fig1 facility 100 achieves environmental isolation through a variety of means discussed below that result in the air circulating through the facility 100 being contained to the facility 100 and not escaping to neighboring facilities not shown facility 100 includes a plurality of facility access doors 102 and 104 which may provide a connection to other facilities not shown adjacent to the facility 100 or may provide an exit from the facility 100 to the outdoors a global ventilation system 106 is used to ventilate areas within facility 100 global ventilation system 106 helps to achieve environmental isolation of facility 100 by being dedicated to facility 100 and not connected to other facilities thus air existing in facility 100 may circulate through the facility or exit to the outdoors but is limited from entering neighboring facilities through the global ventilation system 106 global ventilation system 106 may include a high efficiency particulate arresting hepa filter to sanitize air recirculated through the facility 100 a plurality of areas exist within the facility 100 including in bound mail area 108 mail sorting area 110 and clean mail area 112 with each area 108 112 coupled to the global ventilation system 106 in bound mail area 108 includes facilities for receiving mail from outside sources and preparing the mail to be sorted mail sorting area 110 includes a plurality of devices for processing and sorting the mail each of which may be coupled to a local ventilation system 114 local ventilation system 114 is provided for circulating air through the devices and detecting mails threats in mail processed and sorted by the devices and is discussed in more detail below clean mail area 112 includes facilities.