CHEMICAL DEFENSE EQUIPMENT
MICHAEL R. O’HERN * ; THOMAS R. DASHIELL † ; AND MARY FRANCES TRACY ‡
† Consultant, Life Sciences and NBC Defense, 504 Thomas Avenue, Frederick, Maryland 21701-6251; formerly, Director, Environmental and Life Sciences, Office of the Director of Defense Research, Office of the Secretary of Defense, Department of Defense, Washington, D. C.
‡ Research Scientist, Chemical Warfare/Chemical and Biological Defense Information Center (CBIAC): a Department of Defense Information Analysis Center operated by Battelle Memorial Institute and sponsored by Defense Technical Information Center, Aberdeen Proving Ground, Maryland 21010-5425
A number of countries around the world have the capability to use chemical weapons. In fact, within the past decade, several events have been well documented where chemical weapons were used in armed conflict, most notably during the Iran–Iraq War. The most recent threat of such use was during the Persian Gulf War, where U.S. forces might have been exposed to the effects of both chemical and biological agents. An essential part of preparedness to continue operations in a chemical environment is adequate equipment.1,2 Such equipment must encompass all areas of concern: detection and warning, personal protective equipment, decontamination and medical prophylaxis, and treatment. Only an integrated approach to the problem of protection can allow individuals to provide an effective response in a chemical warfare environment with a minimum degradation in human performance.
The primary item of protection is the personal respirator, designed to protect individuals against volatile agents and aerosols. The respirator must be carefully fitted on the face to ensure minimal leakage, and individuals must be well trained in the donning of masks (a maximum of £ 9 sec being desirable). In addition to the respiratory hazard, many chemical agents are dermally active. This requires that a proper overgarment, usually containing an activated charcoal layer to adsorb chemical agent, be donned, along with protective gloves and boots. The complete ensemble can seriously degrade individual performance; 50% reduction of mission-related task performance has routinely been measured in tests. (The physiological effects of wearing chemical and biological protective gear are discussed in detail in Environmental Hazards of the Battlefield, a forthcoming volume in the Textbook of Military Medicine series.) In addition to physical performance degradation, there are reports of psychological problems with some individuals while wearing the complete ensemble, owing to the claustrophobic effects.3 This subject is discussed separately at the end of this chapter, in a section titled Psychological Problems Associated With Wearing Mission-Oriented Protective Posture Gear.
The rapid detection and warning of an opponent’s use of chemical agents is critical to the protection of forces.4,5 Usually, the chemical agent will be delivered via an aerial or missile attack, or an upwind release where the cloud of agent passes over a troop concentration. Timely detection is required to permit all potentially exposed forces to adopt an adequate posture, since the effects of agents can sometimes occur in less than a minute. Vesicant agents and some nerve agents (eg, VX and some of the G series), which can remain active for long periods of time, can affect individuals via the dermal route, thus requiring that a proper overgarment be part of the protective ensemble. Likewise, detection equipment is also used to confirm agent hazard reduction and facilitates reducing the mission-oriented protective posture (MOPP) level and the removal of protection equipment: the “all clear” signal.
Decontamination of equipment, facilities, and personnel is also required after an attack if effective military operations are to be maintained. Some of this decontamination burden can be mitigated by the use of effective collective protection equipment, which can allow continuing operations such as communications and medical care within protected facilities.
One criterion for the selection and use of protective equipment items is the need for joint service use, although there are some differences between the missions of air and ground crews that must be accommodated. This chapter is not intended to be all-encompassing in chemical defense equipment; rather, it is intended to describe the items and operations that are of greatest interest to the medical community.
The following sections address each of the protection areas described above in detail, with the current equipment items featured and items in development that are designed to overcome the deficiencies of present equipment briefly described. Sufficient technical data are included to allow the healthcare professional to become familiar with the operation, components, and the limitations of the present chemical defense equipment. Should the interested reader desire more detail on chemical defense equipment, several sources are available. First, the written references and expert consultants to this chapter are sources of vast amounts of information. Possibly of more value to the healthcare professional is the nuclear, biological, and chemical (NBC) officer who is an integral part of each combat element and who is available to provide detailed advice as well as hands-on assistance.
Several tangential issues must be noted that impact on the area of chemical defense equipment, especially in the future. First, a continuing intelligence need exists to identify new agents that may be used against combat forces and ensure that the defense equipment meets the new threats. Second, it cannot be overemphasized that a viable, active, training program be maintained. And third, medical input into operations while participants are wearing protective equipment is vital to maintenance of a combat operation. Rest periods consonant with work loads and MOPP gear will allow continuing operations even in a contaminated environment. The development program will provide continuing improvements in the chemical defense equipment available to the forces, and updates will be required as new and better equipment comes on line.
The chemical–biological warfare threat can come in three possible physical forms: gas, liquid, and aerosol (ie, a suspension in air of liquid or solid particles). Protection against chemical agents disseminated as aerosols is especially difficult because the individual particles deliver a large amount of agent at a tiny site, thereby overwhelming the local capacity of the adsorbent.
Chemical agents can gain entry into the body through two broad anatomical routes: (1) the mucosa of the oral and respiratory tracts and (2) the skin. The icon of chemical warfare—the gas mask—protects the oral and nasal passages (as well as the eyes), while the skin is protected by the overgarment.
