Abstract:
A biohazard mask for civilian use comprises bidirectional HEPA filtering to protect both personal and public health during an outbreak. Several measures are taken to maximize comfort and wearability, such as comfort-fit through a gel seal, anti-fogging protection through separation of the eye volume from the mouth-nose volume and through eye moisture release valves, heat-dissipation through a net suspension, and overpressure release valves to maintain the face seal during coughing or sneezing. Wicking exhalation filters promote moisture abatement around the mouth and nose. Attractive and stylish designs, combined with accommodation for telephone communication or audio entertainment, helps wearers keep the mask on during an outbreak.

Description:
RELATED APPLICATIONS 
   This application claims priority to provisional application No. 60/441,802, filed Jan. 22, 2003. 

   FIELD OF THE INVENTION 
   This invention relates to masks which protect against biological hazards. 
   BACKGROUND OF THE INVENTION 
   Terrorists are thought capable of launching a major biological attack on civilian populations. They might use localized biohazardous material, such as weaponized anthrax, or they might use deadly infectious agents, such as smallpox. Numerous such materials and agents exist, each with its own transmission efficiency, survivability in the atmosphere, portability, resulting symptoms, resulting morbidity and resulting mortality. 
   Man-made threats are not the only ones seemingly on the rise. The prospect of a pandemic from the spread of natural infectious agents also seems to be increasing. The 2003 SARS outbreak is a recent example. Putting such natural events into perspective, the 1918 influenza pandemic is widely thought to have killed more soldiers during WWI than did combat. 
   The inventors know of no prior biohazard protective gear designed particularly with the needs of civilians in mind. During an outbreak, public health will require widespread use of the most effective biohazard protection gear available. This entails equipment that maximizes comfort and wearability, yet minimizes the receipt and re-transmission of deadly or dangerous infectious agents. Comfort and wearability are especially important, given that users will need to wear the gear for long periods of time yet will lack the discipline which comes from military training. 
   Biohazard protective gear is most commonly designed for military applications. U.S. Pat. No. 6,158,429, assigned to the United States of America as represented by the Secretary of the Army, is exemplary of this art. It discloses a hood respirator for protection against biological hazards. The device disclosed therein is a complete hooded respirator assembly form fitting to the head and neck of the user. There are two HEPA filters for intake, one adjacent each cheek, as well as an exhalate “breathe-through airflow assembly.” The hooded respirator also contains a clear eye lens. The &#39;429 patent recognizes that protection against biological agents requires only HEPA filtering, whereas protection against chemical agents, too, would require the addition of activated carbon filtering. While the &#39;429 patent discloses filtering inhalate, it does not disclose filtration of outgoing exhalate. The device disclosed therein would therefore be of limited use during a pandemic, or in the presence of any number of infectious biological warfare agents on the battlefield or during a terrorist attack, since an infected wearer of the assembly might still be a disease vector. The &#39;429 patent&#39;s hooded respirator also comprises a single volume enclosing the eyes, nose and mouth. This poses a fogging problem, requiring a “solution” of re-directing inhaled air across the interior of the lens. Under high humidity conditions, this anti-fogging measure might not work. Since this single volume must enclose the eyes as well as the nose and mouth, it also acts as a reservoir for CO 2 , reducing comfort and wearability. The hood can be hot for the wearer, too. 
   U.S. Pat. No. 5,957,131, also assigned to the United States of America as represented by the Secretary of the Army, discloses a biological warfare mask. The mask shown therein does not include eye protection. Instead, it shows two tubes to fit inside the nostrils, and a mouthpiece to fit inside the mouth. Thus this mask cannot protect against the many infectious agents which enter through the eyes. Nor is there filtering of exhalate. 
   Exemplary military gas masks, or combined chemical-biological masks, are shown in U.S. Pat. Nos. 5,181,506 and 6,176,239, respectively, both assigned to the United States of America as represented by the Secretary of the Army. These masks require carbon filtering. These masks were apparently not designed with long-term civilian use in mind. They lack any disclosure of exhalate filtering, and the &#39;239 patent in fact attributes specific disadvantages to filtering of exhalate. And like the device of the &#39;429 patent, the devices disclosed therein permit lens fogging through exhalate moisture build-up, which then must be abated with the “solution” of passing inhalate across the lens interior. 
