Abstract:
Improvements are provided to enable an air-curtain portal to be used for the triage and decontamination of persons who may have been exposed to toxic gas vapour or particulate material.

Description:
This application is a continuation-in-part of application Ser. No. 09/389,019, filed Sep. 2, 1999, now U.S. Pat. No. 6,375,697. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to both an apparatus for and method of screening people and articles to detect exposure and/or to decontaminate with respect to toxic materials, such as condensible gases and vapours and liquid or solid particles originating from industrial accidents or chemical warfare. 
     BACKGROUND OF THE INVENTION 
     Rapid screening techniques are required to quickly identify people who may have been exposed to toxic emissions, notably either from chemical warfare gases and vapours or chemicals spilled or accidentally formed from industrial accidents. Often these substances are released or disseminated in liquid form, and the liquids have effectively low boiling points such that the vapours are readily emitted. 
     Following a chemical warfare agent attack, for example, numerous people could be contaminated, as, for example, in crowded metropolitan underground rail systems. Since nerve and chemical warfare agents are extremely toxic, quick response and remedial action is essential. If liquid agents were disseminated into closed areas, the contamination could be very high. Great care must therefore be taken to ensure that in a mixed population of victims or potential victims, those who are contaminated are quickly separated from those who are not. 
     In the Tokyo Metropolitan Rail attack, sarin was used and the First Responders (i.e., emergency personnel such as Fire, Police or ambulance staff, who first arrived at the scene) were unable to separate contaminated from uncontaminated people. As a consequence, victims whose clothing had been contaminated with the sarin became sources of reliberation of the vapours, which then cross-contaminated people who were originally unaffected. Thus, the casualties from the attack were greatly multiplied. 
     It is most desirable, therefore, to develop a quick screening system where individuals could pass through a walk-through portal, similar to Walk-Through Metal Detectors (WTMD) used in airports for screening passengers for concealed weapons. Just as WTMD systems detect the presence of metal objects, the inventor has realized that a similar screening system could be used to detect the presence of chemical agents. There is a need for easily deployed walk-through portal systems provided with air jets that can air brush people and speedily process possible victims on a walk-through basis. 
     Linker et al in U.S. Pat No. 5,915,268, Settles in U.S. Pat. No. 6,073,499, Arney et al in U.S. Pat. No. 4,896,547 and Corrigan et al. in U.S. Pat. No. 4,987,767, teach that a curtain using flowing air, or other gas, can quickly thermally desorb high vapour pressure materials from the skin and/or clothing of persons, and, further, that such air curtains can be integrated into portals which can be used to screen persons for the presence of a wide variety of materials, most commonly explosives and drugs of abuse. The present invention provides improvements to prior art portals to extend their use to the triage and decontamination of persons who, as the result of chemical warfare, terrorist attack, or industrial or transportation accident, may have been exposed to toxic substances which have become attached to their skin and clothes, thereby prolonging their exposure and increasing the probability of serious injury. 
     SUMMARY OF THE INVENTION 
     A walk-through portal can include a plenum which can deliver a high volume flow of warm air over the person being processed. The person walks into the portal and executes a 90′ turn so that the air jets, preferably heated, can blow over the front and back areas of their body. Typically, the person remains in the examination zone for about 12 seconds, and is swept by about 2,000 L of air. An exhaust system collects the warm air into a plenum containing a filter. Any chemical on skin or clothing is liberated and passes as either particles, droplets or vapour into the plenum for subsequent removal by the filtering system. An analytical instrument such as an ion mobility spectrometer, is used to make chemical measurements on the air flow exhausted through the plenum prior to filtering. However, many other techniques exist. An enrichment process can allow agents to be removed from the high volume air flow so as to be transferred into a much lower air flow compatible with instruments such as an IMS detector. Other instruments can be used to monitor the effluent such as fast gas chromatographs, IR analyzers, electrochemical cells and other such devices according to their analytical capabilities and speed of response for the analytes of interest. Shutting off the main air flow and heating the filter in a much lower air flow can provide an enrichment process and allow agents to be detected at lower levels. Such devices can be provided in a portable form such that they may be readily transported from site to site and quickly reassembled where chemical terrorism acts or industrial accidents may have occurred. Alternatively such portals can be permanently installed at critical sites. Such a portal can also be optimized for detection of contraband substances. 
