What is dangerous exhaust gas. The approximate composition of the exhaust gases of carburetor and

16.07.2019

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. Especially a large number of harmful impurities enter 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 pavement and tire wear.[ ...]

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. To achieve the highest power, mixtures with 10-15% enrichment are required, while the most economical is speed with a slightly lower fuel enrichment. For most engines Idling enriched mixtures are required, and combustion products are not completely ejected from the cylinder. As the vehicle accelerates, the pressure in the fuel system decreases and the fuel condenses on the manifold walls. To prevent lean 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) . An intensive study of the influence of all constituent parts exhaust gases in a chronic experiment, on animals.[ ...]

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.[ ...]

Exhaust gases from vehicles and other engines internal combustion are the main source of urban air pollution (up to 40% of all pollution in the United States). Many experts tend to consider the problem of air pollution as a problem of its pollution with exhaust gases of various engines (cars, motor boats and ships, jet engines aircraft, 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. Analysis of similar compositions containing inorganic and organic compounds with a wide range of boiling points (hydrocarbons C1-C12) encounters significant difficulties, and for its implementation, as a rule, several analytical methods are used. 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 operates for a long time without technical care. 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 effectiveness of the treatment system through regular checks and technical inspections much more difficult than achieving a certain average level of design reliability.[ ...]

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. has a great influence on the composition of exhaust gases. technical condition engine and especially the carburetor. 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 under different operating conditions. 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, special works on their impact on individual objects of the plant world has not been carried out. 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 on outdoors 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 exhaust gases of cars and other vehicles equipped with carburetor internal combustion engines, the exhaust of which contains CO from 2 to 10% (higher values correspond to low speed modes) . Due to this Special attention is given to the development of carburetors, produced under the conditional name "Ozone" for passenger cars "Zhiguli". Thanks to a number of 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 carburetor uses the Cascade device, 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 by 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, starting with the earliest non-equipped vehicles. catalytic converters, to the latest models produced with the latest technology. 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 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 nonspecific 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.[ ...]

Road 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 highways of a busy car traffic in Leningrad, where isolated cases of a slight excess of the permissible concentrations of sulfurous anhydride 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 GOD is coal-fired thermal power plants, and the main source of NO2 is car motors. 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 be reckoned with, without incurring large material and moral losses, with ever more stringent environmental requirements fixed by national and international legislation. The Clean Air Act adopted by the US Congress, the above-mentioned tightening on the chemical composition of exhaust gases from air and land vehicles in Western Europe and other regions of the planet, as well as a number of other legislative measures, essentially serve as the basis for the Global Environmental Code. There is a need to create a national concept for the use of hydrogen in fuel base countries as an environmentally friendly fuel for air and land transport. Such a concept and a corresponding national program can be developed as part of the conversion of defense industries.[ ...]

When studying environmental pollution from emissions of an industrial enterprise, usually only those chemicals are taken into account, which, on the basis of technological process can be considered a priority in terms of gross emissions into the atmosphere 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.

Every year the number of cars in cities increases, and therefore the concentration of exhaust gases increases. You can find out what effect the products of the engine work on the body by understanding their composition.

The development of all mankind is invariably accompanied by an increase in population and, of course, needs. At the same time, industry is developing and automobile transport and more and more toxic chemicals are being released into the environment. Approximately 90 percent of the total amount of pollution is exhaust gases from cars. This problem is becoming increasingly important today.

Automobile exhaust gases are a kind of cocktail of several hundred chemicals that can harm both human health and the environment. They are released during the combustion process.

Statistics say that one "passenger car" emits an average of up to one kilogram of carcinogens, toxins and technical components per day into the environment. At the same time, harmful substances accumulate and can be contained in the atmosphere for up to five to six years. They can harm the environment, humans, plants and animals.

When the concentration of exhaust gases in the air exceeds the norm, they negatively affect human well-being. Drivers of taxis and minibuses, as well as people who spend a lot of time in traffic jams, suffer the most from their impact. At the same time, diesel engines are considered the most harmful, which can work out a lot of soot.

Emissions from the exhaust pipe of cars instantly affect the respiratory system, and in adults it is much less than in children. This is due to the fact that the maximum concentration of gases is concentrated approximately at the level of the child's face.

Composition of car exhaust gases

Harm to the environment is caused due to the toxins contained in the exhaust gases. Of these, the following chemical compounds stand out in particular:

According to statistics, buses and trucks produce much more exhaust gases than cars and motorcycles. This is due to the volume of engines and their mode of operation.

