An air ionizer electrode assembly (10; 50; 60) comprising an inner electrode (11; 52; 66), at least one outer electrode (14, 15; 54; 61) and a dielectric barrier (12, 13; 53; 64) sandwiched between the inner electrode and the at least one outer electrode. The inner electrode has a continuous overall surface and the at least one outer electrode has a plurality of holes (21; 56; 70) to provide a plurality of ion generating points for generation of negative ions.