Chemical composition of atmospheric air. Composition and structure of the atmosphere

Air is an essential condition for the life of the vast majority of organisms on our planet.

A person can live for a month without food. Without water - three days. Without air - just a few minutes.

History of the study

Not everyone knows that the main component of our life is an extremely heterogeneous substance. Air is a mixture of gases. Which ones?

For a long time it was believed that air was a single substance and not a mixture of gases. The heterogeneity hypothesis has appeared in the scientific works of many scientists at different times. But no one moved beyond theoretical guesses. Only in the eighteenth century, Scottish chemist Joseph Black experimentally proved that the gas composition of air is heterogeneous. The discovery was made during subsequent experiments.

Modern scientists have proven that air is a mixture of gases consisting of ten main elements.

The composition differs depending on the place of concentration. Air composition is determined constantly. People's health depends on this. Air is a mixture of what gases?

At higher elevations (especially in the mountains) the oxygen content is low. This concentration is called “rarefied air”. In forests, on the contrary, the oxygen content is maximum. In megacities, the content of carbon dioxide is increased. Determining the composition of air is one of the most important responsibilities of environmental services.

Where can air be used?

• The compressed mass is used when pumping air under pressure. Setting up to ten bar is installed at any tire service station. The tires are inflated with air.
• Workers use jackhammers and pneumatic guns to quickly remove/install nuts and bolts. Such equipment is characterized by low weight and high efficiency.
• In industries using varnishes and paints, it is used to speed up the drying process.
• At car washes, the compressed air mass helps in quickly drying cars;
• Manufacturing enterprises use compressed air to clean tools from all types of contaminants. In this way, entire hangars can be cleared of shavings and sawdust.
• The petrochemical industry can no longer imagine itself without equipment for purging pipelines before the first start-up.
• In the production of oxides and acids.
• To increase the temperature of technological processes;
• They are extracted from the air;

Why do living beings need air?

The main task of air, or rather, one of the main components - oxygen - is to penetrate into cells, as a result of which it promotes oxidation processes. Thanks to this, the body receives energy that is essential for life.

Air enters the body through the lungs, after which it is distributed throughout the body using the circulatory system.

Air is a mixture of what gases? Let's take a closer look at them.

Nitrogen

Air is a mixture of gases, the first of which is nitrogen. The seventh element of Dmitri Mendeleev's periodic table. The discoverer is considered to be the Scottish chemist Daniel Rutherford in 1772.

It is part of the proteins and nucleic acids of the human body. Although its share in cells is small - no more than three percent, the gas is essential for normal life.

Its content in the air is more than seventy-eight percent.

Under normal conditions it is colorless and odorless. Does not combine with other chemical elements.

The largest amount of nitrogen is used in the chemical industry, primarily in the manufacture of fertilizers.

Nitrogen is used in the medical industry, in the production of dyes,

In cosmetology, acne, scars, warts, and the body's thermoregulation system are treated with gas.

Using nitrogen, ammonia is synthesized and nitric acid is produced.

In the chemical industry, oxygen is used for the oxidation of hydrocarbons in alcohols, acids, aldehydes, and the production of nitric acid.

Fishing industry - saturation of water bodies with oxygen.

But gas is most important for living beings. With the help of oxygen, the body can utilize (oxidize) the necessary proteins, fats and carbohydrates, converting them into the necessary energy.

Argon

The gas that is part of the air is in third place in importance - argon. The content does not exceed one percent. It is an inert gas without color, taste or smell. Eighteenth element of the periodic table.

The first mention is attributed to an English chemist in 1785. And Lord Larey and William Ramsay received Nobel Prizes for proving the existence of the gas and experiments with it.

Areas of application of argon:

• incandescent lamps;
• filling the space between glass panes in plastic windows;
• protective environment during welding;
• fire extinguishing agent;
• for air purification;
• chemical synthesis.

It does not bring any particular benefit to the human body. At high concentrations of gas it leads to suffocation.

Argon cylinders in gray or black.

The remaining seven elements make up 0.03% in air.

