the present invention is now described more fully hereinafter with reference to the accompanying drawings in which the illustrative embodiment of the present invention is shown . referring now to fig1 , the system 10 of the present invention includes a closed chamber 12 forming a closed chamber cavity 13 , wherein the chamber 12 has a sealable inlet 15 through which objects enter the cavity 13 . the entering objects travel path 21 in direction of travel 23 and enter a pinching or squeezing subsystem 17 which performs a compression on the entering objects . the compressed objects may emit particles that mix with the air in the cavity to form cavity air 19 that enters the cavity 13 and are drawn into cavity air processing subsystem 11 . objects 25 exit the cavity 13 through pinching subsystem 17 . the cavity air processing subsystem 11 captures the cavity air 19 and tests it for contamination . referring now to fig2 , the illustrative embodiment of the present invention includes system components cavity air processing subsystem 11 , chamber 12 forming cavity 13 , sealable inlet 15 , and pinching subsystem 17 embodied in an operational system 10 in which the objects 25 are , for example , mail pieces . in system 10 , shutter 27 slides aside and inverted tub 30 , shown in pre - unloading ( dotted line 30 a ) and unloading ( solid line 30 ) positions is slid into position atop sealable inlet 15 . the mail pieces in inverted tub 30 fall onto a transport means such as conventional conveyor belt 39 or conventional rollers ( not shown ) driven by power supply 47 . the mail pieces can be prepared for entry into the pinching subsystem 17 by a separator mechanism 37 such as conventional paddles or herringbone rollers that separate mail pieces into single pieces or small clusters of mail . in the illustrative embodiment of the present invention , the mail pieces then enter the pinching subsystem 17 that illustratively includes a chute 18 and a set of pinch rollers 45 . the pinch rollers 45 compress the mail pieces as they pass into hamper 43 which is fitted with sealable hood 41 to maintain isolation between system 10 and the outside environment . the compression of the pinch rollers 45 can release particles and the particles can mix with air in the cavity to create cavity air 19 ( as shown in fig1 ) that remains in cavity 13 while the mail pieces drop into hamper 43 . continuing to refer to fig2 , cavity air processing subsystem 11 captures cavity air 19 through tube 35 , which provides a conduit from cavity 13 into the pathogen detection subsystem 33 which can contain a conventional contaminant sensor such as bioni or biological aerosol real time sensors manufactured by pacific scientific instruments and the biological aerosol warning systems i , pcr system developed by the assignee of this application , or any real - time sensor for airborne contaminants . when contaminated cavity air is detected , cavity air processing subsystem 11 notifies controller 51 , and controller 51 sets an indication . continuing to refer to fig2 , controller 51 can be a personal computer , a programmable logic controller , or an embedded controller , among other possibilities . controller 51 can send commands to and receive data and status from cavity air processing subsystem 11 . controller 51 can also control conveyor belt 39 and pinching subsystem 17 by controlling power supply 47 . controller 51 can also interface with network connection 53 , which is shown in fig2 as a local area network but which can be any wired or wireless network in which electronic communications are enabled . for example , information about the origin of the contents of inverted tub 30 can be fed into controller 51 which can contain an emergency alert notification system or any other conventional or custom program . thus when a contaminant is detected and an indication is set , the operator and network receptors 55 listening for such indications are provided information associated with the contamination that could assist in tracking the source of the contamination . controller 51 can also control the movement of inverted tub 30 ( perhaps through a conventional actuation mechanism , not shown ) so that inverted tub 30 can be remotely and automatically moved into the correct position to unload objects . referring primarily to fig3 a , tub 29 of the illustrative embodiment of the present invention is shown without tub lid 31 ( fig3 c ). tub rim 57 is shown herein with four sides but can be any shape . in the illustrative embodiment , two sides of tub rim 57 are fitted with rim lid interfaces 63 that are herein l - shaped but can be any shape . rim lid interfaces 63 are slidably held within both lid runner 73 ( fig3 c ) and chamber opening runner 77 ( fig4 a ). rim lid interfaces 63 allow inverted tub 30 to be slid into unloading position atop sealable inlet 15 ( fig4 b ). tub interior 65 holds objects that will be emptied through sealable inlet 15 into cavity 13 ( fig4 b ) when inverted tub 30 is in unloading position ( fig4 a , b ). referring primarily to fig3 b , shows shutter 27 including shutter runners 67 along two edges of shutter 27 . the shutter 27 of the illustrative embodiment is preferably slidable , but can be hinged or removable in any other way . shutter runners 67 slidably fit within chamber opening runners 77 ( fig4 a ) allowing the shutter 27 to slide away from sealable inlet 15 ( fig4 b ) as inverted tub 30 is slid into unloading position . referring primarily to fig3 c , lid underside 71 of tub lid 31 is shown with lid runners 73 into which rim lid interfaces 63 ( fig3 a ) slide to cover tub 29 ( fig3 a ). lid chamber runners 69 slidably mate with chamber opening runners 77 ( fig4 a ). on edges where there are no lid runners tub lid 31 is sealed against gas exchange with full coverage lid tub seals 75 . referring primarily to fig4 a – b , the