An air purifier includes a housing, a high voltage power supply, a first electrode assembly in which a wire-like first electrode is either the only first electrode or, alternatively, is spaced sufficiently far from any other such first electrodes so as to avoid undesirable effects upon each other, and a second electrode assembly in which there are a plurality of blade-like second electrodes. The air purifier can be of the type in which air flows through the housing as a result of electro-kinetic effects. To increase air flow velocity, the voltage between first and second electrodes is relatively high, such as 23-50 kV, and the first and second electrodes are accordingly spaced apart a relatively great distance, such as at least 30 mm.