Abstract: A threat detection system includes a facility including at least three separate rooms located in the facility and a positive pressure zone located external to the facility. A ventilation system is coupled to the at least three separate rooms. A first room is located in the facility, wherein the first room includes a first room pressure zone that is negative with respect to the positive pressure zone external to the facility. A second room is located in the facility and connected to the first room, wherein the second room includes a second room pressure zone that is negative with respect to the first room pressure zone.