Abstract:
A system for controlling the temperature and relative humidity of the interior chamber of a respirator is disclosed. In the preferred embodiment, the system includes a body configured to conform to the face of a user and form an interior chamber defined by the respirator body and the face of the user. The system includes a sight region in the upper portion of the body through which the user can see. A thermoelectric module having a first temperature plate and a second temperature plate is interposed in the lower portion of the body so that the first temperature plate contacts the interior chamber and the second temperature plate contacts the external environment. A power source provides DC current to the thermoelectric module causing a temperature differential between the first temperature plate and the second temperature plate. Preferably, the plates of the thermoelectric module include heat exchangers and fans for maximizing the efficiency of the thermoelectric module. The power source includes means for reversing polarity to reverse the temperature differential of the thermoelectric module and means for modulating current to the thermoelectric module to control the temperature differential.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable 
     STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to safety equipment for emergency personnel and, more particularly, to respirators. 
     Some of the most important vocations in our society involve controlling and remediating emergencies. These emergencies such as fires, hazardous substance spills and military operations, often require that individuals place themselves in close proximity to toxic liquids, dangerous airborne particulates and noxious gases. In addition, the environmental conditions at the sites of the emergencies are often inhospitable, if not extreme. The individuals who must encounter these toxic elements and harsh environmental conditions deserve the best protection achievable to permit them to carry out their vital duties with minimal risk to their safety. 
     Many of the dangers confronting emergency personnel are brought about by agents that affect the respiratory system. Smoke, toxic fumes, fomites and chemical/biological weapons usually attack the human body via the respiratory system. The primary mechanism to protect individuals against these agents is the gas mask or respirator, as it is known in the art. Respirators generally function to filter the air inhaled by the user to remove toxins. Efforts have been made to develop respirators to protect the integrity of the user&#39;s respiratory system while also allowing the user to dispatch their duties with minimal discomfort and inconvenience. 
     Respirators, by their nature, require that the user&#39;s face be substantially enclosed within an air-tight structure. This configuration protects the face, eyes, nose and mouth of the user from the external environment. Respirators typically include goggles or shields through which the user can see. Most importantly, though, respirators must have mechanisms that allow the user to breathe clean, toxin-free air. Such mechanisms may include an external clean air supply or a filter that removes harmful agents from the air as it is drawn into the interior chamber of the respirator. 
     The interior chamber defined by the user&#39;s face and the dimensions of the respirator is a confined area prone to elevated temperature and humidity. It is well-known that a individual&#39;s respiration accounts for a significant source of heat and moisture expiration from the body. Consequently, the user&#39;s physiological respiration into the small interior chamber of the respirator creates a significant accumulation of heat and moisture directly in front of the face of the user. This heightened temperature and moisture environment manifests itself in several disadvantageous ways. 
     First, the heightened temperature of the interior chamber is quite uncomfortable to the user. Moreover, the natural heat expellation by the user is dramatically increased during the strenuous activities involved in emergency situations. As the user works harder and as the stress of the emergency increases, the heat expelled into the interior chamber also increases. What is an uncomfortable situation at rest becomes an unbearable situation during activity. 
     Second, the increased moisture content of the air in the interior chamber causes a great deal of fogging on the interior of the goggles or face shield. The fogging on the interior of the shield makes it difficult for the user to see and, correspondingly, makes it increasingly difficult for the user to carry out their important emergency functions. As the relative humidity increases in the interior chamber, condensation forms inside the respirator and moisture accumulates within the air-sealed chamber. Not only does condensate accumulate within the respirator, but perspiration from the user&#39;s face caused from the extreme heat within the chamber also accumulates. As a result, a large volume of condensate and perspiration often settles in the lower regions of the respirator. The accumulated moisture occasionally finds its way to the air filtering mechanism of the respirator, which could greatly impede or defeat the air exchange needed by the user. If this occurs, the respirator becomes largely useless and the user is placed in serious peril. 
     Third, the combined effects of the elevated temperature and heightened humidity of the interior chamber of the respirator raises the overall body temperature of the user. Individuals who utilize respirators in emergency situations almost always wear external protective gear on their bodies. This external gear is necessarily waterproof and insulated against extreme temperatures. The external gear traps heat around the body and obstructs proper ventilation. It is well-known that the temperature of the head and face of a individual can greatly affect the overall temperature of the body. Thus, when the temperature of the face of the user increases during use of a conventional respirator, the overall temperature of the body of the user also increases and the external gear prevents adequate elimination of this heat. Elevated body temperatures can result in severe health consequences, including heat exhaustion and heat stroke. Untreated, these heat-related ailments can cause critical illness and, occasionally, death. 
