Patent Publication Number: US-2022226771-A1

Title: Infectious Agent Air Treatment System, Apparatus, and Method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Applications No. 63/075,090, filed on Sep. 4, 2020, which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to an air filter or air filtration system and more particularly to an antiviral air filter or antiviral air filtration system that attenuates and/or inactivates viruses, including coronaviruses, including SARS-COV-2 viruses. 
     BACKGROUND OF THE INVENTION 
     Over the past year and a half, an increasing number of people working in the field of epidemiology, including epidemiologists, clinical researchers, clinicians, medical doctors, scientists, engineers and others have made it clear that greater attention must be paid to aerosols as a mode of transmission of the novel coronavirus, aka the SARS-Cov-2 virus, in addition to the larger respiratory droplets already known as a SARS-Cov-2 virus transmission mode. While the size of actual SARS-Cov-2 viruses ranges between a relatively minute 0.06 μm and 0.14 μm, they are known to be found in larger respiratory droplets having a size of at least 5 μm expelled from an infectious person coughing, wheezing, sneezing and even breathing, but have only recently been discovered to be found in smaller aerosols having a size smaller than 5 μm also expelled from an infectious person coughing, wheezing, sneezing and even breathing. 
     While the difference in size between aerosols and droplets in these two modes of transmission is literally minuscule, acknowledging aerosols as a mode of coronavirus transmission would result in significant changes in how to combat and try to bring an end to the global coronavirus pandemic. In the near term, it would reinforce the clear need for everyone to wear personal protective equipment (PPE), including in the form of surgical masks, N95 respirators, KN95 respirators, to install HEPA room and building air filtration, as well as to continue to engage in social distancing. In the long term, it will require these same people, including engineers, architects, HVAC equipment makers, and HVAC installers to work together to rethink ventilation and air filtration in the design of everything from schools to cruise ships as well as in the retrofitting of HVAC systems of these and other types of buildings and structures to include HEPA filtering in order to try to minimize and preferably prevent the spread of the novel coronavirus via aerosols in the air. 
     Recent studies have confirmed that floating respiratory aerosols expelled from people infected with the SARS-Cov-2 virus can contain live SARS-Cov-2 viruses and not just fragments of viral genetic material. Live SARS-Cov-2 viruses have been isolated in aerosols at distances ranging from seven feet to as much as sixteen feet from infected hospitalized patients. Other studies have indicated that coronavirus-carrying aerosols can remain airborne for hours and travel distances greater than 40 feet. Such aerosols are typically less than 5 μm in size and can become even smaller while airborne due to evaporation that can occur while they are floating in the air. This has caused a shift from the view that the primary mode of airborne coronavirus transmission was believed to be through larger respiratory droplets having a size typically between 5 μm and 10 μm expelled at considerable velocity from an infected person during a sneeze or cough, it was thought that requiring social distancing by spacing people at least six feet apart would reduce viral transmission because these respiratory droplets are so large and heavy that gravity typically causes them to fall to the ground within four to six feet of the infected person expelling them. Acknowledging these smaller-sized aerosols as another mode of transmission will require even greater steps to be taken than at present to mitigate aerosols as a mode of SARS-Cov-2 virus transmission. 
     These smaller sized aerosols are of significant concern because they remain airborne much longer than larger respiratory droplets, theoretically can remain airborne indefinitely under many indoor conditions, unless they are removed by or from air currents, dilution with uncontaminated, e.g., outdoor air, ventilation, or via other means. These smaller sized aerosols are also of great concern because it has been found these same size range of particles (i.e., &lt;5 μm) tend to deposit themselves in the more vulnerable lower respiratory tract in humans, as well as has been shown by laboratory testing to do the same in guinea pigs, mice, and monkeys. In contrast, the transmission threat from larger sized respiratory droplets is known to be much less because the spread of larger sized respiratory droplets in the air is typically limited by gravity to only a few feet and such larger sized droplets of between 5-10 μm nearly always only reach the upper airways of the head and neck making their mode of infection less threatening. 
     What is needed is a better and more efficient way of attenuating or inactivating infectious agents, particularly viruses, more particularly coronaviruses, and even particularly SARS-Cov-2 viruses in both respiratory droplets and especially in airborne aerosols that float in the air inside and throughout buildings and other structures where people work, live or frequently gather. What also is therefore needed is a system, personal protective device and method of attenuating or inactivating viruses, particularly coronaviruses, more particularly SARS-Cov-2 viruses carried by airborne aerosols by infectious agent attenuating or inactivating filter media of such a system, personal protective device and method. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an infectious agent air treatment system configured for treating air in a stream of air flowing therethrough in a manner that disinfects the air by attenuating or inactivating, including by denaturing, airborne infectious agents, including bacteria, viruses, coronaviruses, SARS-Cov-2 viruses, mold, mold spores, fungi and fungi spores, carried in the airstream before a treated airstream exits from the system with any infectious agents in the airstream not filtered out before exiting being attenuated or inactivated. The infectious agent air treatment system is equipped with an infectious agent air treatment stage having an infectious agent attenuating or inactivating air treatment media carrying an infectious agent attenuator that can be coated thereon and/or impregnated therein that includes a biocide, such as preferably an acid-based biocide, more preferably an organic acid that preferably is citric acid, and which is formulated or configured to maintain an infectious agent attenuating or inactivating pH during air flow therethrough that within a desired pH range of between 2-5, preferably a more optimal pH range of between 1-4, and more preferably an optimal or ideal pH range of between 0-3. 
     A preferred infectious agent attenuator also includes a humectant, which preferably is an organic humectant, such as a humectant which is or includes sorbitol, for preventing inactivation of the biocide by retaining sufficient moisture for keeping the biocide at an optimal pH falling withing an aforementioned desired pH range and preferably within an aforementioned more optimal or ideal pH range that maintains infectious agent attenuation or inactivation efficiency of the infectious agent attenuating or inactivating air treatment media. A preferred infectious agent attenuating or inactivating air treatment media treated with an infectious agent attenuator that includes a humectant that preferably is or includes sorbitol advantageously is configured to be self-activating or at least maintains activation by the humectant capturing moisture in air passing through the infectious agent attenuator coated or impregnated air treatment media during operation helping the attenuator maintain a pH within the aforementioned desired range, preferably within the aforementioned more optimal pH range, and more preferably within the aforementioned ideal pH range. 
     An embodiment of a treatment media of an infectious agent disinfecting air treatment system of the present invention is equipped with at least one infectious agent inactivating or attenuating air treatment medium that includes, is configured with, and/or adapted as a particulate air filter that filters particulates, including droplets, e.g., respiratory droplets, and particularly aerosols of a size 5 μm and smaller, airborne or entrained in air in the airstream flowing through the at least one infectious agent air treatment medium while also substantially simultaneously attenuating and/or inactivating infectious agents, including viruses, particularly coronaviruses, more particularly SARS-Cov-2 viruses and mutations and variants thereof, which are airborne or entrained in the airstream flowing through the at least one infectious agent air treatment medium. In one such embodiment, the air treatment medium is configured not only to attenuate and/or inactivate infectious agents, including bacteria, viruses, mold, and funguses, but also is configured as an air filter that filters airborne particulates, including bacteria or viruses contained in respiratory droplets and carried by aerosols, as well as filtering out solid particulates, like dust, dander, and the like. 
     The air treatment media is configured with air flow-through flow passages of relatively small width or diameter formed therein in and/or along an infectious agent attenuating or inactivating attenuator, preferably a moisture carrying an infectious agent attenuating or inactivating attenuator gel, is disposed for ensuring infectious agents in air flowing the infectious agent attenuating or inactivating attenuator containing air treatment media during use and operation contact and are attenuated or inactivated by infectious agent attenuator disposed in and along one or more of these flow paths in and through the air treatment media before exiting the air treatment media. These infectious agent air treating flow paths of the air treatment medium can be defined by at least a plurality of pairs of pores, perforations, dimples, waves, corrugations, passages, channels and/or tubes formed in an infectious agent attenuator containing or carrying air treatment medium and/or which extend substantially completely through the infectious agent attenuator containing or carrying air treatment medium in the general direction of airflow through the treatment media and system during operation and which can have one or more portions thereof extending in one or more different directions relative to the general direction of airflow through the treatment media and system. A plurality or even a plurality of pairs of infectious agent attenuating or inactivating air treatment or air treating flow paths in and/or through the infectious agent treatment media can be and preferably are elongate, non-straight, meandering, crisscrossing, overlapping, generally parallel, disposed alongside one another, arranged in a zig-zagging pattern, or arranged in another pattern, orientation, and/or configuration. These air treatment or air treating flow paths formed in the air treatment media have a relatively small maximum width or maximum diameter of no greater than 0.1 inch, preferably no greater than 10 microns, more preferably no greater than about 1 micron, and even more preferably no greater than 0.1 micron formed therein and/or therethrough distributed throughout every square millimeter of the hard-surfaced air treatment medium, preferably distributed throughout every cubic millimeter of volume of the air treatment media, more preferably distributed substantially uniformly throughout the air treatment media, even more preferably distributed throughout every square millimeter of the air treatment media, and even more preferably substantially uniformly distributed throughout every cubic millimeter of volume of the air treatment media to increase the surface area of infectious agent attenuator disposed along and/or lining each of the flow paths in the air treatment media exposed to air and infectious agents in the air flowing through the air treatment medium during air treatment system operation. 