Impact on the human body

In its composition, the exhaust gases of cars contain toxic and harmful chemical compounds that can cause the development of chronic and acute diseases. In the respiratory system, the following pathologies may occur:

asthma;
allergy;
bronchitis;
malignant neoplasms;
sinusitis;
emphysema;
airway inflammation.

In addition, due to the content of harmful substances in emissions, the cardiovascular system can also suffer. It is characterized by the following phenomena:

dizziness;
shortness of breath and difficulty breathing;
signs of angina;
the formation of thrombosis;
myocardial infarction.

Substances present in the composition of car exhaust can accumulate inside the body. Because of this, its slagging occurs, leading to the development of serious diseases. There is a lot of controversy about the impact of exhaust gases on human health, but they all boil down to the fact that harm is inevitable.

Many people have known from school that plants can "breathe". That is, they also feel the effects of exhaust gases. Microparticles of toxins poison the body of the plant, which is why the trees and flowers growing along the roads look so dull and lethargic.

In addition, the huge volume had an impact on the composition of climatic precipitation. It is because of the operation of vehicles that acid rains, multi-colored fogs or dark snow are increasingly occurring. Of course, such precipitation helps to purify the air, but the pollution gets into the ground. After that, heavy metals and chemical compounds spread further, through crops and animal feed. This "circulation" of harmful substances adversely affects the state of health.

Protective Measures

Maximum harm automotive emissions have on people who stand in traffic jams for a long time. Motorists, not having a gas mask or respirator, are literally forced to inhale them. However, the mouth or nose can be covered with a scarf or handkerchief. The fabric will not be able to protect against the ingress of harmful substances into the body, but it at least minimizes their amount.

If you often have to stand in traffic jams, then it is recommended to supplement the diet with green vegetables, berries, and seeds. It is also advisable to drink as much water as possible, because it eliminates intoxication.

The impact of exhaust gases on the environment also extends to houses and apartments that are located next to motorways. Often exhausts in the dwelling get through air vents and windows. To improve safety, experts advise installing sealed structures, and using breathers for ventilation.

Today, scientists are still developing alternative fuels, electric vehicles and other environmentally friendly technologies. But so far this is only a matter of the future, because the problem of exhaust emissions is now so relevant.

Exhaust gases (or exhaust gases) - the main source of toxic substances of an internal combustion engine - are a heterogeneous mixture of various gaseous substances with a variety of chemical and physical properties, consisting of products of complete and incomplete combustion of fuel, excess air, aerosols and various microimpurities (both gaseous and in the form of liquid and solid particles) coming from engine cylinders into its exhaust system. In their composition, they contain about 300 substances, most of which are toxic.

The main regulated toxic components of engine exhaust gases are oxides of carbon, nitrogen and hydrocarbons. In addition, saturated and unsaturated hydrocarbons, aldehydes, carcinogens, soot and other components enter the atmosphere with exhaust gases. Sample composition.

Composition of exhaust gases

Exhaust gas components	Content by volume, %		Toxicity
	Engine
	petrol	diesel
Nitrogen	74,0 - 77,0	76,0 - 78,0	No
Oxygen	0,3 - 8,0	2,0 - 18,0	No
water vapor	3,0 - 5,5	0,5 - 4,0	No
Carbon dioxide	5,0 - 12,0	1,0 - 10,0	No
carbon monoxide	0,1 - 10,0	0,01 - 5,0	Yes
Hydrocarbons are non-carcinogenic	0,2 - 3,0	0,009 - 0,5	Yes
Aldehydes	0 - 0,2	0,001 - 0,009	Yes
Sulfur oxide	0 - 0,002	0 - 0,03	Yes
Soot, g/m3	0 - 0,04	0,01 - 1,1	Yes
Benzopyrene, mg/m3	0,01 - 0,02	up to 0.01	Yes

When the engine is running on leaded gasoline, lead is present in the exhaust gases, and for engines running on diesel fuel- soot.

Carbon monoxide (CO - carbon monoxide)

Transparent, odorless poisonous gas, slightly lighter than air, poorly soluble in water. Carbon monoxide is a product of incomplete combustion of fuel that burns in air with a blue flame to form carbon dioxide (carbon dioxide). In the combustion chamber of an engine, CO is formed due to poor atomization of the fuel, as a result of cold flame reactions, during the combustion of fuel with a lack of oxygen, and also due to the dissociation of carbon dioxide at high temperatures. During subsequent combustion after ignition (after the top dead center, on the expansion stroke), combustion of carbon monoxide is possible in the presence of oxygen with the formation of dioxide. At the same time, the process of burning CO continues in the exhaust pipeline. It should be noted that during the operation of diesel engines, the concentration of CO in the exhaust gases is low (approximately 0.1 - 0.2%), therefore, as a rule, the concentration of CO is determined for gasoline engines.

