Unlike the hot and cold planets in our solar system, planet Earth has conditions that allow life in some form. One of the main conditions is the composition of the atmosphere, which gives all living things the opportunity to breathe freely and protects from the deadly radiation that reigns in space.
What is the atmosphere made of?
The Earth's atmosphere is made up of many gases. Basically which occupies 77%. Gas, without which life on Earth is unthinkable, occupies a much smaller volume, the oxygen content in the air is 21% of the total volume of the atmosphere. The last 2% is a mixture of various gases, including argon, helium, neon, krypton and others.
The Earth's atmosphere rises to a height of 8,000 km. Breathable air exists only in the lower layer of the atmosphere, in the troposphere, which reaches 8 km at the poles, upwards, and 16 km above the equator. As altitude increases, the air becomes thinner and the more oxygen is depleted. To consider what oxygen content in the air is at different heights, we will give an example. At the peak of Everest (altitude 8848 m), the air holds this gas 3 times less than above sea level. Therefore, the conquerors of high mountain peaks - climbers - can climb to its top only in oxygen masks.
Oxygen is the main condition for survival on the planet
At the beginning of the existence of the Earth, the air that surrounded it did not have this gas in its composition. This was quite suitable for the life of the simplest - single-celled molecules that floated in the ocean. They didn't need oxygen. The process began about 2 million years ago, when the first living organisms, as a result of photosynthesis, began to release small doses of this gas obtained as a result of chemical reactions, first into the ocean, then into the atmosphere. Life evolved on the planet and took on a variety of forms, most of which have not survived to our times. Some organisms eventually adapted to life with the new gas.
They learned to use its power safely inside the cell, where it acted as a power plant, in order to extract energy from food. This way of using oxygen is called breathing, and we do it every second. It was breathing that made it possible for the emergence of more complex organisms and people. Over millions of years, the oxygen content in the air has soared to its current level - about 21%. The accumulation of this gas in the atmosphere contributed to the creation of the ozone layer at a height of 8-30 km from the earth's surface. At the same time, the planet received protection from the harmful effects of ultraviolet rays. The further evolution of life forms on water and on land increased rapidly as a result of increased photosynthesis.
anaerobic life
Although some organisms have adapted to the rising levels of the gas being released, many of the simplest life forms that existed on Earth have disappeared. Other organisms survived by hiding from oxygen. Some of them today live in the roots of legumes, using nitrogen from the air to build amino acids for plants. The deadly organism botulism is another "refugee" from oxygen. He quietly survives in vacuum packaging with canned foods.
What oxygen level is optimal for life
Prematurely born babies, whose lungs are not yet fully opened for breathing, fall into special incubators. In them, the oxygen content in the air is higher by volume, and instead of the usual 21%, its level of 30-40% is set here. Toddlers with severe breathing problems are surrounded by air with 100% oxygen levels to prevent damage to the child's brain. Being in such circumstances improves the oxygen regime of tissues that are in a state of hypoxia, and normalizes their vital functions. But its excessive amount in the air is just as dangerous as the lack of it. Too much oxygen in a child's blood can damage the blood vessels in the eyes and cause vision loss. This shows the duality of the properties of the gas. We must breathe it in order to live, but its excess can sometimes become a poison for the body.
Oxidation process
When oxygen combines with hydrogen or carbon, a reaction called oxidation takes place. This process causes the organic molecules that are the basis of life to decay. In the human body, oxidation proceeds as follows. Red blood cells collect oxygen from the lungs and carry it throughout the body. There is a process of destruction of the molecules of the food that we eat. This process releases energy, water and carbon dioxide. The latter is excreted by the blood cells back into the lungs, and we exhale it into the air. A person can suffocate if they are prevented from breathing for more than 5 minutes.
Breath
Consider the oxygen content in the air we breathe. Atmospheric air that enters the lungs from the outside when inhaled is called inhaled, and the air that goes out through the respiratory system when exhaled is called exhaled.
It is a mixture of air that fills the alveoli with that which is in the respiratory tract. The chemical composition of the air that a healthy person inhales and exhales under natural conditions practically does not change and is expressed in such numbers.
