In an electrostatic precipitator for filtering particulate matter from a gas, a fan (10) draws the gas (5) through an ioniser section (7) and a collector section (6). Ioniser blades (3) with sawtooth spikes (8) create a corona discharge (4) when charged to a high voltage, so that gas-borne particles are charged when passing through the corona area. The collector section (6) consists of a set of metallic plates (1, 2) of which every other plate (1) is connected to ground, while the remaining plates (2) receive a charge by induction from the ioniser blades (3), and act as repeller plates, pushing charged particles in the gas flow (5) over to the grounded plates (1).