Patent Publication Number: US-2022212040-A1

Title: Personal protective equipment ensemble made up of a launderable hood and an air dispersion protective headgear

Description:
TECHNICAL FIELD 
     The present invention generally relates to a Personal Protective Equipment (PPE) ensemble made up of a launderable hood and an air dispersion protective headgear. More specifically, the PPE ensemble is made up of a launderable hood that is detachably affixed to and forms a gas-restrictive seal with a protective face shield assembly, an air-supplied protective suit having an air supply inlet/outlet assembly, and an air dispersion protective headgear (e.g., a hardhat) releasably coupled to the air supply inlet/outlet assembly of the protective suit. 
     BACKGROUND 
     Protective hoods are used to shield or isolate individuals from chemical, physical, and biological hazards that may be encountered during hazardous materials operations. A protective hood may be designed to cover only the head, face, and shoulders, or it may form part of a smock style top worn with pants, coveralls, or a full-body suit, where the smock style top covers the head, face, arms, and torso. A protective hood may also form part of a protective full-body suit, which typically covers the wearer from neck to toe and provides cooling air and an optional communications line. 
     Tritium hoods and protective suits protect a wearer against inhalation and skin exposure of Hydrogen-3, H-3, or  3 H (a.k.a. tritium) in nuclear plants. Tritium is a radioactive isotope of hydrogen that contains one proton and two neutrons. It is a gas at standard temperature and pressure. Tritium is produced in nature and is also industrially produced as a by-product in nuclear reactors by neutron activation of Lithium-6 as well as in heavy water-moderated reactors. Tritium is difficult to contain; rubber, plastic, and some kinds of steel are somewhat permeable to tritium. The emitted electrons from small amounts of tritium cause phosphors to glow; hence, tritium is used to make self-illuminating devices, such as watches and exit signs. Tritium is also used in nuclear weapons. 
     Some tritium hoods are made with a TYVEK® QC fabric containing a thin, ten millimeter LEXAN® shield or visor which is affixed permanently to the fabric, while other tritium hoods employ a visor assembly, which allows for a visor to be press fit into the visor assembly for easy removal and replacement. Examples of the latter visor assemblies are shown and described in U.S. Patent Application Publication No. US 2009/0100560 A1 and Canadian Patent Application No. 2852110. These visor assemblies utilize many fasteners around the perimeter of the assembly, which require relatively large holes in the visor and suit material to accommodate the fasteners, thus causing greater difficulty in sealing. 
     Headgear in the form of, for example, a hard hat may be worn under these protective hoods with an optional wireless or wired communication headset. 
     As indicated above, tritium hoods may be worn with a one-piece full-body Tritium suit, an example of which is the MARK IIIB™ protective suit. The MARK IIIB™ protective suit is composed of a polyvinyl chloride (PVC) coated polyester that is double sealed, which serves to ensure a consistent positive pressure within the suit thereby protecting the wearer from contamination. 
     Protective suits such as the MARK IIIB™ suit exhaust air through the neck of the suit which fills the protective hood. As soon as the upper part of the hood is filled, however, air will exit through the arm sleeves of the hood resulting in a loss in air flow. This causes heat stress in the worker which results in moisture build up under the hood from the worker&#39;s perspiration and the concomitant fogging of the visor. As will be readily appreciated by those skilled in the art, such factors reduce worker productivity by shortening the worker&#39;s “jump” time, thus limiting the scope of work that can be completed in an allotted amount of time. 
     The present invention serves to address these problems by providing a PPE ensemble that maintains or cools the skin temperature of the wearer of the ensemble and that includes a protective face shield assembly that demonstrates reduced or no lens fogging. Although tritium hoods and protective suits are described herein, the contemplated use(s) of the PPE ensemble of the present invention is not so limited. The inventive PPE ensemble can be utilized to shield or isolate individuals from chemical, physical, and biological hazards that may be encountered during any hazardous materials operation. Moreover, although launderable hoods are described herein, nonwashable hoods are also contemplated for use in the subject invention. 