Carbon dioxide

Carbon dioxide in the air is colorless and odorless.

Formed as a result of rotting or burning of organic materials, released during breathing and operation of cars and other vehicles.

In the human body, it is formed in tissues as a result of vital processes and is transported through the venous system to the lungs.

It has a positive meaning, because under load, it expands the capillaries, which allows for greater transport of substances. Positive effect on the myocardium. Helps increase the frequency and strength of the load. Used in the correction of hypoxia. Participates in the regulation of breathing.

In industry, carbon dioxide is obtained from combustion products, as a by-product of chemical processes or during air separation.

Application is extremely wide:

• preservative in the food industry;
• saturation of drinks;
• fire extinguishers and fire extinguishing systems;
• feeding aquarium plants;
• protective environment during welding;
• use in canisters for gas weapons;
• refrigerant

Neon

Air is a mixture of gases, the fifth of which is neon. It was opened much later - in 1898. The name is translated from Greek as “new”.

A monatomic gas that is colorless and odorless.

Has high electrical conductivity. Has a complete electronic shell. Inert.

Gas is obtained by separating air.

Application:

• Inert environment in industry;
• Refrigerant in cryogenic installations;
• Filler for gas discharge lamps. Found widespread use thanks to advertising. Most colored signs are made using neon. When an electric discharge is passed through, the lamps produce a bright colored glow.
• Signal lights at lighthouses and airfields. They perform well in heavy fogs.
• Air mixture element for people when working with high pressure.

Helium

Helium is a colorless and odorless monatomic gas.

Application:

• Like neon, when passed through an electrical discharge it produces a bright light.
• In industry - to remove impurities from steel during smelting;
• Refrigerant.
• Filling of airships and balloons;
• Partially in breathing mixtures during deep dives.
• Coolant in nuclear reactors.
• The main joy of children is flying balloons.

It is not of particular benefit to living organisms. In high concentrations it can cause poisoning.

Methane

Air is a mixture of gases, the seventh of which is methane. Gas is colorless and odorless. In high concentrations it is explosive. Therefore, odorants are added to it for indication.

It is most often used as fuel and raw material in organic synthesis.

Home furnaces, boilers, and geysers operate primarily on methane.

A product of the vital activity of microorganisms.

Krypton

Krypton is an inert monatomic gas without color or odor.

Application:

• in the production of lasers;
• rocket fuel oxidizer;
• filling incandescent lamps.

The effect on the human body has been little studied. Application in deep sea diving is being studied.

Hydrogen

Hydrogen is a colorless flammable gas.

Application:

• Chemical industry - production of ammonia, soap, plastics.
• Filling spherical shells in meteorology.
• Rocket fuel.
• Cooling of electric generators.

Xenon

Xenon is a monatomic colorless gas.

Application:

• filling incandescent lamps;
• in spacecraft engines;
• as an anesthetic.

It is harmless to the human body. Not particularly useful.

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The atmosphere is the air environment that surrounds the globe and is one of the most important reasons for the emergence of life on earth. It was atmospheric air, its unique composition, that gave living beings the opportunity to oxidize organic substances with oxygen and obtain energy for existence. Without it, human existence will be impossible, as well as all representatives of the animal kingdom, most plants, fungi and bacteria.

Meaning for humans

The air environment is not only a source of oxygen. It allows a person to see, perceive spatial signals, and use the senses. Hearing, vision, smell - they all depend on the state of the air.

The second important point is protection from solar radiation. The atmosphere envelops the planet with a shell that blocks part of the spectrum of solar rays. As a result, about 30% of solar radiation reaches the earth.

The air environment is a shell in which precipitation forms and evaporation rises. It is she who is responsible for half of the moisture exchange cycle. Precipitation formed in the atmosphere affects the functioning of the World Ocean, contributes to the accumulation of moisture on continents, and determines the destruction of exposed rocks. She takes part in climate formation. The circulation of air masses is the most important factor in the formation of specific climatic zones and natural zones. Winds arising above the Earth determine temperature, humidity, precipitation levels, pressure, and weather stability in the region.

