normal oxygen content. The chemical composition of air and its effect on the body

Less than 200 years ago, the earth's atmosphere contained 40% oxygen. Today, the air contains only 21% oxygen.

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 decrease in performance by 30%.

The lack of oxygen is the result of automobiles, industrial emissions and pollution. In the city, oxygen is 1% less than in the forest.

But the biggest culprit in the lack of oxygen is ourselves. Having built warm and airtight houses, living in apartments with plastic windows we shielded ourselves from 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 the 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.

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.

Favorable levels of oxygen in the air

Zone 1-2: this level of oxygen content is typical for ecologically clean areas, forest areas. The oxygen content in the air on the ocean can reach 21.9%

Insufficient level of oxygen in the air

Zano 5-6: minimally limited acceptable level oxygen content 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 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 in skin color

- fatigue, decreased mental, physical and sexual activity

- depression, irritability, sleep disturbance

- headache

Prolonged exposure to a room with insufficient oxygen levels can lead to more serious problems with health, because oxygen is responsible for all metabolic processes of the body, then the consequence of its lack is:

Metabolic disease

Decreased immunity

Properly organized ventilation system of residential and working premises can be the key to good health.

The role of oxygen in human health. Oxygen:

Increases mental performance;

Increases the body's resistance to stress and increased nervous stress;

Supports the level of oxygen in the blood;

Improves the coordination of the work of internal organs;

Increases immunity;

Promotes weight loss. Regular oxygen consumption, combined with physical activity, leads to active breakdown of fats;

Sleep normalizes: it becomes deeper and longer, the period of falling asleep and physical activity decreases

Conclusions:

Oxygen affects our life, and the more it is, the more colorful and diverse our life is.

You can buy an oxygen tank or drop everything and go to live in the forest. If this is not available to you, air your apartment or office every hour. Draft, dust, noise interfere, install ventilation that will supply you with fresh air, clean it from exhaust gases.

Do everything to fresh air in your home and you will see changes in your life.

Atmospheric air is a mixture of various gases. It contains constant components of the atmosphere (oxygen, nitrogen, carbon dioxide), inert gases (argon, helium, neon, krypton, hydrogen, xenon, radon), small amounts of ozone, nitrous oxide, methane, iodine, water vapor, as well as various impurities of natural origin and pollution resulting from human production activities in varying amounts.

Oxygen (O2) is the most important part of the air for humans. It is necessary for the implementation of oxidative processes in the body. IN atmospheric air the oxygen content is 20.95%, in the air exhaled by a person - 15.4-16%. Reducing it in atmospheric air to 13-15% leads to a violation physiological functions, and up to 7-8% - to death.

Nitrogen (N) - is the main integral part atmospheric air. The air inhaled and exhaled by a person contains approximately the same amount of nitrogen - 78.97-79.2%. The biological role of nitrogen lies mainly in the fact that it is a diluent of oxygen, since life is impossible in pure oxygen. With an increase in the nitrogen content to 93%, death occurs.

Carbon dioxide (carbon dioxide), CO2 - is a physiological regulator of respiration. The content in clean air is 0.03%, in exhaled by a person - 3%.

A decrease in the concentration of CO2 in the inhaled air is not dangerous, because. the necessary level of it in the blood is maintained by regulatory mechanisms due to the release during metabolic processes.

An increase in the content of carbon dioxide in the inhaled air up to 0.2% causes a person to feel unwell, at 3-4% there is an excited state, headache, tinnitus, palpitations, slowing of the pulse, and at 8% there is severe poisoning, loss of consciousness and death occurs.

Behind Lately the concentration of carbon dioxide in the air of industrial cities increases as a result of intense air pollution by products of fuel combustion. An increase in CO2 in the atmospheric air leads to the appearance of toxic fogs in cities and the "greenhouse effect" associated with the delay of the thermal radiation of the earth by carbon dioxide.

An increase in the CO2 content above the established norm indicates a general deterioration in the sanitary condition of the air, since along with carbon dioxide other toxic substances may accumulate, the ionization regime may worsen, dust and microbial contamination may increase.

