Structure of atmospheric air and its hygienic value
Atmospheric air represents a mix of gases in parities.
Except the specified gases in air the certain quantity of a dust and microorganisms always contains.
At breath in lungs there is a gas exchange: in alveoluses the part of oxygen from air passes in blood, and from blood the part of carbonic gas is allocated in alveolar air. Thus in exhaled air contains oxygen and in 100 times more in comparison with inhaled carbonic acids much less.
Oxygen is the basic component of air. At its participation in a human body and animals all oxidising processes proceed. The person in a rest condition consumes about 350 ml of oxygen; at heavy physical activity oxygen consumption increases.
Fluctuations of the maintenance of oxygen in atmospheric air are insignificant. Its suppliers are plants which absorb carbonic acid, acquiring thus carbon, and the released oxygen is allocated in atmosphere. An oxygen source is also photochemical decomposition of water steams in an upper atmosphere under the influence of ultra-violet radiation of the Sun. Therefore practically the oxygen maintenance in atmospheric air remains almost constant in spite of the fact that it is spent for breath of the person and animals, burning and oxidation processes.
At low concentration of oxygen in air (submarines, refuges, germetizirovannye cabins of planes, mines, the mines, the thrown wells etc.) when oxygen is superseded by other gases and its level considerably decreases (4-5%), is marked the expressed oxygen insufficiency promoting decrease of working capacity and accompanied by cough, sensation of heat in a breast, a headache, tachycardia, a hypertensia, etc.
Carbonic gas - colourless gas without a smell, in 1,5 times is heavier than air (1 g С0 2 occupies volume of 506 ml), enters into its structure. Concentration of carbonic gas (0,04%) in atmosphere is almost always constant, as its surplus is absorbed by plants. oksida carbon in atmospheric air it is a lot of suppliers: it is allocated at fuel burning, at the expense of ability to live of the person and animals, from soil. However even in air of badly ventilated public buildings maintenance С0 2 usually does not exceed 1%. Maximum permissible concentration of carbonic gas in air of the closed premises makes 0,1%.
Carbonic gas - the activator of the respiratory centre. Increase and breath deepening are observed at its concentration in air, equal 2-3%. In considerable quantities carbonic gas causes narcotic action and death. Signs of a poisoning with carbonic acid (it is angry a mucous membrane of respiratory ways, cough, sensation of heat in a breast, a headache, the tachycardia, the raised arterial pressure, working capacity decrease) appear, if its concentration in air makes 4-5%, at 10-12% loss of consciousness and death are observed.
The Poisoning can be observed in the closed or hermetically sealed premises (mines, submarines), and also in places, where probably intensive decomposition of organic substances: sewer pipes, barmy tubs on breweries, deep wells, silage holes etc.
Hygienic value of carbonic gas consists that under its maintenance judge cleanliness of air of inhabited and public premises. At a congestion of people in badly ventilated premises concentration of carbonic gas can exceed 0,1%. Air thus gets an unpleasant smell and can cause infringement of a functional condition of an organism. In parallel accumulation С0 2 in air the maintenance of other products of ability to live of the person increases, its temperature and humidity raise. Arising thus the unpleasant state of health and the painful phenomena at people are caused by infringement of thermoregulation at the expense of rise in temperature and humidity of air, instead of as a result of toxic action SOg.
Nitrogen and other gases. Nitrogen is the basic component of atmospheric air. In an organism it is in the dissolved condition in blood, in a fabric liquid, but in physiological reactions of participation does not accept.
Hygienic value of other gases (inert) in air is insignificant, as they do not participate in reactions and do not render adverse influence on the person. Their value, as well as nitrogen, consists only in razbavlenii oxygen in air.
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