   It is thus an object of the invention to provide a biohazard mask designed with the needs of civilian populations (adults and children) in mind. 
   SUMMARY OF THE INVENTION 
   The present invention accommodates the goals of a civilian biohazard mask through a number of design features, appearing as recited in various instances and combinations in the appended claims. For maximum effectiveness against disease re-transmission (particularly useful during household quarantines or at healthcare facilities), the invention provides HEPA filtering for both inhalate and exhalate. For maximum protection against lens fogging, the eye volume is separate from the mouth and nose volume. The eye volume further includes water vapor-permeable, agent-impermeable, membranes to allow release of built-up water vapor, augmented with a passive air-circulation system. For maximum breathing comfort, the mouth-nose volume is minimized, and measures are taken to maximize moisture discharge. For maximum wearability and comfort, the mask is sealed to the face using a combination memory seal/gel seal, and is suspended from the head using netting. 
   Bidirectional filtering is of particular significance during a pandemic or localized epidemic. When a highly transmissible and particularly deadly infectious agent pervades the environment, civil authorities will likely impose quarantines. Thus there will be an increased likelihood of infected people living in close quarters with otherwise uninfected people. Moreover, health care facilities will likely receive many infected people for care, creating another highly concentrated population of infected people in close quarters with otherwise uninfected people. Since in many cases a person may re-transmit a disease long before the onset of symptoms, there is a heightened need to provide a biohazard mask that minimizes re-transmission. 
   Other inventive aspects of the contributions herein will be apparent from the detailed description as augmented by the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a perspective view of the mask of the present invention. 
       FIG. 2  shows a frontal view of the mask of the present invention. 
       FIG. 3  shows a side view of the mask of the present invention. 
       FIG. 3A  shows the side view of  FIG. 3  which includes a view of a screw-type receptacle for an exhalation filter cartridge. 
       FIG. 4  shows a view of the interior surface of the mouth-nose cone of the present invention. 
       FIG. 5  shows a side view of the mask of the present invention, with the removable lens omitted making it a half mask. 
       FIG. 6A  shows an inhalation filter cartridge and an exhalation filter cartridge designed for slidable engagement. 
       FIG. 6  shows a view of the underside of the mask of the present invention. 
       FIG. 7  shows a perspective view of an alternate embodiment of the mask of the present invention. 
       FIG. 8  shows a perspective view of an alternate half mask embodiment of the present invention. 
       FIG. 9  shows a frontal view of the alternate embodiment of  FIG. 8 . 
       FIG. 10  shows a frontal view of the alternate embodiment of  FIG. 9 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Identical reference numerals are intended to reflect identical parts and features in each of the figures. 
   Directing attention to  FIG. 1 , there is shown a perspective view of one embodiment of the biohazard protective gear of the present invention.  FIG. 1  shows a mask of the present invention covering the face of the wearer. The mask includes a lens portion  100 , a mouth-nose portion  200 , and a suspension portion  300 . 
   The lens portion  100  may be made of any clear lens material, preferably polycarbonate, and most preferably polycarbonate that may flex during ordinary movement of the wearer. Lens portion  100  also preferably includes two further structures (not shown) that function to remove moisture from the eye area. One is a water vapor-permeable, biological agent-impermeable membrane, preferably TYVEK, and most preferably TYVEK of over one square inch surface area on each side of the lens portion. The other is a one way air release valve in communication with the air in the eye volume that acts at a pressure resistance lower than the membrane for gradually releasing moist eye-volume air into the ambient environment upon ordinary flexion of the lens material or ordinary movement of the face against the seal. That is, ordinary face and body movements of the wearer are sufficient to “squeeze” moist air out of the valve on a regular basis, which will then be replaced by continual entry of sanitary, dry ambient air passing inwardly through the permeable membrane. The membrane and release valve act to abate moisture buildup in the eye area, and thus minimize fogging. Another feature of the mask that contributes to moisture abatement and anti-fogging is that the eye volume is sealed separately from the mouth-nose volume, to be discussed below. 
   In an alternative embodiment, lens portion  100  may suitably accommodate prescription lenses, either by permitting a large enough interior volume to fit conventional glasses or pince-nez, or alternatively by permitting snap-fit engagement of prescription lenses in the manner described in column 5 of U.S. Pat. No. 5,181,506, or equivalent means. 
