Causes and control measures of air pollution Abstract: With the rapid development of industry and transportation and the extensive use of fossil fuels, dust, sulfur oxides, nitrogen oxides, carbon oxides, ozone and other substances are discharged into the atmosphere, which seriously deteriorates the air quality. Human beings need development, but they need to protect the environment more. How to protect the environment is a common concern. This paper mainly discusses the causes of air pollution and its control measures. Keywords: air pollution; Cause analysis; At present, the main pollutants brought by industrial production to the environment are industrial waste gas, industrial wastewater and waste residue (that is, industrial "three wastes"), in which a large number of industrial waste gases discharged into the atmosphere every day by factories pose a great threat to human health, so it is very necessary to reduce the discharge of pollutants as much as possible. With the rapid development of industry and transportation and the extensive use of fossil fuels, dust, sulfur oxides, nitrogen oxides, carbon oxides, ozone and other substances are discharged into the atmosphere, which seriously deteriorates the air quality. Air pollution in China belongs to "soot pollution", and the concentration of total suspended particulate matter in urban air in China generally exceeds the standard. But also aggravate the corrosion and damage of buildings, railways and bridges, and bring huge losses to industry and agriculture. The greenhouse effect and ozone layer destruction caused by air pollution directly threaten human survival. 1 analysis of the causes of air pollution 1. 1 the concept of air pollution refers to the discharge of various pollutants into the atmosphere by human production and living activities or nature, the content of which exceeds the carrying capacity of the environment, which deteriorates the air quality and adversely affects and damages people's work, life, health, equipment, property and ecological environment. Pollution sources can be divided into natural pollution sources and man-made pollution sources. Natural pollution sources refer to places or areas where nature discharges pollutants into the atmosphere, such as active volcanoes that discharge pollutants such as dust, sulfur dioxide and hydrogen sulfide, escaping natural gas, and places where natural disasters such as forest fires and earthquakes occur. Man-made pollution sources can be classified in different ways: according to their spatial distribution, they can be divided into point pollution sources, non-point pollution sources and regional pollution sources; According to people's social activities, it can be divided into domestic pollution sources, industrial pollution sources and traffic pollution sources. According to the existing forms of pollution sources, they can be divided into fixed pollution sources and mobile pollution sources. 1.2 The components of waste gas pollution have a great impact on the ecological environment and pose a great threat to human health. The exhaust gas with large absolute emission mainly includes: toxic gases containing pollutants such as nitrogen oxides, SO2, P, As, PH3, CO, HF, C2HCl3, C2H3Cl3, and other gases. 1.3 Cause analysis 1. 3. 1 Terrain and climate factors are the basic reasons that affect air quality. Special terrain and meteorological conditions are not conducive to the dilution and diffusion of air pollutants. Taking Lanzhou as an example, the overall topographical feature of the whole city is that the residual vein of Qilian Mountain in the northwest and the red pine mountain in the southeast end in a stepped manner, and the east-west direction of the central part gradually descends to the alluvial valleys and valleys of the Yellow River and its tributaries as the saddle bottom. A huge saddle shape with a relative height difference of 2 1 8 1 m is formed. In addition, the exposed peaks on the valley side have obvious heating effect on the inter-valley atmosphere. Because the surface temperature of mountain peak absorbs solar radiation, its surface temperature is higher than the air temperature, which leads to the decline rate of super adiabatic temperature. During the day, the peak heats the air at the top of the valley, while the air temperature at the bottom of the valley is low, which leads to the inversion from the ground. Inter-valley radiation at night, cold air sliding down the slope, resulting in inter-valley radiation inversion at night. The inversion layer above the ground in the valley basin during the day and the inversion layer formed by the cold Hu effect in the valley at night are responsible for 1. 