Oxygen is the main constituent of air for life. Changes in the amount of this gas in the atmosphere are small. If by the sea the oxygen content in the air contains up to 20.99%, then even in the very polluted air of industrial cities, its level does not fall below 20.5%. Such changes do not reveal effects on the human body. Physiological disorders appear when the percentage of oxygen in the air drops to 16-17%. At the same time, there is a clear one that leads to a sharp drop in vital activity, and with an oxygen content in the air of 7-8%, a lethal outcome is possible.
Atmosphere in different eras
The composition of the atmosphere has always influenced evolution. At different geological times, due to natural disasters, rises or falls in the level of oxygen were observed, and this entailed a change in the biosystem. Approximately 300 million years ago, its content in the atmosphere rose to 35%, while the planet was inhabited by gigantic insects. The largest extinction of living beings in the history of the Earth happened about 250 million years ago. During it, more than 90% of the inhabitants of the ocean and 75% of the inhabitants of the land died. One version of the mass extinction says that the low oxygen content in the air was to blame. The amount of this gas has dropped to 12% and it is in the lower atmosphere up to a height of 5300 meters. In our era, the oxygen content in the atmospheric air reaches 20.9%, which is 0.7% lower than 800 thousand years ago. These figures are confirmed by scientists at Princeton University who examined samples of the Greenland and Atlantic ice that formed at that time. The frozen water saved the air bubbles, and this fact helps to calculate the level of oxygen in the atmosphere.
What is its level in the air
Active absorption of it from the atmosphere can be caused by the movement of glaciers. As they move away, they reveal vast areas of organic layers that consume oxygen. Another reason may be the cooling of the waters of the oceans: its bacteria absorb oxygen more actively at low temperatures. The researchers argue that the industrial leap and with it the burning of a huge amount of fuel does not have a special impact. The world's oceans have been cooling for 15 million years, and the amount of vital matter in the atmosphere has decreased regardless of human impact. Probably, some natural processes are taking place on Earth, leading to the fact that the consumption of oxygen becomes higher than its production.
Human impact on the composition of the atmosphere
Let's talk about the influence of man on the composition of the air. The level that we have today is ideal for living beings, the oxygen content in the air is 21%. The balance of carbon dioxide and other gases is determined by the life cycle in nature: animals exhale carbon dioxide, plants use it and release oxygen.
But there is no guarantee that this level will always be constant. The amount of carbon dioxide released into the atmosphere is increasing. This is due to the use of fuel by mankind. And it, as you know, was formed from fossils of organic origin and carbon dioxide enters the air. Meanwhile, the largest plants on our planet, trees, are being destroyed at an increasing rate. Kilometers of forest disappear in a minute. This means that part of the oxygen in the air is gradually falling and scientists are already sounding the alarm. The earth's atmosphere is not a limitless pantry and oxygen does not enter it from the outside. It has been developed all the time along with the development of the Earth. It must be constantly remembered that this gas is produced by vegetation in the process of photosynthesis due to the consumption of carbon dioxide. And any significant reduction in vegetation in the form of deforestation inevitably reduces the ingress of oxygen into the atmosphere, thereby disturbing its balance.
The quality of the air necessary to support the life processes of all living organisms on Earth is determined by the content of oxygen in it.
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 the air
Favorable levels of oxygen in the air
Zone 1-2: this level of oxygen content is typical for ecologically clean areas, forests. The oxygen content in the air on the ocean can reach 21.9%
The level of comfortable oxygen content in the air
Zone 3-4: limited by the legally mandated minimum indoor oxygen standard (20.5%) and the "reference" fresh air (21%). For urban air, an oxygen content of 20.8% is considered normal.
Insufficient level of oxygen in the air
Zone 5-6: limited by the minimum allowable level of oxygen when a person can be without a breathing apparatus (18%).
A person's stay 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 oxygen levels in the air
Zone 7 onwards: at an oxygen content of 16%, dizziness, rapid breathing are observed, 13% - loss of consciousness, 12% - irreversible changes in the functioning of the body, 7% - death.
