The main sources of vehicle emissions are the engine internal combustion, evaporation of fuel through the ventilation system fuel tank, and chassis: as a result of tire friction on pavement, wear brake pads and corrosion of metal parts, regardless of engine emissions, fine dust particles are formed. Catalyst erosion releases platinum, palladium and rhodium, while clutch lining wear also releases toxic substances such as lead, copper and antimony. Limit values ​​should also be set for these secondary vehicle emissions.

Harmful substances

Rice. Compound exhaust gases

The composition of the exhaust (exhaust) gases of a car includes many substances or groups of substances. The predominant part of the exhaust gas components are non-toxic gases contained in normal air. As shown in the figure, only a small part of the exhaust gas is harmful to environment and people's health. Despite this, a further reduction in the concentration of toxic components of the exhaust gas is necessary. Although modern cars today they give very clean exhaust (for Euro-5 cars it is in some aspects even cleaner than intake air), a huge number of used cars, of which there are about 56 million units in Germany alone, emit a significant amount of toxic and harmful substances. New technologies and the introduction of more stringent requirements for the environmental friendliness of exhaust gas are called upon to correct the situation.

Carbon monoxide (CO)

carbon monoxide(carbon monoxide) CO is a colorless and odorless gas. It is a poison for the respiratory system, disrupting the function of the central nervous and cardiovascular systems. In the human body, it binds red blood cells and causes oxygen starvation, which in a short time leads to death by suffocation. Already at a concentration in the air of 0.3% by volume, carbon monoxide kills a person in a very short time. The action depends on the concentration of CO in the air, on the duration and depth of inhalation. Only in an environment with a zero concentration of CO can it be excreted from the body through the lungs.

Carbon monoxide always occurs when there is a lack of oxygen and incomplete combustion.

Hydrocarbons (CH)

Hydrocarbons are emitted into the atmosphere in the form of unburned fuel. They have an irritating effect on the mucous membranes and respiratory organs of a person. Further optimization of the engine's workflow is only possible through improved production technologies and improved knowledge of combustion processes.

Hydrocarbon compounds occur as paraffins, olefins, aromas, aldehydes (especially formaldehydes) and polycyclic compounds. Experimentally proved carcinogenic and mutagenic properties of more than 20 polycyclic aromatic hydrocarbons, which, due to their small size, are able to penetrate to the pulmonary vesicles. The most dangerous hydrocarbon compounds are benzene (C6H6), toluene (methylbenzene) and xylene (dimethylbenzene, general formulaС6Н4 (CH3)2). For example, benzene can cause changes in the blood picture in a person and lead to the occurrence of blood cancer (leukemia).

The reason for the release of hydrocarbons into the atmosphere is always incomplete combustion of the fuel, lack of oxygen, and in the case of a very lean mixture, too slow combustion of the fuel.

Nitrogen oxides (NOx)

At a high combustion temperature (more than 1100°C), the reaction-inert nitrogen contained in the air is activated and reacts with free oxygen in the combustion chamber, forming oxides. They are very harmful to the environment: they cause smog, forest death, acid rain; nitrogen oxides are also transitional substances for the formation of ozone. They are poison to the blood, cause cancer. In the combustion process, various nitrogen oxides - NO, NO2, N2O, N2O5 - are formed, which have the general designation NOx. When combined with water, nitric (HNO3) and nitrous (HNO2) acids are formed. Nitrogen dioxide (NO2) - red-brown poisonous gas with a pungent odor, irritating to the respiratory system and forming compounds with hemoglobin in the blood.

This is the most problematic of all nitrogen oxides, and in the future separate standards for permissible concentrations will apply for it. The share of NO2 in total nitrogen oxide emissions in the future should be less than 20%. Since 2010, directive 1999/30/EC has set a limit value of 40 µg/m for N02. Compliance with this limit places special demands on protection against harmful emissions.

The most favorable conditions for the formation of nitrogen oxides are the high combustion temperature of lean air-fuel mixture. Exhaust gas recirculation systems reduce the proportion of nitrogen oxides in vehicle exhaust.

