Abstract: Apparatus for the purification of air, flue gases in which apparatus the air, flue gases or equivalent are directed into a duct, in which apparatus the air, flue gases are ionized, and in which apparatus charged impurity particles (7) present in the air, flue gases or equivalent are attracted by one or more collector surfaces (2) by virtue of a difference in the states of charge, causing the particles to settle on the surface. The air, flue gases are ionized by virtue of one or more ionizing electrodes (5) directed at a collector surface. The distance between the ionizing electrode or equivalent and the collector surface and the difference between the state of electric charge of the collector surface and the charged impurity particles are so adjusted that the impurity particles will move essentially directly towards the collector surface and settle on it.