     Conversely, while heat is the primary impediment to respirator use, some emergencies occur in cold environments, both natural and man-made. The above-detailed problems associated with elevated temperatures within the interior chamber of the respirator have corresponding drawbacks associated with depressed temperatures within the chamber. Cold air is more difficult to breathe and lowers the overall body temperature. Chilled air, as opposed to ambient or heated air, forms frost on the interior of the face shield or goggles, making it nearly impossible for the user to see. In these situations, the discomfort is no less severe to the user and the health implications are no less serious, including frostbite and hypothermia. 
     Therefore, there exists a compelling deficiency in the art for a system that would control the temperature and humidity within the interior chamber of a gas mask or respirator. The present invention addresses this deficiency and resolves it. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a system that controls the temperature and humidity of the interior chamber of a respirator without compromising the safety of the user or impeding the user&#39;s ability to perform his or her duties. 
     More particularly, it is an object of the present invention to provide a system that incorporates a cooling/heating device directly in the respirator that serves to control the temperature of the interior chamber of a respirator. 
     It is a corresponding object of the present invention to provide a system incorporating a device directly in the respirator that reduces the humidity of the interior chamber of the respirator. 
     It is another object of the present invention to provide a system incorporating a device directly in the respirator that reduces interior fogging or frosting of the face shield or goggles of the respirator. 
     It is still another object of the present invention to provide a system that diverts and/or collects condensate and perspiration within a respirator. 
     It is yet another object of the present invention to develop a system for cooling and dehumidifying the interior chamber respirator which also assists in the cooling of the overall body of the user. 
     It is a corresponding object to the present invention to provide a system for raising the temperature of the interior chamber of a gas mask or respirator for use in environments involving cold conditions. 
     It is yet a further object of the present invention to provide a system for circulating air within the interior chamber of the respirator to aid in the cooling of the face of the user and to reduce fogging of the face shield or goggles of the respirator. 
     The above and other objects of the present invention will be obvious in view of the following disclosure and accompanying drawings. 
     To accomplish these and other related objects of the present invention, a system for controlling the temperature and humidity of the interior chamber of a respirator is disclosed. In the preferred embodiment, the system includes a body configured to conform to the face of a user, thereby forming an interior chamber defined by the respirator body and the face of the user. The system includes a sight region in the upper portion of the body through which the user can see. A thermoelectric module having a first temperature plate and a second temperature plate is mounted in the lower portion of the body so that the first temperature plate contacts the interior chamber and the second temperature plate contacts the external environment. A power source provides DC current to the thermoelectric module causing a temperature differential between the first temperature plate and the second temperature plate. Preferably, the plates of the thermoelectric modules include heat exchangers and fans for maximizing the efficiency of the thermoelectric module. The power source includes means for reversing polarity to reverse the temperature differential of the thermoelectric module and controlling the current thereto. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings form part of the specification and are to be read in conjunction with this disclosure. 
     FIG. 1 is a perspective view of a respirator incorporating the system of the present invention wherein the power source is an external battery pack; 
     FIG. 2 is an enlarged fragmentary front view of the thermoelectric module of the present invention; 
     FIG. 3 is fragmentary sectional view of the thermoelectric module taken along line  3 — 3  of FIG. 2; 
     FIG. 4 is a fragmentary sectional view of the thermoelectric module of FIG. 2 taken along line  4 — 4  of FIG. 3, parts being broken away to reveal details of the construction; 
     FIG. 5 is a fragmentary perspective view of the respirator shown in FIG. 1 illustrating an alternative embodiment wherein the power source is directly mounted to the body of the respirator above the face shield; and 
     FIG. 6 is a schematic of the control circuit of the present invention which coordinates the operation of the thermoelectric module and the fans coupled to the module. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now to the drawings, and initially to FIG. 1, a respirator equipped with the system of the present invention is broadly designated by the numeral  10 . It is to be understood that the system of the invention is usable not only with conventional respirators, but with other masks and face shields designed to limit or restrict the flow of contaminants from the external environment to the user. For purposes of this disclosure, the term “respirator” will be used to designate any and all such apparatuses. 
