About the problem of excess content carbon dioxide spoken in indoor air more and more frequently in the last 20 years. New studies are coming out and new data are being published. Are building codes for the buildings we live and work in keeping pace?

A person’s well-being and performance are closely related to the air quality where he works and rests. And air quality can be determined by the concentration of carbon dioxide CO2.

Why CO2?

• This gas is everywhere where there are people.
• The concentration of carbon dioxide in a room directly depends on human life processes - after all, we exhale it.
• Exceeding the level of carbon dioxide is harmful to the human body, so it must be monitored.
• An increase in CO2 concentration clearly indicates problems with ventilation.
• The worse the ventilation, the more pollutants are concentrated in the air. Therefore, an increase in indoor carbon dioxide is a sign that air quality is declining.

IN last years In the professional communities of doctors and building designers, there are proposals to revise the methodology for determining air quality and expand the list of measured substances. But so far nothing more obvious than changes in CO2 levels have been found.

How do you know if indoor carbon dioxide levels are acceptable? Experts offer lists of standards, and they will be different for buildings for different purposes.

Residential carbon dioxide standards

Designers of apartment and private buildings take as a basis GOST 30494-2011 entitled “Residential and public buildings. Indoor microclimate parameters." This document considers the optimal level of CO2 for human health to be 800 - 1,000 ppm. The mark at 1,400 ppm is the limit of permissible carbon dioxide content in the room. If there is more of it, then the air quality is considered poor.

However, 1,000 ppm is no longer recognized as normal by a number of studies devoted to the dependence of the body’s condition on CO2 levels. Their data indicates that at around 1,000 ppm, more than half of the subjects feel a deterioration in the microclimate: increased heart rate, headache, fatigue and, of course, the notorious “cannot breathe.”

Physiologists consider the normal CO2 level to be 600 – 800 ppm.

Although some isolated complaints about stuffiness are possible even at the specified concentration.

It turns out that building standards for CO2 levels conflict with the conclusions of physiological researchers. In recent years, it is from the latter that there have been increasingly louder calls to update the permissible limits, but so far things have not gone further than calls. The lower the CO2 standard that builders are guided by, the cheaper it costs. And those who are forced to solve the problem of apartment ventilation on their own have to pay for this.

Carbon dioxide standards in schools

The more carbon dioxide in the air, the more difficult it is to concentrate and cope with your workload. Knowing this, US authorities recommend that schools maintain CO2 levels no higher than 600 ppm. In Russia, the mark is slightly higher: the already mentioned GOST considers 800 ppm or less optimal for children's institutions. However, in practice, not only the American, but also the Russian recommended level is a dream for most schools.

One of ours showed: more than half of the school time the amount of carbon dioxide in the air exceeds 1,500 ppm, and sometimes approaches 2,500 ppm! In such conditions it is impossible to concentrate, the ability to perceive information is critically reduced. Other possible symptoms of excess CO2: hyperventilation, sweating, eye inflammation, nasal congestion, difficulty breathing.

Why is this happening? The offices are rarely ventilated, because an open window means cold children and noise from the street. Even if a school building has strong central ventilation, it is usually either noisy or outdated. But the windows in most schools are modern - plastic, sealed, and airtight. With a class size of 25 people in an office with an area of ​​50–60 m2 with a closed window, carbon dioxide in the air jumps by 800 ppm in just half an hour.

Carbon dioxide standards in offices

The same problems are observed in offices as in schools: increased concentrations of CO2 make it difficult to concentrate. Errors multiply and productivity declines.

The standards for carbon dioxide content in the air for offices are generally the same as for apartments and houses: 800 – 1,400 ppm is considered acceptable. However, as we have already found out, even 1,000 ppm causes discomfort to every second person.

Unfortunately, in many offices the problem is not solved in any way. Somewhere they simply don’t know anything about it, somewhere management deliberately ignores it, and somewhere they are trying to solve it with the help of an air conditioner. A stream of cool air does create a short-term illusion of comfort, but carbon dioxide does not disappear anywhere and continues to do its dirty work.

