The main sources of vehicle emissions are the internal combustion engine, the evaporation of fuel through the fuel tank ventilation system, and the chassis: as a result of tire friction on the road surface, brake pad wear and corrosion of metal parts, fine dust particles are formed regardless of engine emissions. Catalyst erosion releases platinum, palladium and rhodium, while clutch lining wear also releases toxic substances such as lead, copper and antimony. Limit values should also be set for these secondary vehicle emissions.
Harmful substances
Rice. Composition of exhaust gases
The composition of the exhaust (exhaust) gases of a car includes many substances or groups of substances. The predominant part of the exhaust gas components are non-toxic gases contained in normal air. As shown in the figure, only a small part of the exhaust gas is harmful to environment and people's health. Despite this, a further reduction in the concentration of toxic components of the exhaust gas is necessary. Although modern cars today they give very clean exhaust (for Euro-5 cars it is in some aspects even cleaner than intake air), a huge number of used cars, of which there are about 56 million units in Germany alone, emit a significant amount of toxic and harmful substances. New technologies and the introduction of more stringent requirements for the environmental friendliness of exhaust gas are called upon to correct the situation.
Carbon monoxide (CO)
carbon monoxide(carbon monoxide) CO is a colorless and odorless gas. It is a poison for the respiratory system, disrupting the function of the central nervous and cardiovascular systems. In the human body, it binds red blood cells and causes oxygen starvation, which in a short time leads to death by suffocation. Already at a concentration in the air of 0.3% by volume, carbon monoxide kills a person in a very short time. The action depends on the concentration of CO in the air, on the duration and depth of inhalation. Only in an environment with a zero concentration of CO can it be excreted from the body through the lungs.
Carbon monoxide always occurs when there is a lack of oxygen and when complete combustion.
Hydrocarbons (CH)
Hydrocarbons are emitted into the atmosphere in the form of unburned fuel. They have an irritating effect on the mucous membranes and respiratory organs of a person. Further optimization of the engine's workflow is only possible through improved production technologies and improved knowledge of combustion processes.
Hydrocarbon compounds occur as paraffins, olefins, aromas, aldehydes (especially formaldehydes) and polycyclic compounds. Experimentally proved carcinogenic and mutagenic properties of more than 20 polycyclic aromatic hydrocarbons, which, due to their small size, are able to penetrate to the pulmonary vesicles. The most dangerous hydrocarbon compounds are benzene (C6H6), toluene (methylbenzene) and xylene (dimethylbenzene, general formulaС6Н4 (CH3)2). For example, benzene can cause changes in the blood picture in a person and lead to the occurrence of blood cancer (leukemia).
The reason for the release of hydrocarbons into the atmosphere is always incomplete combustion of the fuel, lack of oxygen, and in the case of a very lean mixture, too slow combustion of the fuel.
Nitrogen oxides (NOx)
At a high combustion temperature (more than 1100°C), the reaction-inert nitrogen contained in the air is activated and reacts with free oxygen in the combustion chamber, forming oxides. They are very harmful to the environment: they cause smog, forest death, acid rain; nitrogen oxides are also transitional substances for the formation of ozone. They are poison to the blood, cause cancer. In the combustion process, various nitrogen oxides - NO, NO2, N2O, N2O5 - are formed, which have the general designation NOx. When combined with water, nitric (HNO3) and nitrous (HNO2) acids are formed. Nitrogen dioxide (NO2) - red-brown poisonous gas with a pungent odor, irritating to the respiratory system and forming compounds with hemoglobin in the blood.
This is the most problematic of all nitrogen oxides, and in the future separate standards for permissible concentrations will apply for it. The share of NO2 in total nitrogen oxide emissions in the future should be less than 20%. Since 2010, directive 1999/30/EC has set a limit value of 40 µg/m for N02. Compliance with this limit places special demands on protection against harmful emissions.
The most favorable conditions for the formation of nitrogen oxides are heat combustion of a lean air-fuel mixture. Exhaust gas recirculation systems reduce the proportion of nitrogen oxides in vehicle exhaust.
Sulfur oxides (SOx)
Sulfur oxides are formed from the sulfur contained in the fuel. During combustion, sulfur reacts with oxygen and water to form sulfur oxides, sulfuric (H2SO4) and sulfurous (H2SO3) acids. Sulfur oxide is the main constituent of acid rain and the cause of forest death. It is a water-soluble caustic gas, the effect of which on the human body is manifested by redness, swelling and increased secretion of moist mucous membranes of the eyes and upper respiratory tract. Sulfur dioxide affects the mucous membranes of the nasopharynx, bronchi and eyes. The most common site of "attack" sulfur dioxide are the bronchi. The strong irritant effect on the respiratory tract is due to the formation of sulfurous acid in a humid environment. Sulfur dioxide SO2 suspended in fine dust and sulfuric acid aerosol get deep into the respiratory tract. Asthmatics and young children are most sensitive to the growing concentration of sulfur dioxide in the air. High content sulfur in fuel shortens the life of catalysts in gasoline engines.
The reduction of sulfur dioxide emissions is realized by limiting the sulfur content in the fuel. The goal is a sulfur-free fuel.
Hydrogen sulfide (H2S)
The consequences of the impact of this gas on organic life are not yet entirely clear to science, but it is known that in humans it can cause severe poisoning. In severe cases, there is a threat of suffocation, loss of consciousness and paralysis of the central nervous system. In chronic poisoning, irritation of the mucous membranes of the eyes and respiratory tract is noted. The smell of hydrogen sulfide is already felt at its concentration in the air in the amount of 0.025 ml/m3.
Hydrogen sulfide in exhaust gases occurs under certain conditions, and, despite the presence of a catalyst, and depends on the sulfur content in the fuel.
Ammonia (NH3)
Inhalation of ammonia results in respiratory irritation, coughing, shortness of breath and choking. Ammonia also causes inflamed redness on the skin. Direct ammonia poisoning is rare, as even large amounts of it are rapidly converted to urea. When large amounts of ammonia are directly inhaled, lung function is often impaired for many years. This gas is especially dangerous for the eyes. With a strong effect of ammonia on the eyes, clouding of the cornea and blindness can occur.
Under certain conditions, ammonia can even form in the catalyst. At the same time, ammonia is useful as a reducing agent for SCR catalysts.