     The air treatment media can be made of plastic, e.g., polyethylene and/or polypropylene, composite, or synthetic material; constructed of mesh, wires, fibers, matting, tubes, or the like; and/or be composed of woven or nonwoven material, including woven or nonwoven material, e.g., mesh, made of one or more of plastic, e.g., polyethylene and/or polypropylene, composite, or other synthetic material, such as expanded polytetrafluoroethylene, e.g., expanded polytetrafluoroethylene washable filter membranes, and/or constructed of one or more of mesh, e.g., stainless steel mesh, wires, fibers, matting, tubes, or the like. The above-described airborne infectious agent treating flow paths in the air treatment media are defined by infectious agent attenuator carrying surfaces, coated surfaces or lined surfaces formed of or by structure(s) defining the flow paths, e.g., formed of pores, perforations, dimples, waves, corrugations, passages, channels and/or tubes that define the flow paths, and/or mesh, wires, fibers, matting, tubes, woven material, and/or nonwoven material in at least one layer of air filtration material from which the air treatment media is made or manufactured by impregnating the air filtration material layer with infectious agent attenuator, preferably infectious agent attenuator gel. Prior to infectious agent attenuating or inactivating air treatment system use and operation, infectious agent inactivating or attenuating attenuator is applied in a treatment step to the aforementioned at least one layer of air filtration material to produce infectious agent attenuating or inactivating air treatment media in a manner that coats, adheres, impregnates, clings, absorbs, adsorbs, attaches, affixes or otherwise applies infectious agent attenuator to, on, in, onto and/or into filaments, fibers, fibrils, and other structures of the at least one layer of air filtration material that define the flow paths in the resultant air treatment media produced after application of the infectious agent attenuator. 
     In a preferred embodiment, the present invention is directed to an infectious agent attenuator carrying, coated and/or impregnated air treatment media configured for use in a personal protective infectious agent inactivating or attenuating air treatment device, which preferably also filters particulates from the air, such as in the form of a surgical mask, N95 respirator, KN95 respirator, N99 respirator, filter mask, or mask filter, and which can be a personal protective air treatment device, which preferably also filters particulates in the air being treated thereby, which is made with an infectious agent attenuator carrying, coated or impregnated air treatment media treated where the infectious agent attenuator is composed of an acid-based biocide along with a humectant and which can be formulated as a gel, such as a hydrogel, containing enough moisture to keep the acid-based biocide moisturized and at a desired pH of less than 5 and preferably less than 3.5 or within a desired pH range of between 0-4 that keeps the biocide activated. The personal protective infectious agent attenuating or inactivating air treatment device, preferably personal protective infectious agent attenuating or inactivating air treatment and filtering device, is configured to be body worn, such as by being configured for being removably mounted to or on a head of a person in a manner that positions the infectious agent attenuator impregnated air treatment media in air flow communication with a mouth and/or nose of the person so infectious agents, including viruses, particularly coronaviruses, more particularly Sars-Cov-2 coronaviruses, in the ambient air, e.g., room air, such as carried by airborne aerosols in the air, inhaled by the person are either attenuated or inactivated by the infectious agent attenuator impregnated air treatment media before entering the person&#39;s mouth and/or nose. 
     The personal air filtering device has a mounting arrangement configured for removably mounting the device onto the head of a person, which can be in the form of a strap, e.g., head strap, band, e.g., adjustable head band, one or more loops, e.g., ear loops, or the like. The personal air filtering device can include a flexible woven structure that structurally supports the infectious agent attenuator impregnated air treatment media as well as any other perforate or porous flow through material, e.g., filter material or filter layers, disposed inline upstream and/or downstream of the infectious agent attenuator impregnated air treatment media. In alternative embodiments, the personal air filtering device can also include one or more valves, such as bypass valves and/or exhaust valves configured to allow air exhaled from a person wearing the personal air filtering device to be exhausted without having to pass through the infectious agent attenuator impregnated air treatment media as well as any other perforate or porous flow through material, e.g., filter material or filter layers, disposed inline with the infectious agent attenuator impregnated air treatment media. 
     The personal air filtering device preferably has at least one layer of infectious agent attenuator impregnated air treatment media disposed between an ambient air source, e.g., room air, and the mouth and/or nose of a person wearing the device for attenuating or inactivating infectious agents in air being drawn through the air filtering device during inhalation. At least one layer of infectious agent attenuator impregnated air treatment media of the personal air filtering device can be made of a perforate material, such as a perforate mesh filter material, woven filter material, nonwoven filter material, or another type of filter material that can be a hard-surfaced air treatment media material like that disclosed above that is configured not only to receive and carry infectious agent attenuator, but also to filter and trap particulates, aerosols and/or droplets during personal filtering device use and operation. The personal air filtering device can also include one or more additional layers of perforate or porous flow through material not treated or impregnated with infectious agent attenuator disposed in air flow communication with, preferably inline with, and more preferably overlapping at least one layer of the infectious agent attenuator impregnated air treatment media. Where the personal air filtering device is constructed with one or more such additional perforate flow through material layers, each such layer can be composed of an air filtering material, e.g., comprise an air filtering layer, not treated or impregnated with infectious agent attenuator, but which is configured (a) to filter particulates, aerosols, and/or droplets, (b) as a moisture barrier, (c) as a vapor barrier, (d) as an electrostatic filter media, (e) as another type of filter or filter media, and/or (f) as another type of flow-through layer disposed either or both upstream and/or downstream of at least one layer of the infectious agent attenuator impregnated air treatment media. Where one or more such additional layers are present, one or more of the additional layers can be composed or constructed of one or more of the hard-surfaced air treatment media materials of the air treatment system disclosed above. 
     The infectious agent attenuator impregnated air treatment media is composed of a biocide that preferably is an acid-based biocide at a desired pH, preferably under 5, more preferably under 4, or even more preferably under 3. A preferred acid-based biocide is composed of a carboxylic acid, preferably citric acid, in a strength and pH suitable for disinfecting air coming in contact with such an acid-based acid-containing attenuator by attenuating or inactivating infectious agents in the air including by denaturing the infectious agents. A preferred attenuator is in the form of a liquid or gel, such as a hydrogel, which defines a matrix, a gel matrix or hydrogel matrix, in which the biocide is disposed and which adheres to the air treatment media. In a preferred embodiment, the gel or at least part of the gel is formed of the humectant, which can be a gel forming humectant or gellant, with the gel forming the matrix, e.g., gel matrix or hydrogel matrix, in which the biocide is relatively uniformly, preferably substantially uniformly, distributed. 
     When such an infectious agent attenuator gel is applied onto the treatment media, the gel coats or lines hard surfaces within the treatment media that define air flow paths therethrough thereby exposing biocide within the gel to infectious agents in the air flowing through the treatment media during personal air filter device use and operation. Where the treatment media is a perforate or porous filter fabric, such as of woven, nonwoven and/or fibrous construction, infectious agent attenuator in a liquid form is applied thereto with the composition of the infectious agent attenuator configured to cause the infectious agent attenuator to gel up upon or after application forming a gel, i.e., infectious agent attenuator gel, which becomes impregnated into the perforate or porous filter fabric. 
     An infectious agent attenuator impregnated treatment media made with such an infectious agent attenuator formulation, particularly an infectious agent attenuator gel formulation, and a personal protective filter mask having at least one air treatment layer, preferably filter layer, of a treatment media made such an infectious agent attenuator formulation, particularly an infectious agent attenuator gel formulation, is of regenerable construction after being used by application of moisture, e.g., an aqueous regenerating solution, thereto in a manner that wets the infectious agent attenuator, preferably infectious agent attenuator gel, impregnated into the treatment media. Wetting the infectious agent attenuator, preferably infectious agent attenuator gel, impregnated into the treatment media with an aqueous regeneration fluid increases the moisture content of the infectious agent attenuator, preferably infectious agent attenuator gel, thereby regenerating it by the increased moisture content changing its pH. Regenerating the infectious agent attenuator, preferably infectious agent attenuator gel, by remoisturizing it to increase its moisture content after treatment media and/or a personal protective filter mask use advantageously enables the treatment media and personal protective filter mask made with such an attenuator impregnated or attenuator gel impregnated treatment media to be reused over and over again. During regeneration, water in the aqueous regenerating fluid wetting an attenuator gel not only wets and moisturizes biocide in the gel to regenerate the biocide by returning its pH within an aforementioned desired pH range and/or at about a desired pH, but water is absorbed by the gel, preferably absorbed into the gel matrix, that keeps the biocide in the gel moist and within an aforementioned desired pH range and/or at about a desired pH. 
     In another preferred embodiment and regeneration method where the treatment media is impregnated with an infectious agent attenuator gel, the regeneration fluid preferably is a replenishing fluid containing biocide in an aqueous solution applied onto the infectious agent attenuator gel impregnated treatment media. The applied regeneration fluid wets the treatment media and wets the infectious agent attenuator gel impregnated into the treatment media replenishing the gel impregnated into the treatment media with biocide lost, e.g., via neutralizing reaction, evaporation, sublimation, etc. during treatment media and/or personal protective filter mask use and operation. When wetted by such a biocide-containing aqueous replenishing fluid, water in the fluid advantageously substantially simultaneously regenerates biocide remaining in the gel by moisturizing it, thereby maintaining disinfecting efficiency by keeping it within an aforementioned desired pH range or pH. When wetted by such a biocide-containing aqueous replenishing fluid, biocide in the fluid is advantageously absorbed by the gel and retained within the gel during treatment media and personal protective filter mask use and operation increasing the amount and exposed surface area of biocide available to attenuate or inactivate infectious agents. 
     The present invention also is directed to an infectious agent attenuating or inactivating personal protective equipment device, such as a surgical mask, multilayer mask or respirator having at least one porous filtering layer impregnated with an infectious agent attenuating or inactivating solution that tries to leave behind an infectious agent attenuating or inactivating attenuator composed of an organic acid that preferably is citric acid, a humectant that preferably is a gelling humectant that preferably is sorbitol which produces or forms a self activating or self replenishing infectious agent attenuator gel and infectious agent attenuating and inactivating air treatment media having a pH of no greater than 5, preferably no greater than 4 and more preferably no greater than 3.5 which is kept moist and activated at or below the desired pH by moisture in the breath of a person wearing the mask. The solution can include a surfactant, such as preferably a rhamnolipid biosurfactant that reduces surface tension both during impregnation of the solution thereby more uniformly impregnating the solution into the at least one porous filtering layer producing an air treatment media having infectious agent attenuating gel more uniformly distributed throughout. The surfactant remains in the gel and reduces surface tension of aerosols and droplets containing viruses and bacteria entrained in the air flowing through the air treatment media contacting the infectious agent attenuating gel more rapidly and efficiently attenuating or inactivating the viruses and bacteria preferably also destroying them by lysing the viruses and bacteria. 
    