     SUMMARY 
     In particular, the present invention provides a PPE ensemble which serves to shield or isolate workers entering radiation control areas from chemical, physical, and biological hazards, and which comprises: a launderable protective hood that is detachably affixed to and forms a gas-restrictive seal with a low fogging protective face shield assembly; and a protective headgear worn under the hood that defines an air flow pathway. 
     In an exemplary embodiment, the PPE ensemble comprises: the launderable protective hood; an air-supplied protective suit having an air supply inlet/outlet assembly; and the protective headgear releasably coupled to the air supply inlet/outlet assembly of the protective suit. 
     The present invention also provides a method for laundering the protective hood of the PPE ensemble, the method comprising: removing the shield or visor from the protective face shield assembly of the protective hood; laundering the protective hood; and either separately cleaning and reinstalling the shield or visor, or replacing the shield or visor. 
     The present invention further relates to a method for reducing or eliminating fogging of a shield or lens in the protective face shield assembly of the PPE ensemble of the present invention, the method comprising:
         diverting a portion of air from the air supply inlet/outlet assembly of the protective suit to the protective headgear (thus causing air flow within the protective headgear in contrast with prior art motionless air/no air flow hoods currently in use); and   directing the diverted air over the top of a wearer&#39;s head and down over the wearer&#39;s face, thereby cooling the wearer&#39;s face and reducing worker perspiration and concomitant fogging of the shield or lens.       

     The present invention also relates to a method for reducing worker fatigue when wearing headgear under the protective hood of the PPE ensemble of the present invention, the method comprising:
         diverting a portion of air from the air supply inlet/outlet assembly of the protective suit to the protective headgear; and   directing the diverted air over the top of the worker&#39;s head and down over the worker&#39;s face, thereby cooling the worker&#39;s face and reducing worker fatigue.       

     Other features and advantages of the invention will be apparent to one of ordinary skill from the following detailed description and accompanying drawings. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the relevant art(s). All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure may be better understood with reference to the following drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. 
       Particular features of the disclosed invention are illustrated by reference to the accompanying drawings of the following exemplary embodiments of the present invention: 
         FIG. 1  is a frontal view of the PPE ensemble of the present invention, which includes a launderable protective hood in the form of a smock style top, the protective face shield assembly attached to, and forming a gas-restrictive seal with the protective hood, and protective headgear; 
         FIG. 2  is an exploded side perspective view of the protective face shield assembly with removable shield or visor of the PPE ensemble of the present invention; 
         FIGS. 3A and 3B  are plan views of the inner arcuate frame member of the protective face shield assembly, wherein  FIG. 3A  is a plan view of the outer surface of the inner arcuate frame member, and  FIG. 3B  is a plan view of the inner surface of the inner arcuate frame member; 
         FIGS. 4A and 4B  are plan views of the outer arcuate frame member of the protective face shield assembly, wherein  FIG. 4A  is a plan view of the outer surface of the outer arcuate frame member, and  FIG. 4B  is a plan view of the inner surface of the outer arcuate frame member; 
         FIG. 5  is a top perspective view of the assembly jig, which is used to assemble and disassemble the protective face shield assembly of the present invention; 
         FIG. 6A  is an exploded side perspective view of the air supply inlet/outlet assembly of the present invention, while  FIG. 6B  is a side perspective view of the assembly; 
         FIG. 7A  is a side perspective view of the protective headgear in the form of a hard hat of the inventive PPE ensemble, while  FIG. 7B  is a bottom perspective view of the hard hat; and 
         FIG. 8  is a bottom perspective view of another exemplary embodiment of the protective headgear in the form of a hard hat of the inventive PPE ensemble. 
     
    
    
     DETAILED DESCRIPTION 
     As indicated above, the PPE ensemble of the present invention comprises: a launderable protective hood that is detachably affixed to and forms a gas-restrictive seal with a protective face shield assembly; and a protective headgear worn under the hood that defines an air flow pathway. 
     In a preferred embodiment, the PPE ensemble further comprises an air-supplied protective suit having an air supply inlet/outlet assembly, wherein the protective headgear is releasably coupled to the air supply inlet/outlet assembly of the protective suit. 