As noted earlier, total individual protection requires an integrated approach with the primary mechanism being respiratory protection which, when combined with an overgarment, gloves, and boots all properly fitted and used correctly, can provide excellent protection against chemical agents of all known types.
Much of the basis of our understanding of the general principles of respiratory protection is contained in four source documents:
The fundamental question of protective mask design was first addressed in World War I: should the mask completely isolate the soldier from the poisonous environment or should the mask simply remove the specific threat substance from the ambient air before it can reach the respiratory mucosa? The first approach requires that a self-contained oxygen supply be provided. Because of a multitude of practical logistical constraints (eg, weight, size, expense), this approach is not used except for specialty applications in which the entire body must be enclosed.
The more common practice has been to follow the second approach: to prevent the agent from reaching the respiratory mucosa by chemically destroying it, removing it in a nonspecific manner by physically adsorbing it, or both. Destruction by chemical reaction was adopted in some of the earliest protective equipment such as the “hypo helmet” of 1915 (chlorine was removed by reaction with sodium thiosulfate) and in the British and German masks of 1916 (phosgene was removed by reaction with hexamethyltetramine).6 More commonly, the removal of the agent was brought about by its physical adsorption onto activated charcoal. (Due to its mode of formation, this substance has an extraordinarily large surface area, some 300–2,000 m2 / g,10 with a corresponding plethora of binding sites.) It was soon recognized that impregnation of the charcoal with substances such as copper oxide, which reacted chemically with certain threat agents, further increased protection.6
The effectiveness of modern masks depends on both physical adsorption and chemical inactivation of the threat agent. For example, in the M17 protective mask the adsorbent, known as ASC Whetlerite charcoal, is charcoal impregnated with copper oxide and salts of silver and chromium.6 The M40 protective mask uses an ASZ impregnated charcoal, which substitutes zinc for the hexavalent chromium (CrVI). The Centers for Disease Control and Prevention and the National Institute for Occupation Safety and Health have identified CrVI as a potential human carcinogen.11 A filter layer to remove particles and aerosols greater than 3 µm in diameter is also a component of all protective masks.
| The location of the filters and
adsorbent vis-à-vis the respiratory tract was also one of the questions
that mask designers addressed in World War I.
Several of the essential features of modern protective mask design—features that might be thought to be more recent—also originated during World War I. For example, designing the inside of the mask so that inhaled air is first deflected over the lenses (which prevents exhaled air, saturated with water vapor, from fogging the lenses) and the use of separate one-way inlet and outlet valves (to minimize the work of breathing) were World War I–era inventions. The need of masked soldiers to be able to talk to one another was also recognized then. Interestingly, in the period after World War I, the U.S. Navy introduced the first useful solution to this problem: a moveable diaphragm held in place by perforated metal plates in the front of the mask. This device ultimately became the voicemitter found in today’s protective masks.6
An important question of mask design is the composition of the elastic material used to cover the face: the faceblank. The first masks introduced in World War I were made of rubberized cloth or leather. Subsequent masks used natural rubber, but recently, sophisticated synthetic polymers using silicone, butyl, and perfluorocarbon rubbers have been used.6 Silicone rubber has the advantage of making possible a tight fit or seal between the mask and skin, with a correspondingly decreased potential for leaking (a factor said to be responsible for about 5% of mask failures).12
Unfortunately, silicone rubber offers rather low resistance to the penetration of common chemical agents. Perfluorocarbon rubber is very impermeable but is expensive and tears easily. Butyl rubber offers both good protection and seal and has therefore become the material of choice.7 Even this description of materials used to construct the faceblank underestimates the complexity of actual mask design. In today’s standard U.S. military masks, the faceblank consists of two separate layers: an inner layer made of silicone rubber (for maximum seal) and an outer layer made of butyl rubber for maximum protection (Figure 16-2).
| The work of breathing added by the mask
is an important factor; it determines not only soldiers’ acceptance of
a given mask, but more importantly, the degree that a soldier’s
exercise tolerance is degraded. Since the pressure gradient that is
required to move a given mass of air is flow-rate dependent, to make a
quantitative comparison between the work of respiration of different
masks, it is necessary to specify a specific flow rate. For example, at
a flow rate of 85 L/min, a pressure gradient of about 8 cm H2O
is observed in World War II–vintage masks. At the same flow rate, the
gradient for the M17 is 4.5 cm H2O, and for the M40, 5 cm H2O.6
By way of contrast, breathing at a rate of 85 L/min without a mask
requires a pressure gradient of 1.5 cm H2O. 13
Some mask wearers perceive the 3-fold increase in the work of breathing
as “shortness of breath.”
Developmental objectives in personal respiratory protection equipment generally encompass factors such as personal comfort, breathing resistance, mask weight, and the ability to provide protection from new agents. Present equipment has met a number of these objectives but much remains to be done, especially in the area of new and improved chemical-resistant materials, manufacturing methods, and scratch-resistant lenses. All of these items must be integrated into a new, reliable, less cumbersome, and less degrading system.
Ground Crew Personal Protective Equipment
The equipment described below is generally suitable for use by all services, although oceanic environments may require that other construction materials be developed for the navy and marine corps. The masks protect against all known chemical and biological agents, whether in droplet, aerosol, or vapor form. However, a protective mask is only as good as its fit. In the past, the degree of fit was assessed by field-expedient qualitative indices (eg, the degree to which the mask collapsed with its inlet valve obstructed). The modern technology incorporated into the M41 Protection Assessment Test System allows the degree of fit to be quantitated.