It may also be that the office space was built in compliance with all standards, but is operated with violations. For example, the employee density is too high. According to building regulations, there should be from 4 to 6.5 m2 of space per person. If there are more employees, then carbon dioxide accumulates faster in the air.

Conclusions and outputs

The problem with ventilation is most acute in apartments, office buildings and child care facilities.
There are two reasons for this:

1. Discrepancy between building standards and sanitary and hygienic recommendations.
The first say: no higher than 1,400 ppm CO2, the second warn: this is too much.

2. Failure to comply with standards during the construction, reconstruction or operation of a building.
The simplest example is the installation of plastic windows that do not allow outside air to pass through and thereby aggravate the situation with the accumulation of carbon dioxide indoors.

Very big. Carbon dioxide takes part in the formation of all living matter on the planet and, together with water and methane molecules, creates the so-called “greenhouse (greenhouse) effect.”

Carbon dioxide value ( CO 2 dioxide or carbon dioxide) in the life of the biosphere consists primarily of maintaining the process of photosynthesis, which is carried out by plants.

Being greenhouse gas, carbon dioxide in the air affects the heat exchange of the planet with the surrounding space, effectively blocking re-radiated heat at a number of frequencies, and thus participates in the formation.

IN Lately There is an increase in the concentration of carbon dioxide in the air, which leads to.

Carbon (C) in the atmosphere is contained mainly in the form of carbon dioxide (CO 2) and in small quantities in the form of methane (CH 4), carbon monoxide and other hydrocarbons.

For atmospheric gases, the concept of “gas lifetime” is used. This is the time during which the gas is completely renewed, i.e. the time during which the same amount of gas enters the atmosphere as it contains. So, for carbon dioxide this time is 3-5 years, for methane - 10-14 years. CO oxidizes to CO 2 over several months.

In the biosphere, the importance of carbon is very high, since it is part of all living organisms. Within living beings, carbon is contained in reduced form, and outside the biosphere - in oxidized form. Thus, a chemical exchange is formed life cycle: CO 2 ↔ living matter.

Sources of carbon in the atmosphere.

The source of primary carbon dioxide is the eruption of which releases a huge amount of gases into the atmosphere. Part of this carbon dioxide arises during the thermal decomposition of ancient limestones in various metamorphic zones.

Carbon also enters the atmosphere in the form of methane as a result of anaerobic decomposition of organic residues. Methane under the influence of oxygen quickly oxidizes to carbon dioxide. The main suppliers of methane to the atmosphere are tropical forests and.

In turn, atmospheric carbon dioxide is a source of carbon for other geospheres - the biosphere and.

Migration of CO 2 in the biosphere.

Migration of CO 2 occurs in two ways:

In the first method, CO 2 is absorbed from the atmosphere during photosynthesis and participates in the formation organic matter with subsequent burial in the form of minerals: peat, oil, oil shale.

In the second method, carbon participates in the creation of carbonates in the hydrosphere. CO 2 turns into H 2 CO 3, HCO 3 -1, CO 3 -2. Then, with the participation of calcium (less commonly magnesium and iron), carbonates are deposited via biogenic and abiogenic pathways. Thick layers of limestone and dolomite appear. According to A.B. Ronov, the ratio of organic carbon (Corg) to carbonate carbon (Ccarb) in the history of the biosphere was 1:4.

How does the geochemical cycle of carbon occur in nature and how does carbon dioxide return to the atmosphere?

Soda, volcano, Venus, refrigerator - what do they have in common? Carbon dioxide. We have collected for you the most interesting information about one of the most important chemical compounds on the ground.

What is carbon dioxide

Carbon dioxide is known mainly in its gaseous state, i.e. as carbon dioxide with simple chemical formula CO2. In this form it exists in normal conditions- at atmospheric pressure and “normal” temperatures. But at increased pressure, above 5,850 kPa (such as, for example, the pressure at a sea depth of about 600 m), this gas turns into liquid. And when strongly cooled (minus 78.5°C), it crystallizes and becomes so-called dry ice, which is widely used in trade for storing frozen foods in refrigerators.

