Traffic fumes
In the European Union, the permitted level of harmful substances in the exhaust depends on the age of the car. If the car's production year is earlier than 1978, then there are no fixed restrictions, the only requirement is that there is no visible smoke coming from exhaust pipe. If the car is manufactured in 1979-1986, then the maximum limit of harmful substances emitted by it, measured at idle speed, 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 the vehicle's systems to reduce CO levels. From 1986 to 1990, in most countries the requirements became higher: CO - 3.5%, CH - 600 ppm. Since 1991, new rules have been established regarding vehicles equipped with a catalytic afterburner. exhaust gases. Now the level of harmful vehicle emissions is measured in two ways: at idle and at 2500 engine revolutions per minute. With the help of a catalytic exhaust afterburner, the level of harmful emissions has been significantly 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 should be less than 0.5% and the CO2 control level should be less than 16.
Owners of new cars have no problems obtaining permission to use their vehicles. Although, for example, in Finland average age passenger car is 10.5 years. But when a car has significant mileage and age, it may be sent for repairs if it passes an emission test.
Very often, these problems occur in old cars, when the engine has already had significant mileage and has lost its former power. Often, owners do not notice that their car has already lost power.
Car exhaust gas quantity
Mainly determined mass flow fuel for cars. Distance consumption is standardized and usually indicated by manufacturers (one of the consumer characteristics). In relation to the total volume of exhaust gases coming out of the muffler, we can approximately focus on the following figure - one liter of burned gasoline 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 little problem. We can only determine the amount of different gases emitted when a certain number of liters of fuel is burned, but not in any single exhaust, and certainly not over a period of time (hour, day, month, etc.). Therefore, in principle, we cannot judge the amount of gases emitted into the atmosphere every hour. It is not established anywhere that all cars travel a certain number of kilometers per day at the same speed. And to look for any average number means to deceive yourself, because the data can be not only very approximate, but also completely erroneous.
Table No. 1. Fuel consumption for cars of different brands
K -- carburetor 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 +20C according to GOST 305-82 no more than 0.86 g/cm³
Table No. 2. Composition of automobile exhaust gases
Exhaust gases (or exhaust gases) are the main source of engine toxicants internal combustion is 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 the engine cylinders into its exhaust system. 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, carcinogenic substances, soot and other components enter the atmosphere with exhaust gases. The approximate composition of exhaust gases is presented in Table 1. When an engine runs on leaded gasoline, lead is present in the exhaust gases, and for engines running on diesel fuel- soot. 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)
A transparent, odorless, poisonous gas, slightly lighter than air, poorly soluble in water. Carbon monoxide is a product of incomplete combustion of fuel; it burns with a blue flame in air 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 unsatisfactory atomization of fuel, as a result of cold-flame reactions, during combustion of fuel with a lack of oxygen, and also due to the dissociation of carbon dioxide during high temperatures. In this case, the process of CO burnout continues in the exhaust pipeline.
It should be noted that when operating diesel engines, the CO concentration in the exhaust gases is small (approximately 0.1-0.2%), therefore, as a rule, the CO concentration is determined for gasoline engines. On average, cars emit about 800 liters of carbon dioxide into the air when burning a liter of gasoline.
Nitrogen oxides (NO, NO2, N2O, N2O3, N2O5, further - 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 engine exhaust gases, more than 90% of the total amount of NOx is nitrogen oxide NO, which is easily oxidized into dioxide (NO2) in the exhaust system and then in the atmosphere.
Nitrogen oxides irritate the mucous membranes of the eyes and nose, and destroy human lungs, since when moving through the respiratory tract they interact with the moisture of the upper respiratory tract, forming nitric and nitrous acids. As a rule, NOx poisoning of the human body does not appear immediately, but gradually, and there are no neutralizing agents. When a liter of gasoline is burned, approximately 128 liters of nitrogen oxides are released from the exhaust pipe.
Nitrous oxide (N 2 O - hemioxide, laughing gas) is a gas with a pleasant odor, highly soluble in water. Has a narcotic effect.
NO 2 (dioxide) is a pale yellow liquid involved in the formation of smog. Nitrogen dioxide is used as an oxidizer in rocket fuel. It is believed that nitrogen oxides are approximately 10 times more dangerous than CO for the human body, and 40 times more dangerous when secondary transformations are taken into account.