Nitrogen oxides (NO, NO2, N2O, N2O3, N2O5, hereinafter NOx)

Nitrogen oxides are among the most toxic components of exhaust gases. Under normal atmospheric conditions, nitrogen is a highly inert gas. At high pressures and especially temperatures, nitrogen actively reacts with oxygen. In the exhaust gases of engines, more than 90% of the total amount of NOx is nitric oxide NO, which is easily oxidized into dioxide (NO2) even in the exhaust system, and then in the atmosphere. Nitrogen oxides irritate the mucous membranes of the eyes, nose, and destroy human lungs, because when moving through the respiratory tract, they interact with the moisture of the upper respiratory tract, forming nitric and nitrous acids. As a rule, poisoning of the human body with NOx does not appear immediately, but gradually, and there are no neutralizing agents.

Nitrous oxide (N2O hemioxide, laughing gas) is a gas with a pleasant odor and is highly soluble in water. Has a narcotic effect.

NO2 (dioxide) is a pale yellow liquid involved in the formation of smog. Nitrogen dioxide is used as an oxidizing agent in rocket fuel. It is believed that for the human body, nitrogen oxides are about 10 times more dangerous than CO, and when secondary transformations are taken into account, 40 times. Nitrogen oxides are dangerous for plant leaves. It has been established that their direct toxic effect on plants manifests itself when the concentration of NOx in the air is in the range of 0.5 - 6.0 mg/m3. Nitric acid is highly corrosive to carbon steels. The temperature in the combustion chamber has a significant effect on the emission of nitrogen oxides. So, with an increase in temperature from 2500 to 2700 K, the reaction rate increases by 2.6 times, and with a decrease from 2500 to 2300 K, it decreases by 8 times, i.e. the higher the temperature, the higher the NOx concentration. Early fuel injection or high compression pressures in the combustion chamber also contribute to the formation of NOx. The higher the oxygen concentration, the higher the concentration of nitrogen oxides.

Hydrocarbons (CnHm ethane, methane, ethylene, benzene, propane, acetylene, etc.)

Hydrocarbons are organic compounds whose molecules are built only from carbon and hydrogen atoms, are toxic substances. Exhaust gases contain more than 200 different CHs, which are divided into aliphatic (open or closed chain) and those containing a benzene or aromatic ring. Aromatic hydrocarbons contain in the molecule one or more cycles of 6 carbon atoms interconnected by single or double bonds (benzene, naphthalene, anthracene, etc.). They have a pleasant smell. The presence of CH in the exhaust gases of engines is explained by the fact that the mixture in the combustion chamber is heterogeneous, therefore, at the walls, in over-enriched zones, the flame is extinguished and chain reactions break. Incompletely burned CH, emitted with exhaust gases and representing a mixture of several hundred chemical compounds have bad smell. CH are the cause of many chronic diseases. Gasoline vapors, which are hydrocarbons, are also toxic. Permissible average daily concentration of gasoline vapors is 1.5 mg/m3. The content of CH in the exhaust gases increases with throttling, when the engine is running in forced idle modes (PHX, for example, during engine braking). When the engine is running in these modes, the process of mixture formation (mixing of the air-fuel charge) worsens, the combustion rate decreases, ignition worsens and, as a result, its frequent misfires occur. The release of CH is caused by incomplete combustion near cold walls, if until the end of combustion there are places with a strong local lack of air, insufficient fuel atomization, with poor swirling of the air charge and low temperatures (for example, idling). Hydrocarbons are formed in overenriched zones where oxygen access is limited, as well as near the relatively cold walls of the combustion chamber. They play an active role in the formation of biologically active substances that cause irritation of the eyes, throat, nose and their disease, and damage the flora and fauna.

Hydrocarbon compounds have a narcotic effect on the central nervous system, can cause chronic diseases, and some aromatic CH have toxic properties. Hydrocarbons (olefins) and nitrogen oxides, under certain meteorological conditions, actively contribute to the formation of smog.

Exhaust smog.

