When an emergency occurs, a person is faced with many different problems. But the main one, especially in the first hours and minutes, is the problem of preserving life and working capacity. In any natural zones, natural factors are of great importance: temperature and humidity, air temperature, wind, solar radiation. They can be quite comfortable for a person or unfavorable for him.
Adverse natural factors in extreme or emergency situations.
It all depends on the season, the presence or absence of personal protective equipment to maintain normal body temperature, to provide protection against diseases and injuries. This becomes especially important when a person finds himself in unusual conditions for him and is not ready psychologically for them. The main thing is to avoid both overcooling and overheating of the body. Consider the main factors affecting the human body.
Natural factors such as extremely high or low air temperatures equally negatively affect human performance, often reducing the ability to move. And in some cases they can be fatal..
Since water provides intense heat transfer in the body, it is a fairly effective medium that can dramatically reduce body temperature. However, it is very dangerous if, having bathed or doused with water directly in the clothes, a person then goes into the wind. As a result, the temperature drops 25 times faster than if he was in the wind in dry clothes. This is especially dangerous if it gets into cold water in spring, autumn or winter..
Wind enhances the effects of cold, accelerating the evaporation of moisture from the surface of the body, which in turn significantly increases the body’s heat loss. But at the same time, the danger of hypothermia is significantly reduced (about 10 times) if a person is in continuous motion.
Heat transfer has a special effect on the human body, no less than ordinary natural factors. The heat exchange of the body with the environment occurs in different ways..
1. Heat radiation, that is, the transfer of heat waves from the human body to the environment or vice versa, and is the main cause of heat loss.
2. Heat conductivity, that is, the transfer of energy of motion from one molecule to another in a solid medium. Rapid heat loss by the body occurs when frostbite or burns occur when you touch the metal in extreme cold or in extreme heat. The same thing happens if you sit (lie) on snow, cold earth, a stone or a strongly cooled (warmed) object.
3. Convection. This is the phenomenon of heat transfer through the movement of air masses. Our body is constantly warmed by a thin layer of air under the clothes in contact with it. If this air layer evaporates by convection, then the body begins to cool. Thus, clothing, as it were, protects our body from heat loss. At the same time, the wind, penetrating under our clothes at different times of the year, acts in different ways. In winter, it contributes to hypothermia; in summer, it creates a comfortable state of the body.
4. Evaporation. This is a process in which a liquid turns into steam and transfers its heat to the atmosphere. When a person sweats, the same thing happens, regardless of climatic conditions. Sweating in winter is especially dangerous if the clothing does not breathe, i.e. does not allow air to pass on one side, and water vapor cannot evaporate through the fabric on the other. Drops of sweat accumulate on the body and inside of the garment. The heat-insulating properties of clothes are reduced, and the body is hypothermia (freezing).
In hot climates, especially at ultra-high temperatures, the rate of evaporation of sweat from the body due to blowing it by the wind is of great importance. The higher it is, the faster the dehydration of the body and the accumulation of heat in it occurs. The body becomes unable to maintain thermal balance, and the limit of survival (i.e., the beginning of the destruction of the physiological functions of the body) will be reached the sooner the higher the air temperature.
5. breath. Also one of the methods of heat transfer. It combines the processes of heat radiation, and convection, and evaporation. Each inhalation and exhalation warms or cools the inhaled air and accordingly cools or heats the lungs. And this, in turn, has a significant effect on the body, most often negative, such as a burn of the lungs with dry hot air or, conversely, their frostbite when inhaled frosty, below minus 50 degrees air.
Based on materials from the book Encyclopedia of Survival.
Chernysh I. V.