Currently, chemicals are extracted from the air: oxygen, helium, argon, nitrogen. The technology is still at the testing stage, but in the future this can be considered a promising direction for the chemical industry.

The above are obvious things. But the air environment is also important for industry and human economic activity:

• It is the most important chemical agent for combustion and oxidation reactions.
• Transfers heat.

Thus, atmospheric air is a unique air environment that allows living things to exist and people to develop industry. There is a close interaction between the human body and the air environment. If you violate it, serious consequences will not keep you waiting.

Hygienic characteristics of air

Pollution is the process of introducing impurities into the atmospheric air that should not normally exist. Pollution can be natural or artificial. Impurities that come from natural sources are neutralized in the planetary cycle of matter. With artificial pollution the situation is more complicated.

Natural pollution includes:

• Cosmic dust.
• Impurities formed during volcanic eruptions, weathering, and fires.

Artificial pollution is anthropogenic in nature. There are global and local pollution. Global is all emissions that can affect the composition or structure of the atmosphere. Local is a change in indicators in a specific area or in a room used for living, work or public events.

Ambient air hygiene is an important section of hygiene that deals with the assessment and control of indoor air parameters. This section appeared in connection with the need for sanitary protection. The hygienic importance of atmospheric air is difficult to overestimate - along with breathing, all the impurities and particles contained in the air enter the human body.

Hygienic assessment includes the following indicators:

1. Physical properties of atmospheric air. This includes temperature (the most common violation of SanPin in workplaces is that the air heats up too much), pressure, wind speed (in open areas), radioactivity, humidity and other indicators.
2. The presence of impurities and deviations from the standard chemical composition. Atmospheric air is characterized by its suitability for breathing.
3. The presence of solid impurities - dust, other microparticles.
4. The presence of bacterial contamination – pathogenic and conditionally pathogenic microorganisms.

To compile a hygienic characteristic, the readings obtained on four points are compared with established standards.

Environmental protection

Recently, the state of atmospheric air has been causing concern among environmentalists. As industry develops, environmental risks also grow. Factories and industrial zones not only destroy the ozone layer, heating the atmosphere and saturating it with carbon impurities, but also reduce hygiene. Therefore, in developed countries it is customary to carry out comprehensive measures to protect the air environment.

Main directions of protection:

• Legislative regulation.
• Development of recommendations for the location of industrial zones, taking into account climatic and geographical factors.
• Carrying out measures to reduce emissions.
• Sanitary and hygienic control at enterprises.
• Regular monitoring of composition.

Protection measures also include planting green spaces, creating artificial reservoirs, and creating barrier zones between industrial and residential areas. Recommendations for carrying out protective measures have been developed by organizations such as WHO and UNESCO. State and regional recommendations are developed on the basis of international ones.

Currently, the problem of air hygiene is receiving more and more attention. Unfortunately, at the moment, the measures taken are not enough to completely minimize anthropogenic harm. But we can hope that in the future, together with the development of more environmentally friendly industries, it will be possible to reduce the load on the atmosphere.

Air is necessary for all living organisms: animals for breathing, and plants for nutrition. In addition, air protects the Earth from the harmful ultraviolet radiation of the Sun. The main components of air are nitrogen and oxygen. The air also contains small admixtures of noble gases, carbon dioxide and a certain amount of solid particles - soot and dust. All animals need air to breathe. About 21% of air is oxygen. An oxygen molecule (O2) consists of two bonded oxygens.

Air composition

The percentage of different gases in the air varies slightly depending on location, time of year and day. Nitrogen and oxygen are the main components of air. One percent of the air consists of noble gases, carbon dioxide, water vapor and pollutants such as nitrogen dioxide. Gases contained in air can be separated by fractional distillation. The air is cooled until the gases turn into a liquid state (see article ““). After this, the liquid mixture is heated. Each liquid has its own boiling point, and the gases formed during boiling can be collected separately. Oxygen, nitrogen and carbon dioxide are constantly moving from the air into and returning to the air, i.e. a cycle occurs. Animals inhale oxygen from the air and exhale carbon dioxide.

