BACKGROUND OF THE INVENTION This invention relates to an air capture, filtration and purification apparatus and method. More particularly, this invention relates to the capture of contaminated air from the proximity of a dental or medical operation or treatment site, the filtration of the captured air to remove solid particles and liquid droplets from the air, and the purification of the captured air to kill bacteria, viruses, and other matter that may transmit disease. During dental treatment and operations, such as the removal of teeth and the filling of cavities, dentists and oral surgeons remove sections of teeth and bone using high speed drills and other tools. During the removal process, the tools pulverize the teeth and bone into particles of various sizes. Dental hygienists, on the other hand, use high speed tools in conjunction with abrasive cleaning agents to clean the teeth. In each of these processes, some of the particles generated are small and light enough to form clouds of dust. The particles, which usually contain bacteria, viruses and other contaminants, may be inhaled or ingested by the patient and other persons that work in close proximity to the patient. Once inhaled or ingested, the particles can enter the respiratory tract, the oral cavity, and the upper reaches of the gastro-intestinal tract. The smallest of the contaminated particles, which are often atomized, are capable of reaching the terminal cells of the lungs. Once

introduced into the body, the particles and dust may cause a number of ailments. Other, non-dental, types of surgery, especially those types involving the removal of hard tissue such as bone, also produce debris and particles that may be inhaled and ingested by the persons in proximity with the patient. The threat of exposure to the HIV virus, which causes AIDS, has heightened the awareness of preventing cross contamination between dentists and doctors and their patients during treatment. Because of the close proximity between the doctors and patients during surgery and other treatment, airborne bodily fluids such as those exhaled from the lungs and exiting from the mouth and nose may easily be exchanged. Further, these particles, debris, and fluids may travel great distances such that they may be inhaled and ingested by any person present in the operating or treatment room. Prior devices have addressed these and other related problems and have presented solutions to some of the problems. U.S. Patent 3,768,970 to Malmin, for example, discloses a device for sterilizing and controlling aerosol clouds generated during either dental or medical operations. The Malmin device included a large mouthpiece that was placed in the vicinity of the operation site and a remote unit which connected to the mouthpiece via a large flexible intake tube. A blower within the remote unit drew air into the mouthpiece, moved it to the remote unit, and expelled the air from the remote unit. Within the remote unit, a filter removed particles from the air and an ultraviolet light attempted to purify the air. The Malmin device, however, suffered a number of shortcomings. The mouthpiece was large, cumbersome, not self supporting, could not be selectively positioned, and

resultantly inhibited the doctor and the assistant from performing the operation. The intake tube connecting the mouthpiece to the remote unit tended to collect and retain contaminated particles. Air drawn into the remote unit was not pretreated before it passed before the ultraviolet light and therefore the effectiveness of the ultraviolet light was reduced. Further, the ultraviolet light sources were poorly positioned and did not properly sterilize the air. Finally, in addition to being cumbersome, the device required a remote exhaust vent, the added cost of which made the device too expensive for most applications. Another device, described in U.S. Patent 4,252,054 to Bakels, included a cabinet with an air intake on the upper surface of the cabinet and also a portable air collector that could be connected to the cabinet via a suction hose. Within the cabinet were components for filtering and sterilizing the air as well as a blower for drawing air into the cabinet through the air intake. Because the blower was in close proximity to the patient, however, the device created a high noise level in the treatment room. Further, the device sterilized the contaminated air while it was still humid thus reducing the effectiveness of the sterilizer. Additionally, the hose mounted portable air collector was awkward to use and it could not be selectively positioned to draw in the contaminated air. In both the Bakels and the Malmin devices, the suction hoses and internal components of the devices were subject to contamination by the particles inherent in the contaminated air. Because the suction hoses and the internal device components were difficult to clean, the costs required to maintain the devices were high which further strained their usefulness.

SUMMARY OF THE INVENTION It is therefore a general object of the invention to overcome the above described limitations and others of the prior air treatment devices. More particularly, it is an object of the invention to provide an apparatus and method for the capture, filtration and sterilization of contaminated air for particular use during medical and dental treatments and surgery. To accomplish these objects, an air receiving, filtering and purifying apparatus preferably comprises an air collector, air prefiltering means, a suction tube, a housing, air circulation means, a dehumidifier, at least one air filter, and an air sterilizer. Preferably, the air collector is self supporting, incrementally positionable, and capable of firmly and unobtrusively resting in close proximity to a portion of a patient's anatomy to selectively draw in contaminated air. In a preferred form, the air collector comprises a rigid body and a supporting means. The rigid body includes a first end through which contaminated air is drawn and a second end adapted to sealably attach to the suction tube. The supporting means, which connects to the rigid body, facilitates the incremental positioning of the rigid body so that the device may be operating while the doctor or dentist performs his or her work. Preferably, the air prefiltering means is contained within the rigid body, removes large solid particles and water droplets from the contaminated air, and absorbs a portion of the humidity from the contaminated air that passes through the rigid body. In one form of the invention, the rigid body and the suction tube may be constructed of disposable material and replaced after each use. The remaining components are contained in a housing. The housing is preferably

