The present invention provides a system (10) for humidification of a pressurized flow of breathable gas delivered to a patient, the system comprising; a ventilator (12) for generating a pressurized flow of breathable gas; a patient circuit (14) in fluid communication with the ventilator and connectable to the respiratory system of a patient; and an aerosol generator (18). The patient circuit defines an internal space (26) for transporting the flow of breathable gas which internal space accommodates the outflow opening (20) of the aerosol generator. This enables to prevent so-called rainout and a relatively light weight portable system. The invention also relates to an insert (30) that is connectable to the patient circuit and that accommodates the aerosol generator.