Ozone (O3). Its main quantity is noted at the level of 20-30 km from the Earth's surface. The surface layers of the atmosphere contain a negligible amount of ozone - no more than 0.000001 mg/l. Ozone protects the living organisms of the earth from the damaging effects of short-wave ultraviolet radiation and at the same time absorbs long-wave infrared radiation coming from the Earth, protecting it from excessive cooling. Ozone has an oxidizing ability, so its concentration in the polluted air of cities is lower than in countryside. In this regard, ozone was considered an indicator of the purity of the air. However, it has recently been established that ozone is formed as a result of photo chemical reactions during the formation of smog, so the detection of ozone in the atmospheric air major cities considered an indicator of contamination.

Inert gases - do not have a pronounced hygienic and physiological significance.

Human economic and industrial activity is a source of air pollution with various gaseous impurities and suspended particles. Increased content harmful substances in the atmosphere and indoor air adversely affects the human body. In this regard, the most important hygienic task is the regulation of their permissible content in the air.

The sanitary and hygienic state of the air is usually assessed by the maximum permissible concentrations (MPC) of harmful substances in the air of the working area.

The MPC of harmful substances in the air of the working area is the concentration that, during daily 8-hour work, but not more than 41 hours a week, during the entire working experience does not cause diseases or deviations in the state of health of the present and subsequent generations. Establish the MPC average daily and maximum one-time (action up to 30 minutes in the air of the working area). MPC for the same substance may be different depending on the duration of its exposure to humans.

At food enterprises, the main causes of air pollution with harmful substances are violations technological process and emergencies (sewerage, ventilation, etc.).

Hygienic hazards in indoor air are carbon monoxide, ammonia, hydrogen sulfide, sulfur dioxide, dust, etc., as well as air pollution by microorganisms.

Carbon monoxide (CO) is an odorless and colorless gas that enters the air as a product of incomplete combustion of liquid and solid fuels. He calls acute poisoning at a concentration in the air of 220-500 mg / m3 and chronic poisoning - with constant inhalation of a concentration of 20-30 mg / m3. The average daily MPC of carbon monoxide in the atmospheric air is 1 mg/m3, in the air of the working area - from 20 to 200 mg/m3 (depending on the duration of work).

Sulfur dioxide (S02) is the most common air pollutant, as sulfur is found in various fuels. This gas has a general toxic effect and causes respiratory diseases. The irritating effect of the gas is detected when its concentration in the air is more than 20 mg/m3. In the atmospheric air, the average daily maximum allowable concentration of sulfur dioxide is 0.05 mg/m3, in the air of the working area - 10 mg/m3.

Hydrogen sulfide (H2S) - usually enters the atmospheric air with waste from chemical, oil refineries and metallurgical plants, and is also formed and can pollute indoor air as a result of decay food waste and protein products. Hydrogen sulfide has a general toxic effect and causes discomfort in humans at a concentration of 0.04-0.12 mg/m3, and a concentration of more than 1000 mg/m3 can be fatal. In the atmospheric air, the average daily allowable concentration of hydrogen sulfide is 0.008 mg/m3, in the air of the working area - up to 10 mg/m3.

Ammonia (NH3) - accumulates in the air of enclosed spaces during the decay of protein products, malfunctions of refrigeration units with ammonia cooling, in case of accidents in sewer facilities, etc. It is toxic to the body.

Acrolein is a product of the decomposition of fat during heat treatment, which can cause allergic diseases under industrial conditions. MPC in the working area - 0.2 mg/m3.

Polycyclic aromatic hydrocarbons (PAHs) - their association with the development of malignant neoplasms has been noted. The most common and most active of these is 3-4-benz (a) pyrene, which is released during fuel combustion: hard coal, oil, gasoline, gas. Maximum amount 3-4-benz (a) pyrene is released during the combustion of coal, the minimum - during the combustion of gas. In food processing plants, long-term use of overheated fat can be a source of PAH air pollution. The average daily MPC of cyclic aromatic hydrocarbons in the atmospheric air should not exceed 0.001 mg/m3.

Mechanical impurities - dust, soil particles, smoke, ash, soot. Dustiness increases with insufficient landscaping of the territory, unimproved access roads, violation of the collection and removal of production waste, as well as violation of the sanitary cleaning regime (dry or irregular wet cleaning, etc.). In addition, the dustiness of the premises increases with violations in the device and operation of ventilation, planning decisions (for example, with insufficient isolation of the pantry of vegetables from production workshops, etc.).