made of metal and constructed such that the longitudinal axis of the housing orients vertically. Access doors allow for easy cleaning and maintenance of the components within the housing. The air circulation means draws the contaminated air from the air collector, through the suction tube, and into a first housing opening which sealably attaches to a second end of the suction tube. The air circulation means, which is contained within the housing is selectively positioned within the housing to produce low levels of noise. Preferably, the air circulation means is operable at varying speeds so that the flow of air through the apparatus may be controlled to suit the situation and so that the produced noise may be further reduced when full suction is not needed. Advantageously, the air dehumidifier then dehumidifies the air moving through the housing. Preferably, the dehumidifier comprises a thermoelectric cooler. Once dehumidified, a first air filter, preferably an electrostatic filter, filters the air. Next, the air sterilizer, which preferably comprises a plurality of ultraviolet radiation tubes, sterilizes the dry air moving through the housing. Next, a second air filter filters the air before it exits the housing through a second housing opening. The apparatus and method of the present invention provide important advantages over prior air filtration and purification devices. As previously described, a serious limitation of prior devices was the obtrusive nature of the device.used to collect the air from the proximity of the operation or treatment site. The present invention includes a selectively positionable air collector that may unobtrusively be placed in close proximity to the operation site without interfering with the doctor or his or her assistants. Because the

air collector is self supporting and incrementally adjustable, a doctor or dentist may place the air collector in the optimum location without having to hold it or reposition it during surgery. Further, the air collector may be moved away from its operating position between uses so that it does not otherwise interfere with the operation of the dental chair or operating table. Because the air collector and the suction tube may be constructed of a disposable material, they may be discarded after each use to prevent the spread of disease. However, even if the air collector and the suction tube are not disposable, the air prefiltering device traps a large portion of the water droplets and larger particles and a portion of the humidity contained in the contaminated air, thus leaving fewer particles remaining to contaminate the housing. Further, because the air collector and the housing may both be opened for cleaning, maintenance is easy and costs are further reduced. Importantly, because the apparatus of the present invention includes an air dehumidifier, the air sterilizer efficiently sterilizes the air as it passes through the housing. Prior devices did not include dehumidifiers and the applicant has determined that resultantly, the prior devices poorly and only partially sterilized the contaminated air. The present invention more fully sterilizes the contaminated air than did the prior devices. The capability of the air circulation means to be operated at slower speeds when a large suction volume is not required results in lower noise levels at those times. A major limitation of the prior local air purification devices was the high noise levels that they produced. Prior devices that produced high levels of noises were annoying and could interfere with a doctor's performance during the operation. Resultantly, prior devices were

often not used because of the noise problem. The present invention overcomes this limitation. These and other objects, advantages, and features of the invention will be apparent from the following description of the preferred embodiment, considered along with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view of a preferred embodiment of the present invention as used during dental treatment and oral surgery. FIGURE 2 is an enlarged view in perspective of the preferred embodiment of the present invention taken from within circle 2.2 highlighting the air collector and its connection with a dental chair. FIGURE 3 is a partial perspective view of the preferred embodiment of the present invention detailing the housing. FIGURE 4 is the view of FIGURE 3 with a portion of the housing broken away to show the components within the housing. FIGURE 5 is a side view in perspective of the air collector. FIGURE 6 is a rear view in perspective of the air collector. FIGURE 7 is a diagrammatic top view of the air collector detailing the air prefiltering means. FIGURE 8 is a diagrammatic view in perspective of the air prefiltering means

isolated from the air collector.