Nitrogen oxides pose a danger to plant leaves. It has been established that their direct toxic effect on plants occurs at Nox concentrations in the air in the range of 0.5-6.0 mg/m 3 . Nitric acid is highly corrosive to carbon steels.
The amount of nitrogen oxide emissions is significantly influenced by the temperature in the combustion chamber. Thus, when the temperature increases from 2500 to 2700 K, the reaction rate increases by 2.6 times, and when it decreases 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 pressure compression in the combustion chamber also contributes 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 and 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 a molecule one or several cycles of 6 carbon atoms connected to each other by simple or double bonds (benzene, naphthalene, anthracene, etc.). They have a pleasant smell. Its quantity is measured in the conventional unit ppm (parts per million). So even a slight increase in combustion efficiency can have big influence to his level. Usually, extremely high level hydrocarbons are a problem not only for car owners, but also for mechanics.
The presence of CH in engine exhaust gases is explained by the fact that the mixture in the combustion chamber is heterogeneous, therefore, near the walls, in over-enriched zones, the flame is extinguished and chain reactions are broken. There are several factors that influence the amount of hydrocarbons 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. The approximate amount of hydrocarbons formed during the combustion of a liter of gasoline is 400-450 liters.
These numbers may scare some, but let's figure it out: liters are a measure of volume, and in no case should these numbers be confused with liquid, because 800 liters is a fairly large number for a liquid. What about gas? Gas is a substance whose molecules are several hundred or thousand times smaller than the distance between them. If you imagine something denser, then the volume will decrease tens and hundreds of times. And now carefully - a liter of gasoline, the combustion of which produces this volume, 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 at the moment of exhaust an unpleasant odor is released, and it seems to us that the composition of the air around us has changed dramatically. But there wasn’t even any residue left on our clothes.
A small educational program for those who like to breathe from the exhaust pipe.
Spent internal combustion engine gases contain about 200 components. The period of their existence lasts from several minutes to 4-5 years. By chemical composition and properties, as well as the nature of the impact on the human body, they are combined into groups.
First group. It contains 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 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 hemoglobin in the blood, leading to the formation of carboxyhemoglobin, which does not bind oxygen. As a result, gas exchange in the body is disrupted, oxygen starvation occurs and the functioning of all body systems occurs. Car drivers are often susceptible to carbon monoxide poisoning Vehicle when spending the night in the cab with the engine running or when warming up the engine 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 the person. Mild poisoning causes pulsation in the head, darkening of the eyes, and increased heart rate. In severe poisoning, consciousness becomes clouded and drowsiness increases. With very large 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 chamber internal combustion engine combustion at a temperature of 2800 °C and a pressure of about 10 kgf/cm2. Nitric oxide is a colorless gas, does not interact with water and is slightly soluble in it, and 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 gas, brown in color with a characteristic odor. It is heavier than air, so it collects in depressions, ditches and poses a great danger when maintenance Vehicle.
Nitrogen oxides are even more harmful to the human body than carbon monoxide. The overall nature of the effect varies depending on the content of various nitrogen oxides. When nitrogen dioxide comes into contact with a moist surface (mucous membranes of the eyes, nose, bronchi), nitric and nitrous acids are formed, which irritate the mucous membranes and damage the alveolar tissue of the lungs. At high concentrations of nitrogen oxides (0.004 - 0.008%), asthmatic manifestations and pulmonary edema occur. When inhaling air containing nitrogen oxides in high concentrations, a person does not have any unpleasant sensations and does not expect negative consequences. With prolonged exposure to nitrogen oxides in concentrations exceeding the norm, people get sick with chronic bronchitis, inflammation of the gastrointestinal mucosa, suffer from heart weakness, as well as nervous disorders.
A secondary reaction to the effects of nitrogen oxides manifests itself in the formation of human body nitrites and their absorption into the blood. This causes the conversion of hemoglobin to metahemoglobin, which leads to cardiac dysfunction.
Nitrogen oxides also have a negative effect on vegetation, forming solutions of nitric and nitrous acids on leaf blades. This same property is responsible for the effect of nitrogen oxides on Construction Materials And metal constructions. In addition, they participate in the photochemical reaction of smog formation.