An atmosphere unsuitable for breathing 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 different definitions that are given to the concept of "insufficient oxygen content", gas rescuers very often make mistakes when describing gas rescue work. This happens, including as a result of the study of charters, instructions, standards and other documents containing an indication of the oxygen content in the atmosphere.
Consider the differences in the percentage of oxygen in the main regulatory documents.
1.Oxygen content less than 20%.
Gas hazardous work carried out at the 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 Gosgortekhnadzor on February 20, 1985):
1.5. Gas-hazardous work includes ... 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 of July 4, 1995 N 144):
1.3. Gas hazardous work includes ... when the oxygen content in the air is less than 20% by volume.
- National standard of the Russian Federation GOST R 55892-2013 "Objects 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 with oxygen less than 18%.
- Regulations on the gas rescue formation (approved and put into effect by the First Deputy Minister of Industry, Science and Technology Svinarenko A.G. on 06/05/2003; agreed: 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 the organization and conduct of emergency rescue operations at the enterprises of the chemical complex (approved by the UAC No. 5/6 protocol No. 2 of 07/11/2015).
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 in the aftermath of accidents at chemically hazardous facilities. General requirements (adopted as an interstate standard GOST 22.9.02-97)
6.5 At high concentrations of OHV and insufficient oxygen content (less than 18%) in the focus of chemical contamination, use only insulating respiratory protective equipment.
3. Oxygen content less than 17%.
The use of filters is prohibited. PPE with oxygen content less than 17%.
- GOST R 12.4.233-2012 (EN 132:1998) System of labor 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 PPE cannot be used.
- Interstate standard GOST 12.4.299-2015 System of labor safety standards. Personal respiratory protection. Recommendations for the 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 the 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 Commission of the Customs Union of December 9, 2011 N 878 On the adoption of the technical regulation of the Customs Union "On the safety of personal protective equipment"
7) ... it is not allowed to use filtering means of personal respiratory protection when the oxygen content in the inhaled air is less than 17 percent
- Interstate standard GOST 12.4.041-2001 System of labor safety standards. Means of individual protection of respiratory organs filtering. General technical requirements
1 ... filtering means of personal respiratory protection designed to protect against aerosols, gases and vapors harmful to health and their combinations in the ambient air, provided that the oxygen content in it is at least 17 vol. %.
That part of the atmosphere, which is adjacent to the Earth and which, accordingly, a person breathes, is called the troposphere. The troposphere has a height of nine to eleven kilometers and is a mechanical mixture of various gases.
The composition of the air is not constant. Depending on the geographical location, terrain, weather conditions, the air can have a different composition and different properties. The air can be gassed or discharged, fresh or heavy - all this means that it contains certain impurities.
Nitrogen - 78.9 percent;
Oxygen - 20.95 percent;
Carbon dioxide - 0.3 percent.
In addition, other gases are present in the atmosphere (helium, argon, neon, xenon, krypton, hydrogen, radon, ozone), as well as their sum is slightly less than one percent.
It is also worth pointing out the presence in the air of some permanent impurities 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 away from populated areas includes about three to five thousandths of a milligram per cubic meter), methane (its level is on average two ten thousandths of a milligram per cubic meter), nitrogen oxides (in the atmosphere their concentration reaches approximately fifteen thousandths of a milligram per cubic meter), hydrogen sulfide and other gaseous products.
In addition to vapor and gaseous impurities, the chemical composition of the air usually includes dust of cosmic origin, which falls on the Earth's surface in the amount of seven hundred thousandths of a ton per square kilometer during the year, as well as dust particles that come from volcanic eruptions.
However, to the greatest extent (and not for the better) the composition of the air and pollute the troposphere is the so-called ground (vegetable, soil) dust and smoke from forest fires. 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 say with confidence that an ideally clean air environment simply does not exist, and it is a concept that exists only theoretically.
The composition of the air tends to change constantly, 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 production 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 indicators of the atmosphere.
These and many other types of human activity have led to the fact that the basic composition of the air began to undergo slow and insignificant, but nevertheless absolutely irreversible changes. For example, scientists have calculated that over the past fifty years, mankind has used about the same amount of oxygen as over the previous million years, and in percentage terms - two-tenths of a percent of its total supply in the atmosphere. At the same time, the release into the air increases accordingly. This release, according to the latest data, has reached almost four hundred billion tons over the past hundred years.
