Abstract: The invention relates to an ionization filter for purifying air that is enriched with dust particles and other inorganic and organic pollutants. The filter has at least one electrically charged emission electrode for producing electrically conductive particles, and at least one passive electrode for collecting the pollutant particles that are in movement in the electric field between the emission electrode and the passive electrode. In accordance with the invention, an extra layer having denaturing properties is placed in the flow path of the pollutant particles that are to be precipitated. This layer is preferably composed of strongly acidic and strongly alkaline layers, or vice versa, with a neutral intermediate layer between layers of different pH values in each case. Micro-organisms, such as bacteria, fungi, spores and/or allergens which move in the electric field of the ionization filter are simultaneously destroyed by this denaturing property.