Patent Publication Number: US-2023136014-A1

Title: Process and apparatus for three-stage biological particulate eliminator

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of PCT Patent Application No. PCT/US2021/040304 filed Jul. 2, 2021, and U.S. Provisional Application No. 63/047,488 filed Jul. 2, 2020, which are hereby incorporated by reference. 
    
    
     It is well known that pathogens, allergens and other airborne contaminants including pathogenic microbes, pollutants, viruses and other microorganisms cause a number of health hazards. In particular, in indoor spaces each time an occupant of that indoor space exhales or sneezes, microorganisms are carried into the indoor air that is ultimately breathed in by others. With the recent outbreak of COVID-19, which is caused by the SARS-CoV-2 virus, the importance of reducing, and if possible removing pathogens from indoor environments in which humans live, work and otherwise occupy has received much recent attention. Known efforts to reduce pathogens and/or microbes in an indoor environment typically are associated with the use of components connected to and used within existing HVAC systems that supply air to an indoor space. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    schematically shows an arrangement of an air treatment system for an indoor space. 
         FIG.  2    shows a cross section of a burner configuration in the embodiment of  FIG.  1   . 
         FIG.  3    is a perspective view of an embodiment of an updraft hood utilized with the system of  FIG.  1   . 
         FIG.  4    schematically shows a portion of the system of  FIG.  1    with a heat exchanger included. 
         FIG.  5    is a schematic of an additional embodiment system for treating air. 
         FIG.  6    schematically shows an example of an indoor space with which the systems and methods disclosed and claimed may be used. 
         FIG.  7    is a close-up view of an embodiment of updraft hoods positioned at work spaces in an interior of a building. 
         FIG.  8    is an additional building configuration. 
         FIG.  9    is a view identical to that in  FIG.  8    but includes embodiments of updraft hoods for human occupiable spaces. 
         FIG.  10    shows an embodiment of a heating arrangement for the system. 
         FIG.  11    is a partial interior view of one of the silos that may be utilized with the system of  FIG.  10   . 
         FIG.  12    shows the use of an induction coil proximate a burner cylinder housing. 
         FIG.  13    is a partial cross section of an individual burner cylinder used with the embodiment of  FIG.  10   . 
         FIG.  14    shows an additional indoor space. 
         FIG.  15    schematically shows a test arrangement of the system as described herein. 
         FIG.  16    are results of tests conducted with the arrangement of  FIG.  15   . 
     
    
    
     DESCRIPTION OF AN EMBODIMENT 
     Embodiments herein include systems and methods for reducing the pathogen load in an indoor space. Embodiments also include systems and methods for preventing air expelled by humans from entering an indoor space. The systems and methods described herein include systems for eliminating, or at least reducing pathogens including harmful microbes, viruses and other life-threatening pathogens in an indoor space. Pathogens, as used herein, is intended to include harmful microbes and viruses including but not limited to SARS CoV-2. The systems and methods described herein operate independent of existing HVAC systems used to condition the air in an indoor space, and do not connect to or use the ductwork or other components of HVAC systems. 
     Referring now to the figures,  FIG.  1    schematically shows an air treatment system  5  configured to prevent pathogens expelled by humans from entering indoor spaces, and to eliminate, or at least reduce pathogens from the indoor space  6 . The air in the indoor space  6 , including air expelled by humans may at times be referred to as contaminated air. The system  5  was developed to target SARS-CoV-2. However, the usefulness of the system is not limited to SARS-CoV-2 and the system may be utilized to remove not only SARS-CoV-2 but other pathogens. In the embodiment of  FIG.  1   , system  5  includes an air duct  10  with a closed end  15  and a plurality of air inlets  20 . 