M41 Protection Assessment Test System
The protective masks issued to members of the U.S. armed forces protect the individual’s face, eyes, and respiratory tract from field concentrations of chemical–biological agents, toxins, and radioactive fallout particles. Several critical steps must be taken to ensure that an assigned mask will function properly in a toxic chemical environment:
| Communication is provided by two
voicemitters. One is mounted in the front to allow face-to-face
communication; the second is located in the cheek to permit the use of a
radio telephone handset. A drinking system consists of internal and
external drink tubes; the external tube has a quick-disconnect coupling
that connects with the M1 canteen cap. A six-point, adjustable harness
with elastic straps located at the forehead, temples, and cheeks comes
together at a rectangular head pad.
The M40 mask comes in three sizes: small, medium, and large. Optical inserts are provided for vision correction and outserts are available to reduce fogging and sun glare and to protect against scratching. A check valve on the nosecup prevents exhaled air from fogging the lenses inside, and an air deflector directs inhaled air over the lenses, which also helps prevent fogging. Accessory items available include a carrier, a hood to protect the neck areas, and a waterproof bag.16–18
Mask, Chemical–Biological: Field, M42
The M42 Chemical–Biological Field Mask is the same series as the M40. The materials of construction and the basic features are identical, but the M42 protective mask is used by combat vehicle crews (Figure 16-8).
Filtration is provided by a C2A1 canister attached to the mask by a corrugated hose; the canister is housed in a specially designed canister carrier. The M42 integrates with the combat vehicle filtration protection system. The M42 also has a dynamic microphone that integrates with the combat vehicle via a microphone cable.19,20
Mask, Chemical–Biological: MCU-2/P
The MCU-2/P Chemical–Biological Mask is used by U.S. Air Force ground crews and aircrews when not in flight. This protective mask is constructed of molded silicone rubber facepiece material, and an integral, molded, polyurethane, one-piece panoramic lens is bonded to it (Figure 16-9).
Aircrew Personal Protective Equipment
Each protective mask in current use is described in detail. There are some differences between the masks designed for helicopter use and high-performance aircraft, owing notably to the operational envelope. All masks protect against all known chemical and biological agents whether in droplet, aerosol, or vapor form.
|Mask, Chemical–Biological: Aircraft, M43
The facepiece of the M43 Chemical–Biological Aircraft Mask is fabricated of bromo butyl and natural rubber with an integral butyl hood and skull-type suspension system (Figure 16-10). The M43 has two models, designated Type I and Type II. The two models are identical with the following exceptions: Type I has a notch in the right eyepiece that accommodates a special sighting device used by Apache helicopter pilots, and uses a different microphone for communication; Type II has two spherical lenses and uses a dynamic microphone. Both microphones interface with the helicopter communications systems.
The mask has an inhalation air-distribution assembly for regulating the flow of air to the mouth and nose, eyelenses, and hood assembly. The M43 mask has a drink capability which couples with the canteen cap. The mask is produced in four sizes from small to extra-large. Accessories include a mask carrier, vision correction outserts, winterization kit, nuclear hood, facepiece carrier, eyelens cushions, and a blower and harness assembly.
This new design effort was based on the need for little-to-no visual impairment. The requirement was met by placing the protective mask’s eyelens 14 mm from the eye, which kept the spherical curvature equidistant from the corneal surface to eliminate parallax. This lens configuration increased visual capability to within 4% of nonmasked vision in the same individual. Each mask is fitted to an individual crewman and remains with that crewman while he remains on flight status.21,22
Mask, Chemical–Biological: Aircrew MBU-I9/P
The MBU-19/P Chemical–Biological Aircrew Mask is the newest generation to be fielded by the U.S. Air Force exclusively for aircrews. This mask, dubbed the Aircrew Eye/Respiratory Protection (AERP) system, is issued in a helmeted version for fighter pilots and in a nonhelmeted version for aircrew and pilots of other types of aircraft (Figure 16-11).
The blower system incorporates a variable-speed motor, battery, external power-supply cable, housing assembly, control switch, chemical–biological canister, and a means of securing the blower while the crew member is mobile. The mask receives filtered air from the blower unit, which also allows overpressure within the hood which defogs the lens and is vented through an exhaust valve. The communication system consists of the intercommunication unit, battery, electrical branch assembly, microphone, and bracket.
Developmental Respiratory Protection Equipment
The objective of development systems is to provide the next generation of respiratory protection equipment that will minimize mission degradation and assure compatibility with future weapons systems and equipment while maintaining protection levels. RESPO 21 is the latest generation wherein new materials and manufacturing technology are being investigated and evaluated. 23 New and improved filtration systems designed to remove or degrade new classes of agents are under evaluation. Systems designed to meet all service needs in one equipment item are in the design phases. It is hoped that these systems will overcome the deficiencies found in current equipment (eg, excessive weight and performance degradation).
An overgarment can be made to protect skin from chemical agents by either physical or chemical means:
Placing a soldier into full chemical protective equipment—mask, overgarment, gloves, and boots—is a decision that appropriately considers not only the protection aspect but also the added heat stress and potential for dehydration. The heat stress problem must be recognized from the start.
|Personnel must begin a drinking regimen prior to encapsulation to
ensure that they do not become dehydrated quickly. The physical burden
of a full ensemble can add 9 to 14 lb to a normal load; this added
weight combined with heat stress, dehydration, and physical exertion can
cause significant impairment to any mission.