The impact of dust on a person depends on the size of dust particles and their specific gravity. The most dangerous for humans are dust particles smaller than 1 micron in diameter, because they easily penetrate the lungs and can cause their chronic disease (pneumoconiosis). Dust containing impurities of toxic chemical compounds, has a toxic effect on the body.

MPC for soot and soot is strictly regulated due to the content of carcinogenic hydrocarbons (PAH): the average daily MPC for soot is 0.05 mg/m3.

In high-capacity confectionery workshops, dustiness of the air with sugar and flour dust is possible. Flour dust in the form of aerosols can cause irritation of the respiratory tract, as well as allergic diseases. MPC flour dust in the working area should not exceed 6 mg/m3. Within these limits (2-6 mg/m3), maximum allowable concentrations of other types of vegetable dust containing no more than 0.2% of silicon compounds are regulated.

LECTURE No. 3. Atmospheric air.

Topic: Atmospheric air, its chemical composition and physiological

meaning constituent parts.

Atmospheric pollution; their impact on public health.

Lecture plan:

The chemical composition of atmospheric air.

The biological role and physiological significance of its constituents: nitrogen, oxygen, carbon dioxide, ozone, inert gases.

The concept of atmospheric pollution and their sources.

Impact of atmospheric pollution on health (direct impact).

Influence of atmospheric pollution on the living conditions of the population (indirect impact on health).

Questions of protection of atmospheric air from pollution.

The gaseous envelope of the earth is called the atmosphere. The total weight of the earth's atmosphere is 5.13  10 15 tons.

The air that forms the atmosphere is a mixture of various gases. The composition of dry air at sea level is:

Table No. 1

The composition of dry air at a temperature of 0 0 C and

pressure 760 mm Hg. Art.

The composition of the earth's atmosphere remains constant over land, over the sea, in cities and rural areas. It also does not change with height. It should be remembered that we are talking about the percentage of air constituents at different heights. However, this cannot be said about the weight concentration of gases. As we rise upwards, the air density decreases and the number of molecules contained in a unit of space also decreases. As a result, the weight concentration of the gas and its partial pressure decrease.

Let us dwell on the characteristics of the individual components of air.

The main component of the atmosphere is nitrogen. Nitrogen is an inert gas. It does not support breathing and combustion. In a nitrogen atmosphere, life is impossible.

nitrogen plays an important role biological role. Air nitrogen is absorbed by some types of bacteria and algae, which form organic compounds from it.

Under the influence of atmospheric electricity, a small amount of nitrogen ions is formed, which are washed out of the atmosphere by precipitation and enrich the soil with salts of nitrous and nitric acid. Salts of nitrous acid under the influence of soil bacteria turn into nitrites. Nitrites and ammonia salts are absorbed by plants and serve for the synthesis of proteins.

Thus, the transformation of the inert nitrogen of the atmosphere into the living matter of the organic world is carried out.

Due to the lack of nitrogenous fertilizers of natural origin, mankind has learned to obtain them artificially. A nitrogen-fertilizer industry has been created and is developing, which processes atmospheric nitrogen into ammonia and nitrogenous fertilizers.

The biological significance of nitrogen is not limited to its participation in the cycle of nitrogenous substances. He plays important role as a diluent of atmospheric oxygen, since life is impossible in pure oxygen.

An increase in the nitrogen content in the air causes hypoxia and asphyxia due to a decrease in the partial pressure of oxygen.

With an increase in partial pressure, nitrogen exhibits narcotic properties. However, in an open atmosphere, the narcotic effect of nitrogen does not manifest itself, since fluctuations in its concentration are insignificant.

The most important component of the atmosphere is gaseous oxygen (O 2 ) .

Oxygen in our solar system in a free state is found only on Earth.

Many assumptions have been put forward regarding the evolution (development) of terrestrial oxygen. The most accepted explanation is that the vast majority of the oxygen in the modern atmosphere came from photosynthesis in the biosphere; and only the initial, small amount of oxygen was formed as a result of water photosynthesis.