    
     
       DRAWING DESCRIPTION 
       One or more preferred exemplary embodiments of the invention are illustrated in the accompanying drawings in which like reference numerals represent like parts throughout and in which: 
         FIG. 1  is a top plan view of an elongate oblong infectious agent attenuating or inactivating air treating filter panel of an infectious agent attenuating or inactivating air treatment media formed of a layer of perforate or porous air filtering material treated with an infectious agent attenuating or inactivating attenuator; 
         FIGS. 2A and 2B  depict a first pair of side by side enlarged photomicrographs of a fragmentary top plan view of an enlarged portion of the oblong layer of perforate or porous air filter material before and after treatment with infectious agent attenuator; 
         FIGS. 3A and 3B  depict a second pair of side by side enlarged photomicrographs of a fragmentary side elevation view of an enlarged portion of a side edge of the oblong layer of perforate or porous air filter material before and after treatment with infectious agent attenuator; 
         FIG. 4  is a fragmentary perspective cutaway view of a 3-ply or 3-layer infectious agent attenuating or inactivating surgical mask having a first ply or outermost layer composed of a polypropylene spunbound non-woven fabric, a second or middle ply or layer composed of a layer of infectious agent attenuating or inactivating air treatment media made of a perforate or porous air filtering material composed of a meltblown nonwoven fabric impregnated with infectious agent attenuator, and a third ply or innermost layer that is a support layer that composed of a mesh made of a polypropylene spunbound non-woven fabric; 
         FIG. 5  is a perspective exploded view of the 5-plys or 5-layers of a 5-ply or 5-layer infectious agent attenuating or inactivating air filtering personal protective mask of the present invention that preferably is an N95 respirator mask having a nonwoven first or outer layer made of a fabric like a polypropylene spunbound non-woven fabric, a second outer intermediate double meltblown layer composed of infectious agent attenuating or inactivating air treatment media, a third or middle double nonwoven layer composed of a polypropylene spunbound non-woven fabric, a fourth or inner intermediate double meltblown layer composed of infectious agent attenuating or inactivating air treatment media, and a fifth or inner double nonwoven layer composed of a polypropylene spunbound non-woven fabric; 
         FIG. 6  is a lower front left perspective view of a person removably wearing a infectious agent attenuating or inactivating respirator assembly of the present invention equipped with a middle layer of air filtering and infectious agent attenuating or inactivating construction composed of infectious agent attenuating or inactivating air treatment media sandwiched between an outer perforate hardshell respirator cover and an inner respirator frame to which ear loops or head anchor straps extend outwardly from; and 
         FIG. 7  is a front top right perspective exploded view of the infectious agent attenuating or inactivating respirator assembly of  FIG. 6 . 
     