Thus, the composition of the air is changing for the worse, and it is difficult to imagine what it will become in a few decades.
Air is necessary for all living organisms: animals for breathing, and plants for food. In addition, the air protects the Earth from the destructive ultraviolet radiation of the Sun. The main constituents of air are nitrogen and oxygen. In the air there are also small impurities of noble gases, carbon dioxide and a certain amount of solid particles - soot, dust. All animals need air to breathe. About 21% of air is oxygen. An oxygen molecule (O 2) consists of two bound oxygens.
Composition of air
The percentage of various gases in the air varies slightly depending on the place, time of year and day. Nitrogen and oxygen are the main components of air. One percent of the air is made up of noble gases, carbon dioxide, water vapor, and pollutants such as nitrogen dioxide. The gases in air can be separated by fractional distillation. The air is cooled until the gases become liquid (see the article ""). After that, 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 constantly enter from the air into and return to the air, i.e. a cycle takes place. Animals breathe in oxygen and breathe out carbon dioxide.
Oxygen
Nitrogen
More than 78% of the air is nitrogen. The proteins from which living organisms are built also contain nitrogen. The main industrial application of nitrogen is ammonia production needed for fertilizer. Nitrogen for this is combined with. Nitrogen is pumped into packages for meat or fish, because. when exposed to ordinary air, the products oxidize and deteriorate. Human organs intended for transplantation are stored in liquid nitrogen because it is cold and chemically inert. The nitrogen molecule (N 2) consists of two linked nitrogen atoms.
noble gases
Noble gases are 6 of the 8th group. They are extremely inert chemically. Only they exist in the form of individual atoms that do not form molecules. Because of their passivity, lamps are filled with some of them. 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 light when an electrical discharge passes. It is used in sodium street lamps and neon lamps. Radon is radioactive. It is formed as a result of the decay of radium metal. No helium compounds are known to science, and helium is considered absolutely inert. Its density is 7 times less than the density of air, so airships are filled with it. Helium-filled balloons are equipped with scientific instruments and launched into the upper atmosphere.
Greenhouse effect
This is the name of the currently observed increase in the content of carbon dioxide in the atmosphere and the resulting global warming, i.e. an increase in average annual temperatures around the world. Carbon dioxide keeps heat from leaving the Earth, just like glass keeps heat inside a greenhouse. As there is more and more carbon dioxide in the air, more and more heat is trapped in the atmosphere. Even a slight warming causes an increase in the level of the World Ocean, a change in winds and the melting of some ice near the poles. Scientists believe that if the carbon dioxide content continues to rise at the same rate, then in 50 years the average temperature could increase by 1.5°C to 4°C.
The chemical composition of the air is of great hygienic importance.
It contains: 78% nitrogen, 21% oxygen, 0.03% carbon dioxide and small amounts of other inert gases (argon, neon, krypton, etc.), ozone and water vapor. In addition to permanent components, the atmospheric air may contain some impurities of natural origin, as well as a variety of pollution introduced into the atmosphere due to human production activities.
A huge influence on the gas composition and humidity of the indoor air is exerted by a variety of metabolic products emitted by animals in the course of their life.
So, when breathing, animals release a large amount of water vapor and carbon dioxide into the environment. As a result of the decomposition of urine and feces, ammonia, hydrogen sulfide and other gaseous products often accumulate in pigsties, most of which belong to the group of harmful and toxic gases.
Indoor air is significantly different from atmospheric air. The degree of this difference depends on the sanitary and hygienic regime of livestock buildings (ventilation, sewerage, animal density, etc.). The concentration of oxygen and nitrogen in the air of livestock buildings under normal conditions remains unchanged. The concentration of carbon dioxide can increase significantly (by a factor of 10 or more), and ammonia, hydrogen sulfide, cesspool, and other gases often appear.