The biological role of oxygen is extremely high. Life is impossible without oxygen. The earth's atmosphere contains 1.18  10 15 tons of oxygen.

In nature, the processes of oxygen consumption are continuously going on: the respiration of humans and animals, the processes of combustion, oxidation. At the same time, the processes of restoring the oxygen content in the air (photosynthesis) are continuously going on. Plants absorb carbon dioxide, break it down, absorb carbon, and release oxygen into the atmosphere. Plants emit 0.5  10 5 million tons of oxygen into the atmosphere. This is enough to cover the natural loss of oxygen. Therefore, its content in the air is constant and amounts to 20.95%.

The continuous flow of air masses mixes the troposphere, which is why there is no difference in the oxygen content in cities and rural areas. The oxygen concentration fluctuates within a few tenths of a percent. It does not matter. However, in deep pits, wells, caves, the oxygen content can drop, so descending into them is dangerous.

With a drop in the partial pressure of oxygen in humans and animals, oxygen starvation phenomena are observed. Significant changes in the partial pressure of oxygen occur when rising above sea level. The phenomena of oxygen deficiency can be observed when climbing mountains (mountaineering, tourism), during air travel. Climbing to a height of 3000m can cause altitude sickness or altitude sickness.

With long-term living in highlands, people develop an addiction to a lack of oxygen and acclimatization occurs.

A high partial pressure of oxygen is unfavorable for humans. At a partial pressure of more than 600 mm, the vital capacity of the lungs decreases. Inhalation of pure oxygen (partial pressure 760 mm) causes pulmonary edema, pneumonia, convulsions.

Under natural conditions, there is no increased oxygen content in the air.

Ozone is an integral part of the atmosphere. Its mass is 3.5 billion tons. The ozone content in the atmosphere varies with the seasons of the year: in spring it is high, in autumn it is low. The ozone content depends on the latitude of the area: the closer to the equator, the lower it is. The ozone concentration has a diurnal variation: it reaches its maximum by noon.

The ozone concentration is unevenly distributed along the height. Its highest content is observed at an altitude of 20-30 km.

Ozone is continuously produced in the stratosphere. Under the influence of ultraviolet radiation from the sun, oxygen molecules dissociate (break down) to form atomic oxygen. Oxygen atoms recombine (combine) with oxygen molecules and form ozone (O 3). At altitudes above and below 20-30 km, the processes of photosynthesis (formation) of ozone slow down.

The presence of an ozone layer in the atmosphere is of great importance for the existence of life on Earth.

Ozone delays the short-wave part of the solar radiation spectrum, does not transmit waves shorter than 290 nm (nanometers). In the absence of ozone, life on earth would be impossible, due to the destructive effect of short ultraviolet radiation on all living things.

Ozone also absorbs infrared radiation with a wavelength of 9.5 microns (microns). Due to this, ozone traps about 20 percent of the earth's thermal radiation, reducing the loss of its heat. In the absence of ozone, the absolute temperature of the Earth would be lower by 7 0 .

In the lower layer of the atmosphere - the troposphere, ozone is brought from the stratosphere as a result of the mixing of air masses. With weak mixing, the ozone concentration at the earth's surface decreases. An increase in ozone in the air is observed during a thunderstorm as a result of discharges of atmospheric electricity and an increase in turbulence (mixing) of the atmosphere.

At the same time, a significant increase in the concentration of ozone in the air is the result of photochemical oxidation of organic substances that enter the atmosphere with car exhaust gases and industrial emissions. Ozone is one of the toxic substances. Ozone has an irritating effect on the mucous membranes of the eyes, nose, throat at a concentration of 0.2-1 mg/m 3 .

carbon dioxide (CO 2 ) is found in the atmosphere at a concentration of 0.03%. Its total amount is 2330 billion tons. A large amount of carbon dioxide is found in dissolved form in the water of the seas and oceans. In a bound form, it is a part of dolomites and limestones.

The atmosphere is constantly replenished with carbon dioxide as a result of the vital processes of living organisms, the processes of combustion, decay, and fermentation. A person emits 580 liters of carbon dioxide per day. A large amount of carbon dioxide is released during the decomposition of limestone.

