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
Physical factors of the environment

In modern mobile military equipment and weapons, the microclimate often fluctuates due to external weather conditions, thermal insulation structural elements, internal heat-emitting sources, and life support systems. For instance, in a hot and dry climate (air temperatures exceeding 35 °С, solar radiation intensity of 0.04-0.085 W/cm²), the air Temperature inside a tank exceeds the ambient temperature by 4-5 °С, reaching up to 40 °С. Hyperthermia in military equipment is further promoted by the sealing of compartments to protect personnel from weapons of mass destruction, whereas in mobile electronic systems, it is additionally caused by heat radiated from electronic devices and equipment.

In winter (with an ambient temperature of -16 °С), this figure drops to -9 °С. On average, the air temperature inside the compartments of mobile ground military equipment is 10 °С higher than the outside temperature in both summer and winter.

Unlike combat and support vehicles, special stationary facilities virtually never face hypothermia issues, as their air conditioning and ventilation-filtration equipment can effectively heat the air. However, maintaining a stable air gas composition sometimes leads to high air velocities in manned areas that exceed permissible standards due to intensive ventilation.

Another common factor across various types of military hardware is noise. The total level of continuous acoustic noise in mobile ground systems is determined by the vehicle's type, power, and design features (tracked or wheeled), the terrain and road surface (dirt, asphalt, concrete, etc.), the vehicle's speed, and the driver's professional experience.

In stationary facilities, it is primarily determined by the number and capacity of operating equipment (specialized, power, ventilation, etc.).

When several sound waves of the same frequency from different noise sources enter the vehicle's air environment in phase, an increase in the resulting vibration amplitude—and thus the sound loudness—may occur.

The most unfavorable noise environment is found in the compartments of armored and automotive vehicles on tracked chassis (Table 5.3).

Class="center">Table 5.3 Total level of continuous acoustic noise in military equipment compartments

In A number of missile systems, intermittent, non-continuous noise occurs during launches, featuring pulses lasting 1 s or more, with levels remaining constant throughout the noise interval. The intensity of this noise depends on the missile type and launch pad design features, while its impact on the operator depends on the degree of protection at their combat station. During tactical missile launches, the level of intermittent noise reaches 140-155 dB.

Along with steady noise, combat compartments of military equipment also generate non-continuous impulse noise consisting of one or more sound pulses, each lasting less than 1 s. Its spectral composition during firing depends on the weapon system. In some cases, maximum energy is concentrated in the low- and medium-frequency ranges (impulse noise during missile launches), while in others it falls within the infrasonic and low-frequency ranges (firing from artillery systems, mortars, and grenade launchers). Impulse noise levels from certain types of weapons can reach 190-195 dB.

Induced acoustic vibrations may occur As a result of air or seismic Shock waves acting on military equipment. For example, the sound pressure level inside a tank exposed to a shock wave (P_f=2+4 kg/cm²) sometimes exceeds 165 dB.

During the operation of modern military equipment and in combat conditions, fluctuations in internal atmospheric pressure are quite common. This occurs in tanks during underwater crossing of Water obstacles, in sealed compartments during emergency high-pressure air leaks from cylinders, or when an air shock wave from a nuclear or fuel-air explosive blast penetrates military facilities or equipment compartments. The variety of causes altering atmospheric pressure indicates that the parameter values in each specific case may differ. Their impact on the Organism is determined by the magnitude and duration of exposure, as well as the direction and rate of pressure change.

Vibration occurs when riding in all types of wheeled and tracked vehicles and when operating mechanisms in most stationary facility spaces. Its causes may include micro-impacts and surface friction in moving mechanical parts, centering inaccuracies, unbalance of rotating masses, and improperly secured tools or spare parts.

Vibration velocity levels in the compartments of most facilities generally do not exceed 100-110 dB relative to the zero vibrational velocity level, which is 5∙10^-8. This is conventionally adopted as a standard and corresponds to the ROOT-mean-square vibrational velocity at the standard sound pressure threshold for a tone with a frequency of 1000 Hz, equal to 2∙10^-5 N/m² (Pa). Mechanical vibrations resulting from powerful single shock pulses, such as artillery fire, reach significantly higher values. Maximum impulse overloads on modern self-propelled artillery guns reach 260 m/s² in the chest-to-back direction and 160 m/s² in the HEAD-to-toe direction, with a pulse duration of 0.5 s and a rise rate of up to 6000 m/s².

When structures of stationary or mobile objects are displaced by shock waves from various explosions, human-supporting surfaces may shift over distances of 50-100 cm at speeds up to 10 m/s and accelerations up to 100 g (1 g=9.81 m/s²).

Increasing the power of emitting devices at military sites (radar antenna systems, radio stations, etc.) and expanding their numbers among troops can lead to equipment malfunctions, accidents, and subsequent single or sequential exposure of personnel to radio waves across various frequency ranges. Such exposure can also occur during combat operations involving the cooperation of different arms of service. In recent years, THE SPECTRUM OF these ranges has expanded significantly to include medium-, low-, and very low-frequency emissions alongside high-, super-high-, and ultra-high-frequency emissions, exceeding permissible safety limits.

Personnel operating radio-electronic systems may be exposed to electromagnetic fields with electric component field strengths ranging from tens to thousands of volts per meter (V/m) and magnetic component field strengths ranging from amperes per meter (A/m).

Facilities equipped with high-voltage DC electromechanical devices generate static electric and magnetic fields with field strengths up to 90 kV/m and 5∙10⁵ A/m, respectively. These cause the accumulation of electrostatic charges on The Human Body. For instance, even when wearing personal protective equipment, an electrostatic potential of up to 45 kV can build up on the body surface.

Equipping troops with laser rangefinders and target engagement simulators increases the risk of accidental ocular injury to personnel from pulsed laser radiation.