Sulfur oxides (SOx)

Sulfur oxides are formed from the sulfur contained in the fuel. During combustion, sulfur reacts with oxygen and water to form sulfur oxides, sulfuric (H2SO4) and sulfurous (H2SO3) acids. Sulfur oxide is the main constituent of acid rain and the cause of forest death. It is a water-soluble caustic gas, the effect of which on the human body is manifested by redness, swelling and increased secretion of moist mucous membranes of the eyes and upper respiratory tract. Sulfur dioxide affects the mucous membranes of the nasopharynx, bronchi and eyes. The most common site of "attack" sulfur dioxide are the bronchi. The strong irritant effect on the respiratory tract is due to the formation of sulfurous acid in a humid environment. Sulfur dioxide SO2 suspended in fine dust and sulfuric acid aerosol get deep into the respiratory tract. Asthmatics and young children are most sensitive to the growing concentration of sulfur dioxide in the air. High content sulfur in fuel shortens the life of catalysts in gasoline engines.

The reduction of sulfur dioxide emissions is realized by limiting the sulfur content in the fuel. The goal is a sulfur-free fuel.

Hydrogen sulfide (H2S)

The consequences of the impact of this gas on organic life are not yet entirely clear to science, but it is known that in humans it can cause severe poisoning. In severe cases, there is a threat of suffocation, loss of consciousness and paralysis of the central nervous system. In chronic poisoning, irritation of the mucous membranes of the eyes and respiratory tract is noted. The smell of hydrogen sulfide is already felt at its concentration in the air in the amount of 0.025 ml/m3.

Hydrogen sulfide in exhaust gases occurs under certain conditions, and, despite the presence of a catalyst, and depends on the sulfur content in the fuel.

Ammonia (NH3)

Inhalation of ammonia results in respiratory irritation, coughing, shortness of breath and choking. Ammonia also causes inflamed redness on the skin. Direct ammonia poisoning is rare, as even large amounts of it are rapidly converted to urea. When large amounts of ammonia are directly inhaled, lung function is often impaired for many years. This gas is especially dangerous for the eyes. With a strong effect of ammonia on the eyes, clouding of the cornea and blindness can occur.

Under certain conditions, ammonia can even form in the catalyst. At the same time, ammonia is useful as a reducing agent for SCR catalysts.

Soot and particles

Soot is pure carbon and an undesirable product of the incomplete combustion of hydrocarbons. The reason for the formation of soot is the lack of oxygen during combustion or premature cooling of the combustion gases. Soot particles often bind to unburned fuel residues and engine oil, as well as water, wear products of engine parts, sulfates and ash. Particles vary greatly in shape and size.

Table. Particle classification

The table shows the classification and particle sizes. Most often, when the engine is running, particles with a diameter of about 100 nanometers (0.0000001 m or 0.1 microns) are formed; such particles can naturally enter the lungs of a person. During agglutination (gluing) of soot particles with each other and other components, the mass, number and distribution of particles in the air can change significantly. The main components of the particles are shown in the figure.

Rice. Main components of particles

Due to its spongy structure, soot particles can capture both organic and inorganic substances formed during the combustion of fuel in engine cylinders. As a result, the mass of soot particles can increase three times. These will no longer be individual particles of carbon, but correct form agglomerates resulting from molecular attraction. The size of such agglomerates can reach 1 µm. Emissions of soot and other particles are especially active during the combustion of diesel fuel. These emissions are considered carcinogenic. Hazardous nanoparticles represent a quantitatively large proportion of particles, but only a small percentage by weight. For this reason, it is proposed to limit the content of particles in the exhaust gas not by mass, but by quantity and distribution. In the future, differentiation between particle size and particle distribution is envisaged.

Rice. Particle Composition

Emissions of particles during operation gasoline engines two to three orders of magnitude lower than when diesel engines are running. However, these particles are found even in the exhaust of gasoline engines with direct injection fuel. Therefore, there are proposals to limit the maximum content of particles in the exhaust gases of vehicles. Sublimation is the direct transition of a substance from a solid to a gaseous state, and vice versa. A sublimate is a solid precipitate of a gas when it is cooled.

fine dust

During the operation of internal combustion engines, especially fine particles are also formed - dust. It consists mainly of particles of polycyclic hydrocarbons, heavy metals and sulfur compounds. Part of the dust fractions is able to penetrate into the lungs, other fractions do not penetrate into the lungs. Fractions larger than 7 microns are less dangerous, as they are filtered out by the human body's own filtration system.

A different percentage of smaller fractions (less than 7 microns) penetrate the bronchi and pulmonary vesicles (alveoli), causing local irritation. In the region of the pulmonary vesicles, soluble components enter the bloodstream. The body's own filtration system does not cope with all fractions of fine dust. Atmospheric dust pollution is also called aerosols. They can be in a solid or liquid state and, depending on the size, can have a different period of existence. When moving, the smallest particles can combine into larger ones with a relatively stable period of existence in the atmosphere. These properties are mainly possessed by particles with a diameter of 0.1 µm to 1 µm.