     Referring now to the drawings in detail, an exemplary embodiment of the PPE ensemble of the present invention is shown in  FIG. 1  generally at  10 . The inventive PPE ensemble comprises: a launderable protective hood  12  in the form of a smock style top, which is detachably affixed to and forms a gas-restrictive seal with a protective face shield assembly  14 ; and a protective headgear  16 , worn under the hood, which defines an air flow pathway. 
     As noted above, the inventive PPE ensemble may further comprise an air-supplied protective suit (not shown). By way of this embodiment, pressurized air is supplied via an air supply inlet/outlet assembly located on, within, or near the protective suit to both an interior space(s) of the protective suit and to the protective headgear. 
     Launderable Protective Hood 
     The launderable protective hood of the present invention is oversized relative to the spatial envelope of a wearer&#39;s head and receives air during use which fills the hood. The air may be received from any suitable source and in an exemplary embodiment in which a protective suit forms part of the inventive ensemble, the hood receives air exiting the protective suit at or around the shoulders via an exhaust port. The oversized nature of the hood design provides a less constrained and intrusive space for the wearer. 
     The design of the protective hood is such that as soon as the air from, for example, the protective suit exhausts into and fills the hood, the entire hood weight is carried on a wearer&#39;s shoulders, not from the protective headgear, which is different than how the weight from prior art single use hoods is carried. When inflated, the hood is not connected to the worker in any way, which obviates neck fatigue and any interference with the protective headgear. This equates to more freedom of movement under the hood and due to the large size of the lens or visor, better visibility. 
     The protective hood is either manufactured with an opening, or an opening is applied post-manufacture. In a preferred embodiment, a stamping station punches openings into flat stock prior to construction of the protective hoods. The size and shape of the opening approximates the size and shape of the opening formed by the protective face shield assembly  14 . The area surrounding the opening is provided with (a) two slits positioned on opposing sides of the opening at approximately the opening&#39;s midpoint, and (b) a plurality of pinholes (e.g., five (5) pinholes spaced around the area surrounding the opening), which are used to align the hood material to the protective face shield assembly. The diameter of each pinhole preferably ranges from about 1 to about 10 millimeters (mm), more preferably, from about 2.5 to about 8 mm, most preferably, from about 4 to about 8 mm. 
     As shown in  FIG. 1 , the hood may have one or more zippers  18  to facilitate ease of donning and doffing of this garment. 
     The protective hood may be made from any suitable material including, but not limited to, a thermoplastic resin such as polyethylene, PVC, polyurethane, or other suitable material such as PVC/Nylon Scrim or PVC/Nylon Scrim/PVC material, or a neoprene synthetic rubber. In a preferred embodiment, the protective hood is formed using PVC/Nylon Scrim/PVC material. 
     Hoods suitable for use in the present invention include the Mark IIIB™ suit hood. 
     The protective hood is launderable, which greatly reduces the level of radioactive waste to the environment and provides a substantial cost savings to the customer (e.g., a Nuclear Power Plant). The hood withstands being assembled with and disassembled from the protective face shield assembly for laundering at least 50 to 100 times and withstands the rigors of the workplace. It remains sealed through the work sequence and withstands storage in disarrayed conditions stacked in laundry hampers awaiting removal from the work site. 
     When the air exhausts from a protective suit or other source to the hood, the hood is filled with air. However, as soon as the upper part of the hood is filled, a dead head of air is reached, and air effectively exits through arm sleeves of the hood resulting in reduced or little air flow in the hood. With a dead head of air, the worker is uncomfortable as his/her body heat builds up in the hood and the visor starts to fog from high moisture content (perspiration) buildup in the hood. As will be explained in more detail below, these problems are addressed by the protective headgear of the inventive PPE ensemble. 