Despite the presence of numerous sources of formation, there is no significant accumulation of carbon dioxide in the air. Carbon dioxide is constantly assimilated (assimilated) by plants during photosynthesis.

In addition to plants, the seas and oceans are the regulator of carbon dioxide in the atmosphere. When the partial pressure of carbon dioxide in the air rises, it dissolves in water, and when it decreases, it is released into the atmosphere.

In the surface atmosphere, small fluctuations in the concentration of carbon dioxide are observed: it is lower over the ocean than over land; higher in the forest than in the field; higher in cities than outside the city.

Carbon dioxide plays an important role in the life of animals and humans. It stimulates the respiratory center.

There is some amount in the air inert gases: argon, neon, helium, krypton and xenon. These gases belong to the zero group of the periodic table, do not react with other elements, and are inert in the chemical sense.

Inert gases are narcotic. Their narcotic properties are manifested at high barometric pressure. In an open atmosphere, the narcotic properties of inert gases cannot manifest themselves.

In addition to the constituent parts of the atmosphere, it contains various impurities of natural origin and pollution introduced as a result of human activities.

The impurities that are present in the air besides its natural chemical composition are called atmospheric pollution.

Atmospheric pollution is divided into natural and artificial.

Natural pollution includes impurities that enter the air as a result of natural processes (plant, soil dust, volcanic eruptions, cosmic dust).

Artificial atmospheric pollution is formed as a result of human production activities.

Artificial sources of atmospheric pollution are divided into 4 groups:

transport;

industry;

thermal power engineering;

garbage burning.

Let's take a look at their brief description.

The current situation is characterized by the fact that the volume of road transport emissions exceeds the volume of emissions from industrial enterprises.

One car releases more than 200 chemical compounds into the air. Each car consumes an average of 2 tons of fuel and 30 tons of air per year, and emits 700 kg of carbon monoxide (CO), 230 kg of unburned hydrocarbons, 40 kg of nitrogen oxides (NO 2) and 2-5 kg ​​of solids into the atmosphere.

The modern city is saturated with other modes of transport: rail, water and air. The total amount of emissions into the environment from all modes of transport tends to continuously increase.

Industrial enterprises are second only to transport in terms of environmental damage.

The enterprises of ferrous and non-ferrous metallurgy, petrochemical and coke-chemical industries, as well as enterprises for the production of building materials pollute the atmospheric air most intensively. They emit tens of tons of soot, dust, metals and their compounds (copper, zinc, lead, nickel, tin, etc.) into the atmosphere.

Entering the atmosphere, metals pollute the soil, accumulate in it, penetrate into the water of reservoirs.

In areas where industrial enterprises are located, the population is at risk of adverse effects of atmospheric pollution.

In addition to solid particles, industry emits various gases into the air: sulfuric anhydride, carbon monoxide, nitrogen oxides, hydrogen sulfide, hydrocarbons, radioactive gases.

Pollutants can stay in the environment for a long time and have a harmful effect on the human body.

For example, hydrocarbons remain in the environment for up to 16 years, take an active part in photochemical processes in the atmospheric air with the formation of toxic mists.

Massive air pollution is observed during the combustion of solid and liquid fuel at thermal power plants. They are the main sources of air pollution with sulfur and nitrogen oxides, carbon monoxide, soot and dust. These sources are characterized by massive air pollution.

Currently, many facts are known about the adverse effects of atmospheric pollution on human health.

Air pollution has both acute and chronic effects on the human body.

Examples of the acute impact of atmospheric pollution on public health are toxic mists. Concentrations of toxic substances in the air increased under unfavorable meteorological conditions.

The first toxic fog was registered in Belgium in 1930. Several hundred people were injured, 60 people died. Subsequently, similar cases were repeated: in 1948 in American city Donor. 6,000 people were affected. In 1952, 4,000 people died from the Great London Fog. In 1962, 750 Londoners died for the same reason. In 1970, 10 thousand people suffered from smog over the Japanese capital (Tokyo), in 1971 - 28 thousand.

In addition to the catastrophes listed above, the analysis of research materials by domestic and foreign authors draws attention to an increase in the general morbidity of the population due to atmospheric pollution.