Oxygen (O 2) is a gas, without which the life of animals is impossible. Each cell of the body in the process of metabolism constantly uses oxygen to oxidize organic substances - proteins, fats, carbohydrates. The oxygen inhaled with air combines with the hemoglobin of red blood cells, and is carried to tissues and organs. The amount of oxygen consumed depends on the species, age, sex and physiological state of the animal.
The oxygen concentration in livestock buildings is usually constant, fluctuations in do not exceed 0.1-0.5%. A slight deviation from the norm does not cause changes in physiological functions in the body. In the premises for animals, the amount of oxygen remains almost constant and close to its content in the atmospheric air. A decrease in the amount of oxygen in the inhaled air up to 15% is accompanied by accelerated respiration of pigs and an increase in the pulse rate, as well as a weakening of oxidative processes. Animals are very sensitive to the lack of oxygen.
Under normal conditions, animals do not experience a lack of oxygen. In rooms for animals, the decrease in oxygen does not exceed 0.4-1%, which has no hygienic significance, since blood hemoglobin is saturated with oxygen at a lower partial pressure. Lack of oxygen can be observed in exceptional cases (long-term stay of animals in crowded conditions and on high mountain pastures).
Carbon dioxide (CO2) is a colorless, odorless gas with a sour taste. It is formed during the exhalation of animals, as the end product of metabolism. Exhaled air contains more of this gas (3.6%) than atmospheric air. For example, a lactating uterus weighing 150 kg releases 90 liters of carbon dioxide per hour. The maximum content of carbon dioxide in pigsties is allowed no more than 0.3%, i.e. 10 times more than in atmospheric air. Indoor air with a high content of carbon dioxide cannot be considered harmless to animal health from a hygienic point of view.
It is formed during the respiration of animals, as the end product of metabolism. Under natural conditions, continuous processes of emission and absorption of carbon dioxide occur. Carbon dioxide is released into the atmosphere as a result of the vital activity of living organisms, the processes of combustion, decay and fermentation.
Along with the processes of carbon dioxide in nature, there are processes of its assimilation. It is actively absorbed by plants during photosynthesis. Carbon dioxide is washed out of the air by precipitation. Recently, there has been an increase in the concentration of carbon dioxide in the air of industrial cities (up to 0.04% and higher) due to fuel combustion products.
Carbon dioxide plays an important role in the life of animals, as it is a physiological causative agent of the respiratory center. A decrease in the concentration of carbon dioxide in the inhaled air does not pose a significant danger to the body, since the necessary level of its partial pressure in the blood is provided by the regulation of acid-base balance. In contrast, an increase in the content of carbon dioxide in the air leads to a violation of the redox processes in the body. Under such conditions, oxidative processes are suppressed in the body, body temperature decreases, tissue acidity increases, which leads to pronounced acidotic edema and bone demineralization. An increase in the concentration of carbon dioxide in the air to 0.5% causes an increase in blood pressure, increased breathing and heart rate. In a room with an optimal hygienic regime, the content of carbon dioxide increases by no more than 2-3 times compared to atmospheric air. With unsatisfactory operation of ventilation and crowded keeping of animals, carbon dioxide can accumulate in quantities exceeding its content in the atmospheric air by 20-30 times, which is 0.5-1% and more. The main source of carbon dioxide accumulation in the premises are animals, which, depending on the species, age and productivity, emit it up to 16-225 l/h.
In the air of livestock buildings, carbon dioxide does not reach a concentration that causes an acute toxic effect on the body. However, long-term (in conditions of winter stall keeping) exposure of the body to air containing more than 1% carbon dioxide can cause chronic poisoning of animals. Such animals become lethargic, their appetite, productivity and resistance to diseases decrease.
Indicators of carbon dioxide concentration in indoor air have an indirect hygienic value. By the amount of carbon dioxide in indoor air, one can judge to a certain extent its sanitary and hygienic state as a whole. There is a direct relationship between the concentration of carbon dioxide and the content of water vapor, ammonia, hydrogen sulfide, and microflora in it.
The maximum allowable concentration of carbon dioxide in the indoor air for animals, depending on their species, age and physiological state, should not exceed 15-0.25%, and for birds - 0.15-0.20%.