     Protective Face Shield Assembly 
     As best shown in  FIG. 2 , the protective face shield assembly  14  of the inventive PPE ensemble  10 , is made up of:
         an arcuate or bow-shaped frame member  20  that defines an opening  22 , the frame member being formed from similarly sized inner and outer arcuate frame members  24 ,  26 ;   a shield or visor  28  is removably positioned within the opening  22  defined by the arcuate frame member and between the inner and outer arcuate frame members  24 ,  26 , thereby forming an assembly; and   means  30  for holding the assembly in gas-restrictive, detachable engagement.       

     In one exemplary embodiment, the inner and outer arcuate frame members  24 ,  26  are substantially oval in overall shape having a degree of curvature ranging from greater than about 0 to less than about 90 degrees, with each having a maximum vertical height extending from an upper edge to a lower edge ranging from about 30 to about 36 centimeters (cm), a maximum horizontal width extending from one side edge to an opposing side edge ranging from about 45 to about 54 cm, and a thickness ranging from about 0.6 to about 1.3 cm. The opening measures from about 27 to about 31 cm in total height, and from about 43 to about 51 cm in total width. 
     The inner or contacting surface of each frame member has a bowed cross-section and one or more stiffening ridges, which extend mid-way along this bowed inner surface (see  FIG. 2 ). The stiffening ridges are integrated with coupling and alignment means. The stiffening ridges serve to strengthen each frame member as well as the coupling and alignment means. Any distortion of the protective face shield assembly that may occur during use by, for example, direct impact of the assembly against an object, will result in tighter registration between the frame members and thus a greater resistance to disassembly. 
     As shown in  FIGS. 3A and 3B , the inner arcuate frame member  24  has (i) a plurality of recessed areas or holes  34  formed along ridge  32   a , which are sized to receive a coupling means (e.g., magnets) and (ii) a plurality of raised areas or pins  36  also formed along the ridge, which are sized to fit into a corresponding recessed area or hole in the outer arcuate frame member  26  for alignment purposes. In an exemplary embodiment, the pins  36  are made from either a plastic or metal or metallic material. Suitable plastic materials include acrylonitrile butadiene styrene (ABS), polycarbonate, engineered plastics such as glass- or fiber-filled polycarbonates, and the like, while suitable metal or metallic materials include stainless steel. The number and size of these alignment structures (i.e., pins, holes) is less/smaller than those used in prior art devices, which facilitates sealing at the interfaces between the inner arcuate frame member, hood material, visor and outer arcuate frame member. 
     Pin sleeves  44   a ,  44   b , are shown as formed into the outer surface of the inner arcuate frame member  24  to accept the pins of an assembly jig or tool, which is discussed in more detail below. 
     As shown in  FIGS. 4A and 4B , the outer arcuate frame member  26  has a plurality of two different sized recessed areas or holes formed along ridge  32   b . The larger recessed areas  38  are sized to receive a coupling means (e.g., magnets) while the smaller recessed areas  40  are used to register the two frame members  24 ,  26  and are sized to receive the raised pins  36  of the inner arcuate frame member  24 . Finger grips  42  are shown as added to the outer actuate frame member  26  for ease of handling the assembly during assembly and disassembly. 
     In one exemplary embodiment, the frame members each have from about 4 to about 9 (preferably from about 6 to about 8) recessed areas or holes to receive magnets and from about 3 to about 7 (preferably from about 4 to about 6) raised areas or corresponding recessed areas to align the frame members. 
     Referring back to  FIG. 2 , in a preferred embodiment, the means  30  for holding the protective face shield assembly  14  in gas-restrictive, detachable engagement are coupling devices in the form of magnets with very strong magnetic strength properties. In a more preferred embodiment, neodymium (N42 grade) magnets are used with this invention. These are sometimes referred to as “super magnets”. Sintered neodymium-iron-boron (Nd—Fe—B) magnets are a member of the rare earth magnet family and are one of the most powerful permanent magnets known. An advantage of this type of magnet is that they are very resistant to demagnetization and can be expected to hold their magnetism for the lifetime of the PPE ensemble. It should be appreciated by those skilled in the art that other types of magnets that have similar magnetic strength properties to neodymium magnets could be conceivably used with this invention. 