The studies carried out in this plan allow us to conclude that as a result of the impact of atmospheric pollution in industrial centers, there is an increase in:

overall mortality from cardiovascular and respiratory diseases;

acute nonspecific morbidity of the upper respiratory tract;

chronic bronchitis;

bronchial asthma;

emphysema;

lung cancer;

decrease in life expectancy and creative activity.

In addition, at present, mathematical analysis has revealed a statistically significant correlation between the incidence rate of the population with diseases of the blood, digestive organs, skin diseases and levels of atmospheric air pollution.

The respiratory organs, the digestive system and the skin are the “entrance gates” for toxic substances and serve as targets for their direct and indirect action.

The impact of atmospheric pollution on living conditions is regarded as an indirect (indirect) impact of atmospheric pollution on the health of the population.

It includes:

decrease in general illumination;

reduction of ultraviolet radiation from the sun;

changing climatic conditions;

deterioration of living conditions;

negative impact on green spaces;

negative impact on animals.

Substances that pollute the atmosphere cause great damage to buildings, structures, building materials.

The total economic damage to the United States from air pollutants, including their impact on human health, building materials, metals, fabrics, leather, paper, paints, rubber and other materials, is $15-20 billion annually.

All of the above indicates that the protection of atmospheric air from pollution is a problem of extreme importance and the object of close attention of specialists in all countries of the world.

All measures for the protection of atmospheric air should be carried out comprehensively in several areas:

Legislative measures. These are laws adopted by the government of the country aimed at protecting the air environment;

Rational placement of industrial and residential areas;

Technological measures aimed at reducing emissions into the atmosphere;

Sanitary measures;

Development of hygienic standards for atmospheric air;

Control over the purity of atmospheric air;

Control over the work of industrial enterprises;

Improvement of populated areas, landscaping, watering, creation of protective gaps between industrial enterprises and residential complexes.

In addition to the listed measures of the intrastate plan, interstate programs for the protection of atmospheric air are currently being developed and widely implemented.

The problem of protecting the air basin is solved in a number of international organizations - WHO, UN, UNESCO and others.

Air is a natural mixture of gases, mainly nitrogen and oxygen, that makes up the earth's atmosphere. Air is necessary for the normal existence of the vast majority of terrestrial living organisms: the oxygen contained in the air enters the cells of the body during respiration and is used in the oxidation process, as a result of which the energy necessary for life is released. In industry and in everyday life, atmospheric oxygen is used to burn fuel in order to obtain heat and mechanical energy in internal combustion engines. Noble gases are obtained from air by liquefaction. In accordance with federal law“On the Protection of Atmospheric Air”, atmospheric air is understood as “a vital component environment, which is a natural mixture of atmospheric gases located outside residential, industrial and other premises.

The most important factors determining the suitability for human habitation, the air environment are the chemical composition, the degree of ionization, relative humidity, pressure, temperature and speed. Let's consider each of these factors separately.

In 1754, Joseph Black experimentally proved that air is a mixture of gases and not a homogeneous substance.

Normal air composition

Light air ions

Every resident of St. Petersburg feels that the air is heavily polluted. An ever-increasing number of cars, factories and factories emit tons of waste from their activities into the atmosphere. Polluted air contains uncharacteristic physical, chemical and biological substances. The main air pollutants of the metropolis are: aldehydes, ammonia, atmospheric dust, carbon monoxide, nitrogen oxides, sulfur dioxide, hydrocarbons, heavy metals (lead, copper, zinc, cadmium, chromium).

The most dangerous components of smog are microscopic particles of harmful substances. Approximately 60% are products of combustion of automobile engines. It is these particles that we inhale while walking the streets of our cities and accumulate in our lungs. According to doctors, the lungs of a resident of a metropolis are very similar in terms of the degree of contamination to the lungs of a heavy smoker.

In terms of contribution to air pollution, car exhaust gases are in first place, emissions from thermal power plants are in second place, chemical industry- on the third.