Soot and particles
Soot is pure carbon and an undesirable product of the incomplete combustion of hydrocarbons. The reason for the formation of soot is the lack of oxygen during combustion or premature cooling of the combustion gases. Soot particles often bind to unburned fuel residues and engine oil, as well as water, wear products of engine parts, sulfates and ash. Particles vary greatly in shape and size.
Table. Particle classification
The table shows the classification and particle sizes. Most often, when the engine is running, particles with a diameter of about 100 nanometers (0.0000001 m or 0.1 microns) are formed; such particles can naturally enter the lungs of a person. During agglutination (gluing) of soot particles with each other and other components, the mass, number and distribution of particles in the air can change significantly. The main components of the particles are shown in the figure.
Rice. Main components of particles
Due to its spongy structure, soot particles can capture both organic and inorganic substances formed during the combustion of fuel in engine cylinders. As a result, the mass of soot particles can increase three times. These will no longer be individual particles of carbon, but correct form agglomerates resulting from molecular attraction. The size of such agglomerates can reach 1 μm. Emissions of soot and other particles are especially active during the combustion of diesel fuel. These emissions are considered carcinogenic. Hazardous nanoparticles represent a quantitatively large proportion of particles, but only a small percentage by weight. For this reason, it is proposed to limit the content of particles in the exhaust gas not by mass, but by quantity and distribution. In the future, differentiation between particle size and particle distribution is envisaged.
Rice. Particle Composition
Emissions of particles during operation gasoline engines two or three orders of magnitude lower than at work diesel engines. However, these particles are found even in the exhaust of gasoline engines with direct fuel injection. Therefore, there are proposals to limit the maximum content of particles in the exhaust gases of vehicles. Sublimation is the direct transition of a substance from a solid to a gaseous state, and vice versa. A sublimate is a solid precipitate of a gas when it is cooled.
fine dust
During the operation of internal combustion engines, especially fine particles are also formed - dust. It consists mainly of particles of polycyclic hydrocarbons, heavy metals and sulfur compounds. Part of the dust fractions is able to penetrate into the lungs, other fractions do not penetrate into the lungs. Fractions larger than 7 microns are less dangerous, as they are filtered out by the human body's own filtration system.
A different percentage of smaller fractions (less than 7 microns) penetrate the bronchi and pulmonary vesicles (alveoli), causing local irritation. In the region of the pulmonary vesicles, soluble components enter the bloodstream. The body's own filtration system does not cope with all fractions of fine dust. Atmospheric dust pollution is also called aerosols. They can be in a solid or liquid state and, depending on the size, can have a different period of existence. When moving, the smallest particles can combine into larger ones with a relatively stable period of existence in the atmosphere. These properties are mainly possessed by particles with a diameter of 0.1 µm to 1 µm.
When evaluating the formation of fine dust as a result of the operation of an automobile engine, this dust should be distinguished from naturally occurring dust: plant pollen, road dust, sand and many other substances. The sources of fine dust in cities, such as wear on brake pads and tires, should not be underestimated. So diesel exhaust is not the only "source" of dust in the atmosphere.
Blue and white smoke
blue smoke occurs during operation of a diesel engine at temperatures below 180 ° C due to the smallest condensing oil droplets. At temperatures above 180°C, these droplets evaporate. Unburned hydrocarbon fuel components are involved in the formation of blue smoke and at temperatures from 70°C to 100°C. A large amount of blue smoke indicates a large wear of the cylinder-piston group, rods and valve guides. Too late start of fuel supply can also cause blue smoke.
White smoke consists of water vapor generated during combustion of fuel and becomes noticeable at temperatures below 70°C. Particularly characteristic is the appearance white smoke for pre-chamber and vortex-chamber diesel engines after a cold start. White smoke is also caused by unburned hydrocarbon components and condensates.
Carbon dioxide (CO2)
Carbon dioxide It is a colorless, non-flammable, sour-tasting gas. It is sometimes erroneously called carbonic acid. The density of CO2 is about 1.5 times higher than the density of air. Carbon dioxide is an integral part of the air exhaled by a person (3-4%) When inhaling air containing 4-6% CO2, a person has headaches, tinnitus and heart palpitations, and at higher concentrations of CO2 (8-10%) attacks of suffocation, loss of consciousness and respiratory arrest occur. At a concentration of more than 12%, death from oxygen starvation occurs. For example, a burning candle goes out at a CO2 concentration of 8-10% by volume. Although carbon dioxide is an asphyxiant, it is not considered poisonous as a component of engine exhaust. The problem is that carbon dioxide, as shown in the figure, contributes significantly to the global greenhouse effect.
Rice. Share of gases in the greenhouse effect
Together with it, methane, nitrous oxide (laughing gas, dinitrogen oxide), fluorocarbons and sulfur hexafluoride contribute to the development of the greenhouse effect. Carbon dioxide, water vapor and microgases affect the radiation balance of the Earth. Gases transmit visible light but absorb heat reflected from the earth's surface. Without this heat-holding capacity, the average temperature on the Earth's surface would be around -15°C.
This is called the natural greenhouse effect. With an increase in the concentration of microgases in the atmosphere, the proportion of absorbed thermal radiation increases and an additional greenhouse effect occurs. According to experts, by 2050 the average temperature on Earth will increase by +4°C. This can lead to a rise in sea level of more than 30 cm, as a result of which mountain glaciers and polar ice caps will begin to melt, the direction of sea currents (including the Gulf Stream) will change, air currents will change, and the seas will flood vast expanses of land. This is what greenhouse gases produced by human activities can lead to.
The total anthropogenic CO2 emissions are 27.5 billion tons per year. At the same time, Germany is one of the largest sources of CO2 in the world. Energy-related CO2 emissions average about a billion tons per year. This is about 5% of all CO2 produced in the world. The average family of 3 in Germany produces 32.1 tons of CO2 per year. CO2 emissions can only be reduced by reducing energy and fuel consumption. As long as energy is produced by burning fossil fuels, the problem of creating excessive amounts of carbon dioxide will persist. Therefore, the search for alternative energy sources is urgently needed. The automotive industry is working intensively to solve this problem. However, the greenhouse effect can only be combated on a global scale. Even if great progress is made within the EU in reducing carbon dioxide emissions, other countries may, on the contrary, see a significant increase in emissions in the coming years. The US leads by a wide margin in manufacturing greenhouse gases both in absolute terms and on a per capita basis. With a share of only 4.6% of the world's population, they produce 24% of the world's carbon dioxide emissions. This is about twice as much as in China, whose share in the world's population is 20.6%. The 130 million cars in the US (less than 20% of the total number of cars on the planet) produce as much carbon dioxide as the entire industry in Japan, the world's fourth-largest CO2 emitter.