     Both single and groups or clusters of magnets are contemplated for use in this invention. In one embodiment, each magnet is a single magnet of the desired strength. In another embodiment, groups of magnets are used with a spacing and configuration to produce a desired magnetic force. The magnets may adopt any shape (e.g., circular, square, rectangular, triangular) and may be substantially planar or curved to conform to the recess shape of the frame member. 
     In a preferred embodiment, the magnets are single circular magnets affixed to both the outer and inner frame members  24 ,  26  in a quantity preferably ranging from about 4 to about 10, magnets per frame, more preferably from about 6 to about 8 magnets per frame. The diameter of each circular magnet preferably ranges from about 6 to about 25 mm (more preferably, from about 14 to about 20 mm), while the thickness of each circular magnet preferably ranges from about 1 to about 8 mm (more preferably, from about 2 to about 3 mm). 
     The inner and outer arcuate frame members  24 ,  26  may be made from any suitable material including, but not limited to, polymeric materials such as ABS, polycarbonate, polypropylene, engineered plastics such as acetal resins and polycarbonate resins, and the like, as well as metal or metallic materials. In a preferred embodiment, frame members  24 ,  26  are made using an engineered plastic such as an acetal resin or a polycarbonate resin compounded with, for example, glass, fibers, nanoparticles (nanotubes, nanofillers), fire retardants, or similar additives. 
     Each frame member may be formed as a single solid piece or as two or more solid pieces (e.g., two interlocking pieces) by injection molding, computer numeric control (CNC) milling, or other suitable manufacturing method. 
     Shield or Visor 
     The shield or visor  28  used with the inventive protective face shield assembly  14  is flexible and as shown in  FIG. 2  has a size and shape that accommodates or fills the opening  22  formed by the first and second arcuate frame members  24 ,  26 , thereby providing a wider field of vision. The visor  28  is provided with a plurality of through-holes  46  that extend around a perimeter of the visor, the holes lining up with the raised pins  36  of the inner arcuate frame member  24 , which serve as alignment guides. Due to the flexibility of the visor, it readily assumes the arcuate shape of the first and second arcuate frame members. The visor may also be provided with a ventilation opening in the form of, for example, a taped flap. 
     The shield or visor  28  is made from a flexible, transparent sheet-like material, such as polycarbonate resin (e.g., LEXAN® polycarbonate resin), PVC, or other flexible, transparent material, or combinations of materials through which objects can be readily and easily seen. The thickness of the shield or visor  28  ranges from about 0.1 to about 1.0 mm (preferably, from about 0.25 to about 0.76 mm). 
     A thin strip of sealing material (not shown) may optionally extend along the perimeter of the outer surface of the visor  28 . 
     Assembly/Disassembly 
     During assembly of the protective face shield assembly  14  onto the hood material surrounding the hood opening, the inner arcuate frame member  24  is positioned under the hood opening so that its raised pins line up with the holes in the hood material surrounding the opening. Its raised pins are arranged to extend only through the holes in the lower portion of the hood material. The visor  28  is then positioned over this partial assembly such that the upper portion of the visor is applied directly over the raised pins of the inner arcuate frame member  24 , while the lower portion of the visor  28  is fed through the opposing midpoint slits in the hood material and positioned over the lower portion of the hood material. The raised pins will then extend through the holes in the lower portion of the visor  28 . Then, the upper portion of the hood material is positioned over the upper portion of the visor  28  and through the raised pins. This provides an actual natural water resistance when water flows over the visor from top to bottom. The outer arcuate frame member is then applied over and in registration with the resulting assembly with its coupling means forming a gas-restrictive seal between the inner arcuate frame member, hood material, visor and outer arcuate frame member. 
     During disassembly of the protective face shield assembly from the hood material surrounding the hood opening, the grip feature  42  on the outer arcuate frame member  26  may be used to remove this frame member from the assembly. The visor  28  and inner arcuate frame member  24  may then be easily removed from the hood material surrounding the opening. 