   The mouth-nose portion  200  of the mask of the embodiment of  FIG. 1  may be made of any suitable durable and impermeable material, and contains two main parts. These are the inhalation section  220 , and the exhalation section  240 . As shown, these respectively contain inhalation and exhalation apertures. In the embodiment of  FIG. 1 , these are separate sections, each with their own filter and valve assembly, preferably HEPA filters (e.g., polyester/glass filters), and most preferably HEPA filters containing or impregnated with a biocidal agent. Such biocidal agents can be any substance that tends to destroy biologically active agents (such as spores, bacteria or viruses), while being incapable of being inhaled through the filter assembly or otherwise harming the wearer if inhaled. Such substances may preferably include elemental silver, and may also include silver compounds such as silver oxide, silver sulfadiazine and/or silver-hydrogel, or may include chlorhexidine and/or hypochlorite, most preferably in powdered form. Commercially available HEPA filter material of these types are generally available from supply houses such as 3M or Reemay. 
   The suspension portion  300  of the mask of the embodiment of  FIG. 1  is of lightweight but strong material, and is designed to hang the mask from the wearer&#39;s face and/or head in such a manner for the mask to create a proper seal (discussed below). To maximize comfort, and particularly to minimize heat build-up that would otherwise occur with ordinary straps or fabrics, the suspension portion  300  is made of a netting material. This can be in the form of the same material and configuration used in commercially available hair net products. Alternatively, the netting can be in the configuration of a standard fishing net. Appropriate materials may include lycra, nylon, or polyester. Such commercially available netting material may be obtained from George C. Moore Co. Netting provides several advantages, namely, improved weight and heat distribution over fabric head-coverings or straps, as well improved frontal and rear ability to recognize a wearer. The suspension portion  300  need not be a complete head covering. It may instead comprise netted straps configured appropriately to seal the mask to the face (described below). 
   Directing attention to  FIG. 2 , there is further shown the points of attachment  120  of the suspension portion  300  to the lens portion  100 , as well as points of attachment  260  to the mouth-nose portion  200 . These points of attachment may be in the form of loops for receiving buckled nylon straps, or may comprise any sufficient means to fasten the suspension portion  300  to the mask. 
   Directing attention to  FIG. 3 , there is further shown the seal  250 . Seal  250  rests on the substantially annular edge of the curvilinear surface that makes up the mask, and is intended to touch the user&#39;s face to ensure that respiration airflow is exclusively through the filters. As shown also in connection with  FIG. 4 , seal  250  helps define two separate non-communicating volumes within the mask when seated on a wearer&#39;s face: the eye volume and the mouth-nose volume. As mentioned, the separation of these volumes contributes to the anti-fogging aspects of the present embodiment. The seal itself may constitute any number of materials, for example an adhesive, a memory seal (such as that discussed in column 3 of U.S. Pat. No. 5,836,303), or preferably a gel seal (such as that discussed in column 4 of U.S. Pat. No. 5,181,506). Such gel seals are available from companies like Pittsburgh Plastics, Inc. The seal may also constitute a gel seal seated atop a memory seal. 
   Directing attention to  FIG. 4 , there is shown a view of the inside surface  210  of mouth-nose portion  200 . The inhalation section  220  communicates with the interior of the mask through inhalation valves  230 . Valves  230  may be disk or dome valves concave toward the face which are very slightly spring-biased closed. Thus, upon inhalation, valves  230  easily open to permit complete airflow passage into the mouth-nose volume through the inhalation HEPA filters. Note that inhalation section  220  is associated in this embodiment with two inhalation valves  230 , and involves two intake areas, one adjacent each cheek. These exterior of these intake areas are hard three-dimensionally curved surfaces. This is to permit sleeping in the mask with minimum suffocation risk and maximum comfort. The exhalation section  240  communicates with the interior of the mask through exhalation valve  270 . Valve  270  may also be a disk or dome valve, this time convex toward the face and very slightly spring-biased closed. Upon exhalation, valve  270  easily opens to permit complete airflow passage out of the mouth-nose volume through the exhalation HEPA filter. 
