Fuente: WIPO "tomato" An air purifier for use in refrigerators contains in the path for the flow of air through the purifier: a photocatalyst wherein a layer based on tungsten oxide (WO3) is applied on a ceramic foam support. The layer may also contain tin oxide and silver oxide, as well as platinum. The oxide layer may be applied by immersion without the application of a primer. A method for increasing the shelf life of fruits, in particular also of strawberries, salad and vegetables in a refrigerator and a related refrigerator are also described. The purifier is characterized by low energy consumption, thanks to the use of white light to activate the photocatalyst, as well as little toxic impact.