Liquid carbon dioxide and dry ice are produced and used in human activity, but these forms are unstable and easily disintegrate.

But carbon dioxide gas is distributed everywhere: it is released during the respiration of animals and plants and is an important component of chemical composition atmosphere and ocean.

Properties of carbon dioxide

Carbon dioxide CO2 is colorless and odorless. Under normal conditions it has no taste. However, if you inhale high concentrations of carbon dioxide, you may experience a sour taste in your mouth, caused by the carbon dioxide dissolving on mucous membranes and in saliva, forming a weak solution of carbonic acid.

By the way, it is the ability of carbon dioxide to dissolve in water that is used to make carbonated water. Lemonade bubbles are the same carbon dioxide. The first apparatus for saturating water with CO2 was invented back in 1770, and already in 1783, the enterprising Swiss Jacob Schweppes began industrial production of soda (the Schweppes brand still exists).

Carbon dioxide is 1.5 times heavier than air, so it tends to “settle” in its lower layers if the room is poorly ventilated. The “dog cave” effect is known, where CO2 is released directly from the ground and accumulates at a height of about half a meter. An adult, entering such a cave, at the height of his growth does not feel the excess of carbon dioxide, but dogs find themselves directly in a thick layer of carbon dioxide and are poisoned.

CO2 does not support combustion, which is why it is used in fire extinguishers and fire suppression systems. The trick of extinguishing a burning candle with the contents of a supposedly empty glass (but in fact carbon dioxide) is based precisely on this property of carbon dioxide.

Carbon dioxide in nature: natural sources

Carbon dioxide is formed in nature from various sources:

• Respiration of animals and plants.
  Every schoolchild knows that plants absorb carbon dioxide CO2 from the air and use it in the processes of photosynthesis. Some housewives try to make up for shortcomings with an abundance of indoor plants. However, plants not only absorb, but also release carbon dioxide in the absence of light - this is part of the respiration process. Therefore, a jungle in a poorly ventilated bedroom is not a good idea: CO2 levels will rise even more at night.
• Volcanic activity.
  Carbon dioxide is part of volcanic gases. In areas with high volcanic activity, CO2 can be released directly from the ground - from cracks and fissures called mofets. The concentration of carbon dioxide in valleys with mofets is so high that many small animals die when they get there.
• Decomposition of organic matter.
  Carbon dioxide is formed during the combustion and decay of organic matter. Large natural emissions of carbon dioxide accompany forest fires.

Carbon dioxide is “stored” in nature in the form of carbon compounds in minerals: coal, oil, peat, limestone. Huge reserves of CO2 are found in dissolved form in the world's oceans.

The release of carbon dioxide from an open reservoir can lead to a limnological disaster, as happened, for example, in 1984 and 1986. in lakes Manoun and Nyos in Cameroon. Both lakes were formed on the site of volcanic craters - now they are extinct, but in the depths the volcanic magma still releases carbon dioxide, which rises to the waters of the lakes and dissolves in them. As a result of a number of climatic and geological processes the concentration of carbon dioxide in the waters exceeded the critical value. A huge amount of carbon dioxide was released into the atmosphere, which went down the mountain slopes like an avalanche. About 1,800 people became victims of limnological disasters on Cameroonian lakes.

Artificial sources of carbon dioxide

The main anthropogenic sources of carbon dioxide are:

• industrial emissions associated with combustion processes;
• automobile transport.

Despite the fact that the share of environmentally friendly transport in the world is growing, the vast majority of the world's population will not soon have the opportunity (or desire) to switch to new cars.

Active deforestation for industrial purposes also leads to an increase in the concentration of carbon dioxide CO2 in the air.

CO2 is one of the end products of metabolism (the breakdown of glucose and fats). It is secreted in the tissues and transported by hemoglobin to the lungs, through which it is exhaled. The air exhaled by a person contains about 4.5% carbon dioxide (45,000 ppm) - 60-110 times more than in the air inhaled.