Smog (Smog, from smoke smoke and fog - fog) is a poisonous fog formed in the lower layer of the atmosphere polluted with harmful substances from industrial enterprises, exhaust gases from vehicles and heat-producing installations under adverse weather conditions. It is an aerosol consisting of smoke, fog, dust, soot particles, liquid droplets (in a humid atmosphere). Occurs in the atmosphere of industrial cities under certain meteorological conditions. Harmful gases entering the atmosphere react with each other and form new, including toxic compounds. At the same time, reactions of photosynthesis, oxidation, reduction, polymerization, condensation, catalysis, etc. take place in the atmosphere. As a result of complex photochemical processes stimulated by the ultraviolet radiation of the Sun, photooxidants (oxidizers) are formed from nitrogen oxides, hydrocarbons, aldehydes and other substances.

Low concentrations of NO2 can create large amounts of atomic oxygen, which in turn forms ozone and reacts again with air pollutants. The presence of formaldehyde, higher aldehydes and other hydrocarbon compounds in the atmosphere also contributes, together with ozone, to the formation of new peroxide compounds. Dissociation products interact with olefins, forming toxic hydroperoxide compounds. When their concentration is more than 0.2 mg/m3, water vapor condenses in the form of tiny mist droplets with toxic properties. Their number depends on the season of the year, time of day and other factors. In hot, dry weather, smog is observed in the form of a yellow veil (the color is given by nitrogen dioxide NO2 present in the air as droplets of a yellow liquid). Smog irritates mucous membranes, especially the eyes, and can cause headaches, swelling, hemorrhages, and complications of respiratory diseases. It worsens visibility on the roads, thereby increasing the number of traffic accidents. The danger of smog to human life is great. So, for example, the London smog of 1952 is called a disaster, since about 4 thousand people died from smog in 4 days. The presence of chloride, nitrogen, sulfur compounds and water droplets in the atmosphere contributes to the formation of strong toxic compounds and acid vapors, which has a detrimental effect on plants and structures, especially on historical monuments made of limestone. The nature of smog is different. For example, in New York, the formation of smog is promoted by the reaction of fluoride and chloride compounds with water droplets; in London, the presence of fumes of sulfuric and sulphurous acids; in Los Angeles (California or photochemical smog) the presence of nitrogen oxides, hydrocarbons in the atmosphere; in Japan, the presence of soot and dust particles in the atmosphere.

Emissions from internal combustion engines (ICE) are divided into emissions from carburetor and diesel engines. This separation is due to the fact that carburetor engines (CD) operate with homogeneous air-fuel mixtures, while diesel engines (DD) operate with heterogeneous mixtures.

Pollution emissions from carburetor-type internal combustion engines include hydrocarbons, carbon oxides, nitrogen oxides, and intermittent emissions. Pollution arises as a result of reactions and in the process of combustion in the volume and on surfaces. Gas blow-by through piston rings and exhaust from cylinders are a less intense source of pollutant emissions.

In 1980, 4% of cars and trucks produced in the world were equipped with diesel engines, and by the end of the 80s this figure had increased to 25%. The main pollutant emissions of diesel engines are the same as those of carbureted engines (hydrocarbons, carbon monoxide, nitrogen oxides, intermittent emissions), but carbon particles (soot aerosol) are added to them.

A car emits carbon monoxide CO up to 3 m3 / h, a truck - up to 6 m3 / h (3 ... 6 kg / h).

The composition of the exhaust gases of vehicles with different types of engines can be judged from the data given in Table. 8.1.

		Table 8.1.
Approximate composition of vehicle exhaust gases

Components
	carburettor	diesel engine
	engine


H2 O (pairs)
CO2

nitrogen oxides		2. 10-3 -0,5
nitrogen oxides
hydrocarbons		1. 10-3 -0,5
Aldehydes		1 . 10 - 3 -9 .10 -3

	0-0.4 g/m3	0.01-1.1 g/m3
Benzopyrene	(10-20). 10-6, g/m3	up to 1 . 10-5 g/m3

Emissions of carbon monoxide and hydrocarbons from carburetor engines are significantly higher than from diesel engines.

8.2. Reducing emissions from internal combustion engines

An increase in the environmental performance of a car is possible through a set of measures to improve its design and operation mode. To improve the environmental performance of the car lead to: increasing its efficiency; replacement of gasoline internal combustion engines with diesel ones; transfer of internal combustion engines to the use of alternative fuels (compressed or liquefied gas, ethanol, methanol, hydrogen, etc.); the use of exhaust gas neutralizers for internal combustion engines; improvement of the regime ICE operation And Maintenance car.

Known and applied a number of methods to reduce the toxicity of exhaust gases. Among them, the operation of the car in conditions where the engine emits the least amount of toxic substances (decrease in braking, uniform movement at a certain speed, etc.); the use of special fuel additives that increase the completeness of its combustion and reduce the emission of CO (alcohols, other compounds); flame afterburning of some harmful components.

