A respiratory assistance apparatus (4) is provided, adapted to deliver gases to a user or patient (1). The apparatus (4) comprises a housing (10) provided with a chamber (5) and a heater (25), the chamber (5) comprising at least one gas port (15) connected to, or arranged to be connected to, at least one intermediate passageway (12). The apparatus (4) is operative according to a disinfection mode of predetermined profile in which the heater (25) heats liquid in the chamber (5) to produce vapour at or above a target dewpoint temperature and/or humidity level. The apparatus (4) is arranged such that the vapour is delivered to the intermediate passageway (12) to disinfect the intermediate passageway (12) with moist heat throughout a predetermined duration of the disinfection mode. Associated attachments and methods are also provided.