     System  5  further includes a plurality of updraft hoods  25  which may be referred to as updraft cubicles. Air conduits  32  connect updraft hoods  25  with the air duct  10  through inlets  20  defined therein. In the embodiment described updraft hoods  25  may comprise updraft cubicles with an outer wall  34  and an open bottom  36 . A side opening  38  is defined in the outer wall which will allow the entry and exit of a human operator positioned at a work station or other location occupiable by humans. The updraft cubicle in the described embodiment is generally rectangularly shaped in cross section, but is not limited to such a shape. If desired, updraft hoods  25  may have a curtain or wall that covers the opening  38  such that the only opening for the updraft hoods  25  once occupied is the open bottom  36 . 
     A burn zone  40  is communicated with air duct  10 . Burn zone  40  may comprise a burner  42  with outer housing  48  that defines an interior  43  therein. Burner  42  is heatable to a high temperature. In one embodiment burner  42  may comprise a media  44  in an outer housing  48 . The media will be of a type that can be heated to and maintain high temperatures of as much as 500° F. In some embodiments the media can be heated to as much as 600° F., 700° F., 800° F., 900° F. and up to 1000° F. The media may comprise for example a ceramic material or metal beads. The media will in all cases be porous, or will otherwise define a travel path through the burner  42  to allow the flow of air therethrough. 
     A heating element  46  such as for example an electric coil may also be disposed in the outer housing  48  of burner  42 . Other known means of heating may be utilized, such as an induction coil placed proximate a metal rod or other metal object placed in the interior  43 . Outer housing  48  can be comprised of a material that will withstand high temperatures without emitting excessive heat to the surrounding area. The outer housing may also have an insulating material therearound to insulate burner  42 . The heated air stream leaving burner  42  will have reduced pathogens as compared to the contaminated air entering the burner  42 , and will be cooled as described below. 
     A connecting duct  50  communicates burn zone  40  with a scrubber  52 . Scrubber  52  serves a dual purpose in that air passing therethrough will go through a spray of vapor in one embodiment, or in another embodiment will pass through a fill media over which water circulates. In this manner the air can be cooled and filtered at the same time. The water may in some cases be chemically treated such that it may comprise for example chlorinated water at pH levels that are equal or similar to those recommended for public swimming pools. Scrubber  52  is therefore also referred to as a cooling apparatus. A pump (not shown) may circulate water across a fill media in scrubber  52  to allow the air to be cooled and scrubbed. It is not necessary to provide any chemical treatment to the water such that the water may simply be used as a cooling agent. A fresh air damper  51  may be included in connecting duct  50 . Fresh air from the indoor space may be drawn into the connecting duct  50  through fresh air damper  51  to aid in cooling the heated air stream exiting burner  42 . 
     Additional cooling may be supplied by a heat exchanger  56  as schematically shown in  FIG.  4   , Heat exchanger  56  may be of a type known in the art. For example, heat exchanger  56  may comprise a plurality of tubes in which a cooling agent passes. In one embodiment the cooling agent may be cool water circulated from for example an exterior cooling tower, Cool water will pass through tubes over which heated air leaving burner  42  will flow to be cooled. The water will be directed out to an exterior tower through a flow conduit  57  where it will be cooled and recirculated back into the heat exchanger  56  through a conduit  59 . If desired, the water used in scrubber  52  may be circulated through an exterior cooling tower using flow conduits  53  and  55 . Water will flow in the direction of the arrows. A connecting conduit  58  communicates scrubber  52  with a UV chamber  60 . 
     A cooled air stream leaves scrubber  52  and enters the UV chamber at a tangent  62  so that a centrifugal motion is created. Air will move in a centrifugal manner around the inner wall of the UV chamber  60 . Ultraviolet lights  64  may be inserted and extend into an interior  61  of UV chamber  60 . UV chamber  60  may also include a plurality of UV lights arranged in a spiral fashion along the interior  61 . In the schematic of  FIG.  4    an upper portion of UV chamber  60  is not shown so that interior  61  may be seen. Air passing through the UV chamber  60  is thus directly exposed to UV radiation prior to exiting into the indoor space. The UV lamps may comprise UVC lamps with ozone. A pleated filter which may be for example a dust collection, or particulate filter  68  may be positioned at an exit of the UV chamber  60  to collect any particulates that might exist in the cooled air stream passing through the UV chamber  60 . 