IN In carbureted engines, the ratio between air and fuel affects the content of hydrocarbons and carbon monoxide in the exhaust. So, for example, emissions increase with increasing enrichment of the mixture. CO content increases due to incomplete combustion caused by a lack of oxygen in the mixture. The increase in the content of hydrocarbons is primarily due to an increase in the adsorption of fuel and an increase in the mechanism of incomplete combustion of the fuel. Lean mixtures create lower concentrations of Cn Hm and CO in the emission as a result of their more complete combustion.

IN In diesel engines, power changes as the amount of fuel injected changes. As a result, the distribution of the fuel jet, the amount of fuel hitting the wall, the pressure in the cylinder, the temperature, and the duration of injection are changed.

Experts believe that in order to significantly reduce harmful emissions, it is necessary to reduce gasoline consumption from 8 liters (per 100 kilometers - to 2 ... 3 liters. This requires improving the engine design and fuel quality; switching to unleaded gasoline; using catalytic afterburning to reduce CO emissions; introduction of electronic

control system for fuel combustion processes; and other measures, in particular the use of silencers in the exhaust system.

Increasing the fuel efficiency of a car is achieved mainly by improving the combustion process in the internal combustion engine: layered fuel combustion; prechamber-flare combustion; the use of heating and evaporation of fuel in the intake tract; usage electronic ignition. Additional reserves for increasing the efficiency of the car are:

- reducing the mass of the car by improving its design and the use of non-metallic and high-strength materials;

- improvement of the aerodynamic performance of the body (the latest models of passenger cars usually have a 30 ... 40% lower drag coefficient);

- drag reduction air filters and mufflers, shutdown auxiliary units, such as a fan, etc.;

- reducing the mass of transported fuel (incomplete filling of tanks) and the mass of tools.

Modern models of passenger cars differ significantly in fuel efficiency from previous models.

Promising brands of passenger cars will have a gasoline consumption of 3.5 l/100 km or less. Increasing the efficiency of buses and trucks is achieved primarily by the use of diesel internal combustion engines. They have environmental advantages compared to gasoline internal combustion engines, since they have a 25 ... 30% lower specific fuel consumption; in addition, the composition of exhaust gases from a diesel internal combustion engine is less toxic (see Table 8.1).

Compared to gasoline ICEs, engines running on alternative fuels have environmental advantages. General view about reducing the toxicity of internal combustion engines when switching to alternative fuel can be obtained from the data given in table. 8.2.

Table 8.2 Toxicity of ICE emissions on various fuels

Many scientists see a partial solution to the environmental problem in the transfer of cars to gaseous fuels. Thus, the content of carbon oxide

lerod in the exhaust of gas vehicles is less by 25 ... 40%; nitrogen oxides by 25…30%; soot by 40 ... 50%. When used in automotive engines liquefied or compressed gas exhaust gases contain almost no carbon monoxide. The solution to the problem would be wide application electric vehicle. Produced electric vehicles have a limited range due to the limited capacity and large mass of batteries. Extensive research is currently underway in this area. Some positive results have already been achieved. Reducing the toxicity of emissions can be achieved by reducing the content of lead compounds in gasoline without compromising its energy qualities.

The transition to gas fuel does not provide for significant changes in the design of the internal combustion engine, however, it is constrained by the lack of filling stations and required amount cars converted to run on gas. In addition, a car converted to run on gas fuel loses its carrying capacity due to the presence of cylinders and the cruising range by about 2 times (200 km versus 400 ... 500 km for a gasoline car). These shortcomings can be partially eliminated by converting the car to liquefied natural gas.

The use of methanol and ethanol requires changes in the design of the internal combustion engine, since alcohols are more chemically active towards rubbers, polymers, and copper alloys. IN internal combustion engine design it is necessary to introduce an additional heater to start the engine in the cold season (at t< -25 °С); необходима перерегулировка карбюратора, так как изменяется стехиометрическое отношение расхода воздуха к расходу топлива. У бензиновых ДВС оно равно 14,7; у двигателей на метаноле - 6,45, а на этаноле - 9. За рубежом (Бразилия) применяют смеси бензина и этанола в пропорции 12:10, что позволяет использовать gasoline internal combustion engines with minor changes in their design, while slightly increasing the environmental performance of the engine.