FIGURE 9 is a diagrammatical view in perspective detailing how the air collector positions to draw contaminated air away from a patient's mouth without interfering with the work area of the doctor or his assistant.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGURES 1 through 9 illustrate the principles of the present invention by way of example. As shown in FIGURE 1 and FIGURE 4, an air receiving, filtering and purifying apparatus 10 comprises an air collector 12, air prefiltering means 14, a suction tube 16, a housing 18, air circulation means 20, a dehumidifier 22, at least one air filter 24, and an air sterilizer 26. As shown in FIGURES 1, 2, and 5 through 9, the air collector 12 is self supporting and incrementally positionable to selectively draw in contaminated air. Further, the air collector 12 is capable of firmly and unobtrusively resting in close proximity to a portion of a patient's anatomy. The air collector preferably comprises a rigid body 28 and an incrementally adjustable supporting means 30. The rigid body 28 includes a first end 34 through which contaminated air is drawn and a second end 36 adapted to sealably attach to the suction tube 16. The supporting means 30 is associated with the rigid body 28 and is for facilitating the incremental positioning of the air collector 12. The supporting means 30 detachably attaches to a dentist's chair 32 or an operating tahle (not shown). Preferably, the supporting means 30 may be moved aside so that the air collector 12 does not interfere with other uses of the dentist's chair or operating table. The rigid body 28 preferably is constructed of polished stainless steel so that it does

not accumulate debris and so that it may be easily cleaned. The rigid body 28 is constructed so that the top may be removed for cleaning. Further, the rigid body 28 may be constructed of a disposable material such as rigid paper so that it could be disposed of after each use. As shown in FIGURES 7 and 8, the air prefiltering means 14 associated with the rigid body 28 removes large solid particles, water droplets, and a portion of the humidity from the contaminated air as the contaminated air passes through the rigid body. Preferably, the air prefiltering means 14 includes a prefilter frame 37 which connects to the rigid body first end 34, a long bag 38 which connects to the prefilter frame, and a loose net 39. The long bag 38 includes a plurality of partitions extending longitudinally along the longitudinal axis of the rigid body 28. Preferably, the bags 38 are constructed of a humidity absorbent material such as silicon gel or a more advanced absorbent and are disposable. The bag's 38 unique shape provides significant cross sectional area to filter large solid particles and water from the contaminated air, and at the same time provide little resistance to air flow. On the face of the prefilter frame preferably resides the loose net 39 which is made of nylon or another durable material. The net functions to prevent clothing or other larger objects from entering the air collector 12. As shown in FIGURE 9, the air collector 12 may be selectively positioned so that it is neither in the dentist's work area nor in the assistant's work area but is still in close proximity to a patient's mouth 41. Thus the air collector 12 is capable of adequately removing the particles, debris, and other matter emitted from the patient's mouth 41 without interfering with the work of the dentist and assistant. One skilled in the art will readily see that the air collector 12 could be selectively positioned near on operation site as well.

Referring to FIGURE 1, the suction tube 16, which may be constructed of a disposable material in a manner that is known in the art, detachably and sealably connects between the rigid body second end 36 and a first housing opening 40 in the housing 18. Connected in this manner, contaminated air enters the rigid body first end 34, travels through the rigid body 28, exits the rigid body second end 36, travels through the suction tube 16, and enters the first housing opening 40. The housing 18 preferably is constructed of double layer sheet metal, with insulation between the layers to reduce noise, and includes a number of sections that may be removed to clean the components contained within. As shown in FIGURE 4, the air circulation means 20 contained within the housing 18 includes a first circulating fan 42 and a second circulating fan 44. In combination, the first 42 and second 44 circulating fans move air in through the first housing opening 40 and out through a second housing opening 46. Each of the circulating fans 42 and 44 is a low noise level fan and is capable of operating at variable speeds. Referring to FIGURE 1, a speed control switch 47 and knob 49 that are mounted on the supporting means 30, and a foot pedal 48 allow the dentist or surgeon to adjust the speed of the fans 42 and 44 simultaneously. Resultantly, the amount of suction applied to the rigid body first end 34 varies with the fan speed and may be regulated according to the immediate suction needs. The circulating fans 42 and 44 produce less noise at lower speeds and therefore the ambient noise in the room decreases when the dentist or surgeon slows the speed of the fans. Still referring to FIGURE 4, the air dehumidifier 22 dehumidifies the air moving through the housing. The air dehumidifier 22 preferably comprises an air baffle 50 for directing the air flowing through the dehumidifier, a thermoelectric cooler 52, a heat sink