Because of these factors, the completeness of protection is stratified by the anticipated magnitude of the threat from chemical–biological agents: that is, the mission-oriented protective posture (Figure 16-12). Five MOPP levels have been recognized previously, but with Change 2 to Field Manual 3-4, NBC Protection, the number was updated to seven in 1996 (Exhibit 16-1).5 The two new MOPP levels are MOPP Ready and Mask-Only Command, but readers should be aware that MOPP levels are revised frequently to meet newly defined needs.
The MOPP level must be coordinated with the work load if troops are to remain effective. The over-garments in present use must be redesigned to reduce heat stress, reduce weight and bulk, and provide increased comfort as well as reduce the logistical burden. The present clothing will be described in detail except for the special-purpose equipment used by demilitarization personnel or special-purpose forces.
The sources for the following discussion are Items of Combat Clothing and Equipment, 24 and experts at the U.S. Army Natick Research, Development, and Engineering Center, Natick, Massachusetts, 25 whom interested readers can consult for greater detail.
Like various other armies of the world, the U.S. Army has chemical protective clothing available for individual protection. Several types are available, depending on the protection required to perform a specific mission and whether the protective clothing needs to be permeable or impermeable. Most troops use permeable protective clothing, which allows for air and moisture to pass through the fabric without hindering the chemical protection capabilities of the clothing. This type of permeable protective clothing is described in the following section.
The current standard A protective overgarment is the battledress overgarment (BDO). The BDO protects the wearer from all chemical agent vapors, liquid droplets, biological agents, toxins, and radioactive alpha and beta particles; however, the BDO does not stop either X or gamma radiation. For weartime and protective capabilities of the BDO following removal from the protective bag, refer to Field Manual 3-4/Fleet Marine Force Manual 11-9, NBC Protection.5 The BDO protects the wearer for 24 hours after contamination from chemical agent vapors, liquids, and droplets; and biological agents and toxins.
The effectiveness of the BDO is in its serviceability. Weartime of the BDO begins when it is removed from the sealed vapor-barrier bag and stops when it is returned to the vapor-barrier bag. Wearing the BDO for any part of a day constitutes a day’s wear. The BDO becomes unserviceable if it is torn, ripped, a fastener is missing or broken, or petroleum, oils, or lubricants are splashed or spilled on the overgarment. This unserviceableness necessitates replacement.
The BDO is manufactured in two layers: a tightly woven outer layer and a charcoal-impregnated inner layer to adsorb agent liquid or vapor (Figure 16-13). The garment consists of a hip-length coat and trousers with appropriate fasteners and multiple pockets. It is manufactured in eight sizes ranging from XXX Small through XX Large. The BDO is not designed to be decontaminated or reimpregnated for reuse.
Chemical Defense Aircrew Ensemble
The chemical defense aircrew ensemble (CDAE) is the newest generation of aircrew protective clothing to be fielded by the U.S. Air Force. It is a one-piece garment consisting of the Nomex flight suit, a charcoal undergarment, and long cotton underwear. The CDAE incorporates carbon-sphere technology to adsorb chemical agent. It is basically two suits differing in color: the CWU-66/P is green and the CWU-77/P is brown. It may be laundered as many as 10 times prior to chemical agent exposure without destroying the protective capabilities of the coverall. 26
Protective Boots and Gloves
A soldier wearing the chemical protective boots and gloves discussed here will soon realize that mobility is compromised by the boots and that tactile ability is degraded by the gloves. The present boots provide good protection against chemical warfare agents but are only an interim solution to the need for combined chemical protection, ease of decontamination, and safety. Wearers are at serious risk of falls due to the lack of adequate traction, and the weight of the boot contributes to the increased fatigue from complete protection ensemble wear.
| The boots do not protect the wearer from
heat or cold and in some cases may contribute to medical problems such
as trench foot, frost bite, or other cold weather injuries. The
protective gloves degrade tactility and again will not protect against
heat or cold and may increase the chance of cold weather injuries if the
work glove is not worn over the protective glove. The following
descriptions of protective boots and gloves are based on information
from NBC Protection. 5
Green and Black Vinyl Overboots
Chemical Protective Footwear Cover
Chemical Protective Glove Set
The chemical protective glove set consists of an outer glove for chemical protection and an inner glove for perspiration absorption. The outer glove is made of impermeable butyl rubber and the inner glove is made of white cotton. The gloves come in three thicknesses: 7, 14, and 25 mil. Soldiers such as medical, teletypist, and electronic repair personnel, whose tasks require extreme tactility and sensitivity, and who will not expose the gloves to harsh treatment, will use the 7-mil glove set. Aviators, vehicle mechanics, weapons crews, and other soldiers whose tasks require tactility and sensitivity will use the 14-mil glove set (Figure 16-17). Soldiers who perform close combat tasks and other heavy labor tasks will use the 25-mil glove set.