     A connecting conduit  72  communicates UV chamber  60  with a blower, or pump  70  of a type known in the art. Blower  70  will operate to create a negative pressure, or soft vacuum at air inlets  20 . As a result, air will be pulled into air duct  10  through updraft hoods  25 . Updraft hoods  25  are positioned at human occupiable locations. Human occupiable locations as used herein means those places in a room or building that in a typical situation are occupied by humans, such as a work station, a desk, seating at a restaurant or in an office area. By strategically locating updraft hoods  25  at such locations, the system  5  can prevent pathogen laden air expelled by a human in those locations from ever entering the indoor space outside the updraft hood. At least a portion of the air expelled by the human will be contained within the updraft hood and passed into the system  5  for treatment as described, and in some cases all of the air expelled by the human will be contained within the updraft hood and passed into the system  5 . 
     A human worker in the updraft hood  25  will expel air through normal exhalation, coughing, sneezing, talking and other bodily functions that require air to be expelled through the nose or the mouth. The vacuum created by the pump  70  should be at a level sufficient to pull the majority of the air, and in some cases all of the air expelled by the human positioned in the updraft hood  25 . Any pathogens in the expelled air pulled into the air duct  10  will be treated and conditioned as described. In this way, pathogens expelled by humans are prevented from ever entering indoor space  6  and contaminating the air therein. Air is pulled into air duct  10  and communicated through the burn zone  40 . In one embodiment temperature in the burn zone exceeds 500° F. degrees. In additional embodiments the temperature in the burn zone is between 500 and 1,000° F. In other embodiments, the temperature may be between 500° F. and 900° F., 500° F. and 800° F., 500° F. and 700° F., and 500° F. and 600° F. and any ranges therebetween. In any event, burner  42  is configured to heat the burn zone to an internal temperature of as much as 1,000° F. The heated air stream leaving the burner  42  may likewise reach the foregoing temperatures. The treated air leaving burner  42  will have a reduced pathogen load as compared to the contaminated air. The cooled, treated air stream is delivered into the indoor space through an air exit  74  at, or near the ambient temperature of the indoor space. 
     As is understood from the drawings a method of removing pathogens may comprise positioning a plurality of air inlets at a plurality of locations in the indoor space. The method may further include pulling indoor air into the air inlets  20  and passing the indoor air through a burner  42  having an internal temperature sufficient to eliminate, or at least significantly reduce pathogens in the air passing through the burner. The method may comprise exposing the air to high temperatures for a short period of time at the high temperature. In one embodiment the method may comprise exposing the air in a burner to temperature ranges noted above for no more than three seconds to eliminate, or at least reduce the pathogens that existed in the air prior to the exposure to the temperatures in the burner. In a specific embodiment, the method includes exposing the air to a temperature range of between about 517° F. and 662° F. for no more than 2.61 seconds. 
     The method may comprise passing the indoor air through a burner having an internal temperature of at least 500° F. to create a heated air stream. The method may comprise heating the indoor air to higher temperatures, for example 600° F., 700° F., 800° F., 900° F. or 1000° F. to create a heated air stream. The heated air stream may then be cooled to create a cooled air stream having a temperature about the same as the air in the indoor space. In one embodiment the temperature of the air will be not more than 10° F. different than the temperature of the air in the indoor space. The cooled air stream is then exhausted back into the indoor space. The method may further comprise exposing a cooled air stream to UV radiation prior to the exhausting step. 
