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
Chemical environmental factors

The chemical composition of air is one of the primary environmental characteristics of a habitat. Its formation depends on the release of various hazardous impurities into the atmosphere of a compartment (room) during the operation of weapons, machinery, systems, and devices, as well as from finishing Materials. Environmental Chemical factors are those chemical elements or compounds that make up the air and, due to their properties at certain concentrations, can exert a toxic effect on the body and reduce the combat readiness (performance) of personnel. The Chemical composition of the air and the dynamics of toxic impurity concentrations within it are influenced by the Design Features of the object and its technical equipment: the volume of compartments (rooms) and their mutual layout, the type of power plant, the type and quantity of standard weapons and Methods of their employment, the density of instruments, mechanisms, and synthetic materials, air Temperature, humidity, and barometric pressure, its free volume, and the efficiency of life support systems. The number of personnel and the conditions of their combat activity are also of substantial importance. Chemical factors of the environment affect the Organism in combination with numerous other factors (physical, biological, psychogenic, etc.), As a result of which the exact same absolute value of a chemical factor may cause varying degrees of Changes in the body.

A complete quantitative Description of the Formation of the air's chemical composition does not yet exist, since the emission of toxic impurities into the air of a confined space is time-dependent and random in nature.

Classification of environmental chemical factors for military equipment objects

The extremely large number of toxic substances and The Diversity of their biological effects preclude the creation of an exhaustive classification. One such classification is based on THE PRINCIPLE OF accounting for the state of matter of substances in the air environment, according to which the natural Components of air and the xenobiotics present in it are classified into gases, vapors, and aerosols (liquid and solid).

Based on The Nature of their effect on the organism and the damage caused to various Organs and systems, the most appropriate classification divides chemical compounds into:

- those with a predominantly narcotic (reversible) effect (alcohols, ethers, ketones, aliphatic and acyclic Hydrocarbons);

- those causing persistent changes in The Nervous system (trichloroethylene, methanol, carbon disulfide, etc.);

- those acting as poisons of the Blood and Hematopoietic organs (benzene, toluene, xylene, chlorobenzene, and other benzene derivatives);

- those leading to dystrophic changes in parenchymatous organs (chlorinated hydrocarbons, glycols);

- those damaging multiple organs and systems of the body and causing a complex multi-component effect (inorganic and organometallic compounds of mercury, lead, cadmium, beryllium, phosphorus, arsenic and phosphine hydrogen, etc.).

There are also classifications based on chemical Structure, the degree of xenobiotic hazard, the type of metabolic products formed, individual toxicometric parameters, etc.

Permissible levels of intensity for the main chemical factors in the habitat of military equipment

In the chemical composition of atmospheric air, primary significance is given to the content of oxygen and carbon dioxide, which directly affect the Respiration process. The values of these factors must be considered both in isolation (by the content of each component) and in combination with physical factors, primarily atmospheric pressure and air temperature. Such combined exposures are constantly encountered in the professional activities of specialists. Atmospheric pressure and habitat temperature can act as occupational factors when they increase or decrease, for instance, during diving operations, in pilots during flight, as well as in other military specialists operating in high-altitude conditions or similar environments.

Research has established that when the oxygen content in inhaled air falls below 16% (corresponding to a partial pressure below 122 mm Hg) and rises above 40%, a threat to human life is created. A decrease in oxygen content in the air of military equipment occurs only in emergency situations (fires, breaches of sealing systems, etc.).

An increase in its content in confined spaces may occur during the release of oxygen from cylinders, hydrogen peroxide (rocket propellant oxidizer), or the evaporation of liquid oxygen. Depending on the amount and rate of oxygen intake, its concentration may increase up to 56% of the total volume of other air constituents (partial pressure - 425 mm Hg).

Carbon dioxide and Water vapor can rapidly accumulate in enclosed spaces during prolonged human presence and in the absence of adequate ventilation. In addition, Carbon dioxide is a component of exhaust gases and gaseous combustion products (fires). Under normal barometric pressure, its concentration in the atmosphere should not exceed 0.04%. The Toxic Effect of CO₂ manifests when its content in inhaled air ranges from 3-5% and above. When carbon dioxide reaches 10% in the air, loss of consciousness occurs, soon followed by death from respiratory arrest. At a CO₂ concentration of about 20%, paralysis of the Brain centers occurs within a few seconds in a person who enters such an air environment without isolating respiratory protection equipment.

An excess of water vapor greater than 1% combined with elevated temperature and a lack of air movement impairs heat dissipation via evaporation and causes overheating of the body.

The partial pressure of nitrogen and inert gases in atmospheric air varies under conditions of barometric pressure fluctuations within the range of 700-800 mm Hg. In a confined space, the partial pressure of nitrogen, argon, and other inert gases may increase by a factor of 0.9–1.1 compared to normal values.