Carbon dioxide plays a large role in regulating blood flow and respiration. An increase in CO2 levels in the blood causes the capillaries to dilate, allowing more blood to pass through, which delivers oxygen to the tissues and removes carbon dioxide.

The respiratory system is also stimulated by an increase in carbon dioxide, and not by a lack of oxygen, as it might seem. In reality, the lack of oxygen is not felt by the body for a long time and it is quite possible that in rarefied air a person will lose consciousness before he feels the lack of air. The stimulating property of CO2 is used in artificial respiration devices: where carbon dioxide is mixed with oxygen to “start” the respiratory system.

Carbon dioxide and us: why CO2 is dangerous

Carbon dioxide is necessary for the human body just like oxygen. But just like with oxygen, an excess of carbon dioxide harms our well-being.

A high concentration of CO2 in the air leads to intoxication of the body and causes a state of hypercapnia. With hypercapnia, a person experiences difficulty breathing, nausea, headache, and may even lose consciousness. If the carbon dioxide content does not decrease, then oxygen starvation occurs. The fact is that both carbon dioxide and oxygen move throughout the body on the same “transport” - hemoglobin. Normally, they “travel” together, attaching to different places on the hemoglobin molecule. However, increased concentrations of carbon dioxide in the blood reduce the ability of oxygen to bind to hemoglobin. The amount of oxygen in the blood decreases and hypoxia occurs.

Such unhealthy consequences for the body occur when inhaling air with a CO2 content of more than 5,000 ppm (this can be the air in mines, for example). To be fair, in ordinary life we ​​practically never encounter such air. However, a much lower concentration of carbon dioxide does not have the best effect on health.

According to some findings, even 1,000 ppm CO2 causes fatigue and headaches in half of the subjects. Many people begin to feel stuffiness and discomfort even earlier. With a further increase in carbon dioxide concentration to 1,500 – 2,500 ppm critically, the brain is “lazy” to take the initiative, process information and make decisions.

And if a level of 5,000 ppm is almost impossible in Everyday life, then 1,000 and even 2,500 ppm can easily be part of reality modern man. Ours showed that in rarely ventilated school classes CO2 levels remain above 1,500 ppm most of the time, and sometimes jump above 2,000 ppm. There is every reason to believe that the situation is similar in many offices and even apartments.

Physiologists consider 800 ppm to be a safe level of carbon dioxide for human well-being.

Another study found a link between CO2 levels and oxidative stress: the higher the carbon dioxide level, the more we suffer from oxidative stress, which damages our body's cells.

Carbon dioxide in the Earth's atmosphere

There is only about 0.04% CO2 in the atmosphere of our planet (this is approximately 400 ppm), and more recently it was even less: carbon dioxide crossed the 400 ppm mark only in the fall of 2016. Scientists link rising levels of CO2 in the atmosphere to industrialization: mid-18th century century, on the eve of the industrial revolution, it was only about 270 ppm.

Chemical composition

The Earth's atmosphere arose as a result of the release of gases during volcanic eruptions. With the advent of the oceans and the biosphere, it was formed due to gas exchange with water, plants, animals and the products of their decomposition in soils and swamps.

Currently, the Earth's atmosphere consists mainly of gases and various impurities (dust, water droplets, ice crystals, sea salts, combustion products).

The concentration of gases that make up the atmosphere is almost constant, with the exception of water (H 2 O) and carbon dioxide (CO 2).

In addition to the gases indicated in the table, the atmosphere contains SO 2, NH 3, CO, ozone, hydrocarbons, HCl, HF, Hg vapor, I 2, as well as NO and many other gases in small quantities. Constantly located in the troposphere a large number of suspended solid and liquid particles (aerosol).

Carbon dioxide in the Earth's atmosphere, as of 2011, is represented in the amount of 392 ppm or 0.0392%. The role of carbon dioxide ( CO 2 dioxide or carbon dioxide) in the life of the biosphere consists primarily of maintaining the process of photosynthesis, which is carried out by plants. As a greenhouse gas, carbon dioxide in the air affects the heat exchange of the planet with the surrounding space, effectively blocking re-radiated heat at a number of frequencies, and thus participates in shaping the planet's climate.

