A multilayer filter material for an interior air filter element of an air conditioning system of a vehicle may include an ion exchange layer including ion exchange particles and a plurality of further layers. The ion exchange layer may directly adjoin at least one of the plurality of further layers. The plurality of further layers may include an active layer including non-impregnated active carbon particles, and an impregnation layer including impregnated active carbon particles. The active layer may be arranged between the ion exchange layer and the impregnation layer. The ion exchange layer may be hygroscopic and may contain ions which form a toxic environment with water. The impregnation layer may include a component of active carbon particles impregnated with potassium iodide and a component of active carbon particles impregnated with potassium carbonate. The component impregnated with potassium iodide may be greater than the component impregnated with potassium carbonate.