Without additional climate protection measures, global CO2 emissions will increase by 39% by 2020 (relative to 2004) and amount to 32.4 billion tons per year. In the next 15 years, carbon dioxide emissions in the United States will increase by 13% and exceed 6 billion tons. In China, we should expect an increase in CO2 emissions by 58%, to 5.99 billion tons, and in India - by 107%, to 2.29 billion tons. m. In the EU, on the contrary, the increase will be only about one percent.
A small educational program for those who like to breathe from the exhaust pipe.
The exhaust gases of internal combustion engines contain about 200 components. The period of their existence lasts from a few minutes to 4-5 years. According to the chemical composition and properties, as well as the nature of the impact on the human body, they are combined into groups.
First group. It includes non-toxic substances (natural components of atmospheric air
Second group. This group includes only one substance - carbon monoxide, or carbon monoxide (CO). The product of incomplete combustion of petroleum fuels is colorless and odorless, lighter than air. In oxygen and in air, carbon monoxide burns with a bluish flame, releasing a lot of heat and turning into carbon dioxide.
Carbon monoxide has a pronounced toxic effect. It is due to its ability to react with blood hemoglobin, leading to the formation of carboxyhemoglobin, which does not bind oxygen. As a result, gas exchange in the body is disturbed, oxygen starvation appears and there is a violation of the functioning of all body systems.
Car drivers are often exposed to carbon monoxide poisoning. Vehicle when spending the night in the cab with the engine running or when the engine is warming up in a closed garage. The nature of carbon monoxide poisoning depends on its concentration in the air, the duration of exposure and the individual susceptibility of a person. A mild degree of poisoning causes a throbbing in the head, darkening of the eyes, increased heart rate. In severe poisoning, consciousness becomes clouded, drowsiness increases. At very high doses of carbon monoxide (over 1%), loss of consciousness and death occur.
Third group. It contains nitrogen oxides, mainly NO - nitrogen oxide and NO 2 - nitrogen dioxide. These are gases formed in the combustion chamber of an internal combustion engine at a temperature of 2800 ° C and a pressure of about 10 kgf / cm 2. Nitric oxide is a colorless gas, does not interact with water and is slightly soluble in it, does not react with solutions of acids and alkalis.
Easily oxidized by atmospheric oxygen and forms nitrogen dioxide. Under normal atmospheric conditions, NO is completely converted into NO 2 - a brown-colored gas with a characteristic odor. It is heavier than air, therefore it collects in depressions, ditches and is a great danger when maintenance Vehicle.
For the human body, nitrogen oxides are even more harmful than carbon monoxide. The general nature of exposure varies depending on the content of various nitrogen oxides. Upon contact of nitrogen dioxide with a wet surface (mucous membranes of the eyes, nose, bronchi), nitric and nitrous acids are formed, which irritate the mucous membranes and affect the alveolar tissue of the lungs. At high concentrations of nitrogen oxides (0.004 - 0.008%), asthmatic manifestations and pulmonary edema occur.
Inhaling air containing nitrogen oxides in high concentrations, a person does not have unpleasant sensations and does not imply negative consequences. With prolonged exposure to nitrogen oxides in concentrations exceeding the norm, people get chronic bronchitis, inflammation of the mucosa of the gastrointestinal tract, suffer from heart failure, and nervous disorders.
A secondary reaction to the effects of nitrogen oxides is manifested in the formation of nitrites in the human body and their absorption into the blood. This causes the conversion of hemoglobin to metahemoglobin, which leads to a violation of cardiac activity.
Nitrogen oxides also have a negative effect on vegetation, forming solutions of nitric and nitrous acids on leaf plates. The same property determines the effect of nitrogen oxides on building materials and metal structures. In addition, they are involved in the photochemical reaction of smog formation.
Fourth group. This most numerous group includes various hydrocarbons, that is, compounds of the C x H y type. The exhaust gases contain hydrocarbons of various homologous series: paraffinic (alkanes), naphthenic (cyclanes) and aromatic (benzene), about 160 components in total. They are formed as a result of incomplete combustion of fuel in the engine.
Unburned hydrocarbons are one of the causes of white or blue smoke. This occurs when the ignition of the working mixture in the engine is delayed or at low temperatures in the combustion chamber.
Hydrocarbons are toxic and have an adverse effect on the human cardiovascular system. Hydrocarbon compounds of exhaust gases, along with toxic properties, have a carcinogenic effect. Carcinogens are substances that contribute to the emergence and development of malignant neoplasms.
The aromatic hydrocarbon benz-a-pyrene C 20 H 12, contained in the exhaust gases of gasoline engines and diesel engines, is distinguished by a special carcinogenic activity. It dissolves well in oils, fats, human blood serum. Accumulating in the human body to dangerous concentrations, benz-a-pyrene stimulates the formation of malignant tumors.
Hydrocarbons under the influence of ultraviolet radiation from the Sun react with nitrogen oxides, resulting in the formation of new toxic products - photooxidants, which are the basis of "smog".
Photooxidants are biologically active harmful effect on living organisms, lead to the growth of pulmonary and bronchial diseases in people, destroy rubber products, accelerate the corrosion of metals, and worsen visibility conditions.
Fifth group. It consists of aldehydes - organic compounds containing an aldehyde group -CHO associated with a hydrocarbon radical (CH 3, C 6 H 5 or others).
Exhaust gases contain mainly formaldehyde, acrolein and acetaldehyde. The largest amount of aldehydes is formed at idle and low loads. when combustion temperatures in the engine are low.
Formaldehyde HCHO is a colorless gas with an unpleasant odor, heavier than air, and readily soluble in water. It irritates human mucous membranes, respiratory tract, affects the central nervous system. Causes the smell of exhaust gases, especially in diesel engines.
Acrolein CH 2 \u003d CH-CH \u003d O, or acrylic acid aldehyde, is a colorless toxic gas with the smell of burnt fats. It has an effect on the mucous membranes.