Despite the fact that emissions of toxic substances (Cn Hm and CO) from the crankcase and fuel system engine at least an order of magnitude lower in exhaust emissions, combustion methods are currently being developed crankcase gases ICE. Known closed circuit neutralization of crankcase gases with their supply to the inlet pipeline of the engine with subsequent afterburning. A closed crankcase ventilation system with the return of crankcase gases to the carburetor reduces the release of hydrocarbons into the atmosphere by 10 ... 30%, nitrogen oxides by 5 ... 25%, but at the same time, the emission of carbon monoxide increases by 10 ... 35%. When crankcase gases return after the carburetor, Cn Hm emission decreases by 10...40%, CO by 10...25%, but NOx emission increases by 10...40%.

To prevent emissions of gasoline vapors from the fuel system, most of which enters the atmosphere when the engine is not running, a system for neutralizing fuel vapors from the carburetor and fuel tank is installed on cars, consisting of three main components (Fig. 8.1): sealed fuel tank 1 with special capacity 2 to compensate for the thermal expansion of the fuel; caps 3 of the fuel filler neck of the tank with double-sided safety valve to prevent excessive pressure or vacuum in the tank; adsorber 4 for absorbing fuel vapors when the engine is off with a system for returning vapors to the intake tract of the engine during its operation. Activated carbon is used as an adsorbent.

Rice. 8.1. Gasoline ICE fuel vapor recovery scheme

Compliance with the maintenance schedule and control of the composition of exhaust gases (EG) of internal combustion engines can significantly reduce toxic emissions into the atmosphere. It is known that at 160 thousand kilometers and in the absence of control, CO emissions increase by 3.3 times, and Sp Ht - by 2.5 times.

Improving the environmental performance of a gas turbine propulsion system (GTPU) on aircraft is achieved by improving the process of fuel combustion, the use of alternative fuels (liquefied gas, hydrogen, etc.), and the rational organization of traffic at airports.

An increase in the residence time of combustion products in the gas turbine engine combustion chamber is accompanied by an increase in combustion efficiency (decrease in the content of CO and Cn Hm in combustion products) and the content of nitrogen oxides in them. Therefore, by changing the residence time of the gas in the combustion chamber, it is possible to achieve only minimal toxicity of combustion products, and not eliminate it completely.

A more effective means of reducing the toxicity of gas turbine engines is the use of fuel supply methods that provide a more uniform mixing of fuel and air. These include devices with pre-evaporation of fuel, nozzles with fuel aeration, etc. Tests on model chambers indicate that such methods can reduce the content of Cn Hm in combustion products by more than an order of magnitude, CO - by several times, provide smokeless exhaust and reduce NOx content.

A significant reduction in the NOx content in the combustion products of gas turbine engines is achieved with a staged process of fuel combustion in two-zone combustion chambers. In such chambers, the main part of the fuel in high thrust modes is burned in the form of a previously prepared lean mixture. A smaller part of the fuel (~25%) is burned in the form of a rich mixture, where nitrogen oxides are formed mainly. Experiments show that with such combustion, the NOx content can be reduced by a factor of 2.

The solution of environmental problems associated with the use of rocket technology is based on the use of environmentally friendly safe fuel especially oxygen and hydrogen.

8.3. Neutralization of exhausts of internal combustion engines

Improving the environmental performance of cars is possible through a set of measures to improve their designs and operating modes. These include increasing the efficiency of engines, replacing their gasoline versions with diesel ones, using alternative fuels (compressed or liquefied gas, ethanol, methanol, hydrogen, etc.), using exhaust gas neutralizers, optimizing engine operation and vehicle maintenance.

A significant reduction in the toxicity of internal combustion engines is achieved by using exhaust gas neutralizers (EG). Liquid, catalytic, thermal and combined converters are known. The most efficient of these are catalytic designs. Equipping cars with them began in 1975 in the USA and in 1986 in Europe. Since then, atmospheric pollution by emissions has dropped sharply - by 98.96 and 90%, respectively, for hydrocarbons, CO and NOx.

The converter is an additional device that is introduced into the engine exhaust system to reduce exhaust gas toxicity. Liquid, catalytic, thermal and combined converters are known.

The principle of operation of liquid neutralizers is based on the dissolution or chemical interaction of toxic components of the exhaust gas when they are passed through a liquid of a certain composition: water, water solution sodium sulfite, aqueous solution of bicarbonate of soda.

On fig. 8.2 shows a diagram of a liquid neutralizer used with a two-stroke diesel engine. The exhaust gases enter the converter through pipe 1 and through the collector 2 enter the tank 3, where they react with the working fluid. Purified gases pass through filter 4, separator 5 and are released into the atmosphere. As the liquid evaporates, the liquid is added to the working tank from additional tank 6.