     The cooling step may comprise for example injecting a vapor stream into the heated air stream after it leaves the burner, and/or passing the air through a heat exchanger and/or through a scrubber with fill media over which cool water flows. The method may also include preventing pathogens expelled from a human from entering indoor air space  6 . The method includes placing an updraft hood  25  around at least the head of a human in the indoor space, and pulling the air emitted by the human from the updraft hood  25  through an air inlet into an air duct that communicates the air into the burner  42 , The air is then treated and conditioned as described and is exhausted as treated air into the indoor air space. The treated air will be clean air, and will be free of pathogens or will at least have a reduced level of pathogens than existed in the contaminated air. 
     In the embodiment described in  FIGS.  1 - 3    the system  5  is shown as contained within the indoor space  6  in which the air is being treated. As noted above, the entire system  5  operates completely independent of existing HVAC systems, and is not connected thereto in any way. Other embodiments may be utilized on a larger scale and may include multiple air ducts and a greater plurality of updraft hoods than shown in  FIG.  1   . For example,  FIG.  5    schematically shows a building which may be a large or small building having an enclosed indoor space  101 . Air is directed from indoor space  101  in building  100  to an air treatment system  102  configured to prevent contaminated air expelled from humans from entering the indoor space, and to eliminate, or at least significantly reduce pathogens from the air within indoor space  101 . Air treatment system  102  is shown in  FIG.  5    positioned outside building  100 . 
     Air may be communicated from indoor air space  101  through an air supply duct  104 . Air will pass through a burner  106  which will reach temperatures sufficient such that pathogens in the air passing therethrough, such as in a non-limiting example SARS-CoV-2, will be eliminated or at least significantly reduced. A connecting conduit  108  connects burner  106  with a cooling apparatus  110 . Cooling apparatus  110  may be for example a cooling tower with media over which water is sprayed. One embodiment may have a closed circuit cooling tower which may include a coil through which the heated air stream from burner  106  flows. Water will pass over the coils in the cooling tower to cool the heated air stream so that a cooled air stream exits cooling apparatus  110 . Other cooling apparatus may be utilized to cool the heated air to create a cooled, treated air steam that will exit cooling apparatus  110  through a return air conduit  112 . A UV chamber  114  includes a plurality of UV lamps, which may be UVC lamps, positioned therein. UV chamber  114  is connected in return air conduit  112 . Return air conduit  112  may be divided into a first portion  113  and a second portion  116  so that the UV chamber separates the return air conduit into two portions. The cooled, treated air stream will pass through first portion  113  in return air conduit  112  and into the second portion  116  through UV chamber  114  where the air passing therethrough is directly exposed to UV radiation. The cooled air stream thus passes from return air conduit  112  into the indoor space  101 . The cooled air stream entering the indoor space will be at about the same temperature of the air in the indoor space. In one embodiment the cooled air stream is at a temperature of no greater than 10° F. above the ambient air temperature in the indoor air space and in another no greater than 5° F. 
     An air pump  118  may be used to create a vacuum to pull the contaminated air from updraft hoods in the indoor space  101  through the system  102 . All, or part of the system components including burner  106 , cooling apparatus  110 , UV chamber  114  and air pump  118  may be housed in a system building  119 , or may be separately housed or simply positioned exterior to building  100 . 
     As schematically depicted in  FIG.  6   , building  100  may be for example an industrial building with a plurality of human occupiable locations  120 , which may be work stations  120 . Work stations  120  may be for example adjacent a conveyor belt  121  or other equipment. Air supply duct  104  has indoor air duct  122  connected thereto. Indoor air duct  122  may have a plurality of air duct branches  124  extending therefrom with a plurality of air inlets  126 . A plurality of updraft hoods  25  are connected by air conduits  32  to the indoor air duct  122 . Only one air duct branch  124  is shown with updraft hoods  25  connected thereto, but it is understood that a plurality of air duct branches  124  may be so configured. As shown in  FIGS.  6  and  7    updraft hoods  25  may extend all the way to the ground surface such that a human operator positioned at a human occupiable space  120  is partially enclosed from the ground surface upward. The updraft hood  25  will in some cases be above the head of a human, and in others may only extend downward to partially enclose an upper portion of a human to below the mouth and nose. If desired, a completely closed updraft hood may be created by simply providing a wall or curtain on the open portion  38  of the outer wall. 