Due to mankind's active use of fossil fuels as fuel, there is a rapid increase in the concentration of this gas in the atmosphere. The first anthropogenic influence on carbon dioxide concentrations has been noted since the mid-19th century. Since that time, its growth rate has increased and at the end of the 2000s it occurred at a rate of 2.20 ± 0.01 ppm/year or 1.7% per year. According to separate studies, modern level CO 2 in the atmosphere is at its highest in the last 800 thousand years and possibly in the last 20 million years.

Role in the greenhouse effect

Despite the relatively low concentration in the air, CO 2 is an important component earth's atmosphere, because it absorbs and re-radiates infrared radiation at various wavelengths, including a wavelength of 4.26 μm (vibration mode - asymmetric stretching of the molecule) and 14.99 μm (bending vibrations). This process eliminates or reduces radiation from the Earth into space at these wavelengths, resulting in the greenhouse effect. The current change in the concentration of atmospheric CO 2 is reflected in the absorption bands, where its current influence on the Earth's re-emission spectrum leads to only partial absorption.

In addition to the greenhouse properties of carbon dioxide, it is also important that it is a heavier gas compared to air. Since the average is relative molar mass air is 28.98 g/mol, and the molar mass of CO 2 is 44.01 g/mol, then an increase in the proportion of carbon dioxide leads to an increase in air density and, accordingly, to a change in its pressure profile depending on altitude. By virtue of physical nature greenhouse effect, such a change in atmospheric properties leads to an increase average temperature on a surface.

Overall, an increase in concentration from pre-industrial levels of 280 ppm to modern levels of 392 ppm is equivalent to an additional 1.8 W per square meter surface of the planet. This gas also has the unique property of long-term climate change, which, once the emission that caused it ceases, remains largely constant for up to a thousand years. Other greenhouse gases, such as methane and nitrous oxide, exist free in the atmosphere for a shorter period of time.

Sources of carbon dioxide

Natural sources of carbon dioxide in the atmosphere include volcanic eruptions, the combustion of organic matter in the air, and the respiration of representatives of the animal world (aerobic organisms). Carbon dioxide is also produced by some microorganisms as a result of the fermentation process, cellular respiration and in the process of decay of organic remains in the air. Anthropogenic sources of CO 2 emissions into the atmosphere include: burning fossil fuels to produce heat, generate electricity, and transport people and goods. Some industrial activities, such as the production of cement and the disposal of gases by flaring, lead to significant CO 2 emissions.

Plants convert the resulting carbon dioxide into carbohydrates during photosynthesis, which is carried out through the pigment chlorophyll, which uses the energy of solar radiation. The resulting gas, oxygen, is released into the Earth's atmosphere and used for respiration by heterotrophic organisms and other plants, thus forming the carbon cycle.

Anthropogenic emissions

Carbon emissions into the atmosphere as a result of industrial activities. activity in 1800 – 2004

With the advent of the Industrial Revolution in the mid-19th century, there was a progressive increase in anthropogenic emissions of carbon dioxide into the atmosphere, which led to an imbalance in the carbon cycle and an increase in CO 2 concentrations. Currently, about 57% of the carbon dioxide produced by humanity is removed from the atmosphere by plants and oceans. The ratio of the increase in the amount of CO 2 in the atmosphere to the total CO 2 released is a constant value of about 45% and undergoes short-term fluctuations and fluctuations with a period of five years.

Burning fossil fuels such as coal, oil and natural gas, is the main cause of anthropogenic CO 2 emissions, deforestation is the second leading cause. In 2008, burning fossil fuels released 8.67 billion tons of carbon into the atmosphere (31.8 billion tons of CO2), up from 6.14 billion tons of annual carbon emissions in 1990. The conversion of forests to land use has resulted in an increase in atmospheric carbon dioxide equivalent to the burning of 1.2 billion tons of coal in 2008 (1.64 billion tons in 1990). The cumulative increase over 18 years is 3% of the annual natural CO 2 cycle, which is enough to throw the system out of balance and cause CO 2 levels to rise rapidly. As a result, carbon dioxide gradually accumulated in the atmosphere and in 2009 its concentration was 39% higher than pre-industrial levels.