     As can be seen by FIG. 1, a respirator equipped with the system of the present invention generally includes a body  12 , a face shield  14 , and a fastening harness  16 . The lower portion of body  12  includes a filter  18 , an exhaust valve  20  and a thermoelectric module  22 . A power source  24  is connected to the thermoelectric module  22 . A supplemental oxygen port  34  is positioned at the bottom of body  12  and is enclosed with a cap  36 . Port  34  can be configured to receive an external source of oxygen or other gas where direct filtration of external air is not possible or not desirable. In the preferred embodiment, though, port  34  has been fitted with a cap  36 . 
     Focusing now in greater detail on the constituent elements of the system, the body  12  is generally ovular in shape wherein its vertical axis is greater than its horizontal axis. The ovular shape of body  12  allows the respirator  10  to conform to the face of the user. The body  12  also has a generally concave form along the vertical axis of the respirator  10 . When positioned on the user, the configuration of respirator  10  forms an interior chamber  13 , as best seen in FIG. 3, defined by the body  12 , the face shield  14  and the face of the user. Preferably, the body  12  is sized to substantially enclose the eyes, nose and mouth of the user in an airtight engagement. Body  12  is preferably constructed of a durable, heat-resistant, deformable material, such as rubber. The precise material from which body  12  is formed, though, is not critical and other materials may be used without departing from the scope of the invention. 
     Fastening harness  16  is used to maintain the air-tight engagement of body  12  to the user&#39;s face. Harness  16  is adapted to engage the body  12  at a plurality of positions to promote a secure engagement. Harness  16  include a series of buckles  28  which are used to adjust the respirator  10  to conform to the individual shape characteristics of the head of the user and also to snugly secure the respirator  10  in place during use. It is important that the fastening harness  16  be sufficiently strong and resilient to maintain the respirator  10  in place even during vigorous activity. Preferably, the harness  16  is formed of a durable, heat-resistant rubber. It is also preferable that harness  16  be constructed of an elastic material to promote a snug engagement of the body  12  to the face of the user. 
     The face shield  14  of the respirator  10  is shown to be generally ovular in shape, wherein its horizontal axis is greater than its vertical axis. Shield  14  is preferably a concave piece of a transparent material conforming to the concave form of the body  12  and positioned in its upper portion to be generally aligned with the eyes of the user when the respirator  10  is in place. Face shield  14  is preferably formed as a single piece to permit substantially unobstructed viewing by the user when the respirator  10  is in use, but may be formed as separate lenses if desired. Shield  14  is constructed of a shock resistant transparent plastic or glass. Shield  14  may be tinted or include tinting means to reduce glare or ultraviolet radiation. It is understood that the construction of the face shield is not critical and other configurations of face shield  14  may also be used without departing from the scope of the invention. 
     Face shield  14  may be secured to body  12  by any suitable means, including gluing, integral forming or other fixing mechanisms. It is preferable, however, that face shield  14  be secured in a selectively releasable manner to the body  12  so that it may be replaced in the event it is cracked, scratched or otherwise damaged. To accomplish this, the face shield  14  is preferably sized to fit within a circumferential canal  30  formed in body  12  and secured in place by an annular flange  32 . 
     Respirator  10  includes at least one filter  18  mounted in the bottom portion of body  12  laterally of the longitudinal axis of the respirator  10 . Filter  18  is a commercially available filter adapted for use in connection with the particular respirator  10 . There are many such filters available in the marketplace specifically designed for individual respirators. Depending on the desired application, filter  18  may filter gases, particulate matter, organic vapors or smoke. It is understood by those in the art that the particular filter to be used varies according to the particular application. The function of the filter  18  is to neutralize or remove particles, vapors, or other harmful agents from the exterior air as it is inhaled by the user inside the respirator  10 . Thus, any material or composition capable of dispatching this neutralizing or filtering function may be used in connection with the system of the present invention without departing from its scope. 
     Exhaust valve  20  is also mounted in the lower portion of body  12  laterally of the longitudinal axis of the respirator  10 , preferably opposite the filter  18 . Exhaust  20  may be of any conventional design creating an airtight seal during inhale by the user, but allowing the exhaust of exhaled air outside of the respirator  10 . Generally, exhaust valve  20  comprises a silicone flap which remains closed during negative pressure or ambient pressure in the interior chamber  13  and open during positive pressure, such as during exhalation. It is to be understood that any exhaust valve mechanism capable of achieving this function is within the scope of the present invention. 
     A wick  38  is positioned below and in contact with heatsink  44 . Wick  38  allows for the physical collection of condensate and perspiration from within the interior chamber  13  of respirator  10 . Wick  38  may be removed when saturated and replaced. Wick  38  can be held in place by any suitable means, such as adhesive, snaps, Velcro, or tab structures. The replacement procedure may be accomplished by removing the respirator  10  from the user to access the wick  38 . 