Acetic aldehyde CH 3 CHO is a gas with a pungent odor and a toxic effect on the human body.
Sixth group. Soot and other dispersed particles (engine wear products, aerosols, oils, soot, etc.) are released into it. Soot is black solid carbon particles formed during incomplete combustion and thermal decomposition of fuel hydrocarbons. It does not pose an immediate danger to human health, but may irritate the respiratory tract. By creating a smoky plume behind the vehicle, soot impairs visibility on the roads. The greatest harm of soot lies in the adsorption of benzo-a-pyrene on its surface, which in this case has a stronger negative effect on the human body than in its pure form.
Seventh group. It is a sulfur compound - inorganic gases such as sulfur dioxide, hydrogen sulfide, which appear in the exhaust gases of engines if fuel with a high sulfur content is used. Significantly more sulfur is present in diesel fuels compared to other types of fuels used in transport.
Domestic oil fields (especially in the eastern regions) are characterized by a high percentage of the presence of sulfur and sulfur compounds. Therefore, diesel fuel obtained from it using outdated technologies has a heavier fractional composition and, at the same time, is less purified from sulfur and paraffin compounds. According to European standards introduced in 1996, the sulfur content in diesel fuel should not exceed 0.005 g / l, and according to the Russian standard - 1.7 g / l. The presence of sulfur increases the toxicity of diesel exhaust gases and is the cause of the appearance of harmful sulfur compounds in them.
Sulfur compounds have a pungent odor, are heavier than air, and dissolve in water. They irritate the mucous membranes of the throat, nose, eyes of a person, can lead to a violation of carbohydrate and protein metabolism and inhibition of oxidative processes, at high concentrations (over 0.01%) - to poisoning of the body. Sulfur dioxide also has a detrimental effect on the plant world.
Eighth group. The components of this group - lead and its compounds - are found in the exhaust gases of carburetor vehicles only when using leaded gasoline, which has an additive that increases the octane number. It determines the engine's ability to run without detonation. The higher the octane number, the more resistant the gasoline is to knocking. detonation combustion the working mixture flows at supersonic speed, which is 100 times faster than normal. The operation of the engine with detonation is dangerous because the engine overheats, its power drops, and the service life is sharply reduced. Increasing the octane number of gasoline helps to reduce the possibility of detonation.
As an additive that increases the octane number, an antiknock agent is used - ethyl liquid R-9. Gasoline with the addition of ethyl liquid becomes leaded. The composition of the ethyl liquid includes the actual antiknock agent - tetraethyl lead Pb (C 2 H 5) 4, the scavenger - ethyl bromide (BrC 2 H 5) and α-monochloronaphthalene (C 10 H 7 Cl), the filler - gasoline B-70, an antioxidant - paraoxydiphenylamine and dye. During the combustion of leaded gasoline, the scavenger helps to remove lead and its oxides from the combustion chamber, turning them into a vapor state. They, together with the exhaust gases, are released into the surrounding area and settle near the roads.
In roadside areas, approximately 50% of particulate lead emissions are immediately distributed to the adjacent surface. The rest is in the air in the form of aerosols for several hours, and then is also deposited on the ground near roads. The accumulation of lead in roadside leads to pollution of ecosystems and makes nearby soils unsuitable for agricultural use.
The addition of R-9 additive to gasoline makes it highly toxic. Different grades of gasoline have different percentages of additives. To distinguish brands of leaded gasoline, they are colored by adding multi-colored dyes to the additive. Unleaded gasoline is supplied uncolored (Table 9).
In the developed world, the use of leaded gasoline is limited or has already been completely discontinued. In Russia he still finds wide application. However, the goal is to stop using it. Large industrial centers and resort areas are switching to the use of unleaded gasoline.
Ecosystems are negatively impacted not only by the considered components of engine exhaust gases, divided into eight groups, but also by hydrocarbon fuels, oils and lubricants themselves. Possessing a great ability to evaporate, especially when the temperature rises, vapors of fuels and oils spread in the air and adversely affect living organisms.
Accidental spills and intentional discharges of used oil directly onto the ground or into bodies of water occur at fuel and oil refueling sites. Vegetation does not grow in place of the oil spot for a long time. Oil products that have fallen into water bodies have a detrimental effect on their flora and fauna.
They accompany us almost everywhere - they fly into our kitchen through the window, they chase us in the passenger compartment, at a pedestrian crossing, in public transport ... Car exhaust gases - are they really that dangerous to humans, as the media portrays?
From general to specific - air pollution from exhaust gases
Periodically in major cities Because of the looming smog, you can't even see the sky. The authorities of Paris, for example, on such days are trying to limit the exit of cars - today the owners of cars with even numbers are driving, and tomorrow with odd ones ... But as soon as a fresh wind blows and spreads the accumulated gases, everyone is released onto the road again until a new wave of smog covers the city so that tourists do not see the Eiffel Tower. In many large cities, it is cars that are the main air pollutants, although globally they are inferior to industry leadership. Only the sphere of energy production from petroleum products and organics emits twice as much carbon dioxide into the atmosphere as all cars combined.
Plus, according to ecologists, humanity annually cuts down as much forest as would be enough to process all the CO 2 that enters the atmosphere from the exhaust pipe.
That is, whatever one may say, but the pollution of the atmosphere by car exhaust gases is, on a global scale, only one of the links in the consumption system that is detrimental to our planet. However, let's try to move from the general to the particular - which is closer to us, some kind of factory on the edge of geography, or a car? " iron Horse”- by and large, our personal exhaust “charm” generator, which here and now continues to do this. And it harms, first of all, to ourselves. Many drivers complain of drowsiness and are looking for a way, not even suspecting that the lack of strength and vigor is due to the inhalation of exhaust!
Exhaust fumes - is it that bad?
In total, exhaust gases contain more than 200 different chemical formulas. These are nitrogen, oxygen, water and the same carbon dioxide that are harmless to the body, and toxic carcinogens that increase the risk of serious illnesses up to the formation of malignant tumors. However, this is in the future, the most dangerous substance that can affect our health here and now is carbon monoxide CO, a product of incomplete combustion of fuel. We cannot feel this gas with our receptors, and it inaudibly and invisibly creates a small Auschwitz for our body - the poison restricts the access of oxygen to the cells of the body, which in turn can cause as usual headache, and more serious symptoms of poisoning, up to loss of consciousness and death.
