Particulates are removed from a gas stream by contact with a liquid. The gas stream is conveyed through an inlet channel, towards a liquid reservoir which is located below a perforated sheet. Gas flowing through holes in the sheet creates a pressure drop between the inlet channel and an outlet area above the sheet. This pressure drop draws liquid up from the reservoir, through a relatively narrow liquid transfer channel, so that the liquid covers the sheet. Gas flowing through holes in the sheet therefore encounters a layer of liquid located immediately above the sheet. Particulates in the gas are captured by the liquid in this layer. The device requires no pump for moving the liquid through the system, the liquid being transferred solely as a result of the pressure drop induced by the flow of gas.