     Assembly Jig 
     The present inventors have also devised a jig or tool to facilitate assembly and disassembly of the protective face shield assembly  14  on or from the hood material. As shown in  FIG. 5 , the jig or tool  48  holds the inner arcuate frame member  24  in a fixed position via two pins  50   a ,  50   b , which fit into the pin sleeves  44   a ,  44   b , formed in the frame member  24 . The pins  50   a ,  50   b , and pin sleeves  44   a ,  44   b , prevent distortion during assembly and disassembly of the arcuate frame members. 
     Launderable Aspect of Hood 
     After being worn, the smock style top shown in  FIG. 1  is sent to a laundry where the visor is removed, and the top and visor washed and decontaminated in separate operations using different means. As will be readily appreciated by those skilled in the art, the smock style top can be washed more vigorously than the visor. The visor is washed to remove any contaminants and to preserve the visual clarity and structural integrity thereof. The smock style top and visor are then rejoined for subsequent use. As noted above, the visor may also be replaced instead of cleaned and reinstalled. 
     Air-Supplied Protective Suit 
     A variety of protective suits have been developed to protect wearers against the adverse effects of chemicals as well as biological, nuclear and other environmental contaminants or conditions. The design aspects of these highly specialized suits depend largely upon their specific applications. However, if just trace amounts of toxic vapors penetrate the protective suit, the result can be severe injury or death. Consequently, most all such suits employ an external pressurized air source (typically supplied via a wall, post, or floor mounted air station) for introducing pressurized clean filtered breathable air into the protective suit. The positive pressure offers additional protection in the event of a defect or puncture in the suit. Should the suit&#39;s integrity be compromised, air would be forced out instead of being pulled into the suit. 
     As previously noted, an example of a suitable protective suit for use in this invention is the MARK IIIB™ protective suit. The MARK IIIB™ protective suit is composed of a PVC coated polyester that is double sealed, which serves to ensure a consistent positive pressure within the suit thereby protecting the wearer from contamination. 
     Air Supply Inlet/Outlet Assembly 
     The protective suit is plugged into clean filtered breathable air through an air supply inlet/outlet assembly  52 , which is in fluid communication with a breathable air source  54 , as shown in  FIGS. 6A and 613 . The air supply inlet/outlet assembly  52  includes a bobbin assembly  56 , which serves to direct breathing air to both the protective suit and the protective headgear  16 , and an air control device  68 . As air flows through the bobbin  56 , the bobbin diverts air to: (a) plastic tubing or hose (e.g., TYGON® tubing)  60   a ,  60   b , which then distributes air to the wrists and ankles of the protective suit; and (b) the air control device (e.g., a connector fitting)  68 , connected to elbow fitting  58 , which controls the amount of air that is diverted along tubing or hose (e.g., TYGON® tubing)  70  into the protective headgear  16 . 
     Bobbins may vary somewhat in design, but in this exemplary embodiment, the bobbin  56 , which measures from about 20 to about 60 mm (preferably, from about 30 to about 40 mm) in total height, is made up of two “bobbin-like” cylindrical bodies  62   a ,  62   b , each having an enclosed spoked-wheel shaped midportion positioned between two flat surfaces and a central through hole. The “bobbin-like” cylindrical bodies  62   a ,  62   b , each measure from about 20 to about 140 mm in diameter (preferably, from about 80 to about 90 mm), with the central through hole measuring from about 6 to about 30 mm (preferably, from about 10 to about 20 mm) in diameter. The central through holes are connected by way of a threaded tubular member  64 , which measures from about 6 to about 40 mm (preferably, from about 25 to about 30 mm) in total height. Threaded tubular member  64  extends from the through hole in the lower cylindrical body  62   b  and threads onto the through hole in the upper cylindrical body  62   a  forming a channel therethrough. Two plastic or metal barbed tube fittings  66   a ,  66   b , extend perpendicularly from the threaded tubular member  64  forming another channel. This channel serves to divert breathing air from the breathable air source  54  through the lower cylindrical body  62   b  and threaded tubular member  64  through the plastic or metal barbed tube fittings  66   a ,  66   b , to hoses  60   a ,  60   b , that then distribute air to the wrists and ankles of the plastic suit. 
