The harm of air pollution to human health includes acute and chronic. People exposed to air with high concentrations of pollutants for a period of time will immediately cause poisoning or other symptoms, which is acute harm. Chronic hazard refers to the serious air pollution caused by mountain fires, and refers to people's long-term exposure to air with low pollutant concentration. The cumulative effect of pollution hazards makes people sick. (2) Impact on Ecological Environment Air pollution has a great impact on crops and forests, and it has serious harm to both aquatic products and land animals. For example, air pollution (mainly acid rain and fluorine pollution), 1993, the national agricultural grain production reduction area was as high as 5.3 million hectares. (3) Damage to materials. The damage of air pollution to materials is mainly manifested in the corrosion of buildings and fluid transportation pipelines exposed to air. For example, metal buildings in factories are corroded into rust. Corrosion on the surface of buildings and water pipes, etc. (4) Impact on the global atmospheric environment The impact of air pollution on the global atmospheric environment has been clearly manifested in three aspects: ozone layer consumption, acid rain and global warming. If these problems are not controlled in time, it will cause disastrous harm to the whole earth. (5) Indoor Pollution More and more scientific research shows that the air pollution in indoor and other buildings is more serious than that in outdoor. Even in some highly industrialized countries, some indoor air pollutants and pollution sources are considered to have very adverse effects on human health, including asbestos, formaldehyde, volatile pesticide residues, chloroform, p-dichlorobenzene and some pathogenic organisms.
The harm of air pollution
The harm of air pollution
Air pollution has a great influence on the climate. The pollutants discharged by air pollution will have a certain impact on the local and global climate, especially on the global climate. In the long run, this effect will be very serious.
One: the content of carbon dioxide in the atmosphere increases;
Fuel contains all kinds of complex components, which will produce all kinds of harmful substances after combustion. Even if the fuel without impurities is completely burned, water and carbon dioxide will be produced. It is precisely because of fuel combustion that the concentration of carbon dioxide in the atmosphere is increasing, which destroys the balance of carbon dioxide in nature and may even trigger a "greenhouse effect", leading to an increase in the temperature of the earth.
Two: ozone layer destruction
After air pollution, due to the different sources, nature and duration of pollutants, the differences in meteorological conditions, geographical environment and other factors in polluted areas, as well as the differences in people's age and health status, the harm to human body is not the same. Harmful substances in the atmosphere invade the human body mainly through the following three ways:
(1) enters the human body through direct breathing;
(2) adhering to food or dissolving in water, so that it can invade the human body with diet;
(3) Entering the human body through contact or skin. Among them, invading the human body through breathing is the main way and the most harmful.
The harm of air pollution to people can be roughly divided into three types: acute poisoning, chronic poisoning and carcinogenesis.
The harm of air pollution
Air pollution is a new branch of atmospheric science. It is a science that studies the transport, diffusion, dilution, transformation and removal of pollutants entering the atmosphere under different meteorological conditions and its application.
This discipline sprouted in the 1920s, and the British conducted an atmospheric diffusion experiment at 192 1. However, it was not until the 1950s that the development of modern industry and the high concentration of urban population led to serious pollution incidents in cities or industrial areas. Take 1952 12 as an example, which claimed more than 4,000 lives. The research contents of air pollution meteorology mainly include: ① the types and characteristics of pollution sources and pollutants.
(2) The process and law of pollutant transport and turbulent diffusion in the atmosphere. (3) Observation and calculation method of pollutant concentration.
④ Prevention and control methods of air pollution. ⑤ The harm of air pollution and its influence on human living environment.
Meteorology of air pollution is of great significance to environmental protection, urban planning and energy, chemical industry, metallurgy, health, national defense and other departments. The research methods of air pollution meteorology include field measurement, laboratory (such as wind tunnel test) and numerical simulation.
1) air pollution due to human activities or natural processes, some harmful substances (called pollutants) are discharged into the atmosphere. When the emission is large enough (the concentration of pollutants reaches a certain limit), the original clean air quality will decline. If this situation is maintained for a long time, it will cause harm and adverse effects to human beings, animals, plants and articles in the atmosphere. This atmospheric state is called air pollution. There are three factors that constitute air pollution: pollution source, pollutant concentration and harm to people and organisms.
A clean atmosphere is one of the necessary conditions for human survival. A person can live for five weeks without eating or drinking, but he will die if he doesn't breathe air for more than five minutes. The human body needs to inhale 10- 12 cubic meters of air every day. This shows how important it is to eliminate air pollution or keep the pollution concentration below a certain limit.
