In spite of the fact that air is, as a rule, not visible to a human eye, the set of elements is its part. The mix of gases called air also forms natural protection of the planet against harmful radiations – the atmosphere of Earth.
The set of elements which in many respects define activity of a human body is a part of air, doing it it is better or worse. The carbon monoxide produced by engines of cars, tobacco smoking has negative effect on human health. The increased amount of this gas in air can make sick, a headache, drowsiness. The element seen by us – dust which represents particles of mineral and organic origin also is a part of air. The most important component of air is oxygen. Its sufficient quantity provides to the person normal breath and functioning of lungs and a blood system. Most of all contains in air nitrogen. This gas serves as thinner of other gases. As a result of breath, carbon dioxide which is a part of air along with industrial emissions is formed. It is used at artificial respiration, and, besides, the level of carbon dioxide shows air pollution level. Besides the listed gases, sulphurous gas and carbon monoxide also is composition of the atmosphere (it is formed at incomplete combustion of organic matter). The listed gases form the basis of air mix, however their percentage can change, for example, in the cities with the high content of carbon dioxide. On average ratio of gases of atmospheric air is as follows: 78% of nitrogen, 21% of oxygen, about 0.035% of carbon dioxide, about 1% of carbon monoxide, ozone, inert gases. At last, besides gases the insignificant amount of vapors of water always is a part of air.
On air Wednesday the set of mechanical impurity as a result of combustion of organic and inorganic matter, industrial wastes in the form of smoke, a soot, soot, small particles of the soil arrives. If in a certain area the sand soil prevails, then the dust content of the soil considerably increases. The asphalted roads, on the contrary, reduce dust content level, however process of construction in itself leads to considerable air pollution by a soot.
The air cover may contain also various microorganisms, including microbes, bacteria, fungi, viruses, barmy cages. For this reason infection with cold in badly aired room with a big congestion of people where concentration of microorganisms considerably exceeds norm is possible. In such conditions not only the sneezed person but also who is simply speaking sprays the smallest droplets which with air extend to distance up to 10 meters.