     The bobbin  56  may be made using any suitable material. In a preferred embodiment, the bobbin is made using ultra-high-density polyethylene. 
     The elbow fitting  58  fluidly connects (e.g., threads, snaps or clips) onto the through hole or channel of tubular member  64  of bobbin  56  and is connected to the protective headgear  16  by way of the air control device  68  and tubing or hose  70 . The air control device  68  is configured to allow a portion of air from the breathable air source  54  (preferably, greater than or equal to about 5 percent (%), more preferably, from about 5 to about 20% of air, most preferably, from about 8 to about 12% of air) to be directed to the protective headgear  16 . 
     The air control device  68  has a central orifice or opening that is sized in terms of length and diameter to meet a set flow rate, thereby regulating the amount of air that passes through the device. 
     In an exemplary embodiment, the air supply inlet/outlet assembly  52  delivers twenty-eight (28) standard cubic feet per minute (SCFM) (0.80 cubic meters per minute (m 3 /m) of air to the suit with an inlet supply pressure of 40 to 120 pounds per square inch (PSI) (0.28 to 0.83 megapascal (MPa))(preferably, 60 to 80 PSI (0.41 to 0.55 MPa), while the air control device  68  allows from about 5 to about 20% (preferably, from about 8 to about 12%) of the inlet air to reach the protective headgear  16 . 
     Protective Headgear 
     The protective headgear  16  used in the PPE ensemble of the present invention can be any style or configuration of protective headgear including, but not limited to, safety helmets and hard hats. 
     In an exemplary embodiment, as shown in  FIGS. 7A and 7B , the protective headgear  16  is a hard hat. In its most basic form, the hard hat includes a shell  72 , a bill or brim  74  at the front or face of the shell and a back  76  of the shell. The hard hat has a shock-absorbing lining that incorporates a headband  78  and straps  80  that suspend the shell from about 2.54 to about 3.18 cm away from the head. An air flow pathway is formed at the back of the shell extending up and over the wearer&#39;s head to the front of the hard hat. 
     The air flow pathway of the hat may be defined by an internal structure of the hat which may be formed in the shell or underneath the shell, or it may be defined by an external structure that is not contained within the hard hat interior. 
     In one exemplary embodiment, the air flow pathway of the hat is defined by an internal structure of the hat that extends from an air flow inlet port at the back of the hat and up and over the wearer&#39;s head to the front of the hat where the internal structure defines a plurality of exit ports through which air exits the hat and passes in front of the wearer&#39;s face with sufficient velocity to reduce the wearer&#39;s skin temperature. 
     In another exemplary embodiment, the air flow pathway is formed underneath the shell in the shape of a circular ring or donut which allows the air flow to sweep down over the wearer&#39;s head providing a more even air flow over the wearer&#39;s head and keeping the shield or lens of the protective face shield assembly  14  from fogging. 
     In yet another exemplary embodiment, which is shown in  FIGS. 7A and 7B , an air flow pathway  82  is an internal structure formed using an air dispersion or spreader nozzle  84  and a rectangular piece of thin fabric material (e.g., an optionally coated woven material)  86 . The air dispersion or spreader nozzle  84  serves to spread the air into a substantially flat or planar spray pattern. In one embodiment, the nozzle  84  has an oval-shaped exhaust opening that measures from about 1 cm by 8 cm. The thin fabric material  86  is detachably engaged to the nozzle  84  and the shell  72  and to the front of the headband  78  forming a channel, such that air from the nozzle  84  is directed from the back of the hard hat along the channel to the front of the hat between the shell  72  and the headband  78 , thereby directing air to the front of the wearer&#39;s face. The thin fabric material  86 , which has a thickness ranging from about 0.05 to about 1.0 mm (preferably, from about 0.1 to about 0.3 mm), may be detachably engaged using any suitable fastening material including, for example, a hook and loop fastener. 