Rice. 8.2. Scheme of a liquid neutralizer

The passage of diesel exhaust gases through water leads to a decrease in odor, aldehydes are absorbed with an efficiency of 0.5, and the efficiency of soot removal reaches 0.60 ... 0.80. At the same time, the content of benzo(a)pyrene in the exhaust gases of diesel engines decreases somewhat. The temperature of the gases after liquid cleaning is 40 ... 80 ° C, and heats up to approximately the same temperature. working fluid. As the temperature drops, the cleaning process becomes more intensive.

Liquid neutralizers do not require time to enter the operating mode after starting a cold engine. Disadvantages of liquid neutralizers: large weight and dimensions; the need for frequent changes in the working solution; inefficiency in relation to CO; low efficiency (0.3) in relation to NOx; intense evaporation of the liquid. However, the use of liquid neutralizers in combined systems cleaning can be rational, especially for installations whose exhaust gases must have low temperature upon entering the atmosphere.

Traffic fumes

In the European Union, the permitted level of harmful substances in the exhaust depends on the age of the car. If the year of manufacture of the car is earlier than 1978, then there are no fixed restrictions, there is only one requirement that there is no visible smoke coming out of the exhaust pipe. If the car is manufactured in 1979-1986, then the maximum limit of harmful substances emitted by it, measured at idle, is as follows: CO - less than 4.5%, CH - 100 ppm. Oxygen should be less than 5%. The latter indicator is usually used to confirm that nothing illegal has been done to reduce the level of CO with the car's systems. From 1986 to 1990 in most countries the requirements became higher: CO - 3.5%, CH - 600 ppm. Since 1991, new regulations have been established for vehicles equipped with a catalytic afterburner. Now the level of harmful exhausts of the car is measured in two ways: at idle and at 2500 engine revolutions per minute. With the help of catalytic exhaust gas afterburner, the level of harmful emissions has been greatly reduced, for this reason, the emission limit values have also decreased. At idle, the CO level should be no more than 0.5% and CH no more than 100 ppm. At the same time, the so-called excess air coefficient alpha is calculated mathematically and should be between 0.91 - 1.03. Also the oxygen level must be less than 0.5% and the reference CO2 must be less than 16.

Owners of new cars have no problem getting permission to use their vehicles. Although, for example, in Finland average age passenger car is 10.5 years. But when the car has a significant mileage and age, when passing the exhaust test, it can be sent for repair.

Very often these problems are found in older cars, when the engine already has a significant mileage and has lost its former power. Often the owners do not notice that their car has already lost power.

The amount of exhaust gases of cars

Mainly determined mass flow fuel for cars. Consumption by distance is normalized and is usually indicated by manufacturers (one of the consumer characteristics). With regard to the total volume of exhaust gases coming out of the muffler, one can approximately focus on the following figure - one liter of gasoline burned leads to the formation of approximately 16 cubic meters or 16,000 liters of a mixture of various gases. Based on these data, one can judge the approximate amount of harmful impurities emitted into the atmosphere, but there is a small problem here. We can only determine the amount of different gases emitted during the combustion of a certain number of liters of fuel, but not with any exhaust, and even more so over a period of time (an hour, a day, a month, etc.). Therefore, we cannot, in principle, judge the amount of gases emitted into the atmosphere every hour. Nowhere is it established that all cars a day pass a certain number of kilometers at the same speed. And to look for some kind of average means to deceive yourself, because the data can be not only very approximate, but even completely erroneous.

Table number 1. Fuel consumption for cars of different brands

K -- carbureted engine

i -- injection engine

D -- diesel engine

the density of gasoline at +20C ranges from 0.69 to 0.81 g/cm³

density of diesel fuel at +20С according to GOST 305-82 no more than 0.86 g/cm³

Table number 2. Composition of automotive exhaust gases

Exhaust gases (or exhaust gases) - the main source of toxic substances of an internal combustion engine - are a heterogeneous mixture of various gaseous substances with various chemical and physical properties, consisting of products of complete and incomplete combustion of fuel coming from engine cylinders into its exhaust system. In their composition, they contain about 300 substances, most of which are toxic. The main regulated toxic components of engine exhaust gases are oxides of carbon, nitrogen and hydrocarbons. In addition, saturated and unsaturated hydrocarbons, aldehydes, carcinogens, soot and other components enter the atmosphere with exhaust gases. The approximate composition of exhaust gases is presented in table 1. When the engine is running on leaded gasoline, lead is present in the exhaust gases, and soot is present in engines running on diesel fuel. Now let's try to find out why each exhaust is dangerous, and what is the amount of gases escaping from the exhaust pipe.