Oxygen

Nitrogen

More than 78% of air is nitrogen. Proteins from which living organisms are built also contain nitrogen. The main industrial application of nitrogen is ammonia production needed for fertilizers. For this purpose, nitrogen is combined with. Nitrogen is pumped into packaging for meat or fish, because... upon contact with ordinary air, products oxidize and deteriorate. Human organs intended for transplantation are stored in liquid nitrogen because it is cold and chemically inert. A nitrogen molecule (N2) consists of two bonded nitrogen atoms.

Noble gases

The noble gases are 6 of the 8th group. They are extremely chemically inert. Only they exist in the form of individual atoms that do not form molecules. Because of their passivity, some of them are used to fill lamps. Xenon is practically not used by humans, but argon is pumped into light bulbs, and fluorescent lamps are filled with krypton. Neon flashes red-orange when electrically charged. It is used in sodium street lamps and neon lamps. Radon is radioactive. It is formed by the decay of the metal radium. No helium compounds are known to science, and helium is considered completely inert. Its density is 7 times less than the density of air, which is why airships are filled with it. Helium-filled balloons are equipped with scientific equipment and launched into the upper atmosphere.

Greenhouse effect

This is the name for the currently observed increase in carbon dioxide content in the atmosphere and the resulting global warming, i.e. increase in average annual temperatures around the world. Carbon dioxide prevents heat from leaving the Earth, just as glass maintains high temperatures inside a greenhouse. As there is more carbon dioxide in the air, more heat is trapped in the atmosphere. Even slight warming causes sea levels to rise, winds to change and some of the ice at the poles to melt. Scientists believe that if carbon dioxide levels rise as quickly, then in 50 years the average temperature could increase by 1.5°C to 4°C.

The structure and composition of the Earth’s atmosphere, it must be said, were not always constant values ​​in one or another period of the development of our planet. Today, the vertical structure of this element, which has a total “thickness” of 1.5-2.0 thousand km, is represented by several main layers, including:

1. Troposphere.
2. Tropopause.
3. Stratosphere.
4. Stratopause.
5. Mesosphere and mesopause.
6. Thermosphere.
7. Exosphere.

Basic elements of atmosphere

The troposphere is a layer in which strong vertical and horizontal movements are observed; it is here that weather, sedimentary phenomena, and climatic conditions are formed. It extends 7-8 kilometers from the surface of the planet almost everywhere, with the exception of the polar regions (up to 15 km there). In the troposphere, there is a gradual decrease in temperature, approximately by 6.4 ° C with each kilometer of altitude. This indicator may differ for different latitudes and seasons.

The composition of the Earth's atmosphere in this part is represented by the following elements and their percentages:

Nitrogen - about 78 percent;

Oxygen - almost 21 percent;

Argon - about one percent;

Carbon dioxide - less than 0.05%.

Single composition up to an altitude of 90 kilometers

In addition, here you can find dust, water droplets, water vapor, combustion products, ice crystals, sea salts, many aerosol particles, etc. This composition of the Earth’s atmosphere is observed up to approximately ninety kilometers in altitude, so the air is approximately the same in chemical composition, not only in the troposphere, but also in the overlying layers. But there the atmosphere has fundamentally different physical properties. The layer that has a general chemical composition is called the homosphere.

What other elements make up the Earth's atmosphere? In percentage (by volume, in dry air) gases such as krypton (about 1.14 x 10 -4), xenon (8.7 x 10 -7), hydrogen (5.0 x 10 -5), methane (about 1.7 x 10 -5) are represented here. 4), nitrous oxide (5.0 x 10 -5), etc. As a percentage by mass, the most of the listed components are nitrous oxide and hydrogen, followed by helium, krypton, etc.

