NBC Defense in Cold Conditions
Many effects of nuclear, biological, and chemical (NBC) agents change in the cold weather environment. All NBC protective equipment and supplies must be kept from freezing. FM 3-4, NBC Protection, covers NBC defense.
Severely Degraded NBC Equipment Effectiveness
Materials of protective equipment become brittle, crack, and tear easily in extreme cold. Frozen detection and decontamination solutions clog and damage equipment. Because most decontamination solutions require water, heat must be supplied when conducting decontamination operations. Agent detection reactions are slow in the cold. Great care must be taken in donning and removing protective clothing to avoid contamination. Logistics requirements increase during NBC defensive operations in extreme cold. For example, quantities of fresh, potable water and heated protective shelters may be required.
Extreme cold and high altitudes produce psychological problems that numb the intellect and degrade personal and unit security. Current knowledge prevents precise assessment of the added impact on military operations. However, casualty rates will probably increase if psychological stress slows or stops normal reaction of individuals or units to NBC attacks.
Breathing is more difficult at higher altitudes. There is little data concerning the effectiveness of NBC equipment in the extreme cold of high altitudes. At the lower barometric pressure of high altitudes, chemical agents evaporate or sublime much more rapidly. The increased elevation may, by localized surface heating, speed the vaporization of chemical agents. Contamination may be spread quicker by greater windspeeds at higher altitudes. Contamination may collect in depressions and small valleys.
EFFECTS ON NUCLEAR WEAPONS
Cold conditions can impact the effects of nuclear weapons. Leaders must understand these effects to properly plan for the protection of their soldiers.
Below -25°F, the effective radius of a nuclear blast may increase up to 20 percent. Icepack or hardened snowpack extends the distance of static overpressure, i.e., the crushing effect of the blast. Conversely, the distances of dynamic pressure may decrease due to the soft, absorbent characteristics of drifts and other snow cover. Tundra and ice formations can break up pressure waves. The cratering effects in ice and frozen ground may be reduced to those in solid rock.
Primary and reflected blast waves and ground shock from even small yield nuclear weapons may create earthquake-like fissures, crevasses, avalanches, and rock slides as far as 30 kilometers from ground zero. Secondary effects include snowstorms, avalanches, quick thaws, and ice breakup on lakes and rivers, which can interfere with troop movement. Blast will increase damage to equipment already inflexible from cold-soaking. In heavily forested areas, blown down trees can make large areas virtually impassable to vehicles and personnel. During winter months, trees freeze and become brittle; in a nuclear blast, they can be converted into many splinter-like projectiles. Personnel in heavy, layered clothing are less susceptible to injury from flying debris.
Cold can significantly alter the effects of a thermal blast. Due to the high reflectivity of snow and ice and the increased density of cold air, minimum safe distances may need to be increased by as much as 50 percent. Cold conditions can produce other effects, to include the following:
- Cold temperatures, cloud cover or frost, ice, and snow may reduce thermal effects on combustibles.
- When ice and snow pack melt, flash flooding may occur in low lying areas. Thawing can greatly impede troop movement.
- Snow, ice, and cold temperatures may limit destruction from post-blast fires.
- The average reflecting surfaces of muskeg, tundra, and wet conditions are characteristic of a cold region that may reduce thermal radiation.
- Ice, fog, and snow cloud cover may lessen thermal radiation from airburst detonations.
- The snow's highly reflective surface intensifies thermal radiation.
- The dilating of pupils in winter darkness increases the chance of permanent or temporary light blindness.
- Reflective, over-white camouflage clothing and netting may reduce injurious heat absorption by personnel and equipment.
Weather significantly influences radioactive fallout patterns. Snow can mask radiological hot spots from detection. Snow deposition is erratic due to rapidly changing winds. High winds extend radiation fallout patterns, but at the same time, may reduce radiation dose rates due to the scattering of contamination. At extremely low temperatures, the increased density of the atmosphere may reduce the distances of initial radioactive fallout by as much as 25 percent.
Contaminated snow may spread the fallout. Amounts of induced radioactivity in the soil are reduced and even prevented by deep snow. Poorly drained areas, such as meadows, limit natural flushing and may act as collecting points for radioactive contaminants. Most of the arctic is poorly drained. New snow may lessen fallout contamination of areas, permitting safe crossing by personnel and equipment.