Degree of air ionization

High degree ionization

Atmospheric air is always ionized and contains more or less air ions. The process of ionization of natural air occurs under the influence of a number of factors, of which the main ones are the radioactivity of soil, rocks, sea and groundwater, cosmic rays, lightning, splashing of water (Lenard effect) in waterfalls, in lambs of waves, etc., ultraviolet radiation of the Sun, flame forest fires, some aromatic substances, etc. Under the influence of these factors, both positive and negative air ions are formed. Neutral air molecules instantly settle on the formed ions, giving rise to the so-called normal and light atmospheric ions. Encountering on their way dust particles suspended in the air, smoke particles, the smallest droplets of water, light ions settle on them and turn into heavy ones. On average, 1 cm 3 above the earth's surface contains up to 1500 ions, among which positively charged ions predominate, which, as will be shown below, is not entirely desirable for human health.

In some regions, air ionization is characterized by more favorable indicators. Among the areas where the air is especially ionized are the slopes high mountains, mountain valleys, waterfalls, coasts of the seas and oceans. They are often used to organize places of recreation and spa treatment.

Thus, air ions are constantly operating factor external environment, such as temperature, relative humidity, and air velocity.

A change in the degree of ionization of the inhaled air inevitably entails shifts in various organs and systems. Hence the natural desire to use ionized air in, on the one hand, and the need to develop apparatus and devices for artificially changing the concentration and ratio of ions in atmospheric air, on the other. Today, using special equipment, it is possible to increase the degree of air ionization, increasing the number of ions in 1 cm 3 thousands of times.

The sanitary and epidemiological rules and regulations SanPiN 2.2.4.1294-03 contain hygienic requirements for the aeroionic composition of the air in industrial and public premises. Note that not only the number of negatively and positively charged air ions is important, but also the ratio of the concentration of positive to the concentration of negative, which is called the unipolarity coefficient (see table below).

In accordance with hygienic requirements, the number of negatively charged air ions should be greater or, in extreme cases, equal to the number of positively charged air ions. In the conditions of living in cities and working in office premises, air ionizers should be used in order not to lose concentration and get tired more slowly during the working day.

Microclimate: rel. humidity, temperature, speed, pressure

Under the microclimate is meant a complex of physical parameters of the environment that affect the heat exchange of a person and his health. The main parameters of the microclimate are relative humidity, temperature, pressure and air velocity. Maintaining all these parameters in the norm indoors is a key factor determining the comfort of a person's stay in it.

The normal value of the microclimate parameters allows the human body to spend a minimum of energy: to maintain required level heat exchange, to obtain the required amount of oxygen; at the same time, a person does not feel either heat, or cold, or stuffiness. According to statistics, microclimate violations are the most frequent among all violations of sanitary and hygienic standards.

The microclimate is determined by the influence of the external environment, the features of the construction of the building and heating, ventilation and air conditioning systems.

In multi-storey buildings, there is a strong difference in air pressure outside the building and inside. This leads to the accumulation of various contaminants in the building, and their concentration will be different on the upper and lower floors, which adversely affects.

Features of the microclimate of each particular apartment are formed under the influence of air flows, moisture and heat. The air in the room is constantly in motion. Therefore, one of the key parameters of air is the speed of its movement.

Below is a table that indicates the optimal and permissible values ​​​​of temperature, humidity and air velocity in various rooms in accordance with the current SanPiN 2.1.2.2801-10 "Changes and additions No. 1 to SanPiN 2.1.2.2645-10" Sanitary and epidemiological requirements for living conditions in residential buildings and premises ".

Air parameters at home, in the office or a country cottage, you can take appropriate measures to normalize the identified deviations.

Current sanitary rules and regulations for air

The structure and composition of the Earth's atmosphere, it must be said, have not always been constants at any given time in the development of our planet. Today vertical structure this element, which has a total "thickness" of 1.5-2.0 thousand km, is represented by several main layers, including:

1. Troposphere.
2. tropopause.
3. Stratosphere.
4. Stratopause.
5. mesosphere and mesopause.
6. Thermosphere.
7. exosphere.