Physical properties of different atmospheric layers

The physical properties of the troposphere are closely related to its proximity to the surface of the planet. From here, reflected solar heat in the form of infrared rays is directed back upward, involving the processes of conduction and convection. That is why the temperature drops with distance from the earth's surface. This phenomenon is observed up to the height of the stratosphere (11-17 kilometers), then the temperature becomes almost unchanged up to 34-35 km, and then the temperature rises again to altitudes of 50 kilometers (the upper limit of the stratosphere). Between the stratosphere and the troposphere there is a thin intermediate layer of the tropopause (up to 1-2 km), where constant temperatures are observed above the equator - about minus 70 ° C and below. Above the poles, the tropopause “warms up” in summer to minus 45°C; in winter, temperatures here fluctuate around -65°C.

The gas composition of the Earth's atmosphere includes such an important element as ozone. There is relatively little of it at the surface (ten to the minus sixth power of one percent), since the gas is formed under the influence of sunlight from atomic oxygen in the upper parts of the atmosphere. In particular, the most ozone is at an altitude of about 25 km, and the entire “ozone screen” is located in areas from 7-8 km at the poles, from 18 km at the equator and up to fifty kilometers in total above the surface of the planet.

The atmosphere protects from solar radiation

The composition of the air in the Earth's atmosphere plays a very important role in the preservation of life, since individual chemical elements and compositions successfully limit the access of solar radiation to the earth's surface and the people, animals, and plants living on it. For example, water vapor molecules effectively absorb almost all ranges of infrared radiation, with the exception of lengths in the range from 8 to 13 microns. Ozone absorbs ultraviolet radiation up to a wavelength of 3100 A. Without its thin layer (only 3 mm on average if placed on the surface of the planet), only water at a depth of more than 10 meters and underground caves where solar radiation does not reach can be inhabited. .

Zero Celsius at the stratopause

Between the next two levels of the atmosphere, the stratosphere and mesosphere, there is a remarkable layer - the stratopause. It approximately corresponds to the height of ozone maxima and the temperature here is relatively comfortable for humans - about 0°C. Above the stratopause, in the mesosphere (starts somewhere at an altitude of 50 km and ends at an altitude of 80-90 km), a drop in temperature is again observed with increasing distance from the Earth's surface (to minus 70-80 ° C). Meteors usually burn up completely in the mesosphere.

In the thermosphere - plus 2000 K!

The chemical composition of the Earth's atmosphere in the thermosphere (begins after the mesopause from altitudes of about 85-90 to 800 km) determines the possibility of such a phenomenon as gradual heating of layers of very rarefied “air” under the influence of solar radiation. In this part of the “air blanket” of the planet, temperatures range from 200 to 2000 K, which are obtained due to the ionization of oxygen (atomic oxygen is located above 300 km), as well as the recombination of oxygen atoms into molecules, accompanied by the release of a large amount of heat. The thermosphere is where auroras occur.

Above the thermosphere is the exosphere - the outer layer of the atmosphere, from which light and rapidly moving hydrogen atoms can escape into outer space. The chemical composition of the Earth's atmosphere here is represented mostly by individual oxygen atoms in the lower layers, helium atoms in the middle layers, and almost exclusively hydrogen atoms in the upper layers. High temperatures prevail here - about 3000 K and there is no atmospheric pressure.

How was the earth's atmosphere formed?

But, as mentioned above, the planet did not always have such an atmospheric composition. In total, there are three concepts of the origin of this element. The first hypothesis suggests that the atmosphere was taken through the process of accretion from a protoplanetary cloud. However, today this theory is subject to significant criticism, since such a primary atmosphere should have been destroyed by the solar “wind” from a star in our planetary system. In addition, it is assumed that volatile elements could not be retained in the formation zone of terrestrial planets due to too high temperatures.

The composition of the Earth's primary atmosphere, as suggested by the second hypothesis, could have been formed due to the active bombardment of the surface by asteroids and comets that arrived from the vicinity of the Solar system in the early stages of development. It is quite difficult to confirm or refute this concept.