All of the glove sets protect against liquid chemical agents and vapor hazards. However, if the 7- mil glove set is contaminated, it must be replaced
Developmental Whole-Body-Protection Equipment Items
The Joint Service Lightweight Integrated Suit Technology (JSLIST) program is developing the next generation of overgarment, which will be fielded in Fiscal Year 1997. The JSLIST program provides the future whole-body chemical–biological protective equipment for the joint services (U.S. Army, Navy, Air Force, and Marine Corps). The JSLIST program encompasses a lightweight garment (undergarment, overgarment, duty uniform) and improved chemical protective handwear and chemical protective overboot. It will provide less bulk and heat stress by being constructed of state-of-the-art materials (the exact materials are not yet known, however) and will be more durable and launderable than current designs. The items in the JSLIST series are joint-service standardized items and are planned to be used by all services.28,29
In addition to the JSLIST, new agent-impermeable materials are being evaluated in conjunction with advanced fabrics to replace the carbon-impregnated fabrics, which have limited lifetimes. These new materials will be lighter, allow permeation of moisture while retaining protection, and cause less heat stress.
The JSLIST Overgarment (OG) is a universal, lightweight, two-piece, front-opening garment that can be worn as an overgarment or as a primary uniform over personal underwear (Figure 16-18). It has an integral hood, bellows-type pockets, high-waist trousers, adjustable suspenders, adjustable waistband, and waist-length jacket. This design improves system compatibility, user comfort, and system acceptance, and maximizes individual equipment compatibility. The JSLIST OG provides optimum liquid, vapor, and aerosol protection and also flame protection.
JSLlST Aviation Overgarment
The JSLIST Aviation Overgarment (AVOG) is the aviator’s version of the JSLIST OG and Duty Uniform (DU) configurations. It is a two-piece, front-opening, flame-resistant garment designed as a chemical protective overgarment or uniform. For cockpit compatibility, the integral hood and bellows-type pockets of the OG and the DU have been replaced with a crew-type collar and sewn-down pockets (Figure 16-19).
JSLIST Duty Uniform
The JSLIST Duty Uniform (DU) is a universal, lightweight, two-piece, front-opening garment that is worn as a primary uniform over personal underwear. It has an integral hood, bellows-type pockets, high-waist trousers, adjustable suspenders, adjustable waistband, and waist-length jacket (Figure 16-20). This improves system compatibility, user comfort, system acceptance, and ensures maximum individual equipment compatibility. The DU provides optimum liquid, vapor, and aerosol protection as well as flame protection.
JSLIST Vapor Protective Flame-Resistant Undergarment
The JSLIST Vapor-Protective, Flame-Resistant Undergarment (VPFRU) is a two-piece (jacket and drawers), front-opening, vapor-protective garment (Figure 16-21). It is configured with an integral form-fitting hood and detached vapor-protective, fire-resistant socks. Worn under standard duty uniforms, including the combat vehicle crewman coveralls and battle-dress uniform, the VPFRU is designed to provide the chemical vapor and biological agent protective layer. For Special Operations Forces and armor crews, the VPFRU is intended to provide maximum vapor and aerosol protection and MOPP flexibility.
|JSLIST Improved Chemical and Biological Protective Glove
The JSLIST Improved Chemical and Biological Protective Glove (ICBPG) is designed to provide protection against chemical and biological agents in liquid, vapor, and aerosol form (Figure 16-22). Its protection performance is not degraded by exposure to petroleum, oil, and lubricants and to field decontaminants. To prevent excessive moisture buildup and improve user comfort, the ICBPG is semipermeable. The glove can be worn for up to 30 days without performance degradation and is flame resistant.
JSLlST Multipurpose Overboot
The JSLIST Multipurpose Overboot (MULO) is designed to be used for daily wear as required by the weather and is flame resistant.
As noted in the introduction, timely detection and warning are critical to the protection of forces— especially since chemical agents act very quickly. Detection of an attack, with subsequent warning of affected forces downwind, can allow adoption of an effective protective posture and continuation of military operations with minimal degradation of operations. We discuss here those instruments most widely fielded; some special-purpose items are not discussed.
The army has recently fielded two new systems, the FOX and the Biological Integrated Detection System (BIDS), which are discussed below. Each of these new systems integrates a variety of detectors into a mobile, crew-served system; the composite detectors are vastly superior to any individual detector previously available.
Sources for this discussion are the Worldwide Chemical Detection Equipment Handbook 30 and experts at Aberdeen Proving Ground, whom readers who are interested in greater detail can consult.
Chemical Detection and Warning
This section briefly describes some of the fielded chemical detectors that may be of most use within the medical community. These detectors are divided into two groups: point detectors and standoff detectors.
Point detectors sample the immediate area to determine the presence of chemical agents. The sample is most often taken from the atmosphere; however, specialized detection kits can be used to sample the soil or water. In addition to monitoring the atmosphere, the point detectors provide monitoring after an attack, identify the contaminated area, monitor collective protection areas, monitor effectiveness of decontamination, and identify chemical contamination during reconnaissance efforts.
M8 Chemical Agent Detection Paper detects and identifies liquid chemical agents. It is tan in color and comes in a booklet containing 25 perforated sheets (2 in. x 3 in.), which are heat sealed in a polyethylene envelope. There are three sensitive indicator dyes suspended in the paper matrix. The paper is blotted on a suspected liquid agent and observed for a color change, which will occur within 30 seconds: VX turns the paper dark green, the G series of agents turn the paper yellow (see Chapter 5, Nerve Agents), and blister agent turns it red (Figure 16-24). M8 paper will change color with many interferents such as sodium hydroxide and petroleum products; thus, it is unreliable to use to check for completeness of personnel decontamination and should always be verified with another means of identification.
|M9 Chemical Agent Detection Paper
M9 Chemical Agent Detection Paper is a portable, single roll of paper that comes with a Mylar adhesive- backed and-coated tape. It contains a suspension of an agent-sensitive dye in a green-colored paper matrix. The agent-sensitive dye will turn pink, red, reddish brown, or red-purple when exposed to agent but does not identify the specific agent. M9 paper is more sensitive to nerve and blister agents and reacts more rapidly than M8 paper, although it also reacts to a wide range of interferents such as petroleum products, brake fluid, aircraft cleaning compounds, DS2, insect repellent, defoliant, and antifreeze.