   Turning again to filter characteristics, the inhalation HEPA filter should preferably be selected to provide up to 1 square foot of total filtration surface. The exhalation HEPA filter has different design criterial from the inhalation HEPA filter because of the moisture content of exhaled breath. Thus, it can be preferably of somewhat less total filtration surface, and should have a more open weave. In addition, to maximize water vapor dispersion, some portion of the filter fibers can be of the hollow variety to augment wicking. In addition, the filter medium may be electrically charged, which further helps abate moisture during exhalation. 
   Directing attention to  FIG. 5 , the present embodiment may be made into a half mask by removal of lens  100 . Slots  280  are shown into which one may removably insert lens  100 . For masks designed with a removable lens  100 , the seal  250  must be commensurately designed to allow for free insertion and removal of the lens  100 . 
   Directing attention to  FIG. 6 , there is shown the underside of the mask of the present embodiment. Two additional features come into this view. First, the inhalation filters  222  comprise removable cartridges, and the exhalation filter  242  comprises a further removable cartridge. While the cartridges are depicted as the sliding variety, any variety will do, for example screw-on (See  FIG. 3A  depicting a screw-type receptacle  240 ″ for engaging exhalation filter cartridge  240 ′). The underside also shows the measures taken to facilitate overpressure relief. The sealed mask of the present embodiment filters exhalate. But people sneeze and cough. This poses the risk of temporarily breaking the face seal  250 , or of forcing exhalate out through the HEPA filter faster than is desired for maximum filtration efficiency. Thus, the embodiment shown includes two membranes  224  which serve as an over-pressure relief mechanism. Similar in appearance when inflated to a frog bubbling its chin, the membranes (which may be latex rubber or any equivalent such as polyisoprene) will inflate during sneezes, coughs, or other overpressure situations. In this way, the seal will be maintained, and the inflated membranes holding potentially infected air will be allowed to dissipate the air gradually through the exhalation HEPA filter. 
   Other features of the mask of the present embodiment which are not shown include a KAPTON vocal membrane to facilitate speech. If it is desired, electronic communications may also be accommodated. Thus, a microphone might be placed inside the mouth-nose volume, connected to a microphone jack somewhere on the surface of the mask. In addition, in masks designed to cover the ears, ear speakers may also be included, and similarly jacked in. Thus, in an alternate embodiment, a wearer can interface with a telephone, or with audio entertainment, without removing the mask and compromising personal or public health during an outbreak. Inclusion of telephone or entertainment capabilities also maximizes user comfort and wearability. Also not shown, a drinking straw may be suitably inserted through the mask in an appropriate place to permit ingestion of liquids without removing the mask. It will also be appreciated that the mask of the present embodiment may be ornamented with designs or fashion elements to encourage continued use throughout an outbreak. In this light, the durable material that makes up the mask may be formed from translucent or transparent polymer material, and such material may in turn be infused with various light pastel colors or designs. A substantially clear or translucent mask enhances wearer recognizability, and would also make for an attractive, sleek design that encourages continued use throughout an outbreak. (Of course, the filters are opaque.). 
     FIGS. 7–10  show a second embodiment of the protective gear of the present invention. Unless otherwise noted, the features and characteristics of the second embodiment may be suitably accomplished using the materials and structures described in connection with the first embodiment. There are two main differences between the first and second embodiments. In this second embodiment, the lens  400  is no longer one-piece, but is more of a goggle variety. In addition, instead of mouth-nose portion  200  containing separate filters which segregate inhalation and exhalation through a valve arrangement, mouth-nose portion  500  has no valves and instead comprises a single HEPA filter for both inhalation and exhalation. This configuration allows a greater amount of surface area to be devoted to filtering, and thus has the potential of permitting lower pressure resistance during breathing. In  FIGS. 7–10 , the drinking straw is specifically depicted. 
   It will be appreciated that those skilled in the art may now make many uses and modifications of the specific embodiments described without departing from the inventive concepts. For example, while the embodiments show a mask, those of skill in the art may readily apply the inventive concepts herein to equivalent gear interchangeable with a mask in light of the teachings herein, e.g., a suit, a hood, or any other gear designed for protection of health. The recitation of the features and characteristics of the embodiments shown above is not meant to be limiting, but rather exemplary, with the appended claims and their equivalents defining the patentee&#39;s property rights hereunder.