Carbon monoxide (CO) - accumulates in the indoor air during incomplete combustion of fuel or when internal combustion engines operate in them and insufficient ventilation.
When distributing feed using tractor or automobile traction, the content of carbon monoxide within 10 minutes is 3 mg / m 3, 15 minutes - 5-8 mg / m 3. The formation of carbon monoxide occurs when using electric heaters with open heating elements. At the same time, organic dust (compound feed, fluff, droppings, etc.), especially during air recirculation, in contact with heating elements, does not burn completely and saturates the air with carbon monoxide.
This gas is poisonous. The mechanism of technical action is that it displaces the oxygen of hemoglobin, forming a stable chemical compound with it - carboxyhemoglobin, which is 200-250 times more stable than oxyhemoglobin. As a result, oxygen supply to tissues is disrupted, hypoxemia occurs, oxidative processes decrease, and underoxidized metabolic products accumulate in the body. Poisoning is clinically characterized by nervous symptoms, rapid breathing, vomiting, convulsions, coma. Inhalation of carbon monoxide at concentrations of 0.4-0.5% in 5-10 minutes causes the death of animals. Birds are most sensitive to carbon monoxide.
The maximum allowable concentration of carbon monoxide in the air of livestock buildings is 2 mg/m 3 .
Ammonia (NH3) is a colorless poisonous gas with a pungent odor that strongly irritates the mucous membranes of the eyes and respiratory tract. It is formed during the decomposition of various organic nitrogen-forming substances (urine, manure). It is usually not present in the atmosphere. In the air of pigsties, high concentrations of ammonia occur, in the presence of permeable floors and improperly arranged sewers, as a result of which ammonia and other gases penetrate from the sump into the room.
At high air humidity and low temperature, ammonia is strongly absorbed by walls, equipment, and bedding, and then ammonia is released back into the air. The concentration of ammonia near the floor (in the area where pigs live) is higher than near the ceiling. Its content in indoor air over 0.025% is harmful to animals. Prolonged inhalation of air containing even low concentrations of ammonia (0.1 mg/l) adversely affects the health and productivity of animals.
Prolonged inhalation of air containing low concentrations of ammonia adversely affects the health and productivity of animals. After a short inhalation of air with the presence of ammonia, the body is released from it, turning it into urea. Prolonged action of non-toxic doses of ammonia does not directly cause pathological processes, but weakens the body's resistance.
Ammonia dissolves well in water, as a result of which it is adsorbed by the mucous membranes of the eyes and upper respiratory tract, causing severe irritation. There is a cough, lacrimation, followed by inflammation of the mucous membranes of the nose, larynx, trachea, bronchi and conjunctiva of the eyes. With a high content of ammonia in the inhaled air (1000-3000 mg / m 3), spasms of the glottis, tracheal and bronchial muscles are observed in animals, death occurs from pulmonary edema or respiratory paralysis.
When ammonia enters the blood, it converts hemoglobin into alkaline hematin, as a result of which the amount of hemoglobin decreases and oxygen starvation occurs. With prolonged inhalation of air containing ammonia, the alkaline reserve of the blood, gas exchange and digestibility of nutrients decrease. The intake of large amounts of ammonia into the blood causes a strong excitation of the central nervous system, convulsions, coma, paralysis of the respiratory center and death. At higher concentrations, ammonia causes acute poisoning, accompanied by rapid death of animals.
The toxicity and aggressiveness of ammonia increases significantly at high humidity. Under such conditions, ammonia is oxidized and nitric acid is formed, which, combining with calcium in the plaster of walls and other enclosing structures (calcium nitrate is formed), causes their destruction.
The maximum allowable concentration of ammonia in indoor air for animals, depending on their type and age, is 10-20 mg/m 3 .
Hydrogen sulfide (H2S) is a colorless poisonous gas with a pronounced smell of rotten eggs. It is formed during the decay of protein substances and is excreted by animals with intestinal gases. It appears in pigsties as a result of poor ventilation and untimely manure cleaning. This gas can penetrate into the room and from the liquid collectors in the absence of hydraulic seals (flaps that block the return flow of gases).