Fourth group. This group, the most numerous in composition, includes various hydrocarbons, that is, compounds of the C x H y type. Exhaust gases contain hydrocarbons of various homologous series: paraffin (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 there is a delay in ignition working mixture in the engine or at low temperatures in the combustion chamber.
Hydrocarbons are toxic and have adverse effects on the human cardiovascular system. Hydrocarbon compounds in exhaust gases, along with toxic properties, have a carcinogenic effect. Carcinogens are substances contributing to the emergence and development of malignant neoplasms.
The aromatic hydrocarbon benzo-a-pyrene C 20 H 12 contained in the exhaust gases of gasoline engines and diesel engines is particularly carcinogenic. It dissolves well in oils, fats, and human blood serum. Accumulating in the human body to dangerous concentrations, benz-a-pyrene stimulates the formation of malignant tumors.
Under the influence of ultraviolet radiation from the sun, hydrocarbons react with nitrogen oxides, resulting in the formation of new toxic products - photooxidants, which are the basis of smog.
Photooxidants are biologically active and have harmful effects on living organisms, lead to an increase in 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 in the modes idle move and light loads when combustion temperatures in the engine are low.
Formaldehyde HCHO is a colorless gas with unpleasant smell, heavier than air, easily soluble in water. He irritates human mucous membranes, respiratory tract, affects the central nervous system. Causes the smell of exhaust gases, especially in diesel engines.
Acrolein CH 2 =CH-CH=O, or acrylic acid aldehyde, is a colorless poisonous gas with the smell of burnt fats. Affects mucous membranes.
Acetaldehyde 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, carbon deposits, 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 risk to human health, but may irritate the respiratory tract. By creating a plume of smoke behind a vehicle, soot impairs visibility on the roads. The greatest harm of soot is 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 represents sulfur compounds - inorganic gases such as sulfur dioxide, hydrogen sulfide, which appear in engine exhaust gases 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 sulfur and sulfur compounds. Therefore, the diesel fuel obtained from it using outdated technologies has a heavier fractional composition and, at the same time, is less cleared of 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 causes the appearance of harmful sulfur compounds in them.
Sulfur compounds have a pungent odor, are heavier than air, and dissolve in water. They have an irritating effect on the mucous membranes of the throat, nose, and eyes of a person, and can lead to disruption of carbohydrate and protein metabolism and inhibition of oxidative processes, and at high concentrations (over 0.01%) - to poisoning of the body. Sulfur dioxide also has a detrimental effect on the plant world.
Eighth group. Components of this group - lead and its compounds - are found in exhaust gases carburetor cars only when using leaded gasoline containing an additive that increases octane number. It determines the engine's ability to operate without detonation. The higher the octane number, the more resistant the gasoline is to detonation. Detonation combustion the working mixture flows at supersonic speed, which is 100 times faster than normal. Operating an engine with detonation is dangerous because the engine overheats, its power drops, and its service life is sharply reduced. Increasing the octane number of gasoline helps reduce the possibility of detonation.
An anti-knock agent, ethyl liquid R-9, is used as an additive that increases the octane number. Gasoline with the addition of ethyl liquid becomes leaded. The composition of the ethyl liquid includes the antiknock agent itself - tetraethyl lead Pb (C 2 H 5) 4, the carrier - ethyl bromide (BgC 2 H 5) and α-monochloronaphthalene (C 10 H 7 Cl), filler - B-70 gasoline, antioxidant - paraoxydiphenylamine and dye. When leaded gasoline is burned, the remover helps remove lead and its oxides from the combustion chamber, turning them into a vapor state. They, along with exhaust gases, are emitted into the surrounding area and settle near roads.
In roadside areas, approximately 50% of lead emissions in the form of microparticles are immediately distributed on the adjacent surface. The remaining amount remains in the air in the form of aerosols for several hours, and then also settles on the ground near roads. The accumulation of lead in roadside areas leads to pollution of ecosystems and makes nearby soils unsuitable for agricultural use. Adding the R-9 additive to gasoline makes it highly toxic. Different brands gasoline have different percentages of additives. To distinguish between brands of leaded gasoline, they are colored by adding multi-colored dyes to the additive. Unleaded gasoline is supplied without coloring (Table 9).