Chemical Agent Monitor and Improved Chemical Agent Monitor
The chemical agent monitor (CAM) and improved chemical agent monitor (ICAM) are hand-held, soldier-operated devices designed for monitoring chemical agent contamination on personnel, equipment, and surfaces. They use ion mobility spectrometry technology to detect and discriminate between mustard and nerve agent vapor. The concentrations of agents detected by the CAM and ICAM areas are as follows: for sarin (GB), 0.03 mg/m3; for VX, 0.1 mg/m3; and for mustard (HD), 0.1 mg/m3.
The units are simple to operate, can be held in either hand while the user is wearing chemical protective equipment, and operate day or night (Figure 16-26).
Specific information in this discussion of the CAM and ICAM is drawn from Chemical Agent Monitor Employment31 and Operator’s and Organizational Maintenance Manual for the Chemical Agent Monitor (CAM),32 which interested readers may wish to consult.
Chemical Agent Detector Kit
The detection limits for the M256A1 are as follows: for the G series of nerve agents, 0.005 mg/m3; for VX, 0.02mg/m3; for the vesicants mustard (HD) and Lewisite, above threshold concentrations of 3.0 mg/m3 and 14 mg/m3, respectively; and for hydrogen cyanide (AC), 11 mg/m3, and cyanogen chloride (CK), 10 mg/m3.
The M256A1 kit cannot be used to detect agent in water. It can, however, be used to check an area before a military unit moves in or to define clean areas or routes. Some chemical ingredients in the kit are considered possible carcinogens and should be handled as such. The emissions produced by this kit are also toxic; a mask and gloves must be worn while the kit is being used.
Fig. 16-27. (a) The M256A1 Chemical Agent Detector Kit and (b) the sampler/detector found inside the carrying case. Reprinted from Brletich NR, Waters MJ, Bowen GW, Tracy MF. Worldwide Chemical Detection Equipment Handbook. Edgewood, Md: Chemical Warfare/Chemical and Biological Defense Information Analysis Center; October 1995: 429. Photograph (a): Courtesy of Environmental Technologies Group, Inc, Baltimore, Md.
|Chemical Agent Water Testing Kit
The M272 Chemical Agent Water Testing Kit is designed to detect and identify, via colorimetric reactions, hazardous levels of nerve agents, mustard, Lewisite, and cyanide in treated or untreated water (Figure 16-28). A full kit contains enough supplies to perform 25 tests for each agent, and simulants are included for training use. About 20 minutes is required to perform all four tests. All bodily contact should be avoided with the kit chemicals, as some can be very harmful and should only be handled while wearing protective gloves and equipment.
Detection limits are as follows: for the G-series nerve agents and VX: 0.02 mg/L; for the vesicants Lewisite (L) and mustard (H and HD): 2.0 mg/L; and for the cyanides (AC and CK), 20 mg/L.
The M8A1 Automatic Chemical Agent Alarm is an automatic chemical agent detection and warning system designed to provide real-time detection of the presence of nerve agent vapors or inhalable aerosols. The M8A1 consists of the M43A1 detector and up to five M42 alarms, which will provide both an audible and a visible warning (Figure 16-29). The M43A1 is an ionization product diffusion/ion mobility type detector; it will sound a false alarm in the presence of heavy concentrations of rocket propellant smoke, screening smoke, signaling smoke, engine exhausts, and whenever a nuclear blast occurs.
The M8A1 can be located within a hospital complex, with alarm units placed to cover all critical care, treatment, and support areas. The M43A1 detects nerve agent vapors at concentrations of 0.2 mg/m3 for sarin (GB) and 0.4 mg/m3 for VX.
Early warning of chemical agents provides troops the necessary time to increase protective posture and to avoid contaminated areas. Standoff detectors provide this early warning at a distance of 1 to 5 km.
Optical remote sensing (ORS) technologies, employing infrared spectral analysis techniques, have been utilized in the development of chemical agent standoff detection technologies. Within the ORS technologies, there are two types of remote sensing systems: passive and active (laser). The section below only looks at the passive system, which employs a Fourier Transform Infrared (FTIR) spectrometer.
|Alarm: Remote Sensing Chemical Agent Alarm M21
Usually, the M21 is placed facing into the wind. It measures and stores a background spectrum that is then compared by an onboard microcomputer, which makes agent/no agent decisions based on ambient radiance levels. Response time is 1 minute or less. The system is fielded to NBC reconnaissance units.
The sensitivity of the M21 for detecting nerve agents (GA, GB, and GD) is 90 mg/m3; and for vesicants is 500 mg/m3 for Lewisite and 2,300 mg/m3 for HD mustard.