The need for detailed radiological surveying increases in cold weather. Levels of local radiation can change quickly in windy conditions, causing hot spots far removed from ground zero and very low-intensity areas nearer ground zero.
The extended cold weather clothing system (ECWCS) clothing provides excellent protection from fallout. Radioactive particles may be removed by vigorous shaking and brushing of outer garments. Snow caves and below-ground shelters provide excellent shielding against radiation.
Effects are expected to be the same as in temperate zones. Electromagnetic pulse (EMP) hampers or negates radio and tactical-satellite communication for extended periods. EMP mitigating practices, such as burying and recovering cables and wire links, may be difficult or impossible because of frozen ground.
EFFECTS ON BIOLOGICAL AGENTS
Biological attacks must be anticipated. Up-to-date immunizations, acclimatized personnel, and strictly enforced personal hygiene (often considerably more difficult in the cold) are the best ways to avoid secondary spread of any infection. Vectorborne agents are rare since the vectors rarely survive. Toxins are less susceptible to the cold, and the possibility of their use by covert means must be anticipated. The survival chances of most microorganisms decrease significantly below 32°F. Layers of snow and reduced sunlight lengthen the hazard period for biological agents. Organisms may remain alive but dormant. They become active when exposed to warmer temperatures. The most effective means of biological warfare in cold weather is to covertly deliver live organisms. After a known biological attack, precautions to prevent the spread of its effects must be taken just as they would in a temperate climate.
Temperature inversions frequently found over snow fields and bodies of water tend to prolong the lives of biological agent clouds. Aerosolizing live biological agents is more difficult at extremely cold temperatures. Only some spores form bacteria, and certain viruses survive.
Tents and other areas where temperatures are higher than outside are likely areas of biological contamination spread. Once established in one person, a biological agent is likely to spread rapidly in crowded living conditions. Troops suffering from lack of nourishment or rest, or from dehydration, are more vulnerable to the effects of biological attack.
EFFECTS ON CHEMICAL AGENTS
Chemical agents are especially effective in the cold (Figure E-1). Exposure to any chemical agent requires masking. Conditions for aerosol dispersal are excellent. Most agents freeze at -50°F. Chemical agents, either thickened or frozen on clothing or equipment, produce deadly off-gas concentrations once taken into heated areas.
Blood and Choking Agents
Blood and choking agents are extremely hazardous and nonpersistent throughout low temperatures. These agents may be spread as liquids, solids, or aerosols. Masks are required whenever they are used. Hazard times may be longer. The blood agent AC is extremely hazardous, even as low as -65°F.
Blister agents freeze below 0°F. They can be brushed from clothing and equipment. However, some mixtures, such as HL, remain liquid hazards at fairly low temperatures. The standard winter blister agent is a mixture of mustard and lewisite. In areas that lack water, frozen or otherwise, this blister agent persists in liquid form for up to six months. If water is present, the agent decomposes to form a pure mustard that freezes at 58°F.
Nerve agents freeze in severe cold. However, they present a very serious vapor hazard when brought into warm areas. When used to contaminate key facilities, nerve agents become long-term hazards. These hazards may require tremendous decontamination efforts, or even waiting for a change in seasons, to reduce contamination below lethal levels. Persistency is controlled by three factors: temperature, terrain surface, and windspeed. Nerve agents, particularly VX, are effective when absorbed through the skin or eyes, but the low volatility of VX makes the vapor hazard negligible below 32°F. The physical behavior of persistent nerve agents is only slightly affected by decreasing temperature. As the temperature nears 32°F, persistent nerve agents dissolve in water, have reduced vapor hazard, and increase in persistency. Nonpersistent nerve agents (i.e., GB) tend to become semipersistent, lasting from two to ten days.
NUCLEAR, BIOLOGICAL, AND CHEMICAL DEFENSE
To effectively defend against the effects of NBC weapons, four fundamentals must be applied: detection, contamination avoidance, protection, and decontamination. In a mountainous cold weather environment, the first three fundamentals become extremely important, and decontamination, always difficult and time-consuming, becomes a logistical nightmare.
