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Atmospheric air as an external environment. The complex effect of meteorological factors on the human body. Meteotropic reactions



Atmospheric air is one of the most important components of human ecology. In the process of his life, a person constantly comes into contact with many factors of the external environment in which he lives, and these factors, of course, have a certain effect on the human body. One of the factors with which a person comes into contact most closely is the air environment. Air is the most necessary component for the existence of the human body. Without it, a person can exist only for a few minutes.

In the process of evolution, man has adapted to existence in an air environment with certain properties, and therefore it is quite clear that a change in the chemical composition of this environment or its physical properties affects the state of health, well-being and human performance.

The air envelope of the globe, called the atmosphere, can be traced to an altitude of about 1000 km above the surface of the earth. The properties of the atmosphere at different heights are not the same, therefore it is conditionally divided into several layers: The structure of the atmosphere:

1. Troposphere - up to 12-14 km.

2. Stratosphere - up to 80-100 km.

3. The ionosphere - up to 600 km.

4. Vacuum sphere - up to 1000 km.

The first layer closest to the surface of the earth is called the troposphere and extends to a height of 12-14 km. Unlike other higher layers, it is characterized by the following properties:

1. In the troposphere, daily and seasonal temperature fluctuations constantly occur.

2. The troposphere is characterized by the constant movement of air currents occurring in various directions: horizontal, vertical, turbulent, vortex.

3. A significant amount of water vapor is constantly present in the troposphere, causing the formation of various kinds of condensate phenomena (clouds, fogs, precipitation).

4. The troposphere is characterized by the presence of a fairly significant amount of impurities (solid, liquid and gaseous pollution).

In all overlying layers of the atmosphere, the air temperature is always constant and does not change depending on the time of day or season of the year. In the air of these layers horizontal movements of air masses prevail, there are no water vapor, and therefore the phenomena associated with them (clouds, fogs). They practically do not contain extraneous impurities characteristic of the troposphere, with the exception of those minor contaminants that enter the earth from space (cosmic dust), as well as contaminants that are thrown into the stratosphere from the earth’s surface under certain emergency circumstances (during nuclear weapon explosions and large eruptions volcanoes). The troposphere is followed by a layer called the stratosphere, which extends to a height of about 100 km. In the stratosphere, mainly horizontal displacements of air masses occur, as a result of which large distances spreading into the stratosphere spread and are called global.

Pollution entering the stratosphere has a number of features. Due to the considerable distance from the surface of the earth, they have a very low weight, and therefore their subsidence rate is very low. They are carried by very large distances by horizontal air flows and practically spread over the entire earth's surface, which gave grounds to call them "global." This circumstance played a significant role in the process of concluding an agreement banning the testing of nuclear weapons in the external environment.

Above the stratosphere is a layer called the ionosphere, which extends to an altitude of about 600 km. In addition to the properties that are characteristic of the stratosphere, this layer is characterized by a significant degree of air ionization.

The vacuum sphere, extending to an altitude of about 1000 km, is characterized by a strong degree of rarefaction of air. Almost to this height only individual elements of the air can be detected.

Thus, the air shell has the highest density at the surface of the earth and, gradually being rarefied, is lost at an altitude of about 1000 km.

Naturally, for our ordinary life, the troposphere is the most important - the layer of the atmosphere closest to the earth. We are most in contact with the air of the troposphere, and its properties have a direct impact on us. Currently, the properties of air masses and other layers are being intensively studied, but directly for the human body they cannot matter, since the existence of a person in those layers outside apparatuses with artificial conditions is impossible.

Consider the chemical composition of atmospheric air and the influence of its components on the human body. Naturally, we will consider the composition of clean air, since the next special lecture will be devoted to the issues of air pollution and the effect of these pollution on humans.

Air is a mechanical mixture of gases consisting of oxygen (20.93%), nitrogen (78.1%), carbon dioxide (0.03-0.04%) and a group of inert gases (about 1%). There is a constant gas cycle in the atmosphere: humans and animals absorb oxygen and emit carbon dioxide when breathing, the same processes occur during any oxidative processes (burning, decay, decay, etc.), while the vegetative cover of the earth's surface absorbs carbon dioxide and releases oxygen. For a long time, these processes balanced each other, as a result of which the composition of the air medium remained constant, which was facilitated by the movement of air masses, ensuring uniform mixing of air. It should be noted that the chemical composition of air varies little depending on the height of the air layer. So, at an altitude of 28 km in the air contains 20.39% oxygen (at sea level - 20.93%).