     The term “hook and loop fastener” as used in the present specification refers to either portion of a fastener comprising two portions, namely a hook portion (e.g., J hook, palm tree hook, mushroom hook) and a portion complementary to the hook portion for example a loop portion such that the two portions are releasably interconnected when brought into contact with each other. Such fasteners are sold, for example, under the trade designations VELCRO and 3M DUAL-LOCK. The use of the term also includes those types of fasteners known as hook and hook fasteners in which there are opposing portions of interlockable hooks. The term also includes any other touch and grip type fastener of the type in which temporary interconnection is achieved when the two components thereof are brought into contact with each other. 
     Tubing or hose  70  from the air supply inlet/outlet assembly  52 , which is housed on, within, or near the protective suit, is fed onto a barbed tube fitting of an air filter  88 , which has been threaded onto an inside channel of an air duct adapter  90 . The air dispersion nozzle  84  is threaded onto the outside of the air duct adapter  90 , the air dispersion nozzle  84  containing sound dampening material  92  on either or both the inlet side and the exhaust side, which reduces the sound level. Suitable sound dampening materials  92  include foam, rubber, certain fabrics and any other suitable material. The degree of dampening may be varied by altering the material, its width or thickness, or its density. In one exemplary embodiment, the sound dampening material is an open cell foam having a thickness ranging from about 6 to about 40 mm, and a density ranging from about 6 pores per inch (PPI) to about 120 PPI (from about 3 pores per centimeter (PPC) to about 55 PPC), the sound level within the protective headgear  16  being reduced to less than or equal to approximately 80 A-weighted decibels (dBA), which is measured using a sound level meter comprising a measuring microphone, whereby the sound level meter determines the sound pressure level at or near a wearer&#39;s ear. 
     In an alternative embodiment, which is shown in  FIG. 8 , the air duct adapter and the air dispersion nozzle, which are described above as both being threaded parts, are replaced with non-threaded parts. The air duct adapter is replaced with a substantially circular, recessed coupler (e.g., a substantially circular, recessed, plastic coupler)  94  with a through hole (not shown). An air filter  96  with a shaft having an upper threaded portion and a lower portion in the form of a barbed tube fitting (not shown) is positioned down and threaded onto an inside channel (i.e., the through hole) of coupler  94 , with its barbed tube fitting extending through and beyond the through hole for attachment to tubing or hose  70 . The outside surface  98  of the coupler  94  is affixed to the non-threaded, inside surface of the inlet side  100  of air dispersion nozzle  102  using any suitable means including, but not limited to, securing the parts together with a hot melt or curable (e.g., an ultraviolet (UV) curing) adhesive. 
     By way of the present inventive PPE ensemble, increased wearer comfort is achieved by maintaining or cooling the skin temperature of the wearer and thus reducing or eliminating lens fogging in the protective hood, and by reducing the sound level within the protective headgear. The result is an increase in the “jump” time, essentially increasing worker productivity by allowing for an increase in the allotted amount of work time as well as expanding the scope of work that can be completed within this allotted amount of time. 
     In addition to the inventive PPE ensemble, the present invention also provides a method for reducing fogging of a shield or lens in the protective fact shield assembly of the PPE ensemble, the method comprising:
         diverting a portion of air from the air supply inlet/outlet assembly of the protective suit to the protective headgear; and   directing the diverted air over the top of a wearer&#39;s head and down over the wearer&#39;s face, thereby cooling the wearer&#39;s face and reducing worker perspiration and concomitant fogging of the shield or lens.       

     Further provided by way of the present invention is a method for reducing worker fatigue when wearing headgear under a protective hood of the PPE ensemble, the method comprising:
         diverting a portion of air from the air supply inlet/outlet assembly of the protective suit to the protective headgear; and   directing the diverted air over the top of the worker&#39;s head and down over the worker&#39;s face, thereby cooling the worker&#39;s face and reducing worker fatigue.       

     While the invention is described in connection with certain preferred embodiments, it is understood that it is not intended to limit the invention to those embodiments. Rather, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. For example, the air that is conveyed to the protective headgear  16  may be sourced from other than a protective suit. The source of breathable air may be a cylinder of compressed air, a compressed air network (or ring main) installed within a building, or a large tank of compressed air.