A vacuum cleaner comprising: a body defining an air inlet, an air outlet, and a passageway extending therebetween; an electrostatic dust filter for removing dust from air as it passes through the passageway; and an air pump for drawing air into the air inlet and through the passageway to the air outlet; wherein the electrostatic dust filter comprises an electrode arrangement configured to kill microorganisms present in air passing through the passageway by exposing air to a voltage in excess of a threshold voltage.