Less than 200 years ago, the earth's atmosphere contained 40% oxygen. Today there is only 21% oxygen in the air
In the city park 20,8%
In the forest 21,6%
By the sea 21,9%
In the apartment and office less 20%
Scientists have proven that a 1% decrease in oxygen leads to a 30% decrease in performance.
Oxygen deficiency is a result of automobiles, industrial emissions and pollution. There is 1% less oxygen in the city than in the forest.
But the biggest culprit for the lack of oxygen is ourselves. By building warm and airtight houses, living in apartments with plastic windows, we protected ourselves from the flow of fresh air. With each exhalation, reducing the concentration of oxygen and increasing the amount of carbon dioxide. Often the oxygen content in the office is 18%, in the apartment 19%.
The quality of air necessary to support the life processes of all living organisms on Earth,
determined by its oxygen content.
The dependence of air quality on the percentage of oxygen in it.
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.
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%
Insufficient oxygen levels in the air
Zano 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: at oxygen content16% dizziness, rapid breathing,13% - loss of consciousness,12% - irreversible changes in the functioning of the body, 7% - death.
External signs of oxygen starvation (hypoxia)
- deterioration of skin color
- fatigue, decreased mental, physical and sexual activity
- depression, irritability, sleep disturbance
- headache
Spending a long time indoors with insufficient oxygen levels can lead to more serious health problems because... Since oxygen is responsible for all metabolic processes in the body, the consequences of its deficiency are:
Metabolic disease
Decreased immunity
A properly organized ventilation system for living and working spaces can be the key to good health.
The role of oxygen for human health. Oxygen:
Increases mental performance;
Increases the body's resistance to stress and increased nervous stress;
Maintains oxygen levels in the blood;
Improves the coordination of internal organs;
Increases immunity;
Promotes weight loss. Regular oxygen consumption in combination with physical activity leads to active breakdown of fats;
Sleep is normalized: it becomes deeper and longer, the period of falling asleep and physical activity decreases
Conclusions:
Oxygen influences our lives, and the more of it, the more colorful and diverse our lives are.
You can buy an oxygen tank or give up everything and go live in the forest. If this is not available to you, ventilate your apartment or office every hour. If drafts, dust, or noise interfere, install ventilation that will supply you with fresh air and cleanse you of exhaust gases.
Do everything to bring fresh air into your home and you will see changes in your life.
Atmospheric air entering the lungs during inhalation is called inhaled by air; air released through the respiratory tract during exhalation - exhaled. Exhaled air is a mixture of air filling out alveoli, - alveolar air- with air located in the airways (in the nasal cavity, larynx, trachea and bronchi). The composition of inhaled, exhaled and alveolar air under normal conditions in a healthy person is quite constant and is determined by the following figures (Table 3).
These figures may fluctuate somewhat depending on various conditions (state of rest or work, etc.). But under all conditions, alveolar air differs from inhaled air by a significantly lower oxygen content and a higher carbon dioxide content. This occurs as a result of the fact that in the pulmonary alveoli, oxygen enters the blood from the air, and carbon dioxide is released back.
Gas exchange in the lungs due to the fact that in pulmonary alveoli and venous blood flowing to the lungs, pressure of oxygen and carbon dioxide different: the oxygen pressure in the alveoli is higher than in the blood, and the carbon dioxide pressure, on the contrary, in the blood is higher than in the alveoli. Therefore, in the lungs the transition of oxygen from air to blood takes place, and carbon dioxide from blood to air. This transition of gases is explained by certain physical laws: if the pressure of a gas located in a liquid and in the air surrounding it is different, then the gas passes from the liquid to the air and vice versa until the pressure is balanced.
Table 3
In a mixture of gases, such as air, the pressure of each gas is determined by the percentage content of this gas and is called partial pressure(from the Latin word pars - part). For example, atmospheric air exerts a pressure equal to 760 mmHg. The oxygen content in the air is 20.94%. The partial pressure of atmospheric oxygen will be 20.94% of the total air pressure, i.e. 760 mm, and equal to 159 mm of mercury. It has been established that the partial pressure of oxygen in the alveolar air is 100 - 110 mm, and in the venous blood and capillaries of the lungs - 40 mm. The partial pressure of carbon dioxide is 40 mm in the alveoli, and 47 mm in the blood. The difference in partial pressure between blood and air gases explains gas exchange in the lungs. In this process, the cells of the walls of the pulmonary alveoli and blood capillaries of the lungs, through which gases pass, play an active role.
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:
- Troposphere.
- Tropopause.
- Stratosphere.
- Stratopause.
- Mesosphere and mesopause.
- Thermosphere.
- 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 oxygen-free 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. %.
Air is natural mixture various gases. Most of all it contains elements such as nitrogen (about 77%) and oxygen, less than 2% are argon, carbon dioxide and other inert gases.
Oxygen, or O2, is the second element of the periodic table and the most important component, without which life on the planet would hardly exist. He participates in various processes, on which the vital activity of all living things depends.
In contact with
Air composition
O2 performs the function oxidative processes in the human body, which allow you to release energy for normal life. At rest, the human body requires about 350 milliliters of oxygen, with heavy physical activity this value increases three to four times.