Figure E-1. Persistency table
Automatic detectors must be heated. Detection is vital to identifying a hazard. The vapor hazard of chemical agents may be limited, making the M-256 chemical agent detector kit unreliable. Persistent agents can freeze into solids that may not be identifiable. This creates a potential hazard that does not materialize until temperatures rise. Reagents in the M-256 chemical agent detector kit freeze and provide inaccurate readings in temperatures below -25°F. These kits must be kept close to the body to prevent freezing. Cold slows the response of M-8 chemical detector paper. Extra time must be allowed for the paper to work. M-9 paper is of little value because all the substances that react to it are affected by the cold. Extreme cold, or the physical state of a chemical agent, may make the M-8 alarm system ineffective. Every 50 to 100 feet, detection teams should melt snow, heat it to 70°F, and test it with M-8 paper or CAM. If an agent is suspected, water is taken into a heated shelter and heated until a vapor is given off above 70°F. It is then tested with the M-256A1 kit; data is recorded, reported, and plotted according to unit SOP. Contaminated areas are marked with the standard NATO contamination signs.
Avoidance measures prevent offering the enemy a vulnerable target and prevent accidental contact with existing contamination. To enhance unit survival, employ the following measures:
- Harden positions by improving overhead cover.
- Disperse personnel, supplies, and equipment.
- Conceal positions.
- Provide early warning.
- Develop NBC environmental discipline.
- Remain mobile.
- Keep supplies and equipment covered.
Take active measures to protect units from contamination. Specifically, employ the following measures--
- Find and destroy enemy munitions and delivery systems.
- Use NBC reconnaissance teams to monitor contamination of specific areas.
- Use the standard warning and reporting system to warn others of hazards, or to pass the alarm locally.
- Prioritize the covering of mission essential equipment.
- Build collective protection shelters to provide contamination-free work environments.
Decontamination (decon) is the process of making any person, object, or area safe by absorbing, destroying, neutralizing, making harmless, or removing radioactive material clinging to or around it. Deliberate decon requires extensive time and logistical support. Temperatures below 32°F limit the effectiveness of decontamination operations. Current chemical decontamination procedures that require water rinses are impossible in freezing weather. Non-water decontamination procedures have not yet been developed. Decontamination must often be done in heated facilities. To decontaminate, soldiers must--
- Perform hasty decon.
- Continue to fight after hasty decon.
- Understand the effects of chemical agents.
In cold weather operations, decon and some aspects of detection must be accomplished in heated shelters. One of the most challenging problems is preventing contamination from entering warm areas. For example, frozen agents on clothing are hard to detect because low temperatures slow the effects of the agents. If the temperature rises, or if contaminated individuals enter heated areas, the frozen agents will revaporize and become hazardous. It may be necessary to set up a thawing station for each warm shelter where agents can be isolated before individuals enter the main shelters and unmask.
INDIVIDUAL PROTECTION EQUIPMENT
Use of individual chemical protective equipment presents added challenges in cold weather. Failure to take specific precautions can result in equipment failure and possible contamination.
Field Chemical-Biological Masks
Wearing the M-17 or M-40 Series masks in cold weather requires special attention to ice formation and frostbite. Masks should be carried beneath outer garments, and care should be taken to wipe dry the inside of each mask after wear. After wear, soldiers should inspect for ice buildup in the inlet and outlet valve areas. To prevent frostbite, place small pieces of tape over the exposed metal rivets of the facepiece. During periods between repeated use, take the mask out of the carrier and shake or flex the facepiece to remove ice and snow. Warm the mask when you can, but do not warm close to a heater or open flame as the rubber parts of the facepiece could melt. Dry facepiece with cheesecloth in a warm indoor area.
M-4 winterization kit. The M-4 winterization kit consists of an ice particle prefilter fitted over inlet valves to prevent frost from accumulating on the inlet caps. It also includes two inlet valves and two nose cup valves made of a relatively soft rubber that does not become hard or brittle in the cold.
Mask carriers. The mask carrier should be adjusted to be worn in a side carry beneath the cold weather parka. Body heat helps keep the mask warm and flexible, but masking is slow and difficult. Soldiers must be aware of this requirement when donning their cold weather clothing. They must ensure that the ECWCS parka is large enough to accommodate insulating layers and the gas mask with its carrier.
Outserts. Two outserts are provided with the mask to prevent fogging of the eye lenses. Green- and amber-tinted outserts can be used for bright light and fogging. Avoid wiping eyepieces with gloves when firing because they will smear.
