Abstract: The storage life of cereal grains or other products is extended by reducing biological activity in the storage enclosure. Air is oxidized in a chamber which is external to the storage enclosure. The oxidized air is propelled from the oxidizing chamber to the storage enclosure. Oxidation of the air may be produced by heat, ultra-violet radiation, or catalyzation. Heating may be done in a block provided with anodes for dissipating electrostatic charges. After being heated, the air is cooled before it is propelled to the storage enclosure. When air is oxidized by ultra-violet radiation, it is processed by an ozone decomposition system before it is admitted to the storage enclosure.