The most terrible thing is that it is the children who are most poisoned - just at the level of their inhalation, the greatest amount of poison is concentrated. The ongoing experiments, which took into account all sorts of factors, revealed a pattern - children who are regularly exposed to carbon monoxide and other "exhaust" products simply become dumb, not to mention weakened immunity and "minor" diseases like frequent colds. And this is just the tip of the iceberg - is it worth describing the effects of formaldehyde, benzopyrene and 190 other different compounds on our body?? The pragmatic Britons have calculated that exhaust fumes kill every year. more people than die in car accidents!
Car exhaust fumes - how to deal with them?
And again, let's move from the general to the particular - you can accuse world governments of inactivity as much as you like, scold industrial magnates whenever you or your family members are sick, but you and only you can do something, if not to completely abandon the car, but at least to reduce emissions. Of course, we are all limited by the capabilities of our wallet, but of the actions listed in this article, for sure, there will be at least one that suits you. Just let's agree - you will start performing right now, without postponing for a ghostly tomorrow.
It is quite possible that you can afford to switch to gas engines - do it! If this is not possible, adjust the engine, spend. If everything is in order with the engine, try to choose the most rational mode of its operation. Ready? Go further - use exhaust gas neutralizers! Wallet won't allow? So save money on gasoline - walk more often, ride a bike to the store.
The cost of fuel is so high that in just a few weeks of such savings, you can afford the best catalytic converter! Optimize trips - try to do as many things as possible in one run, combine trips with your neighbors or colleagues. Acting in this way, fulfilling at least one of the above conditions, you can personally be satisfied with yourself - air pollution by exhaust gases has decreased thanks to you! And do not think that this is not a result - your actions are like small pebbles that entail an avalanche.
Vehicle gases remain in the surface layer of the atmosphere, which makes it difficult to disperse them. Narrow streets and tall buildings also help trap toxic exhaust gases in the breathing zone of pedestrians. The composition of vehicle exhaust gases includes more than 200 components, while only a few of them are standardized (smoke, carbon and nitrogen oxides, hydrocarbons).[ ...]
The composition of exhaust gases depends on a number of factors: the type of engine (carburetor, diesel), its mode of operation and load, the technical condition and quality of the fuel (Tables 10.4, 10.5).[ ...]
Exhaust gases, in addition to hydrocarbons that make up the fuel, contain products of its incomplete combustion, such as acetylene, olefins and carbonyl compounds. The amount of VOCs in the exhaust gases depends on the operating conditions of the engine. A particularly large amount of harmful impurities enters the ambient air when the engine is idling - during short stops and at intersections.[ ...]
Exhaust gases include such toxic substances as carbon monoxide, nitrogen oxides, sulfur dioxide, lead compounds and various carcinogenic hydrocarbons.[ ...]
The composition of the exhaust gases of carburetor and diesel engines includes about 200 chemical compounds, of which the most toxic oxides of carbon, nitrogen, hydrocarbons, including polycyclic aromatic hydrocarbons (benz (a) pyrene, etc.). When burning 1 liter of gasoline, 200-400 mg of lead, which is part of the anti-knock additive, enters the air. Transport is also a source of dust arising from the destruction of road surfaces and abrasion of tires.[ ...]
Since the composition of the exhaust gases depends on the mixture of fuel and air and the timing of ignition, it will also depend on the nature of driving. For achievement highest power mixtures with 10-15% enrichment are required, while the most economical is the speed with a slightly lower fuel enrichment. Most engines at idle require rich mixtures and combustion products are not completely ejected from the cylinder. When accelerating, the pressure in fuel system decreases and the fuel condenses on the collector walls. To prevent depletion fuel mixture a carburetor is used to supply more fuel when accelerating. Decreasing speed with a closed throttle increases the vacuum in the manifold, reduces air leakage and excessively saturates the mixture. With such fluctuations, emissions largely depend on the requirements for the engine (tab.[ ...]
The issue of exhaust gases and aerosols released into the air by automobile engines requires much more intensive study. In this direction, some data have already been obtained on the composition of exhaust gases, from which it follows that their composition changes under the influence of numerous factors, which include engine design, engine operation and maintenance, as well as the fuel used (Faith, 1954; Fitton, 1954) . At present, an intensive study of the effect of all components of exhaust gases in a chronic experiment on animals is planned.[ ...]
| 18 |
Colorless gas, odorless and tasteless. Density relative to air 0.967. Boiling point - 190°C. Solubility coefficient in water 0.2489 (20°), 0.02218 (30°), 0.02081 (38°), 0.02035 (40°). Weight of 1 liter of gas at 0°C and 760 mm Hg. Art. 1.25 g. Included in various gas mixtures, coke, shale, water, wood, blast-furnace gases, vehicle exhaust gases, etc.[ ...]
The exhaust gases of automobiles and other internal combustion engines are the main source of urban air pollution (up to 40% of all pollution in the United States). Many experts are inclined to consider the problem of atmospheric pollution as a problem of its pollution by the exhaust gases of various engines (cars, motor boats and ships, aircraft jet engines, etc.). The composition of these gases is very complex, because, in addition to hydrocarbons various classes, they contain toxic inorganic substances (oxides of nitrogen, carbon, sulfur compounds, halogens), as well as metals and organometallic compounds. The analysis of such compositions containing inorganic and organic compounds with a wide range of boiling points (C1-C12 hydrocarbons) encounters significant difficulties, and, as a rule, several analytical methods are used for its implementation. In particular, carbon oxide and dioxide are determined by IR spectroscopy, nitrogen oxides by chemiluminescence, and gas chromatography is used to detect hydrocarbons. It can also be used to analyze inorganic components of exhaust gases, and the sensitivity of the determination is about 10-4% for CO, 10-2% for NO, 3-10-4% for CO2 and 2-10"5% for hydrocarbons, but the analysis complex and time-consuming.[ ...]
Exhaust gas concentrations in the tunnel are affected by: 1) intensity, composition and speed traffic flow; 2) length, configuration and depth of the tunnel; 3) the direction and speed of the prevailing winds in relation to the axis of the tunnel.[ ...]
In table. 12.1 shows the composition of the main impurities in the exhaust gases of gasoline and diesel internal combustion engines (ICE).[ ...]