Donning Protective Masks
Hold your breath. Remove the mask from under your parka, lower the parka hood, and don the mask. Adjust the head harness only tight enough to create a good seal. Raise the parka hood and fasten the outer garment.
NOTE: Do not clear the mask by exhaling a large amount of air because the lens will frost. Exhale slowly and steadily. The outlet valve may stick to the seal. If this occurs, lift the outlet valve cover and rotate the disk with a finger while exhaling only. After freeing the valve, reset the valve cover. Check the mask for leaks by pulling down the cheek flaps on the ice particle prefilter while covering the inlet valves with hands. Fasten the cheek flaps and resume normal breathing.
Removing Protective Masks
Remove gloves or mittens before removing the mask. Loosen the outer garment and lower the hood. Brush snow or ice particles from the mask. Remove the mask and immediately dry your face and the inside of the mask. Raise your parka hood and fasten outer garment. Wipe the mask thoroughly before storing to prevent ice formation. Store the mask in the carrier. Put on gloves or mittens. When possible, further dry the mask by placing it in a warm area, but not in direct heat.
Wearing the Chemical Protective Overgarment
Contamination avoidance measures may fail. The enemy may find and attack with NBC weapons. Soldiers may be downwind of an NBC attack, or the mission may require them to cross contaminated areas. Protection options must be available to survive and continue the mission.
Wearing the chemical protective overgarment presents a particularly difficult operational/logistics decision that com-manders must make before entering the operational theater. The impact of mission oriented protective posture (MOPP) conditions on operations must be considered. If the ECWCS parka is not needed because of the added warmth provided by the chemical protective overgarment, store and seal it in a plastic bag. If the ECWCS is worn outside the chemical protective overgarment, it permits the layering required for added warmth. However, it requires that the contaminated clothing worn over the chemical protective overgarment be removed before entering a heated shelter where the agents can revaporize. Upon decon, the external layers of the overgarment have to be discarded. Also, once the ECWCS is donned, it is not possible to adjust the overgarment. Replacement issues of cold weather clothing are needed. Stocks of ECWCS are not adequate to support this requirement. A method of decontamination of this cold weather clothing is necessary. The chemical protective overgarment produces internal moisture and condensation and dehydration problems that can lead to hypothermia. In full MOPP gear, speed is reduced by at least 50 percent (probably greater due to buildup of condensation and the potential danger of hypothermia).
Chemical Protective Glove Set
Vapor barriers (i.e., medical examination gloves, the wool insert, and the leather shell covered by the butyl-rubber glove) make up the chemical protective glove set. This set allows the insulator (the wool insert) to remain dry and warm. If either outer glove is punctured or torn, the glove set must be replaced.
Vapor barrier (VB) boots are an effective and adequate replacement for the normal overboots. However, the natural rubber composing the VB boot can be penetrated by chemical agents that contain mustard gas. After 50 hours exposure, they must be replaced and turned in for decontamination or discarding.
The M-258A1 decon kit is good to 32°F. It must be kept next to the body to prevent freezing. Because it assumes surrounding air temperature, the solution should be used quickly once it is opened to avoid possible frostbite. The M-13 consists of a bag of Fuller's earth for equipment decon. It is not affected by the cold. Neither are the components of the M291 skin decontamination kit (SDK) or M295 individual equipment decontamination kit (IEDK).
The NAAK M-K1 should be protected from freezing. At temperatures below -40°F, remove from the mask carrier and store in a parka pocket.
Units must be self-sufficient in NBC defense. Cold weather conditions impose many special considerations on defense planning. For example, adjacent units may not be able to provide mutual support, logistical support may be drastically reduced, and rapid movement may become more difficult.
Because of terrain and weather restrictions, bivouac location for effective NBC defense requires considerable planning. Gullies, ravines, ditches, natural depressions, fallen trees, and caves can reduce the effects of nuclear weapons, but low-lying areas are places where toxic clouds can settle. If feasible, positions should be constructed upwind of possible threats. The heat, light, and initial radiation of nuclear blasts are absorbed by hills, while the rest is deflected up by the slope. Likely targets such as MSRs and mountain passes should be avoided. Wooded areas present a mixed blessing. Biological agents persist longer as forests retain moisture and keep out sunlight. Coniferous forests of Europe and the northwestern US reduce the possibility of liquid contamination from chemical weapons. However, the chemical vapor hazard increases.