In the winter-spring period, at a room temperature of up to 10 ° C, the amount of hydrogen sulfide is within acceptable limits. In summer, under the influence of higher air temperatures, the decomposition of organic matter increases and the release of hydrogen sulfide increases. The presence of hydrogen sulfide in the air indicates improper operation of the building's sanitary facilities.
Hydrogen sulfide has the ability to block iron-containing groups of enzymes. The mechanism of action of hydrogen sulfide is that it, in contact with the mucous membranes of the respiratory tract and gas, combining with tissue alkalis, forms sodium or potassium sulfide, which cause inflammation of the mucous membranes. Sulfides are absorbed into the blood, hydrolyzed and release hydrogen sulfide, which acts on the nervous system. Hydrogen sulfide combines with iron in hemoglobin to form iron sulfide. Deprived of catalytically acting iron, hemoglobin loses its ability to absorb oxygen and oxygen starvation of tissues occurs.
At a concentration of 20 mg / m 3 and above, symptoms of poisoning appear (weakness, irritation of the mucous membranes of the respiratory tract, dysfunction of the digestive system, headache, etc.). At a concentration of 1200 mg/m 3 and above, a severe form of poisoning develops, and as a result of inhibition of tissue respiration enzymes, death of animals occurs. Cases of fatal poisoning of people with hydrogen sulfide during the cleaning of slurry wells of pigsties are described.
The maximum allowable amount of hydrogen sulfide in the air of rooms for animals should be no more than 0.0026%. It is necessary to strive in every possible way for the complete absence of ammonia in indoor air.
The presence of elevated concentrations of carbon dioxide, ammonia and hydrogen sulfide indicates the unsanitary state of the pigsty. Maintaining good indoor air conditions, as a rule, is achieved by keeping animals of various age and production groups on daily dry bedding or insulated floors with a slope towards sewer trays. Proper placement of animals and regular cleaning of stalls, dens and feeding areas are of great importance.
The ambient air and rooms always contain water vapor, the amount of which varies greatly depending on climatic conditions, animal species and type of rooms. The air of livestock buildings almost always contains dust, consisting of the smallest particles of mineral substances, fragments of plants, insects, and living microorganisms. Pollution of the skin of animals with dust along with sweat, dead cells of the upper layer of the skin and microorganisms is accompanied by irritation, itching and inflammation. Dust trapped in the upper respiratory tract often leads to diseases of these organs.
The air of livestock buildings often contains intestinal gases: indole, skatol, mercaptan, amines (nitrosamines), which have a bad smell. As a rule, the smell, especially from pigsties, is so intense that a hygienic (protective) belt 0.5-1 km wide or more from settlements is insufficient. Some gases (nitrosamines) are strong chemical carcinogens and can be found in the air in relatively high concentrations.
It must be taken into account that the air quality of livestock buildings affects not only the animal, but also the personnel serving it. Prolonged stay of animals in rooms with a significant accumulation of harmful gases in the air has a toxic effect on the body, reduces their resistance and productivity. Thus, with an increased content of ammonia in indoor air, the increase in the mass of cattle is reduced by 25-28%. Harmful gases reduce the body's resistance and promote the spread of non-contagious (rhinitis, laryngitis, bronchitis, pneumonia, ammonia blindness in chickens, etc.) and infectious (tuberculosis, etc.). Improving the gas composition of the air is achieved through the proper construction and operation of ventilation and sewerage and compliance with the density of animals. An important condition is to ensure the impermeability of solid floors, which prevents the penetration of urine into the underground and its decomposition. With a hydraulic manure removal system, a significant amount of harmful gases is contained in the manure channels. The concentration of ammonia in them reaches more than 35 mg/m 3 , hydrogen sulfide - 23 mg/m 3 , which is 2-3 times higher than the permissible norms. In this regard, the removal of polluted air must be carried out directly from the manure channels of livestock buildings. Effective methods of air deodorization are ultraviolet irradiation, ozonation and ionization. For this purpose. Aerosols from pine needle extracts have been successfully tested. Deodorization in small rooms (opening room) is carried out with aromatic substances in aerosol cans or solutions of chemicals (potassium permanganate, iodine monochloride, bleach, etc.).