It was mentioned above that the composition of the exhaust gases changes markedly with the change in the operating mode of the engine, so the reactor must be designed taking into account changes in concentrations. In addition, elevated temperatures are required for the reaction to proceed, so the reactor must provide a rapid rise in temperature, since water will condense in a cold reactor. Added to the technical difficulties necessary condition so that the reactor system functions for a long time without maintenance. Unlike other devices in the car, in this case the motorist will not pay attention to the reactor system, which does not give him practical returns, and he may not receive real signals that the system has failed. In addition, monitor the efficiency of the treatment system by regular checks And technical inspections much more difficult than achieving a certain average level of design reliability.[ ...]
| 10 |
The quantitative and qualitative composition of exhaust gases depends on the type and quality of fuel, type of engine, its characteristics, technical condition, qualifications of mechanics, provision of vehicle fleet with diagnostic equipment, etc.[ ...]
To determine nitrogen dioxide in the exhaust gases of internal combustion engines of automobiles and in the exhaust gases of silver regeneration baths, a non-flowing electrochemical cell with a long service life of 120 days is proposed. The working electrode is platinum or graphite, and the auxiliary is grade B coal. The absorption solution has a composition of 3% for KBr and 1% for H2304. The lower limit of the analyzed concentration of nitrogen dioxide by this stagnant cell is 0.001 mg/l.[ ...]
In table. 3 shows the approximate composition of the exhaust gases of carburetor and diesel engines (I. L. Varshavsky, 1969).[ ...]
Significant air pollution occurs exhaust! automobile gases. They include a large range of toxic substances, the main of which are: CO, NOx - hydrocarbons, carcinogens. The pollutants of the air basin from road transport should also include rubber dust formed as a result of abrasion of tires.[ ...]
The technical condition of the engine. The technical condition of the engine and, above all, the carburetor has a great influence on the composition of exhaust gases. Studies conducted by J-G. Manusadzhants (1971) showed that after the installation of new, properly adjusted carburetors on cars that previously had an increased content of carbon monoxide in exhaust gases (5-6%), the concentration of this gas decreased to 1.5% . Faulty carburetors after repair and adjustment also ensured a decrease in the content of carbon monoxide in the exhaust gases to 1.5-2%.[ ...]
A simple measure - adjusting engines can reduce the toxicity of exhaust gases by several times. Therefore, in the cities, control and measuring points are being created for diagnosing car engines. In a car fleet, on special running drums that replace the roadbed, the car passes a test, during which it is measured chemical composition engine gases at different modes work. A machine with a large exhaust emission to the line should not be produced. According to data available in the literature, this measure alone can reduce air pollution by 3.2 times in 1980, and by 4 times by 2000.[ ...]
In the scheme under consideration, a part of the thermal energy of exhaust gases during the heating period is used for heating purposes of the CS, adjacent settlements, greenhouses and livestock farms. The integrated power plant at the compressor station includes many units, assemblies and equipment shown in the diagram in Fig. 1, which have shown high efficiency and have been successfully operated for a long time in various industries.[ ...]
In the conditions of Yuzhno-Sakhalinsk, where the main pollutants are vehicle exhaust gases and waste from thermal power plants, no special work has been carried out to influence them on individual objects of the plant world. In the course of work to determine the microelement composition of a number of plants, including meadow and weed grasses, some observations were made on the content of toxic microelements in the above-ground mass of plants within the city and beyond, as well as on reclaimed waste maps of the ash dump of the Yuzhno-Sakhalinskaya CHPP . The chemical composition depends both on the species and on the external conditions of existence, therefore, to determine lead, samples of the following plant species were taken: team hedgehog (Dactylis glomerata L.), creeping clover (Trifolium repens L.), Langsdorf reed grass (Calamagrostis langsdorffii (Link) Trin.), meadow bluegrass (Poa pratensis L.), pharmaceutical dandelion (Taraxacum officinale Web.) - within the city, on roadsides and for control - in places remote from anthropogenic impact.[ ...]
It has already been mentioned that the sun's rays can change the chemical composition of air pollutants. This is especially noticeable in the case of pollutants of the oxidizing type, when the sun's rays can lead to the formation of an irritating gas from a non-irritating one (Haagen-Smit a. Fox, 1954). Photochemical transformations of this type occur in the reaction between hydrocarbons contained in the air and nitrogen oxides, and the main source of both is the exhaust gases of vehicles. These photochemical reactions are of such great importance (for example, in Los Angeles) that great efforts are being made to solve this particular problem posed by automobile exhaust gases. The solution to this problem is approached from three different angles: a) by changing the fuel for engines; b) by changing the design of the engine; c) by changing the chemical composition of the exhaust gases after their formation in the engine.[ ...]
It may seem strange to you that there is no mention of carbon monoxide (carbon monoxide), which, as everyone knows, is part of the exhaust gases of a car. Many people die every year who have the habit of trying out an engine in a closed garage or raising the windows of a car in order to exhaust system which has a leak. In high concentrations, carbon monoxide is certainly deadly: by combining with blood hemoglobin, it prevents the transfer of oxygen from the lungs to all organs of the body. But in the open air, in the vast majority of cases, the concentration of carbon monoxide is so low that it does not pose a danger to human health.[ ...]
Note that a significant amount of carbon monoxide enters the atmospheric air with the exhaust gases of cars and other vehicles equipped with carburettor internal combustion engines, the exhaust of which contains CO from 2 to 10% (large values correspond to low speed modes) . Due to this Special attention is given to the development of carburetors, produced under the code name "Ozone" for cars"Zhiguli". Thanks to a number technical innovations this carburetor can significantly reduce the emission of substances harmful to the human body into the atmosphere with exhaust gases. On the recommendation of the Central Scientific Research Automobile and Automotive Institute, the Cascade device was used on the carburetor, which optimizes the composition fuel-air mixture, thus making it possible not only to reduce the toxicity of emissions, but also to reduce the specific consumption of gasoline.[ ...]
Carbon monoxide is formed during the incomplete combustion of substances containing carbon. It is part of the gases released during the smelting and processing of ferrous and non-ferrous metals, exhaust gases of internal combustion engines, gases formed during blasting, etc.[ ...]