     In actual operation, especially where large numbers of individuals may need to be processed, speed is of essence and a number of such prescreening warm air only portals could be provided. The preliminary processing involves basic air decontamination; the individuals could be subsequently screened through a second portal which incorporates the chemical measurement means to check if decontamination was successful. Where the number of victims are few, a single portal can perform the functions of decontamination and contamination monitoring. 
     The portals could be constructed as portable devices or “knock-down” kits, allowing for ease of transport and rapid assembly at the site of the chemical release. Evidently, such portals could be permanently constructed for us in chemical plants or military installations where dangerous chemical materials are stored, handled, processed or positioned. Additionally, such portals could be used as security screens at airport check points. 
     In accordance with a first aspect of the present invention, there is provided a walk-through portal for at least one of detection of a predetermined substance on a subject and decontamination of a subject from a predetermined substance, the walk-through portal comprising: 
     an enclosure defining an examination zone and being substantially open on at least one side, to permit a subject readily to enter and to exit the examination zone; 
     a closure means for substantially closing off the examination zone from the exterior; 
     an inlet into the examination zone and an outlet from the examination zone; and 
     a pump for pumping a gas through the inlet into the examination zone, over a subject to entrain at least one of vapours, and particulates from such substance, and out through the outlet. 
     The portal preferably includes at least one flexible screen, closing off the examination zone. More preferably, the walk-through portal is open on opposite sides thereof, to enable a subject to walk into the examination zone from one side and out from the examination through the other side, and the walk-through portal further includes flexible screens on both sides, closing off the examination zone. 
     Advantageously, the portal includes an output decontamination filter connected to the outlet from the examination zone, for ensuring that gas exhausted into the atmosphere is free from any contaminating substance and/or an inlet filter, mounted between the inlet and the examination zone, for filtering gas flowing into the examination zone. 
     Preferably, the walk-through portal includes an analyzer, connected to the outlet, for taking a sample of gas flowing through the outlet, whereby the analyzer determines the presence of said substance in the gas flowing through the outlet and/or a detection instrument connected to the inlet, for monitoring gas flowing into the examination zone for presence of contamination. 
     Instead of an open system, the portal can include a recirculation duct connected between the outlet and the inlet and a filter mounted in the recirculation duct, for cleaning gas exhausted from the examination zone of any contaminating substance, before the gas is recirculated back through the inlet into the examination zone. 
     In either version, the portal can include a supply of a decontamination agent, connected to the recirculation duct, downstream from the filter, for supply of a decontamination agent for one of neutralization, destabilizing and breaking down said substance. 
     An indicator can be connected to the analyzer and is operable to provide an indication as to whether a subject is or is not contaminated with said substance. A connection can be provided between the analyzer and the pump, for turning off the pump, after a predetermined period of time, when it is determined that said substance is not present, indicative that subject is not contaminated. 
     Another aspect of the present invention provides a device, for at least one of detection of a predetermined substance on an article and 10 decontamination of an article from a predetermined substance, the device comprising: 
     an enclosure defining the examination zone, the enclosure being openable for insertion and removal of an article and being closable to close off the examination zone from the exterior; 
     an inlet into the examination zone and an outlet from the examination zone; 
     a pump for pumping a gas through the inlet into the examination zone, over the article to entrain at least one of vapours and particulates of said substance, and out through the outlet; and 
     an analyzer connected to the outlet, for sampling gas flowing through the outlet, whereby the analyzer determines the presence of said substance, indicative of contamination of the article by said substance. 
     Yet another aspect of the present invention provides a method of effecting at least one of detection of a substance on a subject and decontamination of the subject, the method of comprising the steps of: 
     (1) enclosing the subject in an examination zone substantially closed off from the exterior; 
     (2) passing gas into the examination zone, to entrain at least one of vapours and particulates of said substance; and 
     (3) withdrawing gas from the examination zone. 
     The present invention further improves portals according to the prior art by adding at least one of, a breathing mask with a clean air supply so that the subject will not inhale toxic materials liberated from their clothing and skin, one or more flexible transparent screens over the entrance and exit of the portal to limit air exchange without inducing claustophobic symptoms in the person in the examination zone, a supply of decontamination agent to neutralize toxic materials, an analyzer to monitor the inlet air for contamination, a camera and an automated image analysis system to examine the person for miosis, or other symptoms of injury by toxic substances. 