    
    
     Before explaining one or more embodiments of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description and illustrated in the drawings. The invention is capable of other embodiments or being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting. 
     DETAILED DESCRIPTION 
       FIG. 1  illustrates a preferred embodiment of an infectious agent attenuating or inactivating air treatment media  420  configured for use in a personal protective air filtering device  422   a - 422   c , such as in the form of a surgical mask  460 , like the 3 ply or 3 layer infectious agent attenuating or inactivating surgical mask  460  depicted in  FIG. 4 , an N-95 or KN-95 air filtering respirator or mask  462 , like 5 ply or 5 layer the infectious agent attenuating or inactivating N95 air filtering respirator or mask  462  depicted in  FIG. 5 , or a hardshell solid frame respirator  464 , like the infectious agent attenuating or inactivating respirator  464  equipped with adjustable head and neck straps  482 , a perforate concave hardshell outer cover  484  and an cushioned substantially rigid inner frame  486  to which the straps  482  anchor and which has an exhalation valve  488  as depicted in  FIGS. 6 and 7 , which each employs at least one layer  485  of treatment media  420  made of a perforate or porous air filtering material layer  423  treated, preferably impregnated, with an infectious agent attenuator  424  composed of an infectious agent attenuating or inactivating biocide and a humectant included to retain moisture to keep the biocide activated during use and operation of the personal protective air filtering device  422   a - 422   c . In a preferred embodiment, a sufficient amount of the humectant is added to the infectious agent attenuating or inactivating biocide to produce an infectious agent attenuator  424  of the present invention that is a self-activating infectious agent attenuating or inactivating composition because only moisture in air passing through the air treatment media  420  during inhalation and exhalation by a person wearing the personal protective air filtering device  422  is needed to replenish the infectious agent attenuator  424  of the air treatment media  420  with enough moisture to keep it at a desired pH within an optimal pH range at which the air treatment media  420  attenuates and/or inactivates infectious agents in the air passing through. 
       FIGS. 2A and 2B  depict a first pair of side by side enlarged photomicrographs of a a top surface  475 ,  475 ′ of an enlarged portion of the layer of perforate or porous air filter material  423  of  FIG. 1  before ( FIG. 2A ) and after ( FIG. 2B ) treatment with an infectious agent attenuator  424  that is preferably impregnated therein.  FIG. 2A  also illustrates that the layer of perforate or porous air filter material  423  has at least a plurality of pairs, i.e. at least 3, of air flow paths or channels  470 ,  472 ,  474  which are preferably non-straight or meandering flow paths or channels  470 ,  472 ,  474  formed between filaments or fibers  476  of a flexible resilient material  478 , such as a material  478  made of a flexible and resilient polypropylene spunbound, meltblown or spunface fabric. It is contemplated that the layer of perforate or porous air filter material can also be made of polyester, cotton, silk or nylon and which can be of woven, nonwoven, knit, meltblown, spunbound or spunface flexible fabric.  FIGS. 3A and 3B  depict a second pair of side by side enlarged photomicrographs of an enlarged portion of a side edge  480 ,  480 ′ of the oblong layer of perforate or porous air filter material  423  of  FIG. 1  before and after treatment, preferably impregnation, with infectious agent attenuator  424 . 
       FIG. 4  illustrates a 3-ply or 3-layer infectious agent attenuating or inactivating surgical mask  460  having a flexible first ply or outermost layer  490  composed of a polypropylene spunbound non-woven fabric, a flexible second or middle ply or layer  492  composed of a layer of infectious agent attenuating or inactivating air treatment media made of a perforate or porous air filtering material  423  composed of a meltblown nonwoven fabric impregnated with infectious agent attenuator  424 , and a flexible third ply or innermost layer  494  that is a support layer composed of a mesh made of a polypropylene spunbound non-woven fabric. The mask also has a pair of elastic ear loops  496  and a bendable metal nose clip  498 . 
       FIG. 5  illustrates a 5-plys or 5-layers of a 5-ply or 5-layer infectious agent attenuating or inactivating air filtering personal protective mask  422   b  of the present invention that preferably is an N95 respirator mask  462  having a flexible nonwoven concave first or outer layer  500  made of a fabric like a polypropylene spunbound non-woven fabric, a flexible second outer intermediate double meltblown layer  502  composed of infectious agent attenuating or inactivating air treatment media  420 , a flexible third or middle double nonwoven layer  504  composed of a polypropylene spunbound non-woven fabric, a flexible fourth or inner intermediate double meltblown layer  506  composed of infectious agent attenuating or inactivating air treatment media  420 , and a flexible fifth or inner double nonwoven layer  508  composed of a polypropylene spunbound non-woven fabric. In other words, the 5 ply or 5 layer mask  422   b  is equipped with a pair of inline but spaced apart infectious agent attenuating or inactivating air treatment media layers  502  and  506  providing double the filtering and infectious agent inactivating or attenuating flow volume. Although equipped with elastic ear loops that are not shown in  FIG. 4 , the outer layer  500  does have an elongate rectangular bendable metal nose clip  510 . 
       FIGS. 6 and 7  illustrate an infectious agent attenuating or inactivating respirator assembly  464  adapted to be worn over the nose and mouth of a person  512  ( FIG. 6 ). The respirator assembly  464  has a concave middle particulate air filtering layer  485  composed of air filtering and infectious agent attenuating or inactivating media  420  sandwiched between a rigid perforate hardshell outer respirator cover  482  and an inner respirator frame  486  to which adjustable head mounting straps  462  releasably secured around the head  514  and neck  516  of the person  512  wearing the respirator  464  are adjustably anchored. 
     As can be seen by looking at the comparison views, treating the layer of perforate or porous air filter material  423  with infectious agent attenuator  424  preferably by impregnating the filter material  423  with infectious agent attenuator  424  coats or lines the fibers and/or filaments  476  producing an infectious agent attenuating or inactivating air treatment media  420  configured so infectious agent carrying air flowing through the reduced diameter or width flow paths or channels  470 ,  472  and  474  comes into contact with the infectious agent attenuator  424  coating or lining the fibers and/or filaments  476 . As a result, airborne liquid aerosols and droplets entrained in the flowing air carry infectious agents, such as one or more viruses, e.g., coronaviruses, such as Sars-Cov-2 viruses, which also contact infectious agent attenuator  424  coating or lining the fibers and/or filaments  476  of the air treatment media  420  attenuating or inactivating the infectious agents in the liquid aerosols or droplets. 
     The infectious agent attenuator  424  preferably is a flowable viscous liquid at room temperature, i.e., 20-22° C. or 68-72° F., during application onto the perforate or porous air filtering material layer  423  such that the attenuator  424  becomes impregnated into the filtering material layer  423  by the liquid or liquified attenuator  424  being distributed substantially completely and preferably substantially uniformly throughout the filtering material layer  423 . Upon drying of the attenuator  424  impregnated into the filtering material layer  423 , preferably by heated and/or convective oven drying in a heated and/or convective drying oven, the attenuator  424  impregnated into the air filtering material layer  423  solidifies producing an infectious agent attenuating or inactivating air treatment media  420  of the present invention having solidified infectious agent attenuating or inactivating attenuator  424  exposed to air flowing therethrough during personal protective air filtering device operation that is substantially uniformly distributed throughout. 
     In a preferred embodiment, the flowable liquid infectious agent attenuator  424  is applied to, e.g., impregnated into, the air filtering material layer  423  and is formulated, such as preferably by including a gellant, to increase in viscosity and gel over time during drying producing an infectious agent attenuating or inactivating air treatment media  420  with a moist resilient and pliable infectious agent attenuator gel  427 , e.g., preferably indurate gel  427 , which will be exposed to air flowing therethrough during personal protective air filtering device operation that congeals substantially uniformly throughout and within the air treatment media  420 . The infectious agent attenuator  423  preferably is in the form of a flowable viscous infectious agent attenuator gel  427  that is flowable at room temperature during application to, e.g., impregnating into, the air filtering material layer  423  as a flowable liquid that increases in viscosity and gels as it solidifies after application to the air treatment media  420  as it dries. 
     A preferred infectious agent attenuator formulation is composed of a biocide and a gellant configured not only to retain water, i.e., a gellant that also is a humectant, to keep the biocide activated, preferably self-activated by human breath moisture during personal protective air filtering device operation, but also to form an infectious agent attenuator gel, preferably during or after application to the air filtering material layer  423  producing an infectious agent attenuating air treatment media  420  of the invention that is ready for use in a personal protective air filtering device  425  like a surgical mask, respirator, or another type of personal protective equipment (PPE). If desired, such a formulation of an infectious agent attenuator  424  can have other constituents including, for example, one or more wetting agents, one or more viscosity modifiers and/or stabilizers, one or more pH modifiers and/or stabilizers, one or more surfactants, e.g., a glycolipid biosurfactant that is a rhamnolipid biosurfactant or supersurfactant, as well as one or more other constituents. 