Basic elements of the atmosphere

The troposphere is a layer in which strong vertical and horizontal movements are observed, it is here that the weather is formed, sedimentary phenomena, climatic conditions. It extends for 7-8 kilometers from the surface of the planet almost everywhere, with the exception of the polar regions (there - up to 15 km). In the troposphere, there is a gradual decrease in temperature, approximately 6.4 ° C with each kilometer of altitude. This figure 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 a height of 90 kilometers

In addition, here you can find dust, water droplets, water vapor, combustion products, ice crystals, sea ​​salts, many aerosol particles, etc. Such a composition of the Earth's atmosphere is observed up to approximately ninety kilometers in height, 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 is fundamentally different. physical properties. The layer that has a common chemical composition is called the homosphere.

What other elements are in the Earth's atmosphere? As a 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 -4), nitrous oxide (5.0 x 10 -5) and others are represented here. hydrogen, followed by helium, krypton, etc.

Physical properties of different atmospheric layers

The physical properties of the troposphere are closely related to its attachment to the surface of the planet. Hence the reflected solar heat in the form of infrared rays is sent back up, including the processes of heat conduction and convection. That is why, with the removal of earth's surface the temperature drops. This phenomenon is observed up to the height of the stratosphere (11-17 kilometers), then the temperature becomes practically unchanged up to the level of 34-35 km, and then there is again an increase in temperatures up to heights of 50 kilometers ( upper bound stratosphere). Between the stratosphere and the troposphere there is a thin intermediate layer of the tropopause (up to 1-2 km), where constant temperatures 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 important element like ozone. There is relatively little of it near the surface (ten to the minus sixth power of a percent), since the gas is formed under the influence of sunlight from atomic oxygen in the upper parts of the atmosphere. In particular, most of the ozone is at an altitude of about 25 km, and the entire "ozone screen" is located in areas from 7-8 km in the region of the poles, from 18 km at the equator and up to fifty kilometers in general above the surface of the planet.

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 people, animals, and plants living on it. For example, water vapor molecules effectively absorb almost all ranges of infrared radiation, except for lengths in the range from 8 to 13 microns. Ozone, on the other hand, absorbs ultraviolet up to a wavelength of 3100 A. Without its thin layer (it will average only 3 mm if it is placed on the surface of the planet), only water at a depth of more than 10 meters and underground caves can be inhabited, where solar radiation does not reach.

Zero Celsius at stratopause

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

In the thermosphere - plus 2000 K!

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

Above the thermosphere is the exosphere - the outer layer of the atmosphere, from which light and rapidly moving hydrogen atoms can escape into space. The chemical composition of the Earth's atmosphere here is represented more by individual oxygen atoms in lower layers, helium atoms in the middle ones, and almost exclusively hydrogen atoms in the upper ones. Here reign high temperatures- 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 a composition of the atmosphere. In total, there are three concepts of the origin of this element. The first hypothesis assumes that the atmosphere was taken in the process of accretion from a protoplanetary cloud. However, today this theory is subject to significant criticism, since such a primary atmosphere must have been destroyed by the solar "wind" from a star in our planetary system. In addition, it is assumed that volatile elements could not stay in the zone of formation of planets like the terrestrial group due to too high temperatures.

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

Experiment at IDG RAS

The most plausible is the third hypothesis, which believes that the atmosphere appeared as a result of the release of gases from the mantle. earth's crust approximately 4 billion years ago. This concept was tested at the Institute of Geology and Geochemistry of the Russian Academy of Sciences in the course of an experiment called "Tsarev 2", when a sample of a meteoric substance 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 vapor (HF), carbon monoxide (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 turned out to be more in a bound state in organic matter and rocks, nitrogen passed into the composition of modern air, and again into sedimentary rocks and organic matter.

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 amounts one and a half billion years ago, as is believed, in connection with the development of the process of photosynthesis in blue-green and other algae, which are the oldest inhabitants of our planet.

Oxygen minimum

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

Revolutionary change in air composition

Approximately in the middle of the Proterozoic (1.8 billion years ago), the “oxygen revolution” took place, when the world switched to aerobic respiration, during which from one molecule nutrient(glucose) you can get 38, and not two (as in anaerobic respiration) units of energy. The composition of the Earth's atmosphere, in terms of oxygen, began to exceed one percent of the modern one, began to appear ozone layer protecting organisms from radiation. It was from her that “hidden” under thick shells, for example, such ancient animals as trilobites. From then until our time, the content of the main "respiratory" element has gradually and slowly increased, providing a variety of development of life forms on the planet.