Oxygen (O2). Turning to the consideration of the individual components of the air environment and their impact on the human body, it should be noted that oxygen is the most important component in the composition of air. First of all, it is necessary to maintain the processes of combustion, decay, and other oxidative processes occurring in nature, which ensure the existence of life on earth. In addition, all oxidative processes in the body itself occur with the direct participation of oxygen. Therefore, it is a vital component, and in its absence, the existence of the organism becomes impossible. It is very important to establish to what extent a decrease in the amount of oxygen in the air is possible without disturbing the physiological functions of the body. Naturally, some fluctuations in the oxygen content in the air by the body are tolerated quite painlessly, since the body has quite powerful compensatory capabilities.
It has been experimentally established that a decrease in the amount of oxygen in the inhaled air to 16 and even 15% (at normal pressure) is transferred by the body quite painlessly, although the compensatory mechanisms are in a state of tension (increased pulmonary ventilation, cardiac activity, etc.). For a short time, a person can survive even in an atmosphere with an oxygen content of about 10%, and people (pilots) well trained for oxygen deficiency - up to 8-7%. Naturally, in this case, the compensatory mechanisms of the body are in extreme tension. A further decrease in the oxygen content in the inhaled air leads to a rapid depletion of the compensatory mechanisms of the body and its death. The central nervous system is particularly sensitive to oxygen deficiency. The body compensates for oxygen deficiency due to: increased pulmonary ventilation (increased and deepened respiratory movements); increased blood circulation (increased systolic volume of heart contractions and an increase in their frequency); increase in the amount of circulating blood (due to its exit from the depot); increase in the number of blood cells that provide the function of oxygen transportation (increase in the number of red blood cells and hemoglobin in the blood), etc.

Inhalation of air with a high oxygen content is well tolerated by the human body. Inhaling even pure oxygen (at normal pressure) does not lead to pathological changes in the body. Only with prolonged breathing with pure oxygen is there a certain drying effect on the mucous membranes of the respiratory tract, which can lead to their irritation and the occurrence of inflammatory phenomena. Inhalation of pure oxygen under elevated pressure (3-4 atmospheres or more) leads to pathological phenomena from the central nervous system, manifested in the form of seizures (oxygen intoxication). Under ordinary conditions of life, such phenomena do not occur, but can occur when using oxygen equipment in case of malfunction (underwater diving).

Carbon Dioxide (CO2). There is very little carbon dioxide in the air. In atmospheric air only 0.03-0.04%, and in indoor air - up to tenths of a percent. However, it has a very great hygienic value.

First of all, it should be noted its role in maintaining the ecological balance of the environment on a global scale.

For a long time, the oxidizing and reducing processes that take place in nature balanced each other out, due to which the composition of the air practically did not change. However, in connection with technological progress, a sharply increasing number of internal combustion engines and other power plants, the number of oxidation processes on the globe has significantly increased. At the same time, as a result of urbanization and industrial development, the number of green spaces, which are the main consumers of carbon dioxide, has decreased significantly. That is, in recent years there has been an increase in the concentration of carbon dioxide in atmospheric air. Scientists believe that if the increase in the amount of carbon dioxide in the air continues to occur, then the so-called "greenhouse effect" may occur in nature, since carbon dioxide in the atmosphere delays the long-wavelength part of infrared radiation emitted by the earth's surface into space. As a result, there will be an increase in the average annual temperature of the atmospheric air, which, in turn, will lead to the melting of polar glaciers, an increase in sea level, and, consequently, to flooding of a significant part of the earth's surface.

For indoor air, the carbon dioxide content is of sanitary significance. In the premises where people are located, various products of the vital activity of the human body enter the air: exhaled air saturated with carbon dioxide and water vapor; evaporation from the surface of the skin and mucous membranes of the respiratory tract, which contain the decomposition products of mucus, sweat, sebum, etc. As a result, the concentration of carbon dioxide in the air increases, ammonia, aldehydes, ketones and other foul-smelling gases appear, humidity, dust and microbial air pollution increase, which is generally characterized as stuffy (residential) air, which affects people's well-being, performance and health. By the concentration of carbon dioxide in such air, one can determine the degree of its total pollution. Therefore, carbon dioxide serves as a sanitary indicator of air purity in residential and public buildings. Air is considered fresh if the concentration of carbon dioxide in it does not exceed 0.1%. This value is considered the maximum permissible for air in residential and public buildings.

In addition, one should take into account the fact that carbon dioxide is heavier than air and can accumulate in the lower parts of enclosed spaces that are not exposed to intensive ventilation. This is most important for those places where enhanced oxidative processes occur (fermentation tanks, abandoned mines or wells, at the bottom of which there are rotting or wandering garbage, etc.). In such places, the concentration of carbon dioxide can reach large values ​​and pose a danger to human health and existence. If the concentration of carbon dioxide in the inhaled air exceeds 3%, then the existence in such an atmosphere becomes hazardous to health. A CO2 concentration of about 10% is considered life-threatening (loss of consciousness occurs after a few minutes of breathing with such air). At a concentration of 20%, paralysis of the respiratory center occurs within a few seconds.

Nitrogen (N2). It is believed that nitrogen is an indifferent gas and plays the role of a filler in air. However, such a representation is correct only at normal pressure. When air is inhaled under increased pressure, nitrogen begins to exert a narcotic effect. This effect is most clearly manifested at an air pressure of 9 or more atmospheres. This is of great importance, since during the work of divers at great depths they have to supply air under high pressure, sometimes exceeding 10 atmospheres. When working in such conditions, unreasonable gaiety, impaired coordination of movements, excessive talkativeness and other manifestations of euphoria are noted in the behavior of divers. These are the manifestations of the narcotic effect of nitrogen. At present, when the divers work at great depths, they do not use air for breathing, but a specially prepared helium-oxygen mixture, i.e. nitrogen in the air is replaced by a more inert gas.

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