A system for keeping moisture in a vapor phase and for removing particles from a gas is described. The system includes a filter and a heating chamber. The filter is capable of being heated and includes a mechanical element that effectively regulates the heating of the filter. Heat production of the heating chamber is coupled to the proper insertion of the filter into the chamber, such that the filter closes an electrical switch in the heating chamber to allow for the production of heat. An exemplary use of the system is the keeping moisture in a vapor phase and removing pathogenic particles from the exhalation path of a ventilated subject.
