV-C light at 254nm without ozone formation, and disabled. The short-wave UV-C radiation has a strong bactericidal effect. It is absorbed by the DNA of the microorganisms and there destroys their structure. In this way, the living cells are inactivated. To further improve the results, the ambient air may be dried. A "fogging" of the goods due to temperature differences is thus successfully avoided.