     The operation of system  102  is generally the same as that with respect to system  5  only on a larger scale. Air pump  118  will create negative pressure at each of the air inlets  126  through conduits  32  and will pull air upwardly from updraft hoods  25  into duct branches  124  and air duct  122 . Thus, air expelled by sneezes, exhalations or otherwise by any human operators in the updraft hoods  25  will be pulled upwardly along with any air that is pulled through the opening  38  from indoor space  101 . As a result, the system  102  is not only a system that eliminates, or reduces pathogens, but is a system and method that prevents pathogens expelled by humans from entering and contaminating the air in indoor space  101 . Air expelled by humans in updraft hoods  25 , along with air from indoor space  101  that passes into updraft hoods  25  through the open side thereof, will pass through air duct  122  into the supply air duct  104  and into system  102 . Burner  106  is configured such that the internal temperature will reach at least 500° F. In other embodiments the burner  106  is configured to reach internal temperatures of at least 600° F., 700° F., 800° F., 900° F., and as much as 1,000° F. Air passing though burner  106  will be exposed to the temperature in the burner  106 , and exposing air to the temperatures described for burner  106  will reduce, and in most cases eliminate pathogens from the air passing therethrough. Based on the below described testing conducted on the impact of increased temperatures on MS-2, which is a surrogate for SARS-CoV-2, it is believed that exposing contaminated air to -elevated temperatures for a short period of time, for example as little as five seconds, and further as little as three seconds, will kill pathogens, and more specifically will kill SARS-CoV-2. It is likewise believed that the higher the temperature, the less residence time will be needed. Thus, it is believed that exposing the contaminated air to temperatures of above 500° F., for example as much 600° F., 700° F., 800° F., 900° F., and/or 1,000° F., and temperature ranges therebetween, may kill pathogens in contaminated air, and will do so with little residence, or exposure time. In one embodiment, air passing through a burner is exposed to an entry temperature of about 517° F. at the point of entry for the air into the burner and an exit temperature is about 662° F. The residence time for air passing through the burner may be less than three seconds, and in one example about 2.61 seconds. 
     A heated air stream will leave burner  106  and will begin to cool in the connecting duct  108  from the burner  106  to the cooling apparatus  110 . The heated air stream will be cooled further by the cooling apparatus  110 . The heated air stream will be cooled by cooling apparatus  110  to a temperature of not greater than 10° F. and preferably not greater than 5° F. over the ambient air temperature in the indoor space. 
     In one embodiment the updraft hoods  25  that are not occupied can be deactivated. One manner of doing this would be simply to have a valve in the conduits  32  that can be automatically controlled from a controller. In this way less power will be required to generate the air flow necessary to pull the air from activated updraft hoods. In addition, an updraft hood  25  can be movable from a lowered position in which it at least partially covers a human, to a raised position in which the updraft hood  25  is positioned above a human in the occupiable space  120 . 
     Burner  106  can be for example a plurality of burners  42  as described earlier connected in series. Burner  106  may have other configurations capable of reaching the internal temperatures described herein. An example of a burner embodiment may be as described with respect to  FIGS.  10 - 13   . As shown therein, burner assembly  130  comprises a pair of burners  132  and  134 . Burners  132  and  134  are generally identical in construction. Burners  132  and  134  have pumps  133  and  135  respectively communicated therewith. Air is received from the inner air space through air supply duct  104 . Air will flow into air supply duct  104  from indoor air duct  122  and into burner  106 . A burner inlet conduit  136  receives air from air supply duct  104 . Burner inlet conduit  136  may have a valve  137  therein that will allow the air received therein to be directed to either of burners  132  or  134 . Each of burners  132  and  134  comprise an outer housing or silo  138  having an interior  140 . 