In developed countries, the use of leaded gasoline is limited or has already been completely phased out. In Russia he still finds wide application. However, the task is to abandon its use. Large industrial centers and resort areas are switching to the use of unleaded gasoline.
Not only the considered components of engine exhaust gases, divided into eight groups, but also hydrocarbon fuels, oils and lubricants themselves have a negative impact on ecosystems. Having a high ability to evaporate, especially when the temperature rises, vapors of fuels and oils spread in the air and negatively affect living organisms.
In places where vehicles are refueled with fuel and oil, accidental spills and intentional discharges of used oil occur directly onto the ground or into water bodies. Vegetation does not grow at the site of the oil stain for a long time. Petroleum products entering water bodies have a detrimental effect on their flora and fauna.
Published with some abbreviations based on the book by Pavlov E.I. Ecology of Transport. The underlining and highlighting are mine.
Traffic fumes(or exhaust gases) - the main source of toxic substances in an internal combustion engine - is a heterogeneous mixture of various gaseous substances with various 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 the engine cylinders into its exhaust system. 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, carcinogenic substances, soot and other components enter the atmosphere with exhaust gases. The approximate composition of exhaust gases is presented in.
When an engine runs on leaded gasoline, lead is present in the exhaust gases, and for engines running on diesel fuel, soot is present.
| Exhaust gas components | Content by volume, % | Note | |
|---|---|---|---|
| Engines | |||
| gasoline | diesels | ||
| Nitrogen | 74,0 - 77,0 | 76,0 - 78,0 | non-toxic |
| Oxygen | 0,3 - 8,0 | 2,0 - 18,0 | non-toxic |
| Water vapor | 3,0 - 5,5 | 0,5 - 4,0 | non-toxic |
| Carbon dioxide | 5,0 - 12,0 | 1,0 - 10,0 | non-toxic |
| Carbon monoxide | 0,1 - 10,0 | 0,01 - 5,0 | toxic |
| Hydrocarbons are non-carcinogenic | 0,2 - 3,0 | 0,009 - 0,5 | toxic |
| Aldehydes | 0 - 0,2 | 0,001 - 0,009 | toxic |
| Sulfur oxide | 0 - 0,002 | 0 - 0,03 | toxic |
| Soot, g/m 3 | 0 - 0,04 | 0,01 - 1,1 | toxic |
| Benzopyrene, mg/m3 | 0,01 - 0,02 | up to 0.01 | carcinogen |
Carbon monoxide (CO – carbon monoxide)
A transparent, odorless, poisonous gas, slightly lighter than air, poorly soluble in water. Carbon monoxide is a product of incomplete combustion of fuel; it burns with a blue flame in air to form carbon dioxide (carbon dioxide).
In the combustion chamber of an engine, CO is formed due to poor fuel atomization, as a result of cold-flame reactions, during 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, during the expansion stroke), combustion of carbon monoxide is possible in the presence of oxygen to form dioxide. In this case, the process of CO burnout continues in the exhaust pipeline.
It should be noted that when operating diesel engines, the CO concentration in the exhaust gases is low (approximately 0.1 - 0.2%), therefore, as a rule, the CO concentration is determined for gasoline engines.
Nitrogen oxides (NO, NO 2, N 2 O, N 2 O 3, N 2 O 5, hereinafter referred to as NO x)
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 engine exhaust gases, more than 90% of the total amount of NO x is nitrogen oxide NO, which is easily oxidized into dioxide (NO 2) in the exhaust system and then in the atmosphere.
Nitrogen oxides irritate the mucous membranes of the eyes and nose, and destroy human lungs, since when moving through the respiratory tract they interact with the moisture of the upper respiratory tract, forming nitric and nitrous acids. As a rule, NO x poisoning of the human body does not appear immediately, but gradually, and there are no neutralizing agents.
Nitrous oxide(N 2 O - hemioxide, laughing gas) - a gas with a pleasant odor, highly soluble in water. Has a narcotic effect.
NO 2 (dioxide)– a pale yellow liquid involved in the formation of smog. Nitrogen dioxide is used as an oxidizer in rocket fuel.
It is believed that nitrogen oxides are approximately 10 times more dangerous than CO for the human body, and 40 times more dangerous if secondary transformations are taken into account.
