The cartridge includes a first tube extending longitudinally, the first tube at least partially defining an air passage within the cartridge, a vapor generator in communication with a first portion of the air passage, a first air inlet defined by the cartridge, the first air inlet being in communication with a second portion of the air passage, the second portion being upstream of the vapor generator relative to a normal direction of an airflow through the air passage during an operational use of the cartridge, and a dilution air passage defined by the cartridge, a discharge end of the dilution air passage intersecting a third portion of the air passage, the third portion being downstream of the vapor generator relative to the normal direction of the airflow.