     Interior  140  may be separated into a dirty air plenum  150  in an upper portion thereof and a clean air plenum  152  in a lower portion thereof. In one embodiment dirty air plenum  150  may comprise a heated plenum. Dirty air plenum  150  may be heated by a gas fired fire box or other known methods.  FIG.  11    shows a view of the interior  140  of a silo  138 . A tube sheet  156  divides the interior into the dirty air and clean air plenums  150  and  152 , respectively. Tube sheet  156  will have a plurality of openings through which individual burner cylinders  158  may be suspended. Only four burner cylinders  158  are shown in the view of  FIG.  11    but it is understood that more or less may be suspended from tube sheet  156  depending upon the amount of air flowing therethrough to be heated. Referring to burner  132 , pump  133  will create negative pressure to pull air into silo  138  of burner  132  from air supply conduit  104 . Air will pass from dirty air plenum  150  into the individual burner cylinders  158 . As depicted in  FIGS.  12  and  13   , individual burner cylinders have an opening  160  at an upper end  162  thereof. A shield  164  may be disposed about an upper portion  166  of burner cylinders  158  to prevent air flowing therein from passing outward prior to the time the air passes through the burner portion  168  of burner cylinder  158 . 
     Burner portion  168  has an outer housing  170  which may be a porous outer housing  170 . In one embodiment the outer housing  170  may comprise a ceramic material. In the partial section view shown in  FIG.  13   , a plurality of metal rods  172  are shown disposed in an interior  174  of outer housing  170 . A heating coil  176 , which may be for example an electric coil or an induction coil is disposed about outer housing  170  and is proximate metal rods  172 . In the embodiment shown the induction coil  176  is wrapped about outer housing  170  and is positioned close enough to metal rods  172  such that when a current is applied thereto induction coil  176  will generate significant heat which will heat metal rods  172  and consequently fill media  178 . 
     Outer housing  170  is filled with fill material  178  through which metal rods  172  extend. The fill material  178  may comprise metal beads, such as stainless steel beads or may comprise a ceramic or other material that can withstand temperatures of the ranges discussed herein and allow air to pass therethrough. The internal temperature of each of burner cylinder  158  will reach a minimum of at least 500° F., and in some embodiments 600° F., 700° F., 800° F., 900° F. and as much as 1,000° F. The operation of a system including the burner apparatus  106  is as described before. Pump  133  will pull air through burner inlet conduit  136  from air supply duct  104 . Air will pass into interior  140  of silo  138  into the dirty air plenum  150 . Air may be heated by a firebox or other heating mechanism in dirty air plenum  150 . Air will be pulled through each of individual burner cylinders  158  and will be heated as it passes therethrough. The heated air stream will pass through outer housing  170  and into clean air plenum  152 . A heated air stream will be communicated into a connecting conduit  177  and into a cooling apparatus  110  and UV chamber  114 . Air will then be delivered into building  100  as previously described. The air will be heated to a temperature sufficient to eliminate, or at least significantly reduce pathogens from the contaminated air treated by the system  102 . As explained below, tests have shown exposing air laden with MS-2 to high temperatures will eliminate, or at least dramatically reduce the MS-2 in the treated air. MS-2 is a bacteriophage that is accepted as a surrogate for SARS-CoV-2 and other pathogens and is more difficult to eliminate than SARS-CoV-2. 
     The temperature of each of burners  132  and  134  may be monitored and if the temperature to which the air is exposed in the burner  132 , or if the temperature of the air leaving the burner falls below a specified temperature the valve  137  may be actuated so that the air from conduit  104  is redirected. For example, the air can be redirected from burner  132  to burner  134 . The burner  132  will be heated to reach temperatures above the specified temperature as the contaminated air is directed to and heated by burner  134 . The temperature at which the valve  137  will be actuated can be specified by the operator. For example, if the minimum desired temperature of the air leaving burner  132  is 500° F. and the temperature falls below 500° F., the valve  137  can be actuated to switch to burner  134 . Rather than air temperature, the monitored temperature can be the internal temperature of the burner  132 . This process can be continuous such that the temperatures to which the air is exposed and the air temperature leaving an individual burner can be monitored and the valve  137  actuated to switch back and forth between burners when the monitored temperature reaches a minimum specified temperature. Two burners are disclosed herein but it is understood that more than two may be utilized. 