     The most rapid and efficient route of ingestion of toxins is by inhalation. While air curtains are well suited to the removal of superficial toxic material, they may produce dangerous concentrations in the air being inhaled by the person being decontaminated. The improvements according to the present invention provide a breathing mask to supply pure air to a person undergoing examination and decontamination in a portal. Advantageously, this breathing mask can also be used to supply a therapeutic gas, such as oxygen. Many airborne toxins compromise respiratory function, and administration of oxygen is a recognised first-aid proceedure in cases of known or suspected exposure to airborne toxics. 
     Toxics made airborne during examination and decontamination could be a hazard not only to the person in the portal, but also to those awaiting processing and to emergency workers. While the design of prior art portals seeks to minimize air exchange with the outside environment in the interests of achieving the maximum concentrations of analyte in the sample airstream, this may not be sufficient to protect persons in the vicinity of a portal being used for decontamination, where the concentrations of evolved material are likely to be higher than in the contraband detection application. The obvious remedy of providing conventional doors on a portal has the disadvantages of slowing throughput and of inducing claustrophobic panic, particularly under the stress of an emergency. Accordingly, the improvements of the present invention provide the entrance and exit of the portal with flexible screens consisting of vertically-disposed ribbons of clear flexible material suspended from the lintels. The ribbons are flexible, slightly weighted at the bottom, and have a slight overlap of their vertical edges, so that they provide a significant barrier to gas exchange and yet even a child can easily walk through them, and this ease, combined with their transparency, makes closures of this type minimally threatening, particularly to chidren and the elderly. 
     Portals of the prior art provide an air flow which removes material from the skin and clothes of the person being processed. The improvements according to the present invention provide for the enhancement of decotamination by addition to the air stream, on the inlet side, of a gas, vapour, or particulate material which reacts with and neutralizes the toxic material to which the victim has been exposed. 
     For some time after a deliberate or accidental release of toxic material, clouds of toxics may continue to drift around the area. If such a cloud were to be ingested into the examination zone of a portal it would compomise the examination and imperil the health of the person being examined. Portals of the prior art are not designed to deal with impurities or hazardous materials in the input air. The improvements according to the present invention provide an analyzer, such as an ion mobility spectrometer, to monitor the inlet air and generate an audible, visible or other alarm if contamination is detected. 
     Portals of the prior art typically include sensors which could be programmed to indicate the level of contamination, but they do not provide any indication of the degree to which potential victims have been affected by their exposure. This information can be vital to triage in emergency situations, where large numbers of persons may be at risk, and highly-trained medical help and treatment resources are likely to be in limited supply or only obtainable at distant sites. The improvements according to the present invention provide a camera and automated image analysis system to examine the person for miosis, or other symptoms of injury by toxic substances. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example to the accompanying drawings, in which: 
     FIG. 1 is a walk-through portal in accordance with the prior art; and 
     FIG. 2 shows schematically a perspective view of additional components of the walk-through portal according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring first to FIG. 1, apparatus includes a main portal structure  2 , which comprises two vertical side members  3 ,  4  and a crosspiece  6  at the top. The vertical side members  3 ,  4  are generally vertical and parallel at the top thereof, and towards the bottom, include trapezoidal sections  8  shaped to match the human silhouette, ensuring efficient airflow and collection. The portal illustrated is one-sided, i.e. “walk-in” rather than “walk-through”. The rear wall can have a solid portion below a window; either walk-in or walk-through versions are possible, but having a solid wall simplifies control of air flow and aids efficient sampling. Note that, in its broadest since, the term “walk-through” is used in the claims to encompass a partial open on just one side and a partial open on both sides. 
     The vertical side members  3 ,  4  together with the crosspiece  6  define an examination zone  10 . To close off this examination zone  10 , flexible screens, indicated schematically at  12  are provided at the front and back of the apparatus, i.e., above and below the plane of FIG.  1 . 
     In the crosspiece  6 , inlets  14  are provided for ambient air. The inlets  14  are connected to a filter canister  16 , which in turn is connected to a plurality of jet orifices  18 . Often a heater  17  for preheating the air is provided downstream from filter  16 . To draw air through the examination zone  10 , a blower  20  is connected by an output decontamination filter  22  to an outlet  24 , opening near the bottom of the examination zone  10 . The orifices  18  are provided towards the top of the examination zone  10 . The exhaust stream from the blower  20  is indicated at  26 . An analyzer  28  having an indicator  32  is connected to the outlet  24 , immediately upstream from the decontamination filter  22  in order to detect the prescence of substances of interest. Here, an ion mobility spectrometer is shown. In some cases, the inlet filter  16  is omitted and the output of the blower is connected via a recirculation duct (not shown) to the orifices  18 . 
