Composition of air

That part of the atmosphere that adjoins the Earth and which is breathed by a person, is called the troposphere. The troposphere has a height of nine to eleven kilometers and is a mechanical mixture of a variety of gases.

The air composition is not constant. Depending on the geographical location, terrain, weather conditions, population density, air can have different composition and different properties. Air can be gassed or discharged, fresh or heavy - all this means that it has certain impurities.

However, it is customary to consider the following air composition as standard:

- nitrogen - 78.9 percent;

- oxygen - 20.95 percent;

- Carbon dioxide - 0.3 percent.

In addition, other gases (helium, argon, neon, xenon, krypton, hydrogen, radon, ozone), as well as nitrous oxide and water vapor are present in the atmosphere . Their sum is slightly less than one percent.

It is also worth pointing to the presence in the air of some permanent admixtures of natural origin, in particular, some gaseous products that are formed as a result of both biological and chemical processes. Ammonia deserves special mention among them (the composition of air far from populated areas includes about three to five thousandth milligrams per cubic meter), methane (its average level is two ten thousandths of a milligram per cubic meter), nitrogen oxides (in the atmosphere their concentration reaches Approximately fifteen ten thousandths of a milligram per cubic meter), hydrogen sulphide and other gaseous products.

In addition to vapor and gaseous impurities, the chemical composition of air usually includes dust of cosmic origin, which falls to the surface of the Earth in the amount of seven hundred thousandths per square kilometer during the year, as well as dust particles that come from eruptions of volcanoes.

However, the composition of the air changes to the greatest extent (and not to the best) and the so-called ground (plant, soil) dust and smoke from forest fires pollute the troposphere. Especially a lot of such dust in the continental air masses, originating in the deserts of Central Asia and Africa. That is why we can confidently state that an ideally clean air environment simply does not exist, and it is a concept that exists only theoretically.

The composition of air has a property to constantly change, and its natural changes usually play a rather small role, especially in comparison with the possible consequences of its artificial disturbances. Such violations are mainly associated with the productive activities of mankind, the use of devices for consumer services, as well as vehicles. These violations can lead, among other things, to air denaturation, that is, to pronounced differences in its composition and properties from the corresponding indices of the atmosphere.

These and many other types of human activity have led to the fact that the main air composition began to be subjected to slow and insignificant, but nonetheless absolutely irreversible changes. For example, scientists have calculated that over the past fifty years, mankind has used about as much oxygen as in the preceding million years, and in percentage terms, two-tenths of a percent of its total stock in the atmosphere. At the same time, the release of carbon dioxide into the air envelope of the Earth is accordingly increased . This release, according to the latest data, reached almost four hundred billion tons over the last hundred years.

Thus, the air composition changes for the worse, and it is difficult to guess how it will become in a few decades.