An electrostatic air cleaning device comprising: a particle charging section; a particle precipitation section, comprising parallel electrode plates; a source of electric potential for applying a voltage between adjacent electrode plates in the precipitation section; a current sensor for measuring an electric current flowing through the electrode plates; a relative humidity sensor; a flow controller; and a device controller, wherein the device controller is adapted to control the source of electric potential and the flow controller in dependence on the measured current flowing through the electrode plates, wherein the device controller is adapted to implement: a first, normal, operation mode when the measured current flowing through the electrode plates is below a current threshold, in which a maximum electric potential is applied between the adjacent electrode plates and the flow controller implements a flow rate as selected by the user of the device; a second mode when the measured current flowing through the electrode plates is above the current threshold and the sensed relative humidity exceeds a humidity threshold, in which the source of electric potential is controlled to reduce the current, the flow controller is controlled so that the flow rate is reduced until the filtration efficiency achieves a desired value, and the measured current is determined to be caused by a high relative humidity; and a third mode when the measured current flowing through the electrode plates is above the current threshold and the sensed humidity is below a humidity threshold, in which the source of electric potential is controlled to reduce the current, the flow controller is controlled so that the flow rate is reduced until the filtration efficiency achieves a desired value, and the measured current is determined to be caused by the level of particle deposition in the particle precipitation section, wherein in the third mode the controller is adapted to provide output information as an output signal indicating that cleaning or replacement of the precipitation section is required. a particle charging section; a particle precipitation section, comprising parallel electrode plates; a source of electric potential for applying a voltage between adjacent electrode plates in the precipitation section; a current sensor for measuring an electric current flowing through the electrode plates; a relative humidity sensor; a flow controller; and a device controller, wherein the device controller is adapted to control the source of electric potential and the flow controller in dependence on the measured current flowing through the electrode plates, wherein the device controller is adapted to implement: a first, normal, operation mode when the measured current flowing through the electrode plates is below a current threshold, in which a maximum electric potential is applied between the adjacent electrode plates and the flow controller implements a flow rate as selected by the user of the device; a second mode when the measured current flowing through the electrode plates is above the current threshold and the sensed relative humidity exceeds a humidity threshold, in which the source of electric potential is controlled to reduce the current, the flow controller is controlled so that the flow rate is reduced until the filtration efficiency achieves a desired value, and the measured current is determined to be caused by a high relative humidity; and a third mode when the measured current flowing through the electrode plates is above the current threshold and the sensed humidity is below a humidity threshold, in which the source of electric potential is controlled to reduce the current, the flow controller is controlled so that the flow rate is reduced until the filtration efficiency achieves a desired value, and the measured current is determined to be caused by the level of particle deposition in the particle precipitation section, wherein in the third mode the controller is adapted to provide output information as an output signal indicating that cleaning or replacement of the precipitation section is required. a first, normal, operation mode when the measured current flowing through the electrode plates is below a current threshold, in which a maximum electric potential is applied between the adjacent electrode plates and the flow controller implements a flow rate as selected by the user of the device; a second mode when the measured current flowing through the electrode plates is above the current threshold and the sensed relative humidity exceeds a humidity threshold, in which the source of electric potential is controlled to reduce the current, the flow controller is controlled so that the flow rate is reduced until the filtration efficiency achieves a desired value, and the measured current is determined to be caused by a high relative humidity; and a third mode when the measured current flowing through the electrode plates is above the current threshold and the sensed humidity is below a humidity threshold, in which the source of electric potential is controlled to reduce the current, the flow controller is controlled so that the flow rate is reduced until the filtration efficiency achieves a desired value, and the measured current is determined to be caused by the level of particle deposition in the particle precipitation section, wherein in the third mode the controller is adapted to provide output information as an output signal indicating that cleaning or replacement of the precipitation section is required.