illustrative embodiment of the present invention can optionally include a specialized sealed inverted tub 30 that , when atop sealable inlet 15 having sealable inlet edge 59 , can become unsealed with respect to cavity 13 but not with respect to the environment . the inverted tub 30 can be constructed of any rigid or semi - rigid material and can be any shape . the inverted tub 30 holds mail until it is inverted and slid or placed ( perhaps automatically ) over the sealable inlet 15 as described in detail below . a shutter 27 , preferably slidable , retractable , sealable , and constructed of any rigid or semi - rigid material , seals the cavity 13 from the outside environment and covers the sealable inlet 15 until inverted tub 30 is inverted and moved into an unloading position . inverted tub 30 can be positioned adjacent to the shutter 27 such that a section of the tub rim 57 ( fig3 a ) is in contact with shutter push 68 . as inverted tub 30 is moved toward shutter 27 against shutter push 68 , shutter 27 simultaneously slides away from sealable inlet 15 , thus opening sealable inlet 15 so that mail pieces from inverted tub 30 can drop into cavity 13 . while inverted tub 30 is being slid into unloading position , tub lid 31 is being held in position by lid stopper 87 . after the mail is unloaded , inverted tub 30 is slid over tub lid 31 while simultaneously shutter 27 slides back into a closed position over sealable inlet 15 , perhaps through the biasing of shutter spring 79 . before , during , and after loading and unloading , seals against ambient air exchanged are maintained through by lid tub seal 75 and shutter seal 81 . in an alternative embodiment ( not shown ), the shutter 27 can remain sealed over sealable inlet 15 until the inverted tub 30 is in place over the sealable inlet 15 . in this embodiment , the shutter 27 is positioned below the tub lid 31 until the inverted tub 30 is correctly positioned above the sealable inlet 15 and locked into position creating a seal . then the shutter 27 is moved into position to open sealable inlet 15 , tub lid 31 is moved into position to open inverted tub 30 , and the mail can drop from the inverted tub 30 into cavity 13 . after the inverted tub 30 is emptied , the shutter 27 is moved under the inverted tub 30 to close sealable inlet 15 . when inverted tub 30 is to be removed , lid 31 is moved into position to close inverted tub 30 . referring now to fig5 , the method of the illustrative embodiment of the present invention includes a first step of accepting at least one object into a cavity defined by a closed chamber having a sealable inlet to the cavity ( method step 501 ). the step of accepting directs the object substantially onto a travel path in a direction of travel . the method next includes the step of pinching or squeezing at least one object by a pinching subsystem and releasing particles into air within the cavity forming cavity air ( method step 503 ). by this step , the object is compressed and may release particles into the cavity . optionally , the step of pinching can further include the steps moving at least one object between juxtapositioned rollers such as a rotating left roller and a rotating right roller , where the left roller is substantially adjacent to the right roller , the left roller is sufficiently spaced from the right roller to allow constricted passage of at least one object , and the left roller rotates clockwise while the right roller rotates counterclockwise . other roller or pinching designs may be used . for example , the juxtapositional rollers may be one on top of the other , if the object to be pinched or squeezed comes in from the side . continuing to refer to fig5 , the method next includes the steps of testing the cavity air for contamination ( decision step 509 ), and setting an indication if the cavity air is contaminated ( method step 507 ). the method of the present invention can optionally include the step of drawing the cavity air through a tube into a pathogen detection subsystem . after the indication is set , the method of the present invention can optionally include the steps of initiating contamination processing that can include the steps of stopping the pinching subsystem and stopping the cavity air processing subsystem ( method step 511 ) and notifying the operator and network of the contamination ( method step 515 ). if no contamination is detected , the system can reset any indication that is set and continue receiving objects into the cavity through the sealable inlet ( method step 513 ). the method of the present invention can optionally include , preceding the step of accepting at least one object into the cavity , the step of depositing from a tub through an airtight connection at least one object into the cavity . the method can further optionally include the step of conveying at least one object from the sealable inlet to the pinching subsystem substantially in the travel path and substantially in the direction of travel by use of a transport device within the cavity . the method can further optionally include the step of preparing at least one object for entry into the pinching subsystem . this step of preparing , in the illustrative embodiment , takes the form of singulating the mail piece from neighboring pieces so that the singulated piece can properly exit the cavity through the pinching subsystem . the method of the illustrative embodiment can further optionally include the steps of sequencing operations among the pinching subsystem , the transport device , and the cavity air processing subsystem , and transmitting the indication through a computer network . although the invention has been described with respect to various embodiments it should be realized this invention is also capable of a wide variety of further and other embodiments within the spirit and scope of the present invention .