Modern methods of analysis allow, along with the age of individual ice layers, to determine the composition of the air during their formation, to monitor the growth of air pollution. So, in 1968 it was found that the level of lead oxide, which enters the air mainly with car exhaust gases, is already about 200 mg per 1 ton of ice. The authors of the book "Besieged eternal ice”, from which these figures are taken, comment on them as follows: “Ice, this silent witness to the evolution of the Earth’s climate, signals a huge danger. Will humanity listen to him? .[ ...]
Such studies also pave the way for the development of specific predictive models linking fuel composition and properties to exhaust emissions for vehicle families ranging from the earliest non-catalytic converter vehicles to automobiles. latest models produced using the most the latest technologies. This relationship between properties, composition, and emissions is extremely complex, so such models allow fuel developers to find specific fuel composition limits where changes in fuel characteristics can have a measurable, quantifiable effect on exhaust emissions. These formulation limits will, of course, depend both on the type of vehicles available on the particular market and on the possibilities of fuel production. Thus, in this case, in order to understand the whole process, it is necessary to have a clear picture that characterizes both of these factors.[ ...]
Phenols are used for disinfection, as well as for the manufacture of adhesives and phenol-formaldehyde plastics. In addition, they are part of the exhaust gases of gasoline and diesel engines, are formed during the combustion and coking of wood and coal.[ ...]
Under the influence of emissions carried out by industrial enterprises, chemically active waste and residues from the main production, the composition of atmospheric air in cities changes significantly. It significantly increases the percentage of dust content, in addition, there are "traces" of substances that are not characteristic of the environment in its natural state. The increasing growth of vehicle exhaust gases contributes to the development of severe respiratory diseases. Emissions of harmful substances from vehicles and industrial enterprises cause increased air pollution with sulfur oxides, sulfates, carbon dioxide, carbon monoxide, nitrogen oxides, hydrogen sulfide, ammonia, acetone, formaldehyde, etc. The irritating effect of atmospheric pollution is manifested by a non-specific reaction of the body. In acute cases of high air pollution, irritation, conjunctiva, cough, increased salivation, spasm of the glottis and some other symptoms are noted. With chronic air pollution, there is a known variability of the listed symptoms and their less pronounced character. Air pollution in cities is the reason that increases the resistance to air flow in the respiratory tract.[ ...]
Control over the state of the air in the Federal Republic of Germany is carried out by a network of posts and nine permanent stations (Munich) that monitor the content of harmful gases and dust in the atmosphere. The measurement data are sent to a processing center equipped with a computer for compiling required characteristics air pollution and their ¡classification.[ ...]
Automobile transport is not one of the leading sources of sulfur dioxide in the atmosphere. In the book by I. L. Varshavsky, R. V. Malov “How to neutralize the exhaust gases of a car” (1968), the issue of sulfur dioxide as an emission from a car engine is not considered at all. This position is consistent with the results of studies in 1974-1975 of air on the highways of busy motor traffic in Leningrad, where isolated cases of a slight excess of the permissible concentrations of sulfur dioxide were observed (G. V. Novikov et al., 1975). However, according to the United States (VN Smelyakov, 1969), the annual emission of sulfur oxides by cars in this country reaches 1 million tons, i.e., it is commensurate with the emission of particulate matter. In England, in 1954, according to the data of Pchop (1956), the emission of sulfur dioxide by car engines amounted to 20,000 tons. and 0.02% - diesel. These materials convince of the expediency of controlling anhydride concentrations on heavy traffic routes.[ ...]
In addition, this knowledge and this approach can be applied to newly developed engine technologies. As shown in fig. 1, it is expected that the future direction of work on minimizing emissions of conventional engines will shift towards the creation of fully optimized systems, while covering the vehicle, engine and fuel. A key factor in this process will be knowing how to properly formulate specific fuels to make them suitable for such systems.[ ...]
As examples of the practical application of promising Pb, Sn, and Te laser diodes, two projects developed by the American firm Texas Instruments (Dallas) can be cited. In the first of these, a compact device (weighing no more than 4.5 kg) based on a tunable laser diode is being developed for monitoring industrial emissions from pipes for the content of 302, NO2 and other gases. The second project is aimed at creating a convenient device for monitoring car exhaust gases for the content of CO, CO2, residues of unburned hydrocarbons and sulfur-containing gases. The constructed layouts are matrices of a number of laser bottoms, each tuned to a specific gas and optically connected by similar matrices of photodetectors. The instrument must be placed directly into the exhaust jet. Difficulties are associated with the development of a convenient cooler necessary to provide continuous laser radiation. This device is being created as a mass control tool in connection with the draft US state standard for the permissible composition of exhaust gases. Both devices are based on the absorption method.[ ...]
While fuel sulfur management and alternative fuel selection have the potential to provide indirect reductions in vehicle emissions, from the oil company's perspective, the main factor to consider when developing fuels with low level harmful emissions is the possibility of direct influence on exhaust gas emissions of such fuel properties as hydrocarbon composition, volatility, density, cetane number etc., as well as oxygen-containing compounds (oxidizers) or biofuels included in the fuel. This section addresses the first question. The latter topic is discussed in more detail in the accompanying article published in the same journal.[ ...]
The nitrogen and sulfur cycles are increasingly affected by industrial air pollution. Nitrogen oxides (NO and N02) and sulfur oxides (50 g) appear during these cycles, but only as intermediate stages and are present in most habitats in very low concentrations. The burning of fossil fuels has greatly increased the content of volatile oxides in the air, especially in cities; at such a concentration, they already become dangerous for the biotic components of ecosystems. In 1966, these oxides accounted for about a third of the total (125 million tons) of industrial emissions in the United States. The main source of HO is coal-fired thermal power plants, and the main source of NO2 is automobile engines. L), and nitrogen oxides are harmful, getting into the respiratory tract of higher animals and humans. As a result of chemical reactions of these gases with other pollutants, the harmful effect of both is aggravated (a kind of synergism is noted). The development of new types of internal combustion engines, the purification of fuel from sulfur and the transition from thermal to nuclear power plants will eliminate these serious disturbances in the nitrogen and sulfur cycles. Parenthetically, such changes in the way humans produce energy will raise other problems that need to be thought about in advance (see ch. 16).[ ...]