The atmosphere has a certain self-purification ability. Before the development of modern large-scale industry, the amount of pollutants discharged into the atmosphere due to natural processes was basically balanced with the amount removed from the atmosphere through self-purification processes. However, after the 1950s and 1960s, with the rapid development of modern large-scale industry, the amount of pollutants discharged into the atmosphere by human beings greatly exceeded the self-purification ability of the atmosphere, resulting in the whole atmosphere being polluted to varying degrees.
This has attracted the attention of all countries, and China has adopted environmental protection (atmospheric environment, water environment, etc.). ) as its basic national policy. 2) Pollution sources and pollutants that discharge harmful substances into the atmosphere are called pollution sources, and harmful substances that enter the atmosphere are called pollutants.
Air pollution sources are divided into artificial sources and natural sources. Natural sources include volcanic eruptions, forest fires, wind-blown dust and so on. They release about 550 million tons of pollutants into the atmosphere every year. Man-made sources include industrial pollution sources, agricultural pollution sources, urban and rural traffic and residents' living pollution sources. In the 1990s, they discharged more than 650 million tons of pollutants into the atmosphere every year on average, among which industrial pollution discharge was the most important. During the period of 1990, the air pollutants emitted by industrial sources in China were about 400 million tons, which was far lower than the emission level of developed countries according to the average population.
Air pollutants are divided into primary pollutants and secondary pollutants, and there are more than 100 kinds. After air is discharged into the atmosphere from pollution sources, it is directly polluted by primary pollutants, the most important of which are sulfur dioxide, carbon monoxide (CO), nitrogen oxides (NO), nitrogen dioxide, particulate matter (floating dust, dustfall, oil fume, etc. ), CO and ammonia, as well as organic compounds containing oxygen, nitrogen, chlorine and sulfur, and radioactive substances.
The so-called secondary pollutants are harmful substances produced by sunlight irradiation, chemical reactions between pollutants and chemical reactions between pollutants and atmospheric components, and photochemical smog is one of the secondary pollutants. 3) Quality of Atmospheric Environment The quality of atmospheric environment for human survival and development is called atmospheric environmental quality or atmospheric quality.
If the air is clean, the quality of the atmospheric environment will be high, for example, in mountainous areas far from cities or industrial areas; The air pollution in big cities or industrial areas is serious and the quality of atmospheric environment is low. The quality of atmospheric environment is usually measured by the concentration of atmospheric pollutants. The concentration of pollutants per unit volume of air is called pollutant concentration.
According to the consideration of not endangering human body, ecosystem and articles, the allowable value of pollutant concentration is artificially specified, which is called the atmospheric environmental quality standard. When the concentration of the corresponding pollutants in the air is lower than the specified value, it is said that the air quality meets the standard, and when it is higher than the specified value, it is said that the air quality exceeds the standard (referred to as exceeding the standard). The more it exceeds the standard, the worse the quality of the atmospheric environment.
All countries in the world have formulated their own standards. China promulgated the atmospheric environmental quality standard for the first time in 1982, and implemented three-level standards according to regional categories. For scenic spots and nature reserves, the first-class standards shall be implemented; Used in residential areas, commercial and cultural areas. , the implementation of secondary standards; Used in industrial areas, transportation hubs, etc. , the implementation of three standards.
Specific standards of some pollutants are listed in the table. The concentration of atmospheric pollutants is usually determined by collecting and analyzing air samples with an atmospheric sampler.
4) Harm and influence of air pollution The harm and influence of air pollution on human beings and their living environment have been gradually recognized by people, which can be summarized as: ① Harm to human health. There are three ways for human body to suffer, that is, inhaling polluted air, skin contact with polluted air, and eating food containing atmospheric pollutants, which will not only cause respiratory and lung diseases, but also harm cardiovascular system and liver, and even seriously endanger people's lives.
② Harm to living things. Animals get sick or die from inhaling polluted air or eating food containing pollutants. Air pollutants will reduce the disease resistance of plants, affect their growth and development, and cause leaf spot or wither and die.
③ Damage to articles. Such as textiles and clothing, leather, metal products, building materials, cultural works of art, etc. , causing chemical damage and pollution damage.
④ Causing acid rain, which has adverse effects on agriculture, forestry and freshwater aquaculture. ⑤ Destroy the upper ozone layer and form an ozone hole, which is harmful to the living environment of human beings and organisms.