Experiment at IDG RAS

The most plausible seems to be the third hypothesis, which believes that the atmosphere appeared as a result of the release of gases from the mantle of the earth's crust approximately 4 billion years ago. This concept was tested at the Institute of Geography of the Russian Academy of Sciences during an experiment called “Tsarev 2”, when a sample of a substance of meteoric origin was heated in a vacuum. Then the release of gases such as H 2, CH 4, CO, H 2 O, N 2, etc. was recorded. Therefore, scientists rightly assumed that the chemical composition of the Earth’s primary atmosphere included water and carbon dioxide, hydrogen fluoride (HF), carbon monoxide gas (CO), hydrogen sulfide (H 2 S), nitrogen compounds, hydrogen, methane (CH 4), ammonia vapor (NH 3), argon, etc. Water vapor from the primary atmosphere participated in the formation of the hydrosphere, carbon dioxide was to a greater extent in a bound state in organic substances and rocks, nitrogen passed into the composition of modern air, and also again into sedimentary rocks and organic substances.

The composition of the Earth's primary atmosphere would not allow modern people to be in it without breathing apparatus, since there was no oxygen in the required quantities then. This element appeared in significant quantities one and a half billion years ago, believed to be in connection with the development of the process of photosynthesis in blue-green and other algae, which are the oldest inhabitants of our planet.

Minimum oxygen

The fact that the composition of the Earth's atmosphere was initially almost oxygen-free is indicated by the fact that easily oxidized, but not oxidized graphite (carbon) is found in the oldest (Catarchaean) rocks. Subsequently, so-called banded iron ores appeared, which included layers of enriched iron oxides, which means the appearance on the planet of a powerful source of oxygen in molecular form. But these elements were found only periodically (perhaps the same algae or other oxygen producers appeared in small islands in an anoxic desert), while the rest of the world was anaerobic. The latter is supported by the fact that easily oxidized pyrite was found in the form of pebbles processed by flow without traces of chemical reactions. Since flowing waters cannot be poorly aerated, the view has developed that the atmosphere before the Cambrian contained less than one percent of the oxygen composition of today.

Revolutionary change in air composition

Approximately in the middle of the Proterozoic (1.8 billion years ago), an “oxygen revolution” occurred when the world switched to aerobic respiration, during which 38 can be obtained from one molecule of a nutrient (glucose), and not two (as with anaerobic respiration) units of energy. The composition of the Earth's atmosphere, in terms of oxygen, began to exceed one percent of what it is today, and an ozone layer began to appear, protecting organisms from radiation. It was from her that, for example, such ancient animals as trilobites “hid” under thick shells. From then until our time, the content of the main “respiratory” element gradually and slowly increased, ensuring the diversity of development of life forms on the planet.

The quality of air necessary to support the life processes of all living organisms on Earth is determined by its oxygen content.
Let us consider the dependence of air quality on the percentage of oxygen in it using the example of Figure 1.

Rice. 1 Percentage of oxygen in air

   Favorable level of oxygen in the air

   Zone 1-2: This level of oxygen content is typical for ecologically clean areas and forests. The oxygen content in the air on the ocean shore can reach 21.9%

   Level of comfortable oxygen content in the air

   Zone 3-4: limited by the legally approved standard for the minimum oxygen content in indoor air (20.5%) and the fresh air “standard” (21%). For urban air, an oxygen content of 20.8% is considered normal.

   Insufficient oxygen levels in the air

   Zone 5-6: limited to the minimum permissible oxygen level when a person can be without a breathing apparatus (18%).
Staying in rooms with such air is accompanied by rapid fatigue, drowsiness, decreased mental activity, and headaches.
Prolonged stay in rooms with such an atmosphere is dangerous to health

Dangerously low levels of oxygen in the air

   Zone 7 onwards: when the oxygen content is 16%, dizziness and rapid breathing are observed, 13% - loss of consciousness, 12% - irreversible changes in the functioning of the body, 7% - death.
An unbreathable atmosphere is also characterized not only by exceeding the maximum permissible concentrations of harmful substances in the air, but also by insufficient oxygen content.
Due to the various definitions given to the concept of “insufficient oxygen content,” gas rescuers very often make mistakes when describing gas rescue work. This occurs, among other things, as a result of studying charters, instructions, standards and other documents containing an indication of the oxygen content in the atmosphere.
Let's look at the differences in the percentage of oxygen in the main regulatory documents.