     An infectious agent attenuator  424  of the present invention is produced using an infectious agent attenuator solution composed of (a) an infectious agent attenuator precursor mixture composed of between 55-85% of an acid, preferably a tribasic acid or triprotic acid that more preferably is an organic acid, preferably citric acid, and between 15-45% of a humectant that preferably is a gelling humectant, which more preferably is an organic gelling humectant, preferably sorbitol, and (b) the remainder water. The infectious agent attenuator solution used to treat the air filtering material layer  423  to produce the infectious agent attenuating air treatment media  420  with the infectious agent attenuator  424  coated thereon and/or impregnated therein after drying is composed of between 5-20% of the precursor mixture and the remainder, between 80-95%, composed of water into which the concentrated precursor mixture is added and mixed. 
     A preferred infectious agent attenuator  424  of the present invention is produced using an infectious agent attenuator solution composed of (a) an infectious agent attenuator precursor mixture composed of between 60-80% of a naturally occurring organic acid, preferably citric acid, and between 20-40% of a naturally occurring organic humectant that preferably is a naturally occurring organic gelling humectant, preferably sorbitol, and (b) the remainder composed of water. The infectious agent attenuator solution used to treat the filtering material layer  423  to produce the infectious agent attenuating air treatment media  420  coated and/or impregnated with the infectious agent attenuator  424  is composed of between 10-15% of the precursor mixture and the remainder, between 85-90%, composed of water with which the precursor mixture is added and mixed. 
     A particularly preferred infectious agent attenuator  424  is produced using an infectious agent attenuator solution having a formulation composed of (a) a precursor mixture of at least 80% of an acid, preferably a naturally occurring organic acid, more preferably citric acid, and no more than 20% of a humectant that preferably is a gelling humectant, more preferably a naturally occurring organic gelling humectant, preferably sorbitol, and (b) water. The infectious agent attenuator solution produced is a flowable liquid solution capable of being applied using a dip-coating application method or being sprayed on using a sprayer or the like that is composed of about 12%±1.5% of the precursor mixture and the remainder, about 88%±1.5%, water mixed together and applied to the air filtering material layer  423  to coat the layer  423  and preferably substantially uniformly impregnate the layer  423  with the solution that solidifies during drying into infectious agent attenuator  424  preferably in the form of an infectious agent attenuator gel  427  transforming the infectious agent attenuator gel-coated and impregnated air filtering material layer  423  into air-filtering infectious agent attenuating treatment media  420 . 
     While a preferred humectant is sorbitol, other humectants, including glycerin, propylene glycol, a longer chain glycol, an acrylic polymer humectant or gellant, and/or calcium chloride can be used. As previously indicated, the infectious agent attenuator solution from which the infectious agent attenuator  424  is produced can be made of a formulation that includes one or more wetting agents, one or more viscosity modifiers and/or stabilizers, one or more pH modifiers and/or stabilizers, one or more surfactants, such as rhamnose lipid(s) surfactants or rhamnolipid biosurfactants, as well as one or more other constituents or components. Where the formulation of the attenuator solution includes one or more of these other components or constituents, the total amount of such one or more of these additional components or constituents makes up no more than 10% of the attenuator solution by solution weight, preferably no more than 5% of the attenuator solution by weight, more preferably no more than about 2.5% of the attenuator solution by weight, at the time of application of the attenuator solution to the air filtering material layer  423  to produce the infectious agent attenuating or inactivating air treatment media  420  containing infectious agent attenuator  424 , preferably infectious agent attenuator gel  427 , upon suitable drying. Where the formulation of the attenuator solution includes one or more of these other components or constituents, the total amount of such one or more of these additional components or constituents present in the attenuator  424 , preferably attenuator gel  427 , of the air treatment media  420  makes up no more than 10% of the attenuator  424 , preferably attenuator gel  427 , by weight, preferably no more than 5% of the attenuator  424 , preferably attenuator gel  427 , by weight, more preferably no more than about 2.5% of the attenuator  424 , preferably attenuator gel  427 , by weight. 
     A preferred formulation of the infectious agent attenuator solution and attenuator  424  may further include a surfactant to facilitate more uniform application of the infectious agent attenuator solution to the air filtering material layer  423  producing an air-filtering infectious agent attenuating treatment media  420  with the attenuator  424 , preferably attenuator gel  427 , more uniformly distributed throughout the resultant air treatment media  420 . In such a preferred infectious agent attenuator solution and attenuator  424  containing a surfactant, the surfactant remains present in the attenuator  424 , preferably attenuator gel  427 , uniformly distributed throughout the air treatment media  420  and facilitates attenuation or inactivation of infectious agents like viruses such as the SARS-COV2 coronavirus by causing the infectious agents in the air flowing through the media  420  to be more readily attracted to exposed surface of the attenuator  424 , preferably attenuator gel  427 . In such a preferred infectious agent attenuator solution and attenuator  424  containing a surfactant, the surfactant remains present in the attenuator  424 , preferably attenuator gel  427 , uniformly distributed throughout the air treatment media  420  and facilitates attenuation or inactivation of infectious agents like viruses such as the SARS-COV2 coronavirus by attracting and encapsulating the infectious agents in the air flowing through the media  420  in the attenuator  424 , preferably attenuator gel  427 , of the media  420 . 
     Where a surfactant is used, at least one drop of surfactant is added to the infectious agent attenuator solution producing an infectious agent attenuator solution having between 0.001% and 0.1% of surfactant by weight of the solution. In one infectious agent attenuator formulation and solution that made with a surfactant, the solution and the attenuator, including attenuator gel, which results after application and drying of the solution contains between 0.001% and 0.1% of surfactant by weight. In another infectious agent attenuator formulation and solution that contains surfactant, the solution and attenuator that results after application and drying of the solution contains between 0.01% and 1% of surfactant by weight. The inclusion of the surfactant not only reduces surface tension during application, preferably impregnation, by enabling the solution to wick along the fibers and filaments of the filtering material layer  423  more uniformly impregnating the layer  423  therewith producing a more uniform attenuator and gel throughout the resultant air treatment media  420  produced but the surfactant acts on viruses and bacteria in droplets and the like flowing through the media  420  by lysing them destroying the viruses and bacteria contacting the surfactant containing attenuator and attenuator gel lining the air flow passages of the media  420 . 
     In the making of infectious agent attenuating or inactivating air treatment media  420 , a filtering material layer  423  can be treated by dipping the filtering material layer  423  into a container of the infectious agent attenuator solution to dip coat the filtering material layer  423  with the solution thereby impregnating the filtering material layer  423  therewith and which is removed from the solution and dried, such as by oven and/or convection drying, to produce an infectious agent attenuating air treatment media  420  of the present invention containing or configured with congealed or solidified infectious agent attenuator  424  exposed to air flowing therethrough that is ready for use in a personal protective air filtering device  422  like a surgical mask, respirator, or another type of personal protective equipment (PPE). The filtering material layer  423  can also be treated by spraying the infectious agent attenuator solution onto the layer  423 , such as by using an air spray or air sprayer, a high volume, low pressure (HVLP) spray or sprayer, a low volume, medium pressure (LVMP) spray or sprayer, an airless spray or airless sprayer, an air-assisted airless spray or airless sprayer, or an electrostatic applicator, such as an air spray electrostatic spray or sprayer, an air-assisted airless spray electrostatic spray or sprayer, or rotary atomization electrostatic spray or sprayer, thereby coating and preferably impregnating the layer  423  therewith producing an infectious agent attenuating air treatment media  420  of the present invention containing or configured with congealed or solidified infectious agent attenuator  424  exposed to air flowing therethrough. 
