A respiratory humidification system having a capillary passage in communication with a ventilator, the ventilator adapted to deliver an air stream, a heater operable to at least partially vaporize water in the capillary passage, a pumping unit adapted to supply water to the capillary passage, wherein the water upon heating is at least partially vaporized to form an aerosol stream. The aerosol stream is combined with the air stream to form a humidified air stream.