⑥ Impact on global climate, such as carbon dioxide.
The harm of air pollution
Causes of air pollution The average residence time of gas pollutants in the atmosphere ranges from a few minutes to decades and hundreds of years.
Atmospheric pollutants are generally divided into two categories: first-class pollutants, that is, pollutants directly discharged into the atmosphere by pollution sources; Secondary pollutants are the products of thermal or photochemical reactions of major pollutants in the atmosphere. The latter is often more harmful.
Air pollution mainly comes from human life and production activities, and there are three kinds of man-made air pollution sources. (1) Domestic pollution sources Due to people's daily needs such as cooking, heating and bathing, such as stoves and boilers burning fossil fuels, the smoke and SO2 discharged into the atmosphere are characterized by large quantity, wide distribution and low emission level, and their harmfulness cannot be ignored.
(2) Industrial pollution sources include pollutants emitted by fuel combustion in coal-fired power plants, steel plants, cement plants and chemical plants, as well as waste gas from various production processes (for example, coking plants emit toxic substances such as H2S, phenol, benzene and hydrocarbons into the atmosphere; All kinds of chemical plants discharge organic and inorganic gases with * * *, corrosiveness, peculiar smell or stench into the atmosphere; H2S, NH3, CS2, methanol, acetone, etc. Chemical fiber factory emissions) and all kinds of mineral and metal dust emissions in the production process. (3) The traffic pollution source is the tail gas emitted by vehicles (mobile sources) such as airplanes, ships and automobiles.
In some developed countries, automobile exhaust has become the main source of air pollution. There are dozens of air pollutants emitted by human beings, and a large number of harmful main air pollutants are as follows.
(1) The sources of particulate matter can be divided into natural sources and man-made sources, with man-made sources as the main source. The direct discharge of pollution sources is called primary particulate matter; Particles produced by the reaction between some pollutants in the atmosphere or between these components and atmospheric components are called secondary particles.
Man-made sources are mainly soot and fly ash formed in the process of fuel combustion, raw materials or product particles discharged from various industrial processes, lead-containing compounds discharged from automobiles, and SO2 converted into sulfate from fossil fuel combustion under certain conditions. Natural sources, such as wind dust, foam splashed by waves, volcanic ash, burning products of forest fires, cosmic meteorite dust and plant pollen.
Particulate matter is an important air pollutant, and some toxic substances in the atmosphere mostly exist in particulate matter, which is very harmful to people, animals and plants. (2) Sulfur oxides SOx The sulfur oxides in the atmosphere are mainly SO2 and a small amount of SO3.
It mainly comes from the combustion of sulfur-containing fossil fuels in power plants and heating plants (80% of which is coal), followed by the waste gas from smelters and sulfuric acid plants, the decomposition and combustion of organic matter, marine and volcanic activities, etc. From the point of view of chemical thermodynamics, the equilibrium transfer rate of SO2 is high, and SO3 is easily generated.
From the point of view of chemical kinetics, SO3 can be generated by catalytic oxidation (iron salts and magnesium salts suspended in the atmosphere act as catalysts) or chemical oxidation (mainly under the action of ultraviolet light with the wavelength of 290~400nm), and SO3 can easily react with water vapor to generate sulfuric acid mist or sulfuric acid rain. SO2 is not only highly toxic to human respiratory tract, but also produces bleaching spots on plants, which inhibits growth, damages leaves and reduces yield.
When there is particulate matter in the air, its harm can be increased by 3~4 times (such as the London haze mentioned above). Many adverse effects of SOx are caused by sulfuric acid produced by the interaction between SOx and water.
Acid rain caused by sulfuric acid and nitric acid has seriously harmed China and many parts of the world, and has become one of the world's three major public hazards. (3) There are many kinds of nitrogen oxides, and NO and NO2 are the main causes of air pollution.
They mainly come from the high-temperature combustion of fossil fuels (such as the combustion of automobiles, airplanes, internal combustion engines and industrial kilns), and some NO and NO2 (N2+O2 = = 2no, 2no+O2 = = 2no2) generated by the reaction between N2 and O2 in the air also come from the waste gas of factories that produce and use HNO3, as well as nitrogen fertilizer plants, organic intermediate plants and organic intermediate plants. Now, tens of millions of tons of nitrogen oxides are discharged into the atmosphere every year.