     When the filtering material layers  423  are treated, the density or thickness of the untreated filtering material  423 A increases as compared to the density of the treated filtering material  423   b . As seen in  FIGS. 1 and 2 , when the filtering material layer  423  is treated, the filtering material layer  423  increases in density and minimizes the pores, holes, or airflows within the filtering material  423  through coating the fibers or strands filtering material  423  by increasing the diameter of the fibers.  FIG. 1  compares the untreated edge of the filtering material  423   a  to the treated edge of the filtering material  423   b  Similarly,  FIG. 2  compares the face of the untreated filtering material  423   a  to the treated filtering material  423   b . As seen in  FIGS. 1 and 2 , the treated filtering material  423   b  is substantially denser than the untreated filtering material  423   a . Thus, the treated filtering material  423   b  increases the likelihood that infectious agents will contact and adhere to the filtering material  423  and also reduces the likelihood that infectious agents will pass through the filtering material  423  when compared to the untreated filtering material  423   a.    
     A preferred layer of infectious agent attenuating or inactivating filter media  420  has an antiviral efficacy of at least 1.3, preferably at least 1.5, more preferably at least 2.0, when tested for antiviral activity using a human coronavirus in accordance with ISO Test Standard 18184 for a contact time of 10 minutes and showed no bacterial growth of Staphylococcus aureus and Klebsiella pneumonia when the infectious agent attenuating or inactivating filter media  420  was placed in a triptych soy agar or nutrient agar-containing petri dish in accordance with test standard AATCC TM147-2011(2016)e—Test Method for Antibacterial Activity of Textile Materials. 
     With continued reference to  FIGS. 4-7 , the present invention is further directed to a personal protective air filtering device  422  made with such an infectious agent attenuator impregnated air treatment media  420  impregnated with infectious agent attenuator  424  composed of acid-based biocide and humectant in an aqueous carrier and which can be formulated as a gel, e.g., a hydrogel, or to form a gel, e.g., hydrogel, which retains enough moisture after application to the treatment media  420  to keep the acid-based biocide moisturized and at or within a desired pH range or pH that keeps the biocide activated and effective. A preferred attenuator formulation is configured as a flowable liquid, e.g., attenuator solution, sprayed onto the treatment media  420 , e.g., applied with a spray applicator, dripped onto the treatment media  420 , e.g., applied with a spray applicator, misted onto the treatment media  420 , e.g., applied with a misting applicator or mister, fogged onto the treatment media  420 , e.g., applied with a fogging applicator or fogger, bubbled onto the treatment media  420 , e.g., applied with a bubble applicator or bubble generator, and/or applied by dipping the treatment media  420  into a container, e.g., tank or vat, containing the liquid attenuator, e.g., liquid attenuator solution. The applied liquid attenuator is configured or formulated to spread via wetting, wicking and/or capillary action into a hard-surfaced fibrous mesh of the treatment media  420  substantially uniformly distributing attenuator within and throughout the treatment media  420 . Such an attenuator is further configured or formulated to increase in viscosity upon or after application to the treatment media  420  until it gels and/or forms a gel that forms an attenuator coating or lining that adheres to the hard surfaces of the mesh of the treatment media  420  thereby impregnating the treatment media  420  with attenuator. 
     The personal protective air filtering device  422  is a body-worn personal air filtering apparatus  427 , preferably a personal air purification filter mask  428 , configured to be body worn, by being configured for being removably mounted to or on a head of a person in a manner that positions the infectious agent attenuator impregnated air treatment media  420  in air flow communication with a mouth and/or nose of the person wearing the air treatment device  422  or air filtering apparatus  427  so infectious agents in air flowing through the treatment media  420  are attenuated or inactivated by biocide in attenuator impregnated into the treatment media  420 . In a preferred embodiment and method, the personal air filtering device  422  has a mounting arrangement  430  constructed and arranged to removably mount the device  422  onto the head of a person using a head strap, harness, ear loops or another type of mounting arrangement that positions the treatment media  420  adjacent to, inline and preferably overlying the mouth or nose of the person wearing it so inhaled air flows through the treatment media  420  before entering the nose or mouth of the person. In such a preferred embodiment and method, ambient air, such as air in a room or outdoors, flows through the treatment media  420  of the personal air filtering device  422  worn by the person during inhalation by a pressure differential between the ambient air and air in a pocket between the treatment media  420  and mouth of the person created by or during inhalation of the person. In such a preferred embodiment and method, a person wearing the personal air treatment device  422  is the air mover responsible for moving air through the treatment media  420  during inhalation. If desired, the personal air treatment device  422  can be equipped with or otherwise configured with one or more exhalation valves that route exhaled air around the treatment media  420  during exhalation. If desired, the personal air treatment device  422  can be equipped with or otherwise configured with one or more exhalation miniature fans or blowers cause air to flow through the treatment media  420  to the person&#39;s mouth and/or nose during use and operation. 
     The personal air filtering device  422  has a mounting arrangement  430  configured for removably mounting the device  422  onto the head of a person, which can be in the form of a strap, e.g., head strap, band, e.g., adjustable head band, a harness, e.g., adjustable harness, one or more loops, e.g., ear loops, or the like. In the preferred but exemplary air filtering device  422  shown in  FIGS. 6 and 7 , the mounting arrangement  430  is a head-mounted harness  432  with a plurality of straps  482  and releasable hook-and-loop fastener closure configured to be received and retained around a rear portion of the head, e.g., around a rear portion of the skull, and/or neck of a person wearing the device  422 . The mounting arrangement  430 , e.g., harness  432 , can be of an adjustable configuration and/or elastic construction to enable location and fitment of an air treatment media carrier  434  in air flow communication with the nose and/or mouth of a person wearing the device  422 . 
     The air treatment media carrier  434  is configured to carry the infectious agent attenuator impregnated air treatment media  420  and locate the treatment media  420  so the treatment media  420  is generally inline with, overlies and is disposed in air flow communication with the nose and/or mouth of a person wearing the air treatment device  422  during air disinfecting use and operation of the device  422 . In the embodiment shown in  FIG. 5 , the air treatment media carrier  434  includes an infectious agent attenuator impregnated air treatment media structural support assembly  436 , such as in the form of a concave housing  438 , e.g., perforate concave outer plastic shell  440 , which mates with a concave perforate structural support frame  442  equipped with a inner peripheral face seal  445  and carries and/or structurally supports the infectious agent attenuator impregnated air treatment media  420  therebetween. Where of multilayer construction, the air treatment media structural support assembly  436  also supports any other perforate or porous flow through material, e.g., filter material or filter layers, e.g., additional layer(s), disposed inline upstream and/or downstream of the air treatment media  420 . Where of multilayer construction, the air treatment media  420  and layer(s) of filter media are removably captured between the outer housing  438  and inner support frame  442 . The personal air filtering device  422  can also include one or more valves  447 , such as bypass valves and/or exhaust valves configured to allow air exhaled from a person wearing the personal air filtering device  422  to be exhausted and can be configured to do so without having to pass back through the treatment media  420  as well as having to flow through any other perforate or porous flow through material, e.g., filter material or filter layers, disposed inline with the treatment media  420  during exhalation. 
     The personal air filtering device  422  has at least one layer of infectious agent attenuator impregnated air treatment media  420  disposed between an ambient air source, e.g., room air, and the mouth and/or nose of a person wearing the device  422  for attenuating or inactivating infectious agents in air being drawn through the device  422  during inhalation by the person. The treatment media  420  of the personal air filtering device  422  is made of a perforate material, such as a perforate mesh material, woven material, nonwoven material, or another type of perforate and/or porous material that can be a hard-surfaced air treatment media material like that disclosed above with regards to the treatment media embodiments. Such a perforate air treatment media material can be a woven material, nonwoven material, or other type of perforate and/or porous material, which can be and preferably is of water-impervious construction, e.g., made of a perforate or porous material impervious to water. Such a perforate or porous air treatment media material, woven material, nonwoven material, or another type of perforate and/or porous material can be and preferably also is of reusable and/or washable construction, e.g., made of a washable material and/or a reusable material. Such a material can be a melt-blown material, a spunbound material, cotton, or another type of woven or nonwoven porous and/or perforate material. 