     System  102 , like the other systems disclosed herein, operate independent of existing HVAC systems, and are not connected thereto in any way. Although in the embodiment described in  FIG.  5    the air treatment system  102  is used in an industrial setting where a plurality of work stations are included, the system may be used in other environments with human occupiable locations such as those shown for example in  FIGS.  8  and  9   .  FIGS.  8  and  9    show an embodiment of a facility  190  that may be for example a restaurant or portion of an office building. 
     Facility  190  has a plurality of human occupiable locations  192 . Facility  190  is shown without a wall and a roof so that the indoor space  194  is visible. Locations  192  may be work stations, eating locations, or other locations occupiable by a human. At least one air duct  196 , and in the embodiment described a plurality of air ducts  196  are positioned in indoor air space  194  and have air duct branches  198  extending outwardly and downwardly therefrom. The air ducts  196  may be communicated with and comprise part of an air treatment system as described herein, like for example air treatment system  102 . Contaminated air from indoor space  194  drawn into and treated by the air treatment system  102  will be communicated back into the indoor air space  194 . 
     In  FIG.  8    air duct branches  198  are hanging above human occupiable locations  192  with no additional conduit or updraft hoods. Air may be withdrawn from the indoor space  194  through air duct branches  198 , into indoor air ducts  196  and into treatment system  102  through air supply duct  104  that will be connected to indoor air ducts  196 . Air duct branches  198  have inlets  200  that communicate air drawn therein into indoor air ducts  196 . Air inlets  200  may in turn be connected to updraft hoods  204  as shown in  FIG.  9   . Updraft hoods  204  are connected to inlets  200  with air conduits  206 . Updraft hoods  204  are shown to completely enclose for example seating areas, work spaces, desk areas and other human occupiable spaces. Air expelled by humans in locations  192  will be pulled into updraft hoods  204 , communicated into air supply duct  104  and treated by system  102  so that pathogens are removed therefrom, and treated air is exhausted back into indoor space  194 . In the example of  FIG.  9   , all of the air expelled by persons in the updraft hoods will be pulled into updraft hoods  204  and treated by system  102 . 
       FIG.  14    shows another example of an environment in which the system might be utilized. Environment  300  may be a waiting room, or other contained area with indoor space  302 . An updraft hood  304  is connected to an indoor air duct  306  that may be connected to and communicated with a system for treating air as described herein. Only one hood  304  is shown, but it is understood that a plurality of hoods  304  may be used. 
     Updraft hoods  304  are placed proximate a human occupiable space for example a chair in which a person may be seated. Air from indoor space  302  will be drawn into indoor air duct  306  and will be treated with a system as described herein. Air will be returned through a return air duct  308  connected to and communicated with the air treatment system. The air exhausted from return air duct  308  will contain fewer pathogens than the air drawn into hood  304 . Air expelled by a person proximate the hood  304 , or at least a portion thereof, will be pulled into hood  304 , so that pathogens contained therein are prevented from entering the indoor space  302 . 
       FIG.  15    shows a test setup establishing the efficacy of an air treatment system and method as described and claimed herein. The test arrangement included an inlet hose  250 , a burner section  252  and a connecting conduit  254  communicating air passing through burner  252  to a cooling unit  256 . A fresh air damper  255  was connected to connecting conduit  254 . Cooling unit  256  may comprise a scrubbing unit as well. Cooling unit  256  has a plurality of inlets  264  through which water is sprayed so that air passing therethrough is cooled by the water. The water was in some cases continuously pumped through the cooling unit  256  as tests were run. A connecting conduit  258  delivered the air into a UV chamber  260  having a plurality of UVC lamps with ozone to expose the air passing therethrough to UV radiation. The air was then passed into a sample container  266  where the air was cultured to determine the existence of any viruses or other pathogens. 