What percentage of oxygen is in the air we breathe? The norm is 20,95% . Exhaled air contains less O2 – 15.5-16%. The composition of exhaled air also includes carbon dioxide, nitrogen and other substances. A subsequent decrease in the percentage of oxygen leads to malfunction, and a critical value of 7-8% causes death.
From the table you can understand, for example, that exhaled air contains a lot of nitrogen and additional elements, but O2 only 16.3%. The oxygen content of the inhaled air is approximately 20.95%.
It is important to understand what an element such as oxygen is. O2 – the most common on earth chemical element, which is colorless, odorless and tasteless. It performs the most important function of oxidation in.
Without the eighth element of the periodic table you can't make fire. Dry oxygen improves the electrical and protective properties of films and reduces their volume charge.
This element is contained in the following compounds:
- Silicates - they contain approximately 48% O2.
- (sea and fresh) – 89%.
- Air – 21%.
- Other compounds in the earth's crust.
Air contains not only gaseous substances, but also vapors and aerosols, as well as various contaminants. This could be dust, dirt, or other various small debris. It contains microbes, which can cause various diseases. Flu, measles, whooping cough, allergens and other diseases are just a small list of negative consequences that appear when air quality deteriorates and the level of pathogenic bacteria increases.
The percentage of air is the amount of all the elements that make up it. It is more convenient to show clearly what air consists of, as well as the percentage of oxygen in the air, on a diagram.
The diagram shows which gas is found more in the air. The values shown on it will be slightly different for inhaled and exhaled air.
Diagram - air ratio.
There are several sources from which oxygen is formed:
- Plants. It is also known from a school biology course that plants release oxygen when they absorb carbon dioxide.
- Photochemical decomposition of water vapor. The process is observed under the influence of solar radiation in the upper layer of the atmosphere.
- Mixing of air flows in the lower atmospheric layers.
Functions of oxygen in the atmosphere and for the body
For a person, the so-called partial pressure, which the gas could produce if it occupied the entire occupied volume of the mixture. The normal partial pressure at 0 meters above sea level is 160 millimeters of mercury. An increase in altitude causes a decrease in partial pressure. This indicator is important, since the supply of oxygen to all important organs and to the body depends on it.
Oxygen is often used for the treatment of various diseases. Oxygen cylinders and inhalers help human organs function normally in the presence of oxygen starvation.
Important! The composition of air is influenced by many factors; accordingly, the percentage of oxygen may change. The negative environmental situation leads to deterioration in air quality. In megacities and large urban settlements, the proportion of carbon dioxide (CO2) will be greater than in small settlements or in forests and protected areas. Altitude also has a big impact - the percentage of oxygen will be lower in the mountains. You can consider the following example - on Mount Everest, which reaches a height of 8.8 km, the oxygen concentration in the air will be 3 times lower than in the lowlands. To stay safely on high mountain peaks, you need to use oxygen masks.
The composition of the air has changed over the years. Evolutionary processes and natural disasters led to changes in, therefore the percentage of oxygen has decreased, necessary for the normal functioning of biological organisms. Several historical stages can be considered:
- Prehistoric era. At this time, the oxygen concentration in the atmosphere was about 36%.
- 150 years ago O2 occupied 26% from the total air composition.
- Currently, the oxygen concentration in the air is just under 21%.
Subsequent development of the surrounding world can lead to further changes in the composition of the air. In the near future, it is unlikely that the O2 concentration could be below 14%, as this would cause disruption of the body's functioning.
What does lack of oxygen lead to?
Low intake is most often observed in stuffy transport, poorly ventilated areas or at altitude . Decreased oxygen levels in the air can cause negative impact on the body. Mechanisms are depleted; the nervous system is most affected. There are several reasons why the body suffers from hypoxia:
- Blood shortage. Called for carbon monoxide poisoning. This situation reduces the oxygen content of the blood. This is dangerous because the blood stops delivering oxygen to hemoglobin.
- Circulatory deficiency. It's possible for diabetes, heart failure. In such a situation, blood transport worsens or becomes impossible.
- Histotoxic factors affecting the body can cause loss of the ability to absorb oxygen. Arises in case of poisoning with poisons or due to exposure to severe...
A number of symptoms indicate that the body requires O2. First of all breathing rate increases. The heart rate also increases. These protective functions are designed to supply oxygen to the lungs and provide them with blood and tissue.
Lack of oxygen causes headaches, increased drowsiness, deterioration in concentration. Isolated cases are not so terrible; they are quite easy to correct. To normalize respiratory failure, the doctor prescribes bronchodilators and other medications. If hypoxia takes severe forms, such as loss of human coordination or even coma, then treatment becomes more complicated.
If symptoms of hypoxia are detected, it is important consult a doctor immediately and do not self-medicate, since the use of a particular drug depends on the causes of the disorder. Helps for mild cases treatment with oxygen masks and pillows, blood hypoxia requires blood transfusion, and correction of circular causes is possible only with surgery on the heart or blood vessels.
The incredible journey of oxygen through our body
Conclusion
Oxygen is the most important air component, without which it is impossible to carry out many processes on Earth. The air composition has changed over tens of thousands of years due to evolutionary processes, but currently the amount of oxygen in the atmosphere has reached at 21%. The quality of the air a person breathes affects his health Therefore, it is necessary to monitor its cleanliness in the room and try to reduce environmental pollution.