     With reference once again to  FIG. 5 , the treatment media  422  can be used in a multilayer filter mask  445 , such as a multilayer surgical mask or more preferably an N-95, N-99, KN-95 or KN-99 respirator  446  having a perforate air filtering and treatment assembly  458  with at least a plurality of pairs of perforate, porous or flow-through layers  500 ,  502 ,  504 ,  506  and/or  508  with at least one of the layers being a particulate filter layer, preferably a plurality of the layers being particulate filtering layers, and at least one of the layers that is or composed of an infectious agent attenuator impregnated air treatment media  420 . In an exemplary embodiment, the air filtering and treatment assembly  458  has at least one inner layer  452  that is an infectious agent attenuator impregnated air treatment media  420  sandwiched between at least a pair of air filter layers and preferably sandwiched between a plurality of pairs of air filter layers  500 ,  504  and  504 ,  508 , such as is depicted in  FIG. 5 . Any of the layers can be made of any of the filter materials and/or air treatment media materials discussed elsewhere herein. 
     In at least one embodiment, the filter media  420 , preferably at least one layer of filter media  420 , where of multilayer construction, is made of such a perforate material, preferably perforate mesh material, configured not only to receive and carry infectious agent attenuator, but also or includes a perforate particulate filter material configured to filter and trap particulates, aerosols and/or droplets during personal filtering device use and operation. The personal air filtering device  422  can also include one or more additional layers of perforate or porous flow through material not treated or impregnated with infectious agent attenuator disposed in air flow communication with, preferably inline with, and more preferably overlapping at least one layer of the infectious agent attenuator impregnated air treatment media. 
     Where the personal air filtering device  422  is constructed with one or more such additional perforate flow through material layers not carrying or being impregnated with infectious agent attenuator, each such layer can be composed of an air filtering material, e.g., comprise an air filtering layer, not treated or impregnated with infectious agent attenuator, but which is configured (a) to filter particulates, aerosols, and/or droplets, (b) as a moisture barrier, (c) as a vapor barrier, (d) as an electrostatic filter media, (e) as another type of filter or filter media, and/or (f) as another type of flow-through layer disposed either or both upstream and/or downstream of at least one layer of the infectious agent attenuator impregnated air treatment media. Where one or more such additional layers are present, one or more of the additional layers can be composed or constructed of one or more of the hard-surfaced air treatment media materials of the air treatment system disclosed above but not containing, treated with nor impregnated with attenuator  424 . 
     A preferred infectious agent attenuator used in the infectious agent attenuator impregnated air treatment media  420  is composed of a biocide that preferably is an acid-based biocide in combination with a humectant configured to retain moisture, e.g., water, to keep the biocide moisturized and at a desired pH, preferably no more than about 3 pH, or within a suitable pH range of between 0 and 5 pH, preferably between 0-4 pH, and more preferably between 0-3 pH. A preferred acid-based biocide is composed of a carboxylic acid, preferably citric acid, in a strength and pH suitable for disinfecting air coming in contact with such an acid-based or acid-containing attenuator by attenuating or inactivating infectious agents in the air including by denaturing the infectious agents. A preferred attenuator is in the form of a gel, such as a hydrogel, which defines a matrix, a gel matrix or hydrogel matrix, in which one or both the biocide and humectant are disposed and which adheres to the air treatment media. In a preferred embodiment, the gel or at least part of the gel is formed of the humectant, which can be a gel forming humectant or gellant, with the gel forming the matrix, e.g., gel matrix or hydrogel matrix, in which the biocide is relatively uniformly, preferably substantially uniformly, distributed. 
     When such an infectious agent attenuator gel is applied onto the treatment media  420 , the gel coats or lines hard surfaces within the treatment media that define air flow paths therethrough thereby exposing biocide within the gel to infectious agents in the air flowing through the treatment media  420  during personal air filter device use and operation. Where the treatment media  420  is a perforate or porous filter fabric, such as of woven, nonwoven and/or fibrous construction, infectious agent attenuator in a liquid form is applied thereto with the composition of the infectious agent attenuator configured to cause the infectious agent attenuator to gel up upon or after application forming a gel, i.e., infectious agent attenuator gel, which becomes impregnated into the perforate or porous filter material of the filter media  420 . 
     An infectious agent attenuator impregnated treatment media  420  made with such an infectious agent attenuator formulation, particularly an infectious agent attenuator gel formulation, and a personal protective filter device  422  having at least one infectious agent attenuating air treatment layer, preferably filter layer, of a treatment media  422  made of such an infectious agent attenuator formulation, particularly an infectious agent attenuator gel formulation, is of regenerable construction after being used for a period of time by application thereto of a regenerating fluid that preferably is an aqueous liquid regenerating solution. Such an aqueous liquid regenerating solution contains water and wets the infectious agent attenuator, preferably infectious agent attenuator gel, impregnated into the treatment media  420  when the aqueous liquid regenerating solution is applied to the treatment media  420 . Wetting the infectious agent attenuator, preferably infectious agent attenuator gel, impregnated into the treatment media  420  with an aqueous regeneration fluid increases the moisture content of the infectious agent attenuator, preferably infectious agent attenuator gel, thereby regenerating it by the increased moisture content changing its pH, preferably increasing its pH, so its pH is within a range of between 4 and 7 pH, preferably between about 5 and 6 pH, and more preferably about 5.5 pH. Regenerating the infectious agent attenuator, preferably infectious agent attenuator gel, by remoisturizing it to increase its moisture content after treatment media and/or a personal protective filter device use advantageously enables the treatment media  420  and personal protective filter device  422 ,  422 ′ made with such an attenuator impregnated or attenuator gel impregnated treatment media  420  to be reused over and over again. In other words, a regeneration cycle or regeneration can be performed at least a plurality of pairs of, i.e., at least three, times to regenerate the treatment media  420  of the device  422  at least a plurality of pairs of, i.e., at least three, times. During regeneration, water in the aqueous regenerating fluid wetting an attenuator gel not only wets and moisturizes biocide in the gel to regenerate the biocide by returning its pH within an aforementioned desired pH range and/or at about a desired pH, but water is absorbed by the gel, preferably absorbed into the gel matrix, that keeps the biocide in the gel moist and within an aforementioned desired pH range and/or at about a desired pH. In one preferred formulation, the aqueous regenerating fluid is a liquid composed substantially completely of water. 
     In another preferred embodiment and regeneration method where the treatment media  420  is impregnated with an infectious agent attenuator gel, the regeneration fluid preferably is a replenishing fluid containing biocide in an aqueous solution applied onto the infectious agent attenuator gel impregnated treatment media. 
     The applied regeneration fluid wets the treatment media and wets the infectious agent attenuator gel impregnated into the treatment media replenishing the gel impregnated into the treatment media with biocide lost, e.g., via neutralizing reaction, evaporation, sublimation, etc. during treatment media and/or personal protective filter mask use and operation. When wetted by such a biocide-containing aqueous replenishing fluid, water in the fluid advantageously substantially simultaneously regenerates biocide remaining in the gel by moisturizing it, thereby maintaining disinfecting efficiency by keeping it within an aforementioned desired pH range or pH. When wetted by such a biocide-containing aqueous replenishing fluid, biocide in the fluid is advantageously absorbed by the gel and retained within the gel during treatment media and personal protective filter mask use and operation increasing the amount and exposed surface area of biocide available to attenuate or inactivate infectious agents. 
     A preferred air breath moisture activated and regenerated infectious agent attenuating mask of the present invention has an air filtering layer of the mask that is or includes a layer of infectious agent attenuating or inactivating filter media  420  with an antiviral efficacy of at least 1.3, preferably at least 1.5, more preferably at least 2.0, when tested for antiviral activity using a human coronavirus in accordance with ISO testing standard 18184 for a contact time of 10 minutes and showed no bacterial growth of Staphylococcus aureus and Klebsiella pneumonia when infectious agent attenuating or inactivating filter media  420  was placed in a triptych soy agar or nutrient agar —containing petri dish in accordance with test standard AATCC TM147-2011(2016)e—Test Method for Antibacterial Activity of Textile Materials. 
     In a preferred embodiment, the personal air filtering device  422  is a three-layer, four-layer or five layer surgical mask having at least one layer composed of an infectious agent attenuator impregnated air treatment media made in accordance with the following specifications: 
     Hypoallergenic Safe &amp; Comfort 
     3 extra thick ply with ear loops 
     Bacterial Filtration Efficiency or B.F.E&gt;95% 
     Particle Filtration Efficiency or P.F.E&gt;95% 
     Manufactured under ISO 9001 and/or meets ISO 9001 
     Has a water repellent top/outer &amp; base/inner layer 
     Made with layers of Fiberglass-free filter medium 
     Outer layer—Hydrophobic non-woven layer 
     Middle layer—Meltblown filter 
     Inner layer—Soft absorbent layer 
     Adjustable nose bridge 
     