     As an alternative to absorbent wick  38 , inner wall section  39  of mask  10  may have a suitably dimensioned aperture formed therein (not shown). Cap  36  may be removed and replaced with a valve similar to silicone flap exhaust valve  20 . This would permit the efflux of condensate or perspiration from interior chamber  13  via port  34  automatically upon exhalation, in addition to the normal air exhausting function of such a valve. 
     An example of a respirator equipped with many of the components of the preferred embodiment is the Willson™ Respirator Model 6000. This respirator may be obtained from a number of commercial sources, including The Industrial Safety Company, located at 1390 Newbrecht Road in Lima, Ohio. The Willson™ Model 6000 respirator is configured in modular form to accept a number of different filter cartridges, exhaust valves and drain tubes that are also commercially available from The Industrial Safety Company. The selection of appropriate components is within the common ability of one skilled in the art. 
     Thermoelectric module  22  is a conventional heat exchange unit utilizing the Peltier effect. The Peltier effect was first discovered in the early 19th century and occurs in plurimetallic alloys wherein the application of a voltage differential creates a displacement of free electrons from lower energy bands to upper energy bands in the form of heat from a high temperature electrode to a low temperature electrode. A conventional thermoelectric module includes an array of two dissimilar semiconductor materials, an N-type material and a P-type material, transversely mounted in parallel disposition between two insulator plates. Upon the application of current, one plate of the module will become cool and the other hot due to the displacement of electrons from one semiconductor to the other. 
     The thermoelectric module  22  of the present invention includes an interior insulator plate  40  and an exterior insulator plate  42  separated by an array of two dissimilar semiconductors, which are collectively represented in FIG. 3 by the numeral  43 . The dissimilar semiconductors may be formed of any semiconductor material suitable for the requisite exchange of electrons. One semiconductor must be constructed of an N-type material, which has more electrons than necessary to complete a perfect molecular lattice structure. The other semiconductor must be a P-type material, which has an insufficient number of electrons to complete a lattice structure. Plates  40  and  42  may be constructed of any suitable insulating material, but are preferably constructed of ceramic. 
     As can be best seen in FIGS. 3 and 4, interior plate  40  is coupled to a metallic interior heat exchanger  44 . Exchanger  44  may be coupled to plate  40  by any suitable means permitting thermal exchange. Heat exchanger  44  operates in a conventional manner to increase the surface area of plate  40  and thereby maximize the heat transfer from the plate  40  to the interior chamber  13 . To maximize such heat transfer it is preferable that exchanger  44  present the greatest surface area possible. However, due to the space confines of the interior chamber  13 , interior heat exchanger  44  preferably utilizes a plurality of parallel ribs, as seen in FIG.  4 . The precise configuration of the interior heat exchanger  44  is largely a function of the design constraints existing with the respirator  10 . It is understood that other configurations of heat exchanger  44  may also prove workable and are within the scope of the present invention. 
     An interior fan  48  is secured to the interior heat exchanger  44 . Interior fan  48  includes a perimeter guard  49  and circulates air across the interior heat exchanger  44  to maximize the efficiency of the heat transfer from the interior plate  40  to the interior chamber  13 . As seen in FIG. 3, fan  48  pulls air from the interior chamber  13  of the respirator  10  through the ribbed shape heat exchanger  44  and expels it circumferentially about interior chamber  13  of mask  10 . This maximizes the cooling effect caused by the thermoelectric module  22  and also maximizes the dehumidifying function of the module  22  by drawing humid air directly onto the surface of heat exchanger  44 . Interior fan  48  also circulates air inside the interior chamber  13  to further promote cooling of the face of the user and enhance the evaporation of moisture. 
     Exterior heat exchanger  46  is coupled to exterior plate  42  to increase the rate of heat exchange from plate  42  to the exterior environment. Exterior heat exchanger  46  operates in the same manner as interior heat exchanger  44 . Plate  42  is bolted to exchanger  46  to permit thermal exchange, but any other suitable coupling means may also be used. In the preferred embodiment, exterior heat exchanger  46  includes a square metallic sheet coupled to plate  42  and projecting outwardly in four U-shaped grills. It is to be understood that the configuration of the exterior heat exchanger  46  may be altered to conform to the specific characteristics of the respirator  10 . It is preferable that exchanger  44  present the greatest surface area possible without compromising the manageability and comfort of use of the respirator  10 . 
     An exterior fan  50  is secured to the exterior heat exchanger  46 . The exterior fan  50  also includes a perimeter guard  51  and provides a function similar to interior fan  48 . Exterior fan  50  maximizes the flow of air across the exterior heat exchanger  46  to maximize the efficiency of the thermoelectric module  22 . 
     There are numerous commercial sources for thermoelectric modules. In selecting the appropriate module, it is important to provide sufficient heating/cooling capacity to bring the interior chamber  13  of the respirator  10  to the desired temperature, which is generally room temperature. The calculation of cooling/heating power necessary for a given respirator is well within the common knowledge of one skilled in the art. Typically, respirators require about 50 Btu to maintain room temperature, which can be generated by a reasonably-sized thermoelectric module. A thermoelectric module conforming to the preferred embodiment of the invention and producing this level of power is the Peltier T.E.M. and heat sink module, Catalog No. 8688, sold by Marlin P. Jones &amp; Associates in Lake Park, Fla. A commercially available fan for interior and exterior fans  48  and  50  is CPU Fan 12V, Catalog No. 7880 FN, which is also sold by Marlin P. Jones &amp; Associates. 
     The thermoelectric module  22  of the present invention may be mounted in body  12  by any suitable means capable of securing module  22  to body  12  in a sealed relationship. Module  22  may be either permanently mounted in body  12  or selectively releasably mounted so that the module  22  can be replaced when needed. In the preferred embodiment, the module  22  is mounted through an orifice formed in the bottom portion of body  12 . Module  22  is then bolted to secure this position. A sealant is applied at the juncture between module  22  and body  12  to ensure an airtight seal. It is to be understood that other means may be utilized to secure the thermoelectric module  22  to the body  12  without departing from the scope of the present invention. 
     The positioning of the thermoelectric module  22  is important to maximize the dehumidifying function of the system. Preferably, the thermoelectric module  22  is positioned in body  12  to be generally aligned with the mouth of the user when the respirator  10  is in place. This permits the thermoelectric module  22  to direct air at a controlled temperature directly to the interior chamber  13 . In addition, body  12  should be configured to provide clearance between the interior fan  48  and the mouth of the user when the respirator  10  is in place. It is important that the thermoelectric module  22  not come into direct contact with the face of the user. The extreme temperature of the module  22  could harm the user if it were to come into direct contact. In addition, the circulating effect of the interior fan  48  requires that it be spaced from the user to promote maximum ventilation. 
     Power source  24  is shown in FIG. 1 as an external unit. Power source  24  includes a pair of conventional batteries. It is understood that one of ordinary skill in the art can readily calculate the power requirements of the system of the present invention for a particular use and, thus, select specified batteries to produce sufficient power to source  24  to meet such requirements. Preferably, source  24  includes a rechargeable power source, such as a pair of nickel cadmium batteries, supplying 14.4 volts of power. Power source  24  includes two switches and a potentiometer. The potentiometer is used to vary the temperature difference across plates  40  and  42 , thus allowing variation of cooling or heating. Switch  52  is a simple on/off switch. When placed in the on position, power source  24  provides DC current to thermoelectric module  22  which both activates the module  22  and fans  48  and  50 . In the off position, power source  24  terminates the flow of current to module  22  and fans  48  and  50 . Switch  54  is a polarity switch. In normal operating conditions, the module  22  will cool interior plate  40  and warm exterior plate  42 . By activating the polarity switch  54 , the reverse takes effect, thereby heating the interior plate  40  and cooling the exterior plate  42 . This function is important when utilizing the respirator  10  in cold environments. 
     Power source  24  is connected to the respirator  10  by lead line  26 . A releasable jack  56  of conventional design allows for the power source  24  to be selectively disconnected from the respirator  10 . Lead line  26  is connected to body  12  at a lateral edge of face shield  14 . The lead line  26  continues under flange  32  to the bottom of shield  14 , where it connects to module  22 . 
     The components of the preferred power source  24  are readily commercially available. Integrated circuit LM 7805 can be purchased at Radio Shack, Part No. 276-1770. A 1 kohm 0.25W potentiometer, SPST switch (reverse polarity) and DPDT switch (power) are also available at Radio Shack. Batteries for source  24  are widely available from commercial outlets such as Radio Shack, Part No. 23-230. Other commercial outlets provide components equally suitable for carrying out the invention and may be used without departing from the scope of the invention. 
     An alternative embodiment of power source  24  is shown in FIG.  5 . In this embodiment, the power source  124  is mounted to the upper portion of the body  12  immediately above the face shield  14 . Switches  152  and  154  and a potentiometer (which is preferably integral to power switch  152 ) are placed on opposite ends of the power source  124  and provide the same function as switches  52  and  54 , respectively. In this embodiment, power source  124  is releasably secured to body  12  by clip  158  and could be located at any suitable location on the mask. Clip  158  permits source  124  to be easily exchanged with a fresh source when spent or replaced if source  124  becomes inoperable. The chief advantage of the alternative configuration of FIG. 5 is that the respirator is completely self-contained with no need for the user to carry an external power source  24 . Power source  124  may be powered by lithium ion batteries which are readily commercially available. The power requirements of the batteries of the power source  124  depends upon the respirator  10  used and the conditions in which the respirator will be used. One skilled in the art can readily determine the power requirements of the respirator  10  in a particular application. Preferably, the batteries of source  124  are capable of providing 14.4 volts of DC current. 
     Turning now to FIG. 6, a schematic diagram showing the preferred embodiment of the power source control of the present invention is shown. The interior fan is designated by the numeral  248  and the external fan is designated  250 . The thermoelectric module is designated by the numeral  222 . The polarity reverse switch is  254  and the power switch is numeral  252 . The area designated by the reference numeral  255  is the circuit diagram for the potentiometer. The area designated  256  could also be a potentiometer circuit similar to that shown in area  255  for adjusting fan speed. The schematic of FIG. 6 provides one of ordinary skill in the art with the necessary information to construct a control for the system of the present invention. 
     In operation, the respirator  10  is first positioned at the face of the user. The fastening harness  16  is placed over the head and adjusted with buckles  28  to secure the respirator  10  to the user. In proper position, the body  12  of the respirator  10  snugly abuts the user&#39;s face and surrounds the user&#39;s eyes, nose and mouth in an airtight engagement. It is important that an airtight seal be obtained at the perimeter of the body  12  against the face of the user. Face shield  14  should be generally aligned with the eyes of the user. Thermoelectric module  22  should be aligned with the mouth of the user. 
     The thermoelectric module is activated by the power switch  52 . Once activated, the power source  24  provides DC current to the thermoelectric module  22 , which begins to cool or heat interior chamber  13  as selected by the user. The power source  24  simultaneously activates both the interior fan  48  and the exterior fan  50 . Fans  48  and  50  operate to increase the flow of air across heat exchangers  44  and  46 , respectively, thereby maximizing the temperature differential of the module  22 . 
     In cooling mode, the system of the present invention significantly reduces the temperature in the interior chamber  13  of the respirator  10 . The thermoelectric module  22 , as enhanced by the interior heat exchanger  44  and the interior fan  48 , provides cool air to the interior chamber  13  which, in turn, cools the face of the user. The thermoelectric module  22  also dehumidifies the interior chamber  13  of the respirator  10 . By reducing the moisture content of the air in the chamber  13 , the system of present invention also reduces the fogging present on the interior surface of the face shield  14 , thereby improving the ability of the user to see. Any condensation that would incur inside respirator  10  collects in the drain tube  34  and is absorbed by wick  38 . The cooperative function of drain tube  34  and wick  38  enhances the dry environment of the chamber  13  and significantly improves the comfort of the user. Finally, the environment inside the chamber  13  serves to reduce the overall body temperature of the user. This reduces the likelihood of heat-related illnesses and allows the user to work longer and more effectively than when using conventional respirators. 
     In heating mode, the user would merely activate the polarity switch  54  which would reverse the function of the thermoelectric module  22 , thereby heating the interior chamber  13  of the respirator  10 . The module  22  would also serve to defrost the inner surface of face shield  14 , which promotes better vision. By warming the face of the user, the system would aid in conserving body heat, thereby preventing frost bite and hypothermia. 
     There are many variations of the present invention. It shall be understood that the present invention is not limited by the specific embodiments discussed above, but encompasses all personalized cooling means using Peltier cells in connection with respirators of all kinds. It is apparent that this invention is well-adapted to obtain all the ends and objections set forth above along with other advantages that are obvious in view of this disclosure. It is to be understood that certain features and subcombinations are useful and may be employed without reference to the other features and subcombinations. This is contemplated by the disclosure and is within the scope of the claims. 
     Because many possible embodiments may be made of the present invention without departing from its scope, it is hereby understood that all matters set forth herein and shown in the accompanying drawings are to be interpreted as illustrative only, and not in the limiting sense.