Special Concerns for Nuclear Protection
The primary concern for nuclear protection is shielding from gamma and neutron radiation. Gamma protection requires thick layers of dense, heavy shielding such as lead, iron, or earth. Light hydrogen-based materials such as water, snow, paraffin, or oil offer good neutron protection. However, the absorption of neutrons produces additional gamma radiation. Dark, rough materials, such as wool or canvas, should be used to cover potential reflecting surfaces. These may burn or char but do not present the hazard a melted poncho would. Avoid direct contact with these materials. View ports should be covered with metal window screening material that can block thermal radiation by up to 50 percent. Smaller openings reduce the amount of initial and residual radiation that enters.
Dehydration injuries are likely when soldiers must perform difficult physical tasks. Soldiers become more prone to suffering subsequent cold weather injuries. Freezing air inside protective clothing, or perspiration that cannot evaporate, leads to chilling or hypothermia. Generally, soldiers in MOPP-4 conditions at 20°F need twice the time required at higher temperatures to accomplish tasks. Added supervision of work loads is necessary to prevent cold weather injuries.
MOPP Gear Exchange
If a unit becomes contaminated, decon will be done by MOPP gear exchange (gloves and overgarment only). Two complete sets of MOPP gear and waterproof bags to seal contaminated clothing per person should be available. Care must be taken with packaging the overgarment. Tears and exposure to air will degrade protective qualities. Extra suits must be provided when crossing water obstacles or conducting amphibious operations. Any contaminated cold weather clothing item must be replaced.
DECON OF EQUIPMENT
Cold temperatures can be expected to adversely affect liquid solutions, pumps, sponges, swabs, brushes, etc.
Water, the most common ingredient in decon operations, is useless if frozen. It should not be used when temperatures are so low that it freezes on contact with equipment. In these temperatures, use undiluted DS2 but remember that DS2 corrodes equipment quickly. Equipment must be replaced quickly. Because of their low freezing points, solvents such as JP4, diesel fuel, or kerosene may be used to physically remove contamination. With present technology, equipment decon problems are hard to overcome in an arctic environment.
Commanders must consider fighting dirty in cold weather areas. Fresh units can be rotated into the contaminated areas so that dirty units can move to decon stations. DS2 and STB freeze at approximately -15°F. In temperatures less than -15°F, JP4 could be used to remove contamination. This removes but does not deactivate the chemicals. The ground and equipment used to remove contaminates must be destroyed or removed properly. JP4 is also highly flammable. The large amount of static electricity in cold dry climates can ignite the fuel. There is a definite risk of frostbite when fuel contacts exposed flesh. Rinse water must be heated, or antifreeze added to the rinse solution, to prevent freezing on contact with a cold vehicle. If the vehicle cannot be rinsed, the DS2 will quickly corrode the vehicle.
Use of the chemical agent monitor is limited by the cold's shortening of battery life. Two nitrogen cylinders may be required to expend the contents of the M-11 decon apparatus at temperatures below 32°F.
Difficulties develop in dispensing DS2 as temperatures near 0°F. To overcome this
problem, the decon apparatus portable (DAP) must be warm enough for the DS2 to pump through the brush assembly. Commanders should consider positioning a contingency supply of the M-13 inside heated vehicles and develop a plan to rotate the other DAPs into heated shelters as needed.
The M-17 sanator decon apparatus has problems in cold temperatures because the system relies on a water-based decon method. Normal engine cold-soaking problems have been observed along with internal pumps, lines, etc., cracking from the expanding freezing water. This system must be used within a heated shelter.
Decon stations should be sited in built-up areas, near road junctions, at intersections of forest lanes, or where they may be approached from several directions.
Snow can be used to cover contaminated areas. However, when the snow blows away or when vehicles or personnel break through this surface, the contamination will reappear. Snow cover provides some protection if left undisturbed, but this protection is unreliable.
Unfrozen earth may not be available to make STB dry mix. Use snow in place of dirt (same proportion) in shuffle pits and for other decon purposes. Burying contaminated materials in frozen ground is difficult. Mark burned or abandoned material with standard contamination signs.
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