Apparatus and a method for electrically sweeping particles from a gaseous effluent are disclosed which are particularly efficient in removing small as well as large particles. A voltage is applied across two electrodes in such a way that a strong electric field can be generated between them. A source of ions is provided by bombardment of the effluent gas stream with electrons. A strong electric field established between the electrodes creates at least one region of ions having only one polarity and moves these ions towards the oppositely charged electrode. In the region having ions of one sign, these ions rapidly charge the particles, especially small sized particles because of the strong electric field. The charged particles are moved by the field and deposited on the oppositely charged collection electrode where they agglomerate in preparation for collection and disposal.