       
         
           
               
               
             
               
                   
               
               
                 Characteristic 
                 N95 
               
               
                   
               
             
            
               
                 Bacterial filtration efficiency 
                 ≥95% 
               
               
                 Sub-micron particulates filtration efficient at 0.3 micron 
                 ≥95% 
               
               
                 Differential pressure, mm H20/cm2 (Breathability) 
                 &lt;5.0 
               
               
                 Resistance to penetration by synthetic blood, the minimum 
                 160 mm Hg 
               
               
                 pressure in mm Hg for pass result 
               
               
                   
               
            
           
         
       
     
     The present invention also is directed to an infectious agent attenuating or inactivating personal protective equipment device, such as a surgical mask, multilayer mask or respirator having at least one porous filtering layer impregnated with an infectious agent attenuating or inactivating solution that tries to leave behind an infectious agent attenuating or inactivating attenuator composed of an organic acid that preferably is citric acid, a humectant that preferably is a gelling humectant that preferably is sorbitol which produces or forms a self activating or self replenishing infectious agent attenuator gel and infectious agent attenuating and inactivating air treatment media having a pH of no greater than 5, preferably no greater than 4 and more preferably no greater than 3.5 which is kept moist and activated at or below the desired pH by moisture in the breath of a person wearing the mask. The solution can include a surfactant, such as preferably a rhamnolipid biosurfactant that reduces surface tension both during impregnation of the solution thereby more uniformly impregnating the solution into the at least one porous filtering layer producing an air treatment media having infectious agent attenuating gel more uniformly distributed throughout. The surfactant remains in the gel and reduces surface tension of aerosols and droplets containing viruses and bacteria entrained in the air flowing through the air treatment media contacting the infectious agent attenuating gel more rapidly and efficiently attenuating or inactivating the viruses and bacteria preferably with the reduced surface tension produced by the inclusion of the surfactant also destroying them by lysing the viruses and bacteria. 
     Understandably, the present invention has been described above in terms of one or more preferred embodiments and methods. It is recognized that various alternatives and modifications may be made to these embodiments and methods which are within the scope of the present invention.