     Test microorganisms were cultured, purified and concentrated prior to commencement. An MS-2 bacteriophage suspension was diluted to a starting concentration of 10 6  plaque forming units (PFU) per milliliter. Aerosols including the MS-2 were generated for five minutes while the test device was running and air was pumped through the test system. An atomizer was connected directly to the input  250  aerosolizing approximately 1.67 mL of the viral suspension. The output of the test device was piped into an ASTM chamber located in a chemical fume hood. Samples were collected using single stage Anderson viable impactor placed into the ASTM chamber. The device was operated for five minute runs. Samples were collected with each run along with temperature readings. The number of viable microorganisms were determined quantitatively using plaque counting techniques and converted to PFU/M 2 . 
     The burner section  252  of the test arrangement was a heating chamber of approximately four inches in diameter by twelve inches in length. The fill media in the heating chamber included 0.177 in. diameter metal beads heated by an electric heating coil. The inlet hose  250  was approximately ½ inch in diameter and air was pulled through the burner and through the system at approximately two cubic feet per minute. With a blower speed set at 2 cubic feet per minute or, 3456 cubic inches per minute within a volume of 0.087 cubic ft or, 150.72 cubic in and utilizing a magnehelic gauged vacuum reading of 0.75 inches the measured residence time of introduced continuous air plume was 2.61 seconds. In other words, the travel time for the air from the top of the burner to the bottom of the burner was 2.61 seconds. The UV chamber  260  included two T5 UVC tube light fixtures with ozone. 
     The results of eight trials are shown in  FIG.  16   . Tests were run with different components on and off to determine the impact. For trials  1 ,  2  and  3 , the fresh air damper  255  was open and water was circulated through cooling unit  256 . The top temperature is that temperature measured at the top of the burner  252  and the bottom is that temperature measured at the bottom of burner  252 , For trial  4  no water was circulated and the damper  255  was closed. On trial  5  water was circulated in cooling unit  256  and the damper was closed. On trial  6  water was circulated through cooling unit  256  and the damper  255  was open, and for trials  7  and  8  the damper  255  was open and no water was circulated. Each trial indicated greater than a 99.1% reduction of MS-2 bacteriophage relative to the recovery on control samples. In effect, zero viable virus remained after treatment. Because it is known that the MS-2 bacteriophage is a surrogate for SARS-CoV-2 and is more difficult to inactivate, it may be concluded that the systems and methods described will effectively kill the SARS-CoV-2 and other pathogens. 
     In addition, there are studies indicating that elevated temperatures may be effective to kill. SARS-CoV-2. SARS-CoV-2 is one of a number of coronaviruses, one of which is SARS-CoV which is closely related to SARS-CoV-2. Different studies have indicated that most coronaviruses would be killed after exposure to 149° F. for longer than three minutes. For temperatures lower than 149° F. indications were that longer exposure times were needed. At least one study estimated that SARS-CoV-2 would be killed after an average of 2.5 minutes at 158° F. Although the studies appear to have considered the impact of elevated temperature on surfaces, the correlation between the temperature and exposure time indicates that the higher the temperature, the less exposure time is required to eliminate SARS-CoV-2. Thus, it is believed that exposing contaminated air to significantly elevated temperatures, for example temperatures of 500° F. and higher as noted herein, should decrease the exposure time needed to eliminate, or at least significantly reduce pathogens in the contaminated air. 
     Thus, it is seen that the apparatus and methods of the present invention readily achieve the ends and advantages mentioned as well as those inherent therein. While certain preferred embodiments of the invention have been illustrated and described for purposes of the present disclosure, numerous changes in the arrangement and construction of parts and steps may be made by those skilled in the art, which changes are encompassed within the scope and spirit of the present invention.