A system and process is provided for removing or treating harmful biologic and organic substances within an enclosure, such as a container, building or vehicle. Air within the enclosure is heated to a predetermined temperature to kill organisms and cause harmful substances in the structure to migrate into the ambient air. Boric acid in combination with the heat may be used to kill mold and similar undesirable organisms. Temperature and pressure levels are monitored. The heated air carrying the harmful substances is passed through a filter to remove the harmful substances, and the heated air is re-circulated to enhance efficiency. The system effectively kills insects, molds, viruses and bacteria and reduces the levels of allergens and volatile organic compounds in the structure.