NO can * * * the respiratory system, and can also combine with heme to form nitroso, which makes people toxic. NO2 will seriously * * * respiratory system, making heme nitrated, which is more harmful than NO.
In addition, NO2 will destroy cotton, nylon and other fabrics, and make citrus defoliate and yellow.
In addition, it will also form nitric acid rain to cause harm. (4) CO and CO2 CO are the biggest pollutants discharged into the atmosphere by human beings, which mainly come from the incomplete combustion of fuel.
However, recent studies have pointed out that naturally occurring carbon monoxide cannot be ignored. Due to the improvement of combustion devices and combustion technology in modern times, the amount of CO emitted by fixed combustion devices has gradually decreased, while the amount of CO produced by combustion of mobile sources such as automobiles is about 250 million tons per year, accounting for about 70% of the total amount of CO emitted by man-made pollution sources.
In modern developed countries, 80% of CO in urban air is emitted by cars. CH4 is quite abundant in the lower atmosphere. It can react with hydroxyl radical (–– --OH) to generate methyl radical (–– --CH3), which is then converted into CO.
The ocean is another important natural resource. Earlier, people thought that the ocean was an important channel to absorb co, but now it is found that the ocean is supersaturated with CO, so the concentration of CO in the ocean is higher than that in the atmosphere.
The ocean releases about 60 million tons of carbon dioxide into the atmosphere every year. Carbon monoxide is a colorless, odorless and odorless gas.
Generally speaking, the level of CO in urban air is harmless to plants and related microorganisms, but harmful to people and animals, because CO can combine with hemoglobin to produce "carboxyhemoglobin". The binding capacity of carbon monoxide to hemoglobin is 200~300 times greater than that of oxygen to hemoglobin. Therefore, after CO enters the blood, it will reduce or even lose the oxygen transmission capacity of the blood, leading to human hypoxia.
Mild poisoning has symptoms such as headache and nausea, and severe poisoning leads to coma, spasm and even death. Unlike CO, CO2 itself is not toxic, so it was not listed as a pollutant in the past, but in the long run, CO2 is also a very important pollutant.
Over the past century, with the rapid development of industry, transportation and energy, the amount of CO2 discharged into the atmosphere is increasing day by day, which exceeds the ability of nature such as photosynthesis of plants to eliminate CO2, and the concentration of CO2 is increasing rapidly. Carbon dioxide.
Explanation of scientific terms: air pollution
What is air pollution? Air pollution: the phenomenon that the concentration of pollutants in the atmosphere or secondary pollutants transformed from it reaches harmful levels is called air pollution. Air pollutants are mainly divided into harmful gases (sulfur dioxide, nitrogen oxides, carbon monoxide, hydrocarbons, photochemical smog and halogen elements). ) and particulate matter (dust, acid mist, aerosol, etc.). Their main sources are fuel combustion and industrial production process. The harm of air pollution to people is mainly manifested in respiratory diseases; It can inhibit the physiological mechanism of plants, leading to poor growth, weakened disease and insect resistance, and even death; Air pollution will also have adverse effects on the climate, such as reducing visibility and solar radiation (according to data, the intensity of solar radiation and the intensity of outside lines in cities are lower than those in rural areas by 10~30% and 10~25% respectively), leading to an increase in the incidence of rickets in cities; Air pollutants will corrode articles and affect product quality; In recent ten years, acid rain has appeared in many countries, and the acidity in rain and snow has increased, which has made rivers and lakes, soil acidification, fish reduction and even extinction, affecting forest development, which is closely related to air pollution. What is the harm of air pollution? (1) Acute hazard: the concentration of pollutants is very high in a short time, or several pollutants can cause acute hazard to human body. (2) Chronic harm: Chronic harm mainly refers to the harm to human body caused by the continuous action of low-dose pollutants, such as the influence of air pollution on the incidence of chronic inflammation of respiratory tract. (3) Long-term harm: Generally, the harm of environmental pollution to human body will only be shown after a long incubation period. For example, the carcinogenic effect of environmental factors. There are mainly physical, chemical and biological factors in the environment. Physical factors, such as leukemia and lung cancer caused by external radiation or inhalation of radioactive substances, and biological factors, such as tropical malignant lymphoma, have been proved to be virus primers transmitted by blood-sucking insects. Chemical factors, according to animal experiments, there are more than 1 100 carcinogenic chemicals. In addition, pollutants have a great influence on heredity. All living things are characterized by genetic variation. The harm of environmental pollution to human heredity is mainly manifested in mutagenicity and teratogenesis.