   1.Oxygen content less than 20%.
   Gas hazardous work carried out when there is oxygen content in the air of the working area less than 20%.
- Standard instructions for organizing the safe conduct of gas-hazardous work (approved by the USSR State Mining and Technical Supervision on February 20, 1985):
   1.5. Gas hazardous work includes work... with insufficient oxygen content (volume fraction below 20%).
- Standard instructions for organizing the safe conduct of gas-hazardous work at oil product supply enterprises TOI R-112-17-95 (approved by order of the Ministry of Fuel and Energy of the Russian Federation dated July 4, 1995 N 144):
   1.3. Gas hazardous work includes work... when the oxygen content in the air is less than 20% by volume.
- National standard of the Russian Federation GOST R 55892-2013 "Facilities of small-scale production and consumption of liquefied natural gas. General technical requirements" (approved by order of the Federal Agency for Technical Regulation and Metrology dated December 17, 2013 N 2278-st):
   K.1 Gas hazardous work includes work... when the oxygen content in the air of the working area is less than 20%.

   2. Oxygen content less than 18%.
   Gas rescue work carried out at oxygen levels less than 18%.
- Regulations on gas rescue formation (approved and put into effect by the First Deputy Minister of Industry, Science and Technology A.G. Svinarenko on 06/05/2003; approved by: Federal Mining and Industrial Supervision of the Russian Federation on 05/16/2003 N AS 04-35/ 373).
   3. Gas rescue operations ... in conditions of reducing the oxygen content in the atmosphere to a level of less than 18 vol.% ...
- Guidelines for organizing and conducting emergency rescue operations at chemical enterprises (approved by UAC No. 5/6 Protocol No. 2 dated July 11, 2015).
   2. Gas rescue operations... in conditions of insufficient (less than 18%) oxygen content...
- GOST R 22.9.02-95 Safety in emergency situations. Modes of activity of rescuers using personal protective equipment when eliminating the consequences of accidents at chemically hazardous facilities. General requirements (adopted as an interstate standard GOST 22.9.02-97)
   6.5 At high concentrations of chemical substances and insufficient oxygen content (less than 18%) in the source of chemical contamination, use only insulating respiratory protective equipment.

   3. Oxygen content less than 17%.
   The use of filters is prohibited RPE at oxygen content less than 17%.
- GOST R 12.4.233-2012 (EN 132:1998) System of occupational safety standards. Personal respiratory protection. Terms, definitions and designations (approved and put into effect by order of the Federal Agency for Technical Regulation and Metrology dated November 29, 2012 N 1824-st)
   2.87...oxygen-deficient atmosphere: Ambient air containing less than 17% oxygen by volume in which filtering RPE cannot be used.
- Interstate standard GOST 12.4.299-2015 System of occupational safety standards. Personal respiratory protection. Recommendations for selection, application and maintenance (put into effect by order of the Federal Agency for Technical Regulation and Metrology dated June 24, 2015 N 792-st)
   B.2.1 Oxygen deficiency. If an analysis of environmental conditions indicates the presence or possibility of oxygen deficiency (volume fraction less than 17%), then filter-type RPE is not used...
- Decision of the Customs Union Commission of December 9, 2011 N 878 On the adoption of the technical regulations of the Customs Union "On the safety of personal protective equipment"
   7) ...the use of filtering personal respiratory protection equipment is not allowed if the oxygen content in the inhaled air is less than 17 percent
- Interstate standard GOST 12.4.041-2001 System of occupational safety standards. Filtering personal respiratory protection equipment. General technical requirements (put into effect by Decree of the State Standard of the Russian Federation dated September 19, 2001 N 386-st)
   1 ...filtering personal protective equipment for the respiratory system designed to protect against harmful aerosols, gases and vapors and their combinations in the ambient air, provided that it contains at least 17 vol oxygen. %.