An aerosol is formed by supplying a material in liquid form to a flow passage and heating the flow passage such that the material volatizes and expands out of an open end of the flow passage. The volatized material combines with ambient air such that volatized material condenses to form the aerosol. An apparatus and method for generating such an aerosol are disclosed wherein the apparatus may include an electrically conductive sleeve at an open end of the flow passage, an electrically conductive flow passage and/or a spacer chamber. The volatilized material may contain a volatilized solute and vehicle such that the resulting aerosol particle sizes of the solute and the vehicle are either different or the same.