The harm of air pollution to people
Air is closely related to human survival, and it directly participates in the processes of gas metabolism, substance metabolism and body temperature regulation.
The air a person breathes every day is about 65438+100000 liters, which is equivalent to 12.9 kg, which is about10 times of the food and water needed every day. With the rapid development of modern industry and transportation, the emission of smoke and automobile exhaust has exceeded the self-purification limit of the atmosphere, but a very serious problem-air pollution has also followed.
The pollutants that have great influence on air pollution are sulfur oxides, nitrogen oxides, hydrocarbons, carbon oxides, dust and so on. Sulfur oxides are acidic substances, which come from the combustion of sulfur-containing fuels (oil and coal), mainly referring to sulfur dioxide and sulfur trioxide.
They can form aerosols and acid rain, which are extremely harmful to human beings under certain conditions. Sulfur oxides not only pollute the environment, but also seriously endanger human health, which can narrow the inner diameter of human respiratory tract and increase the resistance, resulting in a decline in resistance to bacterial infection, damage hematopoietic organs such as bone marrow and spleen, and destroy metabolism in the body.
What gases cause air pollution?
Definition of air pollution In a clean atmosphere, the composition of trace gases can be ignored. However, in a certain range of the atmosphere, there are trace substances that did not exist before, and their quantity and duration may have adverse effects and harm on people, animals, plants, articles and materials. When the concentration of pollutants in the atmosphere reaches a harmful level, it will even destroy the ecosystem and the conditions for the normal survival and development of human beings. The phenomenon that harms people or things is called air pollution. The causes of air pollution are both natural factors and human factors, especially human factors, such as industrial waste gas, combustion, automobile exhaust and nuclear explosion. With the rapid development of human economic activities and production, while consuming a lot of energy, a large number of waste gas and smoke substances are discharged into the atmosphere, which seriously affects the quality of the atmospheric environment. Especially in densely populated cities and industrial areas, the so-called dry and clean air refers to the air in natural state (composed of mixed gas, water vapor and impurities), and its main component is nitrogen, accounting for 78.09%; Oxygen, accounting for 20.94%; Argon, accounting for 0.93%; Other trace gases (such as neon, helium, carbon dioxide and krypton) with the content less than 0. 1%. The classification of air pollutants can be divided into two categories, namely natural pollutants and man-made pollutants, which often cause public hazards, mainly from fuel combustion and large industrial and mining enterprises. Particulate matter: refers to liquid and solid substances in the atmosphere, also known as dust. Sulfur oxides: The general term for sulfur oxides. Include sulfur dioxide, sulfur trioxide, sulfur trioxide, sulfur monoxide, etc. Carbon oxides: mainly include carbon dioxide and carbon monoxide. Nitrogen oxides: the general term for nitrogen oxides, including nitrous oxide, nitric oxide, nitrogen dioxide and nitrogen trioxide. Hydrocarbons: Compounds formed by carbon and hydrogen, such as methane, ethane and other hydrocarbon gases. Other harmful substances: heavy metals and fluorine-containing gases. Chlorine-containing gas, etc. Hazards of Air Pollution Air pollution has a great impact on the climate, and pollutants emitted by air pollution will have a certain impact on the local and global climate, especially on the global climate. In the long run, this effect will be very serious. First, the content of carbon dioxide in the atmosphere will increase: fuel contains various complex components, which will produce various harmful substances after combustion, even if the fuel without impurities is completely burned. It is also necessary to produce water and carbon dioxide. It is precisely because of fuel combustion that the concentration of carbon dioxide in the atmosphere is increasing, which destroys the balance of carbon dioxide in nature and may even trigger a "greenhouse effect", leading to an increase in the temperature of the earth. Second, after the ozone layer destroys the atmosphere and is polluted, due to the differences in the sources, nature and duration of pollutants, meteorological conditions, geographical environment and other factors in the polluted areas, as well as the differences in people's age and health status, the harm to the human body is not the same. Harmful substances in the atmosphere invade the human body mainly through the following three ways: (1) entering the human body through direct breathing; (2) adhering to food or dissolving in water, so that it can invade the human body with diet; (3) Enter the human body through contact or skin. Among them, invading the human body through breathing is the main way and the most harmful. The harm of air pollution to people can be roughly divided into three types: acute poisoning, chronic poisoning and carcinogenesis.