Developmental Detection and Warning Items
In the area of chemical detection, the next developments are
Integrated Mobile Systems
M93A1 FOX Nuclear, Biological, Chemical Reconnaissance System
The M93A1 FOX Nuclear, Biological, Chemical Reconnaissance System (NBCRS) is a recently deployed, comprehensive solution to the problem of early recognition of NBC threats on the modern battlefield. Numerous sophisticated instruments have been mounted in a fast, mobile, 6x6 armored vehicle that weighs about 19 tons and is manned by a crew of three (Figure 16-31). The vehicle is of German origin, and the name FOX is a translation of Fuchs, for whom the design was named.
The FOX is instrumented to detect chemical contamination in its immediate vicinity with a variety of probes, and at a distance via a standoff detector (M21). Meteorological data are also sensed. Data are analyzed, synthesized, and transmitted to higher-echelon units by a secure, jam-resistant communication system. The local area is marked by warning markers ejected through a hatch in the rear of the vehicle. A global positioning system makes possible accurate marking of the contaminated locale. The interior of the vehicle is pressurized and offers collective protection against threat agents.
XM31 Biological Integrated Detection System
The XM31 Biological Integrated Detection System (BIDS) consists of a lightweight, multipurpose, collective protection shelter mounted on a heavy high-mobility, multipurpose, wheeled vehicle (HMMWV) and equipped with a biological detection suite (Figure 16-32). In its present configuration, the BIDS can detect the bacteria Bacillus anthracis and Yersinia pestis, and the toxins botulinum toxin A and staphylococcal enterotoxin B.
Several technological approaches are used sequentially to detect and confirm the presence of specific biological threat agents. Since biological threat agents are likely to be dispersed as aerosols, ambient air is continuously sampled and the background distribution of aerosol particles determined. Aerosol particles in the 2- to 10-µm diameter range are concentrated and then subjected to analysis for
Collective protection serves a vital role in the medical area since treatment of casualties must continue even in a contaminated environment, thus collective protection is required to allow this critical function to continue. In addition, it allows individuals to rest and eat, and provides temporary relief from the individual protection equipment thus allowing continuing military operations in the contaminated environment. Collective protection systems have been designed to be used in either a medical or a nonmedical application.
The sources for this discussion are experts at the U.S. Army Chemical and Biological Defense Command, 34 and Collective Protective Equipment, U.S. Army Training Manual 34240-338-10,35 which interested readers can consult for greater detail.
Medical Collective Protection Systems
The Medical Collective Protection Systems provide ample floor space and are accessible for litter patients through airlocks. Additionally, some of the systems provide airlocks through which ambulatory patients can pass. These options aid the medical community in its tasks when dealing with casualties in a chemically contaminated environment.
Chemically Protected Deployable Medical System
The chemically protected deployable medical system (CP DEPMEDS) consists of the M28 collective protection equipment (CPE), which is designed to protect critical areas within the hospital complex from chemical–biological contamination (Figure 16-33). The M28 CPE can only be used with the TEMPER (tent, extendable, modular, per)sonnel system. The entire composite hospital ensemble consists of expandable tentage, passageways, environmental control units, and ISO (International Organization for Standardization, from the French) shelters.
The M28 CPE consists of the following items: end sections, center sections, and vestibule liner fabricated from a plastic film that is resistant to liquid and vapor agents; a protective entrance airlock for ambulatory personnel that is made from a butyl-coated material and hung in a collapsible aluminum frame, creating a triangular shape; a tunnel airlock for litter-borne patients, consisting of a collapsible frame with entry and exit doors at opposite ends fabricated from an NBC protective cover; the hermetically sealed filter canister and the accessory package, which support the purge requirement during collective protective entry; and the recirculation filter, which is a portable self-contained unit designed to filter any chemical agent vapors brought in through the entry or exit.
Chemically Hardened Air Transportable Hospital
The U.S. Air Force utilizes the Chemically Hardened Air Transportable Hospital (CHATH) in its operations. The CHATH is basically the same as the CP DEPMEDS. The air force is developing a chemically hardened air-management plant (CHAMP), which will provide 800 cu ft/min of filtered air, environmental control, and power generation integrated into a single (albeit very large) package. The CHAMP is intended to replace all M20/M28 filter blower sets. Although the CHAMP is intended to be used with the CHATH, it is competing with the air force’s field deployable environmental control unit (FDECU) as the system to actually be applied to the CHATH.
Chemical and Biological Protected Shelter
The Chemical and Biological Protected Shelter (CBPS) is a direct replacement for the M51 C/B shelter, which eliminates the excessive erection/striking time, the insufficient floor space, lack of natural ventilation, and the unavailability of prime movers, which were the problems with the M51.
The CBPS is staffed by a crew of four, who are carried in the HMMWV. The inflatable rib tent provides 300 sq ft of usable floor space, with a litter-patient airlock (Figure 16-34) and optional ambulatory-patient airlock. The CBPS has removable side entrances to allow side-to-side setup of additional CBPS.
Nonmedical Collective Protection
The nonmedical collective protection systems provide protection for two or more individuals from the effects of chemical agents present in the environment. These systems provide an area for individuals to perform their functions without experiencing deleterious effects.
M20 Simplified Collective Protection Equipment
|Developmental Collective Protection Items
New developments in collective protection will center on
For these systems to provide environmentally controlled atmospheres, environmental control units are being developed to be compatible with collective protection systems. At the present, however, there are neither heaters nor air conditioners that can be used with collective protection equipment. The air force’s FDECU, currently in late-stage development, is the primary candidate and is able to heat and cool.