54, and a wiper 56. The thermoelectric cooler 52 preferably comprises a plurality of individual thermoelectric cooler chips (not shown) installed in an array such that they form a flat cooled surface. Preferably the individual semiconductor chips are model number CP1.4-127-0452 manufactured by MELCOR or equivalents. The semiconductor chips create a heat gradient normal to the chips such that the temperature on the surface of the thermoelectric cooler 52 is as great as 100 degrees fahrenheit lower than the temperature on the opposite side of the thermoelectric cooler. This temperature difference is easily controlled by controlling the supplied current. The heat sink 54 attaches to the opposite side of the thermoelectric cooler 52 and dissipates the heat energy pumped by the thermoelectric cooler. Contaminated air flowing in through the first housing opening 40 is first dehumidified as it follows the path created by the air baffle 50 and passes by the thermoelectric cooler 52. The thermoelectric cooler 52 lowers the temperature of the contaminated air causing condensation to form on the surface of the thermoelectric cooler and resultantly the humidity of the contaminated air to decrease. The wiper 56 operates to remove the condensation from the surface of the thermoelectric cooler thereby increasing the efficiency of the thermoelectric cooler 52. Condensation wiped from the surface of the thermoelectric cooler collects in the condensation pan 58 at the bottom of the housing 18 which preferably contains a disinfectant known in the art and not shown. After the contaminated air passes the surface of the thermoelectric cooler 52 and the humidity of the air is reduced, the air baffle 50 causes the air to pass near the heat sink 54 thereby heating the air. In an alternative embodiment of the dehumidifier, a conventional

compression type dehumidifier could also be employed to remove the humidity from the contaminated air. Conveniently, an access opening 59 in the housing 18 provides easy access to the dehumidifier 22 for cleaning and maintenance. Once the air is dehumidified, it passes through a first air filter 60. Preferably, the first air filter 60 is an electrostatic filter of low air flow resistance but with sufficient filtering capability to remove substantially all particles from the air. Preferably the electrostatic filter is a model DUST FIGHTER 95 manufactured by DUST FREE, INC. or an equivalent thereof. The first air filter 60 removes approximately 90% to 95% of the solid particles in the contaminated air with little resistance to air flow. Still referring to FIGURE 4, the air next passes through the air sterilizer 26. The air sterilizer 26 preferably comprises three 253.7 nm wavelength, non ozone producing, ultraviolet radiation tubes 62, preferably model G30T8 tubes manufactured by PHILIPS or an equivalent thereof. The radiation tubes 62 are oriented so that their longitudinal axes are parallel to the longitudinal axis of the housing 18. Reflective walls 64 in the housing, preferably constructed of reflectant aluminum, surround the volume associated with the air sterilizer 26 so that the ultraviolet radiation produced by the tubes 62 more efficiently kills the bacteria, virus, and other living matter contained in the air flowing through the air sterilizer. The configuration of the air sterilizer 26 within the housing allows the air to be exposed to the radiation tubes 62 for a sufficient period to kill a large amount of the living matter in the air. Thus, the air exiting the air sterilizer 26 is substantially, but not completely sterilized. Conveniently, an access opening 65 in the housing 18 provides easy access to the radiation tubes 26 for cleaning as well as to other components in the housing.

After exiting the air sterilizer 26, the air passes through a second air filter 66 which further removes particles from the air. Preferably, the second air filter 66 is a DUST EATER model manufactured by PERMATRON or an equivalent thereof. The second filter 66 removes particles which the first filter 60 did not remove and may contain an activated carbon layer for odor removal. After the air passes past the second air filter 66 it exits from the housing 18 into the room from the second housing opening 46 thus completing the purification process. Because the air is exhausted from the top of the housing 18, it does not disturb any dust or particles resting on the floor in the room. Further because the air has been cooled then rewarmed before it exits the housing 18, no significant additional burden is placed on the room air conditioning or heating unit. A power supply and electronics required for the operation of the apparatus 10 are contained in an electronics control center 69 in the housing. The power supply provides power to all electrical equipment power associated with the apparatus 10 and includes breakers operable for the protection of both the equipment within the housing 12 and for individuals using the apparatus. An important feature of the apparatus 10 of the present invention is that it may also be used as an air purifier to purify the air contained in the room in which the apparatus resides. The apparatus may be used in such a manner by preventing air from entering the first housing opening 40 and by allowing air to enter the housing 18 through an auxiliary housing opening 68. Used in this manner, the apparatus 10 may be used to remove pollen, mold, bacteria, or other foreign material from the air when not in use during an operation. The present invention also includes a method for receiving, filtering and purifying

contaminated air drawn from near an operation site. The method includes as a first step selectively collecting the contaminated air from near an operation site using a self supporting air collector capable of firmly and unobtrusively resting in close proximity to a portion of a patient's anatomy. A next step includes prefiltering the air to remove large solid particles and water droplets from the air. A further step includes dehumidifying the air. A still further step includes filtering the air at least once to remove small solid particles from the air. And, a final step includes sterilizing the dry air. The above described preferred embodiments are intended to illustrate the principles of the invention, but not to limit the scope of the invention. Various other embodiments and modifications to these preferred embodiments may be made by those skilled in the art without departing from the scope of the following claims.