This circumstance predetermines the following argument in favor of domestic hydrogen energy. It consists in the need for a global approach to solving such problems. The trend towards the general integration of the trade and economic system today is such that it requires an analysis of the world market for the overwhelming range of goods and services. Under these conditions, Russia can no longer be pulled out of global industrial, trade and economic ties. It is impossible not to take into account, without incurring large material and moral losses, with increasingly stringent environmental requirements, enshrined in national and international legislation. The Clean Air Act passed by the US Congress, the above-mentioned tightening on the chemical composition of exhaust gases from air and land transport in Western Europe and other regions of the world, as well as a number of other legislative measures, serve as the basis for the Global Environmental Code. There is a need to create a national concept for the use of hydrogen in the country's fuel base as an environmentally friendly fuel for air and ground transport. Such a concept and a corresponding national program can be developed as part of the conversion of defense industries.[ ...]
When studying environmental pollution with emissions from an industrial enterprise, only those chemicals are usually taken into account that, based on the technological process, can be considered priority in terms of gross emissions into the atmospheric air or into wastewater. Meanwhile, a significant part of the initial and final products of production has a fairly high reactivity. Therefore, there is reason to believe that these compounds interact not only at the stage of the technological process. The possibility of such interaction in the air cannot be ruled out. industrial premises, from where the newly formed products enter the atmospheric air as fugitive emissions. New chemicals can be produced as a result of chemical and photochemical reactions in polluted air, as well as in water and soil. An example is the formation of new chemicals from the products of incomplete combustion of fuel, which is part of the exhaust gases of cars. At present, the pathways of photochemical oxidation of these products have been sufficiently studied. The possibility of atmospheric air pollution by qualitatively new chemicals not specified in the technological regulations of the enterprises under study has been proved.
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The effect of exhaust gases on the atmosphere is an urgent environmental problem. Many people use cars and do not even realize how badly they poison the air. To assess the damage, it is worth studying the composition of exhaust gases and the consequences of their impact on the environment.
What are exhaust gases made of?
Vehicle exhaust gases are produced during engine operation, as well as during incomplete or complete combustion of the fuel used. In total, over two hundred different components are found in them: some exist for only a few minutes, while others decompose for years and hover in the air for a long time.
Classification
All exhausts are divided into several groups according to their properties, constituent components and the degree of impact on the environment and the human body:
- The first group includes all substances that do not have toxic properties. This includes water vapor, as well as natural and integral components of atmospheric air, which inevitably penetrate car engines. This category also includes emissions of CO2 - carbon dioxide, which is also non-toxic, but reduces the concentration of oxygen in the air.
- The second group of constituents of automotive exhaust gases includes carbon monoxide, ie carbon monoxide. It is a product of incomplete combustion of fuel and has pronounced toxic and toxic properties. This substance, getting into the human body by inhalation, penetrates into the blood and reacts with hemoglobin. As a result, the oxygen concentration is greatly reduced, hypoxia occurs, and in severe cases, death.
- The third group covers nitrogen oxides, which have a brownish tint, an unpleasant pungent odor. Such substances are dangerous to humans, as they can irritate mucous membranes and affect the membranes. internal organs, especially the lungs.
- The fourth group of exhaust gas components is the most numerous and includes hydrocarbons that appear due to incomplete combustion of the fuel used in automotive engines. And it is these substances that form bluish or light white smoke.
- The fifth group of exhaust components is represented by aldehydes. The highest concentrations of these substances are observed at minimal loads or during the so-called idling, when temperature regime combustion in the engine is characterized by low rates.
- The sixth group of exhaust components automotive gases are various dispersed particles, including soot. They are considered wear products of engine parts, and may also include oil particles, aerosols, carbon deposits. Soot itself is not dangerous, but it can settle in the respiratory tract and impair visibility from exhausts.
- The seventh group of substances that make up the exhaust gases are various sulfur compounds formed during the combustion in engines of fuels containing sulfur (primarily diesel). Such components have a sharp characteristic odor, and they can irritate the mucous membranes, as well as disrupt metabolic processes and oxidative reactions.
- The eighth group is different lead compounds. They appear during the operation of carburetor engines, subject to the use of leaded gasoline with additives that increase the octane number.
Consequences of exposure to exhaust gases
The impact of exhaust gases on human health, the environment and the atmosphere is extremely detrimental. First of all, the harmful emissions generated during the combustion of fuel in automobile engines greatly pollute the air, forming smog. Some small and light particles are able to rise and reach the atmospheric layers, changing their composition and compacting the structure.
Exhaust gases are one of the causes of the greenhouse effect, which is developing at a rapid pace and poses a real threat to the environment and all of humanity. It causes weather anomalies, warming, melting glaciers, rising sea levels.
Another direction of the negative impact of exhaust gases is to contribute to the formation of acid rain. Recently, they began to go more and more often and greatly harm the ecosystem. Precipitation, which is highly acidic, changes the composition of the soil, which can make it unsuitable for growing plants and growing crops.
The flora suffers greatly: the rains literally corrode the foliage and fruits. Also, acid precipitation is harmful and dangerous to humans: they have an irritating and toxic effect on the skin, scalp.
The impact of car exhausts is extremely dangerous for the human body. Gas components almost immediately enter the respiratory system, irritate the mucous membranes of the lungs and bronchi, disrupt and inhibit respiratory function, and also cause whole line chronic diseases, including asthma and bronchitis. But substances from the respiratory tract are absorbed into the blood and change its composition, for example, significantly reduce the concentration of oxygen. Also, compounds penetrate into all tissues and organs, and some are capable of causing degeneration and mutation of cells in the future, their destruction.
How to avoid the serious effects of exhaust emissions
To minimize the dangerous and serious consequences of the negative effects of automotive exhaust gases, a number of measures should be taken:
- Competent, rational and moderate operation of motor vehicles. Avoid prolonged idling, avoid driving high speeds, if possible, give up the car in favor of using public transport, namely trolleybuses and trams.
- The most effective way is to abandon oil-containing fuels and switch to alternative energy sources. In the past few years, scientists have begun to develop cars that run on electricity and even solar panels.
- Constantly monitor the condition of the car, and especially the condition of the engine and all its parts, as well as the operation of the exhaust system.
- Available modern facilities that reduce the concentration of harmful substances in automobile exhausts. These include the so-called catalytic converters exhaust gases. If you apply them constantly, then the emissions will be less dangerous for the atmosphere and humanity.
Using a car, each owner must take care not only about its serviceability, but also about the impact of transport and emissions on health and the environment. Only in this case will it be possible to avoid sad consequences.