The physical properties of chemical agents are highly variable. They range from nerve agent vapor, which usually dissipates in a few minutes to a few hours, to vesicants such as mustard, which can remain active for weeks (or in some cases, years: buried and recovered World War I mustard projectiles are often still quite toxic). It is imperative, then, that timely decontamination of the skin and personal equipment that has been exposed to agent, especially liquid agent, be completed. Skin decontamination should take place within 2 minutes if possible, and equipment decontamination should be completed within 1 hour.
To effectively perform complete personnel and equipment decontamination operations, decontamination units use truck-mounted tanks, pumps, and water heater units; and trailer-mounted pumps and water heater units. In these processes, reducing the exposure time of the individual or piece of equipment to the chemical contaminant is of the highest priority.
The sources for this discussion are Decontamination of Chemical Warfare Agents37 and NBC Decontamination,38 and experts at the U.S. Army Chemical and Biological Defense Command.39 Readers interested in greater detail can consult these sources and the authors of this chapter.
Personnel Decontamination Items
Personnel decontamination is performed to reduce the level of contamination so it is no longer a hazard to the individual. Personnel decontamination consists of removal of clothing and decontamination of the skin. To expedite this procedure, personnel decontamination kits are used to remove the gross contamination. Complete decontamination, which is conducted by specialized decontamination units, is provided to troops to reduce the requirement for wearing complete NBC protective equipment. Additionally, when both crews and equipment are contaminated, combined complete personnel and equipment decontamination operations are scheduled as the situation and mission permit, bearing in mind the lengthy time required for such an operation. It is during this complete decontamination that commanders can give their soldiers rest and a change of personal protection equipment. 40
The personnel decontamination items described below would be used to quickly decontaminate the skin of an exposed individual. Open wounds, however, should be decontaminated with water, saline, or dilute hypochlorite solutions.
|M258A1 Skin Decontamination Kit
The contents of the kit are highly caustic and should not be used near the eyes or mouth or to decontaminate wounds. A training kit that contains only an alcohol and water solution, the M58A1, has been developed to be used in lieu of the M258A1.
M291 Skin Decontamination Kit
The M291 Skin Decontamination Kit is a soft package consisting of two flexible pockets, each of which contains three decontamination packets (Figure 16-37).
The decontamination is accomplished by merely opening the packet and scrubbing the skin surface with the applicator pad until an even coating of the resin is achieved. Use normal precautions to keep the powder from wounds, the eyes, and the mouth. The M291 kit is also used for training.
Equipment Decontamination Items
Equipment decontamination items are used to destroy, remove, or neutralize most of the NBC hazards from personal gear or unit equipment. Although all of the items that could be used for equipment decontamination are not listed below, those most useful to the medical community are described.
M295 Decontamination Kit, Individual Equipment
The M295 Decontamination Kit, Individual Equipment (DKIE) consists of a pouch containing four wipedown mitts, each enclosed in a soft protective packet (Figure 16-38).
|M11 Portable Decontamination Apparatus
The M11 Portable Decontamination Apparatus (PDA) is a hand-held, pressure-spray apparatus used to coat a surface with DS2 by equipment operators (Figure 16-39).
M17 Lightweight Decontamination System
The M17 Lightweight Decontamination System (LDS) is designed to draw water from any source and deliver it to the two installed spray wands at pressures up to 100 psi and at temperatures up to 120°C (Figure 16-40). The M17 LDS can be used to provide pressurized hot water before or after application of decontaminant at regulated pressures and temperatures. It has a liquid soap siphon hose attachment for use with mud, dirt, or grease removal (these may have absorbed chemical agent). The M17 LDS has a 3,000-gal collapsible water tank that can be prepositioned and filled for hot water showers or hospital use.
M12A1 Power-Driven Decontamination Apparatus
The M12A1 Power-Driven Decontamination Apparatus (PDDA) is used to apply decontamination solutions or hot soapy water and rinses during field decontamination operations. The M12A1 PDDA consists of a pump unit, 500-gal tank, personnel shower assembly, and M2 water heater, all of which is mounted on a 5- or 10-ton truck with drop sides (Figure 16-41). The pump assembly can deliver 50 gal of water or super tropical bleach (STB) decontaminating agent per minute at a pressure of 105 psi to the two spray wands.
Developmental Decontamination Items
There is a need for an effective and environmentally safe reactive decontaminant that does not harm equipment and personnel. Bacterial enzymes, catalytic-type compounds, and other stable decontaminants (eg, quaternary ammonium complexes) are under consideration. Sorbent compounds and nonaqueous decontaminants are also being investigated for use on electronic components and other sensitive equipment.
Patient Protective Wrap
The patient protective wrap (PPW) is designed to protect a patient during evacuation after the BDO has been removed and the patient has received medical treatment (Figure 16-42). A patient can remain in the PPW for 6 hours. The protective mask is not needed inside the PPW, but it should be evacuated with the patient.
The decontaminable litter has been developed to meet the need for a litter that can withstand decontamination (Figure 16-43). The cover fabric is a honeycomb weave of monofilament polypropylene, which will not absorb agent and is not degraded by decontamination fluids. The cover fabric is flame retardant and rip resistant, and is treated to withstand weather and sunlight. It has aluminum poles, painted with chemical agent resistant coating, with round, grip-molded, retractable, black nylon handles. It conforms to all NATO standards and weighs about 15 pounds.
An integrated system of chemical defense equipment is required if we are to be successful in providing an adequate protective posture for all forces. The principal elements of that system include the following: