Military Hygiene and Hygiene in Emergency Situations - K.O. Pashka 2005

Occupational hygiene of military personnel during the mitigation of emergency consequences and in wartime
Occupational hygiene of military tank crews

Modern armed forces are equipped with tanks, infantry fighting vehicles (IFVs), self-propelled artillery systems, armored personnel carriers (APCs), and other armored vehicles. The training and combat activities of these troops involve firing exercises, driving combat vehicles (including underwater driving of tanks), field exercises, and marches. The working conditions and health status of the personnel are influenced by A number of environmental factors, such as:

- limited workspace dimensions;

- jolts and shocks during vehicle movement, as well as intense noise;

- adverse Temperature conditions during the cold and warm seasons of the year;

- air contamination with harmful gases and dust;

- increased contamination of clothing and Skin with fuels, lubricants, Solvents, paint, and dust;

- potential laser radiation hazards in case of non-compliance with safety regulations during training or exercises.

To a significant extent, The impact of these factors is present in all types of armored vehicles.

Dimensions of workstations. The constant drive to reduce the dimensions of a tank has led to a significant decrease in the internal volume of the fighting and control compartments. Their total volume does not exceed 4 m³, but in practice, it is even smaller because this space houses part of the gun and other equipment. The height of the compartments is below the average human stature. The small size of the workspace inside an armored vehicle complicates the crew members' work, forces them into constrained working postures, and requires them to protect themselves from hitting surrounding surfaces during shocks and jolts while the vehicle is in motion, which constantly demands considerable muscular tension. Consequently, increased crew fatigue arises. Forced restriction of movement and prolonged Maintenance of the same posture contribute, during the cold season, to general and local hypothermia among tankers and lead to contact frostbite. Loss of body balance while working inside a moving tank or when firing the gun, inaccurate movements, and failure to observe safety rules during vehicle driving and maintenance can cause injuries to crew members.

Tank observation conditions and workstation illumination. During marches, field training sessions, and combat, the crew must constantly and vigilantly monitor the tactical situation on the terrain; however, to protect against enemy fire, designers have drastically limited the number and size of apertures in the tank's armor. The design of observation devices utilizes periscopic optical systems consisting of two mirrors or two prisms. The driver-mechanics's periscope is of a simple design—it features single magnification and allows viewing only directly ahead of the vehicle. The gunner-operator's observation devices are more complex, offering multiple magnifications, but they also restrict the view strictly to the front of the vehicle. The commander's periscope features variable magnification, allows for all-round surveillance, can tilt forward and backward to increase the vertical field of view, and makes it possible to measure angles in both vertical and horizontal planes as well as determine the distance to the target. A drawback of periscopes is that their lenses easily get dirty, which sharply reduces visual clarity and requires frequent cleaning. The lower part of the periscopes is equipped with rubber pads to prevent facial injuries to the tankers.

Their outer part is protected by an armored cap. Observation through open hatches allows the crew to better orient themselves on the terrain, but this is only possible when there is no danger of shelling or enemy fire.

Thus, tank observation conditions, especially during movement, are extremely unfavorable due to the limited field of view. They require personnel to maintain intense concentration, adequate visual acuity, and systematic training under conditions that closely simulate actual combat. It is particularly difficult to observe the terrain at night when all objects turn gray, their contours blur, depth perception deteriorates, and spatial perceptions change—making objects appear closer than they actually are and increasing their perceived size. The speed of glowing objects also seems greater than it really is.

This necessitates that individuals selected for service in armored units meet specific criteria: visual acuity of at least 0.6 in both eyes without correction, proper color perception, and normal visual adaptation. Maintaining the latter at an adequate level requires constantly providing tankers with sufficient amounts of Vitamins A and B₂.

Observation conditions also depend on the internal lighting of the tank. By day with open hatches, illumination ranges from 30 to 250 lx, while with closed hatches, it drops to 10–2 lx or even less. Such low interior illumination complicates the adaptation of a tanker's eyes when shifting their gaze from brightly lit external objects to internal instruments. At night, observing a dimly lit terrain—especially with headlights turned off—is also difficult if excessive general illumination is created inside the tank or if the instrument dials are illuminated too brightly. In this regard, artificial lighting should facilitate maximum adaptation of the eyes to dim interior light by day and to the outside environment at night, while simultaneously ensuring adequate visibility to operate control panels, read maps, take notes, and perform other tasks.

These conditions correspond to artificial illumination levels of working surfaces of at least 50 lx by day and ranging from 2–3 lx to 5–7 lx at night. Therefore, control instruments are illuminated by concealed miniature bulbs, and instrument scales are coated with luminescent mixtures that glow at night without being radioactive emitters.

Tanks make widespread use of night Vision devices that transform thermal radiation into the visible spectrum, projected onto special screens. The Use of such devices significantly improves nighttime observation conditions from the tank and enhances the combat effectiveness of its armament.

Vibrations, shocks, and noise. Vibrations and shocks inside a tank occur due to engine operation and movement over uneven roads and terrain. Vibrations caused by engine operation are rhythmic and have a small amplitude; their isolated effect on the tanker's body occurs mainly during idling.

More unfavorable effects on the body are produced by arrhythmic, jolting oscillations during tank movement. They are complex in nature and have various directions: horizontal, vertical, angular, etc. The frequency and intensity of shocks depend on the terrain profile and the driver's skill. The amplitude and acceleration during jolts and shocks can be so severe that tankers may sustain bruises or injuries to the HEAD and other body parts.

The constant action of arrhythmic oscillations leads to fatigue among crew members, who are forced to exert muscular effort to maintain balance. This significantly complicates crew working conditions, hinders accurate firing on the move, and interferes with battlefield observation and the use of optical devices. In some individuals, high-amplitude shocks and vibrations can induce motion sickness symptoms.

Reducing shaking and vibration to standard parameters and achieving a smooth ride can be accomplished through design improvements, such as upgrading the suspension system and installing seat Shock absorbers. Of key importance are the general physical and professional conditioning of the crew—especially the gunner and driver-mechanic—and particularly the mastery of driving and firing on the move.

Noise inside the tank and other armored vehicles is generated by the powerful operating engine, various mechanical components, weaponry, and moving equipment. Noise levels largely depend on the serviceability of components, the degree of track tension, the clearance between moving parts, the rigidity of equipment mountings, and the presence of unsecured objects. Noise levels inside a moving tank can reach 130 dBA, which far exceeds the human auditory adaptation limit of around 90 dBA. Prolonged exposure to such noise significantly impairs Hearing sensitivity, which recovers only after two days. Ultra-high-intensity noise is produced during rocket launches and tank gun firing. It drowns out human speech (verbal communication between crew members is often only possible via the tank intercommunication system), hampers coordinated crew performance, damages hearing, causes premature fatigue, and can contribute to injuries. Noise mitigation is achieved by eliminating various vibrations, carefully adjusting track links and maintaining proper track tension, applying sound-absorbing coatings to the interior surfaces of the fighting compartment, and using individual hearing protection devices. To this end, the summer and winter tank helmets are equipped with built-in outer noise attenuators that significantly reduce noise intensity (down to 45 d5), telephone earpieces, and a laryngophone (Fig. 5.1). The forehead and crown sections of the helmet feature ribbed pads made of sponge rubber or foam plastic, which protect the tanker's head from accidental impacts while the tank is moving. In addition, the winter helmet's fur lining protects the head from the cold. However, prolonged wearing of helmets is undesirable because the built-in noise attenuators exert considerable pressure (approximately 5 kg along the perimeter) on the underlying head Tissues.

The working conditions of tankers impose heightened demands on the state of the vestibular apparatus, the Organ of Hearing, and the Upper Respiratory Tract. Service in armored troops requires selecting individuals with low vestibular excitability, adequate hearing acuity (perception of whispered speech from at least 4 m), and an absence of chronic Diseases of the nasopharynx, Paranasal Sinuses, Larynx, and hearing Organs.

Microclimatic conditions. Temperature conditions in the compartments of armored vehicles where the crew is located depend primarily on ambient air temperature, and in summer, also on the degree of armor heating by direct sunlight, as well as its cooling in winter. The temperature regime is significantly influenced by The rate of air exchange inside the vehicle, which is determined by THE POSITION OF the hatches (open or closed), the speed of the tank, and the operation of its ventilation system. In hot weather, the air temperature inside the vehicle exceeds 40 °C, leading to crew overheating and resulting in a loss of combat readiness. In winter, severe cooling of the armor can cause general hypothermia and contact frostbite in areas of the body touching it.

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Fig. 5.1. Tanker's helmet.

Cooling is facilitated by significant air velocities, especially in the driver's compartment (up to 3 m/s with open hatches), as well as the radiant cooling from vehicle armor, the average temperature of which in winter is significantly lower than human skin temperature. Rationally selected clothing and footwear appropriate to environmental conditions play an extremely crucial role in protecting tankers from the cold. In all cases, measures must be implemented to warm personnel during halts and rest stops through active movement, and whenever possible, in warm facilities (warming shelters).

Preserving and strengthening the health of tankers by creating healthy service and living conditions, along with body conditioning, helps enhance the body's thermoregulatory Functions and its resistance to low or high temperatures.

Dust. When tank columns move in dry weather, large amounts of road dust are stirred up into the air, entering the upper respiratory tract and irritating the mucous membranes. Getting into the eyes, dust causes irritation and inflammation of the conjunctiva and eyelids. Contamination of the skin and clothing with dust is one of the leading causes of increased Pyoderma (pus-forming skin infections) among tank crews.

Along with dust, snow, or rain, combat toxic agents, radioactive substances, and biological agents can also enter the tank compartment.

To reduce dust penetration into the tank while moving in a Column, it is necessary to maintain distance between vehicles (approximately 50 m) and, where possible, periodically rotate the positions of the leading and trailing vehicles. When marching through terrain with high dust generation, it is advisable to pre-seal the tank, supplying air inside through a separator-supercharger. If these measures are insufficiently effective, the crew must use personal protective equipment—goggles and respirators. Personal hygiene is of particular importance for tankers: cleaning and dusting clothing, regular bathhouse visits with a change of underwear, showering after completing a march or driving and shooting training sessions, as well as removing dust from the interior compartments of vehicles.

Harmful chemical substances. The air inside tanks, IFVs, and other vehicles can be contaminated with health-hazardous exhaust and propellant gases, which consist of a mixture of various substances, with carbon monoxide posing the greatest danger. When heavy fuels (diesel) burn in engines, exhaust gases have a pungent, unpleasant odor and strongly irritate the mucous membranes due to the aldehydes and sulfur dioxide they contain. Exhaust gases are most hazardous in enclosed spaces with inadequate ventilation (garages, workshops) and field shelters (trenches, depressions, etc.). Propellant gases can enter the compartments of combat vehicles from spent cartridge cases and from the bores of machine guns or cannons when the breech opens. Their concentration during firing exceeds the permissible limit by 4–5 times, which sharply degrades the functional state of the tankers. As a result, firing rate performance drops by 40–50%, and the time required to aim the gun at a target increases by 20–30%.

Laser beam. Modern tanks are equipped with laser rangefinders, whose powerful, highly directional light pulse is hazardous to the unprotected human eye. It can cause varying degrees of visual impairment—from temporary blinding to retinal Burns and permanent vision loss. Not only direct laser radiation is dangerous, but also its beam reflected from mirror-like surfaces or shiny objects. The radii of the hazard zones for direct and specularly reflected laser radiation to the unprotected eye reach up to 10 km during the day and up to 15 km at night. The use of optical observation devices increases the risk of eye injury from the laser beam. The probability of eye injury increases significantly if safety regulations are violated during bilateral exercises, especially at night.

Underwater tank driving. One of the specific types of combat training activities for tankers is underwater tank driving, which requires specialized crew training. When overcoming a Water obstacle, the vehicle, equipped with preliminary installed deep-wading gear, moves along the bottom of the water body. Along this segment, the crew has no visual observation of the surrounding environment, and the driver navigates solely by instruments. If errors are made in determining the course, the tank may enter water deeper than permissible and, consequently, sink. The same can happen in the event of a prolonged underwater stop due to vehicle malfunction. Such a hazardous situation causes significant neuro-psychological stress among crew members. They can abandon a sunken tank through the hatches, but the external water pressure is so intense that opening them is impossible. For example, at a water depth of 1 m, the pressure on the hatch is equal to 300–400 kg. The hatches open relatively easily only after the tank is completely filled with water, when the internal pressure equalizes with the external pressure.

Before proceeding to flood the tank, the crew must thoroughly prepare to breathe underwater for some time before reaching the surface. Special isolating breathing apparatuses, such as IP-5, are designed for this purpose, and tankers are trained in their use during exercises. They provide full breathing capability as the crew escapes from the sunken tank to the surface, but tankers must thoroughly know and strictly follow a number of safety rules. It is essential to protect the gas mask breathing bag from compression, as this leads to respiratory disruption and, within 2–3 minutes, dizziness and suffocation. Sharp impacts on the breathing bag can cause pulmonary barotrauma (rupture of lung tissue with severe consequences).

The evacuation of a flooded tank involves significant challenges. To ensure safe working conditions for divers during underwater tank recovery operations, it is necessary to supply air without interruption and prevent hypothermia by limiting underwater time and using warm clothing and wetsuits. The basic rules for preparing tankers for underwater driving and crew behavior when overcoming water obstacles and potential tank flooding are outlined in relevant specialized manuals.

The medical service is tasked with familiarizing crew members with the PHYSIOLOGICAL CHARACTERISTICS OF the body's functioning while a tanker is underwater using an isolating breathing apparatus, as well as studying safety rules and first aid measures. In addition, for the rescue group formed during tank water-crossing operations, the medical chief assigns a paramedic or medical orderly with the necessary equipment to provide medical assistance to casualties.

Holding park maintenance days. To service combat machines and repair malfunctioning ones, park maintenance days are conducted, during which personnel are exposed to such adverse factors as:

- intensive physical exertion when removing and installing individual assemblies and components weighing from several tens to hundreds of kilograms on the tank (APC, IFV, SPG);

- chemical substances—fuels and lubricants, solvents, paints, antifreezes, acids, exhaust gases, and other technical fluids;

- physical factors—low (high) air temperature, noise, electromagnetic radiation, electric welding arc radiation, or the effects of fire-gas jets, etc.

Hygienic support for a park maintenance day consists of organizing and monitoring compliance with sanitary and safety regulations by military personnel, the failure of which leads to injuries and poisonings. Therefore, medical personnel must inspect the suitability of all maintenance facilities according to their designated purpose—parks, maintenance points, battery charging rooms, fuel and toxic fluid storage facilities. Requirements for these are outlined in special regulatory documents.

Sanitary-epidemiological service specialists monitor the Prevention of environmental pollution by industrial wastewater after washing tanks, vehicles, artillery pieces, etc.

To achieve this, parks must be equipped with a closed-loop wastewater Treatment system for the repeated, multi-use of such water for technical purposes.