Nitrogen oxides pose a danger to plant leaves. It has been established that their direct toxic effect on plants manifests itself at a concentration of NO x in the air within the range of 0.5 – 6.0 mg/m 3 . Nitric acid is highly corrosive to carbon steels.
The amount of nitrogen oxide emissions is significantly influenced by the temperature in the combustion chamber. Thus, when the temperature increases from 2500 to 2700 K, the reaction rate increases by 2.6 times, and when it decreases from 2500 to 2300 K, it decreases by 8 times, i.e. the higher the temperature, the higher the NO x 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 (C n H m – 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 a molecule one or several cycles of 6 carbon atoms connected to each other by simple 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, near the walls, in over-enriched zones, the flame is extinguished and chain reactions break (see).
Rice. 1 – Scheme of CH formation in exhaust gases
1 – piston; 2 – sleeve; 3 – wall layers of the mixture
Incompletely burned CH, emitted with exhaust gases and representing a mixture of several hundred chemical compounds, have an unpleasant odor. CH are the cause of many chronic diseases.
Gasoline vapors, which are hydrocarbons, are also toxic. The permissible average daily concentration of gasoline vapor is 1.5 mg/m3. The CH content in the exhaust gases increases during throttling, when the engine is operating in forced idling modes (ISR, for example, during engine braking.). When the engine operates in the indicated modes, the process of mixture formation (mixing of the fuel-air charge) worsens, the combustion rate decreases, ignition deteriorates and, as a result, 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 atomization of fuel, with unsatisfactory swirl of the air charge and low temperatures(for example, idle mode).
Hydrocarbons are formed in over-enriched zones where oxygen access is limited, as well as near the relatively cold walls of the combustion chamber. They play an active role in education biologically active substances, causing irritation of the eyes, throat, nose and their diseases, and causing damage to flora and fauna.
Hydrocarbon compounds have narcotic effect on the central nervous system, can cause chronic diseases, and some aromatic CH have poisonous properties.
Hydrocarbons (olefins) and nitrogen oxides, under certain meteorological conditions, actively contribute to the formation.
Smog
Smog(Smog, from smoke - smoke and fog - fog) - toxic fog formed in the lower layer of the atmosphere, polluted harmful substances from industrial enterprises, exhaust gases from vehicles and heat-producing installations under unfavorable conditions weather conditions.
It is an aerosol consisting of smoke, fog, dust, soot particles, and 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. In the atmosphere, reactions of photosynthesis, oxidation, reduction, polymerization, condensation, catalysis, etc. occur.
As a result of complex photochemical processes stimulated by ultraviolet radiation from the Sun, photooxidants (oxidizing agents) are formed from aldehydes and other substances.
Low concentrations of NO 2 can create large amounts of atomic oxygen, which in turn forms ozone and again reacts with air pollutants. The presence of formaldehyde, higher aldehydes and others in the atmosphere hydrocarbon compounds Together with ozone, it also promotes the formation of new peroxide compounds.
Dissociation products interact with olefins, forming toxic nitroperoxide compounds. When their concentration is more than 0.2 mg/m 3, condensation of water vapor occurs in the form of tiny droplets of fog 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 NO 2 present in the air - droplets of yellow liquid).
Smog causes irritation of mucous membranes, especially the eyes, and can cause headache, swelling, hemorrhage, complications of respiratory tract diseases. Reduces visibility on the roads, thereby increasing the number of traffic accidents.
The danger of smog to human life is great. For example, the London smog of 1952 is called a disaster, since about 4 thousand people died from the 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, as well as buildings, especially historical monuments made of limestone.
The nature of smog is different. For example, in New York, the formation of smog is facilitated by the reaction of fluoride and chloride compounds with water droplets; in London - the presence of vapors of sulfuric and sulfurous acids; in Los Angeles (California or photochemical smog) - the presence of nitrogen oxides and hydrocarbons in the atmosphere; in Japan - the presence of soot and dust particles in the atmosphere.
Large, industrialized cities, megalopolises with industrial areas, with forests of factory chimneys, endless power lines and hours-long traffic jams have become for millions of people natural environment habitats and of course the air in such places on our planet is very polluted. All the brainchildren of scientific and technological progress daily emit into the atmosphere around the world numerous tons of toxic gases, vapors, combustion products of chemicals collected from throughout the periodic table.
