A radial fan impeller has the following features: a plurality of blades distributed around the periphery; viewed in the radial direction, the blades extend from an inner inlet region to an outer discharge region; the blades extend axially, viewed in the direction of a rotation axis, between an inlet side and an axially opposite hub side; on the inlet side, the blades are connected by means of their radial extension as far as the discharge region to a covering disc which has a central inflow opening, opening out into the inlet region; on the hub side the blades are only connected with their radial inner end regions to a central hub; the blades and the covering disc define an outer fan impeller diameter which is at least ten times an axially measured flow discharge width of the blades provided in the discharge region.