A device (10) for treating at least a portion of a smoking article comprises: a base unit (12) including: one or more elongate chambers (16) for receiving at least a portion of a smoking article and one or more air plenums (22) in fluid communication with at least one of the one or more elongate chambers (16), wherein the one or more air plenums (22) comprises one or more annular channels, the one or more annular channels surrounding the elongate chambers (16) along at least a part of the length of the elongate chambers (16); a treatment unit (26) including one or more reservoirs (32) for containing a liquid treatment agent, wherein each reservoir (32) comprises means (36) for providing fluid communication with an inlet (24) of the one or more air plenums (22); and aerosol generating means (40) connected to the treatment unit (26) for forming an aerosol from the liquid treatment agent in the one or more reservoirs (32).