Carbon monoxide (CO - carbon monoxide)

Transparent, odorless poisonous gas, slightly lighter than air, poorly soluble in water. Carbon monoxide - a product of incomplete combustion of fuel, burns in air with a blue flame to form carbon dioxide (carbon dioxide). If its content is high, the engine consumes too much fuel and oil from the crankcase.

In the combustion chamber of an engine, CO is formed due to poor atomization of the fuel, as a result of cold flame reactions, during the combustion of fuel with a lack of oxygen, and also due to the dissociation of carbon dioxide at high temperatures. At the same time, the process of burning CO continues in the exhaust pipeline.

It should be noted that during the operation of diesel engines, the concentration of CO in the exhaust gases is low (approximately 0.1-0.2%), therefore, as a rule, the concentration of CO is determined for gasoline engines. On average, cars burning a liter of gasoline emit about 800 liters of carbon dioxide into the air.

Nitrogen oxides (NO, NO2, N2O, N2O3, N2O5, further - NOx)

Nitrogen oxides irritate the mucous membranes of the eyes, nose, and destroy human lungs, because when moving through the respiratory tract, they interact with the moisture of the upper respiratory tract, forming nitric and nitrous acids. As a rule, poisoning of the human body with NOx does not appear immediately, but gradually, and there are no neutralizing agents. When burning a liter of gasoline, approximately 128 liters of nitrogen oxides are emitted from the exhaust pipe.

Nitrous oxide (N 2 O - hemioxide, laughing gas) - a gas with a pleasant smell, we will dissolve well in water. Has a narcotic effect.

Nitrogen oxides are dangerous for plant leaves. It has been established that their direct toxic effect on plants manifests itself when the concentration of Nox in the air is in the range of 0.5-6.0 mg/m 3 . Nitric acid is highly corrosive to carbon steels.

The temperature in the combustion chamber has a significant effect on the emission of nitrogen oxides. So, with an increase in temperature from 2500 to 2700 K, the reaction rate increases by 2.6 times, and with a decrease from 2500 to 2300 K, it decreases by 8 times, i.e. the higher the temperature, the higher the NOx concentration. Early fuel injection or high compression pressures in the combustion chamber also contribute to the formation of NOx. The higher the oxygen concentration, the higher the concentration of nitrogen oxides.

Hydrocarbons (CnHm - ethane, methane, ethylene, benzene, propane, acetylene, etc.)

Hydrocarbons - organic compounds, the molecules of which are built only from carbon and hydrogen atoms, are toxic substances. Exhaust gases contain more than 200 different CHs, which are divided into aliphatic (open or closed chain) and those containing a benzene or aromatic ring. Aromatic hydrocarbons contain in the molecule one or more cycles of 6 carbon atoms interconnected by single or double bonds (benzene, naphthalene, anthracene, etc.). They have a pleasant smell. Its quantity is measured in the conventional unit ppm (number of particles per million). So even a slight increase in combustion efficiency can have a big impact on its level. Usually, extremely high levels of hydrocarbons are a problem not only for car owners, but also for mechanics.

The presence of CH in the exhaust gases of engines is explained by the fact that the mixture in the combustion chamber is heterogeneous, therefore, at the walls, in over-enriched zones, the flame is extinguished and chain reactions break. There are several factors that affect the amount of hydrocarbon in exhaust gases. Valve tightness, valve cleanliness and ignition timing are all equally important. Not only the ignition timing adjustment, but also the current combustion force, everything that affects combustion is of great importance in limiting the amount of hydrocarbon in the exhaust gases. Approximate quantity of the hydrocarbon which is formed at combustion of liter of gasoline - 400-450l.

These figures may scare someone, but let's figure it out: liters are a measure of volume, and in no case should these figures be confused with liquid, because 800 liters is a rather large number for a liquid. And for gas? A gas is a substance whose molecules are several hundred and thousand times smaller than the distance between them. If you imagine something denser, then the volume will be reduced by tens and hundreds of times. And now carefully - a liter of gasoline, during the combustion of which this volume is produced, is consumed to cover a distance of 10 km. Let's try to dispel most of the illusions - this is not such a strong pollution, it's just that an unpleasant smell is released at the moment of exhaust, and it seems to us that the composition of the air around has changed dramatically. But there was not even any sediment left on our clothes.