     In operation the person to be processed enters the examination zone  10  and makes a 90° turn. The blower is then activated and the outside ambient air is drawn into the portal through the inlet  14  and filtered through the filter canister  16 . The air is then heated by the heater  17 , if present, and is drawn into the interior volume, or examination zone  10  through the series of jet orifices  18 . The air pressure and flow are sufficient to levitate solid particles off the subject  40  and/or provide sufficient heat input to the toxic materials resident on the surface of the subject or victim  40  and his/her clothing, to cause their evaporation into the exhaust flow. The action of the blower  20  draws the exhaust flow  15  through the outlet duct  24  and decontamination filter  22 . As the flow passes through the duct  24  it is monitored by the analyzer  28 . If a clear indication is given, then the person  40  is told to exit the device. If a warning is given, then the flow is continued until the indication changes to clear or a preset time has passed. If the preset time is insufficient to achieve decontamination, then the person&#39;s status in the triage is advanced and they are diverted to appropriate secondary treatment. 
     Turning to FIG. 2, this shows schematically the improvements according to the present invention which extend the use of prior art portals to the triage and decontamination of persons who may have been exposed to toxic materials. In FIG. 2, the upper portions of the portal have been removed to show interior features. To close off the examination zone  10 , flexible screens, indicated schematically at  12  are provided at the front and optionally, at the back of the apparatus. The flexible screens  12  could be simple plastic strips or sheets, which are preferably easily removable for decontamination. For a simple installation, screens, or a screen, could be provided on just one side, although this would require a person to enter and exit from the same side. In use, a person enters the portal by walking through flexible screens  12 . If a person has bags or luggage, these can be checked with the individual, if small, or subject to a separate check. Once the person is within the examination zone  10 , the flexible screens  12  effectively, efficiently and quickly seal the zone  10 . 
     Where appropriate, a supply of decontamination agent can be provided. When contamination is detected the supply  41  is activated to supply the decontaminating agent via the conduit  42  to the inlet plenum  14  and hence to the examination zone  10 . The agent from the supply  41  can be such as to either break down, neutralize or destabilize the toxic chemical. Although not shown in FIG. 2, it will be obvious to those skilled in the art that, in portals where the output of the blower is recirculated, the conduit  42  will be connected to the recirculation duct. 
     An analyzer  44  furnished with an alarm  45  is connected to the inlet plenum  14  in order to monitor the air being drawn into the examination zone  10  for contamination. The analyzer  14  is advantageously an Ion Moboility Spectrometer. 
     Referring again to FIG. 2, a supply of pure air  50  is connected by a conduit  49  which passes through the wall of the examination zone  10  to a breathing mask  51 . Advantageously, the portion of the conduit  49  which is within the zone  10  is made of a flexible and extensible material so that a person of any size may comfortably use the breathing mask  51 . 
     To assist in assessment of the person being processed, a video camera  46  and lighting system  39  is provided. The camera  46  accquries electronic images of the person&#39;s face which are transferred by the cable  40  to an automatic image processor  48  which activates an alarm  47  if symptoms of injury are detected. In an alternative embodiment, the processor  48  is replaced by telemetric means which relays the image stream to a distant site for display and diagnosis by skilled personnel. It will be obvious that the telemetric means can be bi-directional and can allow the diagnostician at the remote site to control the alarm means  47  and thereby convey instructions to personnel on the scene of the emergency. Advantageously, additional cameras and lights (not shown) can be positioned within the zone  10  so as ensure that an appropriate view of the person being processed is available independently of their size or their orientation within the zone. 
     Several applications are contemplated for the improved walk-through portal of the present invention, including: 
     Transportable Decontamination Portals for First Responders and other emergency response teams. These units would be configured to be quickly set up. In cases of terrorist attacks and chemical toxic releases, the fastest possible response to provide decontamination and provision of uncontaminated air flow is vital. For a portable installation, the portal should be constructed in modular form of lightweight materials, such as plastics, which render easy transportation, and quick stripdown and reassembly, thereby facilitating movement to different sites. 
     Fixed Portal systems could be permanently established in key facilities or in areas where dangerous and volatile chemicals are stored, handled and analyzed, e.g. major manufacturing installations and the like. 
     Other aspects of this invention are shown in co-pending application, Ser. No. 09/389,019 and are hereby incorporated by reference.