When evaluating the formation of fine dust as a result of the operation of an automobile engine, this dust should be distinguished from naturally occurring dust: plant pollen, road dust, sand and many other substances. The sources of fine dust in cities, such as wear on brake pads and tires, should not be underestimated. So diesel exhaust is not the only "source" of dust in the atmosphere.

Blue and white smoke

blue smoke occurs during work diesel engine at temperatures below 180°C due to the smallest condensing oil droplets. At temperatures above 180°C, these droplets evaporate. Unburned hydrocarbon fuel components are involved in the formation blue smoke and at temperatures from 70°C to 100°C. A large number of blue smoke indicates a large wear of the cylinder-piston group, rods and valve guides. Too late start of fuel supply can also cause blue smoke.

White smoke consists of water vapor generated during combustion of fuel and becomes noticeable at temperatures below 70°C. Particularly characteristic is the appearance white smoke for pre-chamber and vortex-chamber diesel engines after a cold start. White smoke is also caused by unburned hydrocarbon components and condensates.

Carbon dioxide (CO2)

Carbon dioxide It is a colorless, non-flammable, sour-tasting gas. It is sometimes erroneously called carbonic acid. The density of CO2 is about 1.5 times higher than the density of air. Carbon dioxide is integral part of air exhaled by a person (3-4%) When inhaling air containing 4-6% CO2, a person has headaches, tinnitus and heart palpitations, and at higher concentrations of CO2 (8-10%), asthma attacks occur, loss consciousness and respiratory arrest. At a concentration of more than 12%, death from oxygen starvation occurs. For example, a burning candle goes out at a CO2 concentration of 8-10% by volume. Although carbon dioxide is an asphyxiant, it is not considered poisonous as a component of engine exhaust. The problem is that carbon dioxide, as shown in the figure, contributes significantly to the global greenhouse effect.

Rice. Share of gases in the greenhouse effect

Together with it, methane, nitrous oxide (laughing gas, dinitrogen oxide), fluorocarbons and sulfur hexafluoride contribute to the development of the greenhouse effect. Carbon dioxide, water vapor and microgases affect the radiation balance of the Earth. Gases transmit visible light but absorb heat reflected from the earth's surface. Without this heat-holding capacity, the average temperature on the Earth's surface would be around -15°C.

This is called the natural greenhouse effect. With an increase in the concentration of microgases in the atmosphere, the proportion of absorbed thermal radiation increases and an additional greenhouse effect occurs. According to experts, by 2050 the average temperature on Earth will increase by +4°C. This can lead to a rise in sea level of more than 30 cm, as a result of which mountain glaciers and polar ice caps will begin to melt, the direction of sea currents (including the Gulf Stream) will change, air currents, and the seas will flood vast expanses of land. This is what greenhouse gases produced by human activities can lead to.

The total anthropogenic CO2 emissions are 27.5 billion tons per year. At the same time, Germany is one of the largest sources of CO2 in the world. Energy-related CO2 emissions average about a billion tons per year. This is about 5% of all CO2 produced in the world. The average family of 3 in Germany produces 32.1 tons of CO2 per year. CO2 emissions can only be reduced by reducing energy and fuel consumption. As long as energy is produced by burning fossil fuels, the problem of creating excessive amounts of carbon dioxide will persist. Therefore, there is an urgent need to search alternative sources energy. The automotive industry is working intensively to solve this problem. However, the greenhouse effect can only be combated on a global scale. Even if great progress is made within the EU in reducing carbon dioxide emissions, other countries may, on the contrary, see a significant increase in emissions in the coming years. The US leads by a wide margin in manufacturing greenhouse gases both in absolute terms and on a per capita basis. With a share of only 4.6% of the world's population, they produce 24% of the world's carbon dioxide emissions. This is about twice as much as in China, whose share in the world's population is 20.6%. The 130 million cars in the US (less than 20% of the total number of cars on the planet) produce as much carbon dioxide as the entire industry in Japan, the world's fourth-largest CO2 emitter.

Without additional measures climate protection, global CO2 emissions will increase by 39% by 2020 (relative to 2004) and amount to 32.4 billion tons per year. In the next 15 years, carbon dioxide emissions in the United States will increase by 13% and exceed 6 billion tons. In China, we should expect an increase in CO2 emissions by 58%, to 5.99 billion tons, and in India - by 107%, to 2.29 billion tons. m. In the EU, on the contrary, the increase will be only about one percent.

Have you ever wondered how much one car absorbs oxygen and releases carbon dioxide CO2 per year?
And how many trees does it take to convert this amount of CO2 back into oxygen? Let's calculate as a "mathematical" interest...

What do we know about CO2?

Plants release oxygen and absorb carbon dioxide.

Humans and animals breathe oxygen and exhale carbon dioxide. This maintains a constant amount of oxygen and carbon dioxide in the air.

However, it would be a mistake to say that animals only emit carbon dioxide, and plants only absorb it. Plants absorb carbon dioxide in the process photosynthesis, and without lighting, they also highlight it.

The air always contains a small amount of carbon dioxide, about 1 liter in 2560 liters of air. Those. The concentration of carbon dioxide in the Earth's atmosphere is on average 0.038%.

When the concentration of CO2 in the air is more than 1%, its inhalation causes symptoms that indicate poisoning of the body - "Hypercapnia": headache, nausea, frequent shallow breathing, increased sweating and even loss of consciousness.

As you can see in the diagram above, the concentration of carbon dioxide on Earth is growing (I draw your attention to the fact that these measurements are not in the city, but on Mount Mauna Loa in Hawaii) - the proportion of carbon dioxide in the atmosphere from 1960 to 2010 increased from 0.0315% to 0 .0385%. Those. steadily growing at +0.007% over 50 years. In the city, the concentration of carbon dioxide is even higher.

The concentration of carbon dioxide in the atmosphere:

• in the pre-industrial era - 1750:
  280 ppm (parts per million) total mass - 2200 trillion kg
• currently - 2008:
  385 ppm, total mass - 3000 trillion kg

Activities accompanied by CO2 emissions(some everyday examples) :

• Driving (20 km) - 5 kg CO2
• Watching TV for an hour - 0.1 kg CO2
• Microwave cooking (5 min) - 0.043 kg CO2

Photosynthesis is the only source of atmospheric oxygen.

In general, the chemical balance of photosynthesis can be represented as a simple equation:

6CO 2 + 6H 2 O \u003d C 6 H 12 O 6 + 6O 2

The English chemist and philosopher Joseph Priestley was the first to discover that plants give off oxygen around 1770. It was soon established that this requires light and that only the green parts of plants give off oxygen. The researchers then found that plant nutrition requires carbon dioxide (carbon dioxide CO2) and water, from which most of the mass of plants is created. In 1817 French chemists Pierre Joseph Pelatier (1788–1842) and Joseph Bieneme Cavantoux (1795–1877) isolated the green pigment chlorophyll.

By the middle of the 19th century. it was found that photosynthesis is a process, as it were, the reverse of respiratory. Photosynthesis is based on the conversion of the electromagnetic energy of light into chemical energy.

Photosynthesis, which is one of the most common processes on Earth, determines the natural cycles of carbon, oxygen and other elements and provides the material and energy basis for life on our planet.

Ecological arithmetic

In one year, an ordinary tree releases the amount of oxygen needed for a family of 3. And the car absorbs the same amount of oxygen when burning 1 tank of gasoline 50 liters.

• 1 tree absorbs on average within 1 year 120 kg CO2, and releases about the same amount of oxygen
• 1 car absorbs the same amount of oxygen (120 kg) by burning about 50 liters of gasoline, and produces various exhaust gases (their composition is indicated in the table)

Composition of exhaust gases:	Gasoline engines	Diesels	Euro 3	Euro 4
N 2 vol.%	74-77	76-78
O 2 vol.%	0,3-8,0	2,0-18,0
H 2 O (pairs), vol.%	3,0-5,5	0,5-4,0
CO 2 vol.%	0,0-16,0	1,0-10,0
CO* (carbon monoxide), vol.%	0,1-5,0	0,01-0,5	up to 2.3	up to 1.0
NOx, Nitrogen oxides*, vol.%	0,0-0,8	0,0002-0,5	up to 0.15	up to 0.08
СH, Hydrocarbons*, vol.%	0,2-3,0	0,09-0,5	up to 0.2	up to 0.1
Aldehydes*, vol.%	0,0-0,2	0,001-0,009
Soot**, g/m3	0,0-0,04	0,01-1,10
Benzpyrene-3.4**, g/m3	10-20×10 −6	10×10 −6

* Toxic components ** Carcinogens

• per year refuel 1 car 1500 liters of gasoline(with a run of 15,000 km and a consumption of 10l / 100km). This means that it is necessary 1500 l/50 l in tank = 30 trees, which will produce the absorbed amount of oxygen.
• 1 car center in Moscow sells order 2000 vehicles per year(size of one car park). Those. 30 trees multiplied by 2000 cars per year = 60,000 trees for 1 car center.
• Let's start small: 2000 trees (1 tree for 1 car) - is it a lot or a little? No more than 400 trees can be planted on one football field (20 x 20 trees every 5 meters is the recommended distance). It turns out that 2000 trees will occupy the territory - 5 football fields!
• How much do you think it costs to plant 1 tree? - you can unsubscribe in the comments.

The most active suppliers of oxygen are poplars. 1 hectare of such trees emits 40 times more oxygen into the atmosphere than 1 hectare of spruce stands.

Ways to reduce emissions and toxicity

• A huge impact on the amount of emissions (not counting the burning of fuel and time) plays movement organization cars in the city (a significant part of emissions occurs in traffic jams and at traffic lights). With a successful organization, it is possible to use less powerful engines, at low (economical) intermediate speeds.
• It is possible to significantly reduce the content of hydrocarbons in the exhaust gases, more than 2 times, using as a fuel associated oil (propane, butane), or natural g basics, despite the fact that main disadvantage natural gas- low power reserve, not so significant for the city.
• In addition to the composition of the fuel, toxicity is affected by engine condition and tuning(especially diesel - soot emissions can increase up to 20 times and carburetor - up to 1.5-2 times nitrogen oxide emissions change).
• Significantly reduced emissions (reduced fuel consumption) in modern structures engines powered by injection with a stable stoichiometric mixture of unleaded gasoline with the installation of a catalyst, gas engines, units with superchargers and air coolers, using a hybrid drive. However, such designs greatly increase the cost of cars.
• SAE testing has shown that effective method reduction of emissions of nitrogen oxides (up to 90%) and toxic gases in general - water injection into the combustion chamber.
• There are standards for produced cars. In Russia European countries EURO standards have been adopted, specifying both toxicity and quantitative indicators (see table above)
• Some regions introduce traffic restrictions heavy vehicles (for example, in Moscow).
• Signing of the Kyoto Protocol
• Various environmental actions, for example: Plant a tree - give the Earth oxygen!

What you need to know about the Kyoto Protocol?

Kyoto Protocol- an international document adopted in Kyoto (Japan) in December 1997 in addition to the UN Framework Convention on Climate Change (FCCC). It obliges developed countries and countries with economies in transition to reduce or stabilize greenhouse gas emissions in 2008-2012 compared to 1990.

As of March 26, 2009, the Protocol was ratified by 181 countries(These countries together account for more than 61% of global emissions). The United States is a notable exception to this list. The first implementation period of the protocol began on January 1, 2008 and will last five years. until December 31, 2012, after which, as expected, it will be replaced by a new agreement.

The Kyoto Protocol was the first global environmental agreement based on a market-based regulatory mechanism - the mechanism for international trading in greenhouse gas emissions.

Trees are artificial, oxygen is real

Scientists at Columbia University in New York have teamed up with French design studio Influx Studio to develop artificial trees. By and large, this is a machine stylized as a dracaena, with wide branches and an umbrella-shaped crown. The branches are used to support the solar panels that power the trees.

Artificial trees will look like huge lanterns that shimmer in the dark with different colors. Mechanical dracaena will not only bring practical benefits, but will also become an adornment of the modern metropolis.

In addition to converting carbon dioxide into oxygen, artificial trees can serve as an additional source of energy. In addition to solar panels, it will be generated by converting mechanical energy from a swing set at the base.

Outwardly, such artificial trees resemble dracaena, and they consist of recycled wood and plastic. In the bark of such a "tree" are solar panels and filters to absorb carbon dioxide. In the "trunks" of artificial trees there is water and tree resin - with their participation, the process of photosynthesis will take place. To support the health of such trees, special swings will be used: the townspeople having fun will become electricity generators.

I bought a car - plant 12 hectares of forest

In everyday life, we often encounter problems of lack of water or food. They cause us some inconvenience. There are, however, things, the deficit of which is accumulating imperceptibly, but in the near future risks becoming a serious problem for the life of mankind.

They accompany us almost everywhere - they fly into our kitchen through the window, they pursue us in the car, on pedestrian crossing, V public transport… Traffic fumes cars - are they really as dangerous to humans as the media portrays?

From general to specific - air pollution from exhaust gases

Periodically in major cities Because of the looming smog, you can't even see the sky. The authorities of Paris, for example, on such days are trying to limit the exit of cars - today the owners of cars with even numbers are driving, and tomorrow with odd ones ... But as soon as a fresh wind blows and spreads the accumulated gases, everyone is released onto the road again until a new wave of smog covers the city so that tourists do not see the Eiffel Tower. In many large cities, it is cars that are the main air pollutants, although globally they are inferior to industry leadership. Only the sphere of energy production from petroleum products and organics emits twice as much carbon dioxide into the atmosphere as all cars combined.

Plus, according to environmentalists, humanity cuts down as much forest every year as would be enough to process all the CO 2 that enters the atmosphere from exhaust pipe.

That is, whatever one may say, but the pollution of the atmosphere by car exhaust gases is, on a global scale, only one of the links in the consumption system that is detrimental to our planet. However, let's try to move from the general to the particular - which is closer to us, some kind of factory on the edge of geography, or a car? " iron Horse”- by and large, our personal exhaust “charm” generator, which here and now continues to do this. And it harms, first of all, to ourselves. Many drivers complain of drowsiness and are looking for a way, not even suspecting that the lack of strength and vigor is due to the inhalation of exhaust!

Exhaust fumes - is it that bad?

In total, exhaust gases contain more than 200 different chemical formulas. These are nitrogen, oxygen, water and the same carbon dioxide that are harmless to the body, and toxic carcinogens that increase the risk of serious illnesses up to the formation of malignant tumors. However, this is in the future, the very same dangerous substance one that has the potential to affect our health here and now is carbon monoxide CO, a product of the incomplete combustion of fuels. We cannot feel this gas with our receptors, and it inaudibly and invisibly creates a small Auschwitz for our body - the poison limits the access of oxygen to the cells of the body, which in turn can cause both an ordinary headache and more serious symptoms of poisoning, up to loss of consciousness and lethal outcome.

The most terrible thing is that it is the children who are most poisoned - just at the level of their inhalation, the greatest amount of poison is concentrated. The ongoing experiments, which took into account all sorts of factors, revealed a pattern - children who are regularly exposed to carbon monoxide and other "exhaust" products simply become dumb, not to mention weakened immunity and "minor" diseases like frequent colds. And this is just the tip of the iceberg - is it worth describing the effects of formaldehyde, benzopyrene and 190 other different compounds on our body?? The pragmatic Britons have calculated that exhaust fumes kill every year. more people than die in car accidents!

Car exhaust fumes - how to deal with them?

And again, let's move from the general to the particular - you can accuse world governments of inactivity as much as you like, scold industrial magnates whenever you or members of your family are sick, but you and only you can do something, even if not for complete failure from the car, but at least to reduce emissions. Of course, we are all limited by the capabilities of our wallet, but of the actions listed in this article, for sure, there will be at least one that suits you. Just let's agree - you will start performing right now, without postponing for a ghostly tomorrow.

It is quite possible that you can afford to switch to gas engines - do it! If this is not possible, adjust the engine, spend. If everything is in order with the engine, try to choose the most rational mode of its operation. Ready? Go further - use exhaust gas neutralizers! Wallet won't allow? So save money on gasoline - walk more often, ride a bike to the store.

The cost of fuel is so high that in just a few weeks of such savings, you can afford the best catalytic converter! Optimize trips - try to do as many things as possible in one run, combine trips with your neighbors or colleagues. Acting in this way, fulfilling at least one of the above conditions, you can personally be satisfied with yourself - air pollution by exhaust gases has decreased thanks to you! And do not think that this is not a result - your actions are like small pebbles that entail an avalanche.

Traffic fumes

Permitted level in the European Union 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 per Idling is: 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 limits of harmful emissions 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 little problem. 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 - is heterogeneous mixture various gaseous substances with a variety of chemicals 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. Approximate composition exhaust gases is presented in table 1. When the engine is running 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)

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 during 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 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 (NO 2) 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. 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.

NO 2 (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, they are 40 times more dangerous.

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 pressures 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 - 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 level hydrocarbon is a problem not only for owners of cars, 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.