Thus, despite the fact that (as of 2011) the total anthropogenic emission of CO 2 does not exceed 8% of its natural annual cycle, there is an increase in concentration due not only to the level of anthropogenic emissions, but also constant growth emissions levels over time.

> Carbon dioxide concentration

Scientists have long suspected that increased concentrations of carbon dioxide in the atmosphere have a direct connection to global warming, but as it turns out, carbon dioxide can also be directly related to our health. Humans are the main source of carbon dioxide indoors, as we exhale between 18 and 25 liters of this gas per hour. High levels of carbon dioxide can be observed in all areas where people are: in school classrooms and college auditoriums, in meeting rooms and office spaces, in bedrooms and children's rooms.

It is a myth that we lack oxygen in a stuffy room. Calculations show that, contrary to the existing stereotype, headaches, weakness, and other symptoms occur in a person indoors not from a lack of oxygen, but from a high concentration of carbon dioxide.

More recently in European countries and the USA, the level of carbon dioxide in a room was measured only to check the quality of ventilation, and it was believed that CO2 was dangerous for humans only in high concentrations. Research on the effects of carbon dioxide at a concentration of approximately 0.1% on the human body has appeared quite recently.

Few people know that fresh air outside the city contains about 0.04% carbon dioxide, and the closer the CO2 content in the room is to this figure, the better a person feels.

Do we understand the impact of poor indoor air quality on our health and the health of our children? Do we understand the impact of high indoor carbon dioxide levels on our productivity and student achievement? Can we understand why we and our children are so tired at the end of the working day? Are we able to solve the problem of our morning fatigue and irritability, as well as poor night sleep?

A group of European scientists conducted studies on how high (approximately 0.1-0.2%) levels of carbon dioxide in classrooms affect the body of schoolchildren. Studies have shown that more than half of schoolchildren regularly experience the negative effects of high levels of CO2, and the consequence of this is that problems with the respiratory system, rhinitis and weak nasopharynx are observed in such children much more often than in other children.

As a result of studies conducted in Europe and the USA, it was revealed that increased level CO2 in the classroom leads to a decrease in the attention of schoolchildren, to a deterioration in academic performance, as well as to an increase in the number of absences from classes due to illness. This is especially true for children who have asthma.

Such studies have never been conducted in Russia. However, as a result of a comprehensive survey of Moscow children and adolescents in 2004-2004. It turned out that among the diseases discovered among young Muscovites, respiratory diseases predominated.

As a result of recent studies conducted by Indian scientists among residents of the city of Kolkata, it was found that even in low concentrations, carbon dioxide is a potentially toxic gas. Scientists concluded that carbon dioxide is similar in toxicity to nitrogen dioxide, taking into account its effects on the cell membrane and biochemical changes that occur in human blood, such as acidosis. Prolonged acidosis, in turn, leads to diseases of the cardiovascular system, hypertension, fatigue and other unfavorable health conditions. human body consequences.

Residents of a large metropolis are exposed to the negative influence of carbon dioxide from morning to evening. First, in crowded public transport and in their own cars, which sit in traffic jams for a long time. Then at work, where it is often stuffy and you can’t breathe.

It is very important to maintain good air quality in the bedroom because... people spend a third of their lives there. In order to get a good night's sleep, the quality of air in the bedroom is much more important than the duration of sleep, and the level of carbon dioxide in bedrooms and children's rooms should be below 0.08%. High level CO2 in these areas can cause symptoms such as nasal congestion, throat and eye irritation, headaches and insomnia.

Finnish scientists have found a way to solve this problem based on the axiom that if in nature the level of carbon dioxide is 0.035-0.04%, then in rooms it should be close to this level. The device they invented removes excess carbon dioxide from indoor air. The principle is based on the absorption (absorption) of carbon dioxide by a special substance.