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Sanitary indices of the efficiency of air ventilation.






Sanitary indices of the efficiency of air ventilation in living and public locations are as follows: smell (or absence of smell), concentration of carbon dioxide in the air, temperature of the air, air humidity, air velocity, bacterial content in the air. If the air is polluted with chemical contaminants, the degree of air pollution should be determined.

The significance of carbon dioxide in the indoor environment.

Carbon dioxide plays a significant role in our life. Life on the Earth would not exist without carbon dioxide. Besides, it is a physiological stimulus of the respiratory centre when its concentration in the air is 0, 03 – 0, 04%.

Inhaling highly concentrated carbon dioxide can result in impaired oxidation and reduction processes. When the concentration of carbon dioxide in the air increases to 4%, one can develop headaches, tinnitus, palpitation, agitation. When the concentration of carbon dioxide in the air is 8%, it could be fatal.

Air purity of in a room is evaluated considering the concentration of carbon dioxide in the air. High concentration of carbon dioxide in the air usually suggests inadequate sanitary conditions (overcrowding, poor ventilation, etc.).

The higher the concentration of carbon dioxide in the air is, the worse some other physical properties of the air are. For example, when the temperature of the air and air humidity increase, the number of microorganisms in the air increase as well and anthrapotoxins begin to appear in the air.

Anthropotoxins include the following substances: dimethylamine, benzol, methylethylkethon, hexane, methylbenzene, mercaptan, indole, ammonia, nitrogen oxides, etc. The content of these substances in the air depends on the number of people in the room, duration of their stay indoors, type of work done, etc.

Concentration of anthropotoxins in the air is inversely proportional to the air supply. If the air supply is 120 m³ /h, the index of reduction of anthropotoxin accumulation in the air should be 80 – 85%. In these conditions the air can be cleaned up easily.

As the concentration of carbon dioxide in the air increases and microclimatic conditions worsen, ionization of the air changes as well (i.e. the number of heavy ions increases and the number of light ions decreases). It can be due to light ion retention during respiration and contact to skin as well heavy ion delivery with the exhaled air.

When estimating the quality of the air in the indoor environment, the concentration of carbon dioxide in the air should be considered. The maximum permissible concentration of carbon dioxide in the air is 0, 07% (for patient care institutions) and 0, 1% (for residential and public premises). The latter is accepted as the calculation value when estimating the efficiency of ventilation in living and public facilities.






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