Are a by-product of the work various engines vehicles using hydrocarbon fuel. Their education is one of the most important problems of the ecological state of cities.
Composition and environmental impact
Together with exhaust gases, a huge amount of toxins and carcinogens enter the atmosphere. According to environmentalists, almost 90% of air pollution in cities occurs due to the emission of vehicle exhaust.
Compound exhaust gases (%)
* - Toxins
** - Carcinogens
Depending on the type of gasoline, the composition of the exhaust gases differs; it is known that sulfur-containing gasoline can emit sulfur oxide, and leaded gasoline can emit lead, chlorine, bromine and other compounds based on these substances.
: influence on the body
When they enter the human body, the respiratory system is most affected, which can subsequently cause a number of dangerous, both acute and chronic diseases. Doctors also associate an increase in congenital chronic diseases in children, such as allergies, bronchitis, sinusitis, etc., with increasingly deteriorating environmental conditions and air pollution in cities.
Nitrogen oxides have a detrimental effect on the respiratory system, irritating the respiratory tract, promoting the appearance of tumors and inflammatory processes.
Carbon oxides can cause oxygen deficiency in tissues and reduce the effect of hemoglobin in the blood. They have a destructive effect on the nervous and cardiovascular systems. Frequent ailments, headaches, shortness of breath, dizziness, lethargy, irritability, sleep disturbances and many other disorders of the body are in one way or another related to the environmental condition environment.
Exhaust gases contain many heavy metals, which tend to settle in the body, accumulating gradually. The danger is that slagging of the body occurs unnoticed by a person, and in the future, quite unexpectedly, it can result in a serious illness, in particular, a sharp increase in the incidence of cancerous tumors of the respiratory system in people is recorded in large cities, doctors attribute this to the constant absorption of our lungs toxic substances from the atmosphere.
A high concentration of exhaust gases in the air of an enclosed space can be fatal to humans. There have been many cases of poisoning and suffocation from exhaust gases in garages, where their accumulation far exceeded the permissible limit.
Since childhood, a modern city dweller has become so accustomed to the smell of exhaust gases that he no longer notices it at all, while continuing to breathe toxic fumes.
Exhaust gases are the working fluid spent in the engine. On average, one resident produces more than 100 kilograms of pollutants annually. This air is with us everywhere - on the street, at home and especially in the car.
Car exhaust gases contain:
Products of incomplete combustion of liquid fuels (CO, soot, hydrocarbons, etc.);
Products of air nitrogen oxidation - various nitrogen oxides;
Polycyclic aromatic hydrocarbons (including benzo(a)pyrene).
According to Spanish scientists, 225 thousand people in Europe die from diseases caused by exhaust fumes. In Russia, similar statistics are not kept, but here the situation is at least 2 times worse than in Europe and especially “gets” Muscovites. A group of scientists from the University of Ontario has concluded that car exhaust fumes are responsible for the death of one in six infants from a disease called sudden infant death syndrome. An outwardly completely healthy baby, most often at the age of two to four months, suddenly quietly passes into another world in a dream. After analyzing infant mortality in the United States from 1995 to 1997. and comparing the data with the level of air pollution, they revealed a direct connection between these phenomena.
In Europe there are already harmless hydrogen engines, the exhausts of which are water vapor. But they are not yet widely used.
If every motorist followed simple rules, the city’s ecology would noticeably improve: we need to switch to gas engines; effective way To reduce toxic substances is the injection of water into the combustion chamber.
In order to significantly reduce pollution of air, soil and surface water bodies, the Ecopromika company has developed and produces a set of gas purification equipment based on plasma technology of gas-discharge catalytic air purification - the Yatagan Gas Converter. Today, this gas purification equipment has best performance for cleaning exhaust gases in terms of price-quality and efficiency-size ratio, has practically no replaceable parts, does not require waste disposal and has the most low cost operation.
Bibliographic link
Zaitseva O.Yu. HARM OF VEHICLE EXHAUST GASES // Advances modern natural science. – 2010. – No. 8. – P. 45-45;URL: http://natural-sciences.ru/ru/article/view?id=8548 (date of access: 07/08/2019). We bring to your attention magazines published by the publishing house "Academy of Natural Sciences"