3.2 Urban construction is an important factor affecting air quality. According to the classified statistical analysis of major air pollution, its main sources can be summarized into three aspects: fuel combustion; Industrial production process: transportation, etc. Although the air pollution emissions produced in various industrial production processes only account for about 1/5 of the total air pollution emissions. However, due to the concentration of emission points. High concentration, so the air pollution in industrial and mining areas or local areas is more serious. (1) fuel combustion. In some cities, natural gas has not been popularized in residents' lives, and coal is still the first choice fuel for people. In the coal-fired market, high-sulfur coal still dominates. Due to the limitation of economic conditions, it is impossible for people to give up cheap high-sulfur coal and buy environmentally friendly low-sulfur coal; This leads to a large amount of SO2 emission. (2) Industrial production process. Chemical industry and coal industry are the key development departments of the country. It is also the most polluted enterprise. Most of these industrial and mining enterprises have become the main force of air pollution. (3) Transportation. In recent years, transportation has developed rapidly. Especially in recent years, the number of private cars has increased dramatically. However, the development of traffic has brought serious environmental problems. Automobile exhaust contains a lot of CO, which is very harmful to human body, especially some diesel cars and smoking cars. A large number of inhalable particles are mixed in exhaust gas, which is an important factor leading to diseases. (4) Municipal construction. The problem of road slope is common in urban roads, that is, the sidewalks on both sides of the road are obviously higher than the road surface and perpendicular to the road surface, showing a "concave" shape. As a result, the dust on the road cannot be blown away and accumulates more and more, which is also the direct cause of dusty weather. (5) Industrial layout. The dispersion of industrial and mining enterprises has affected the air pollution in urban areas to varying degrees. (6) greening. In some new industrial cities, greening has not kept pace with industrial development. Only the internal greening of the government, some enterprises and institutions and government organizations has basically reached the standard, but the greening of the whole city is far from meeting the requirements. 2 Measures to control air pollution 2. 1 Ways to prevent air pollution There are many ways to prevent air pollution, mainly including adjusting energy strategy, adopting clean energy, popularizing clean production technology, rationally utilizing coal resources, strengthening atmospheric environmental management, controlling the total amount of pollutants, and purifying the atmosphere with green plants. (1) Adjust the energy strategy and adopt clean energy. Vigorously develop water resources, gradually develop nuclear energy, and strive to use clean energy such as solar energy, wind energy and ocean energy. Only 5% of China's hydropower resources have been developed, and 95% remains to be developed. Vigorously developing and utilizing water resources is the primary task of adjusting China's energy strategy and changing its energy structure. (2) Implementing cleaner production technology is an important way to realize cleaner production and reduce air pollution. (3) Adopting high technology, rationally utilizing coal resources, popularizing briquette and improving combustion mode. (4) Strengthen the management of urban air pollution according to law and control the total amount of air pollutants. 2.2 Monitoring the quality of the atmospheric environment There are various harmful substances in the atmosphere, and the types of pollution and pollutants discharged in different regions are also different. Therefore, when evaluating air quality. The atmospheric environmental indicators that need to be detected should be determined according to the actual situation in various places. The common pollutants in the atmosphere are total suspended particulate matter, dustfall, inhalable particulate matter, sulfur dioxide, nitrogen oxides, total hydrocarbons, lead, fluoride, ozone and benzopyrene. Determination of particulate matter: Particulate matter is one of the largest air pollutants with complex composition, diverse properties and great harm. It can be the toxic substance itself or the carrier, catalyst or reaction bed of other toxic and harmful substances in the atmosphere. In some cases, the combination of particulate matter and adsorbed gas or vapor matter will produce greater synergistic toxicity than a single component. Therefore, the study of particulate matter is an important content to control air pollution. The detection items of particulate matter in the atmosphere include: determination of total suspended particulate matter, determination of inhalable particulate matter concentration and particle size distribution, determination of dust fall, and determination of chemical components in particulate matter. One of them is. Gravimetric analysis is the most commonly used method to determine the concentration of particulate matter. Determination of sulfur dioxide: Sulfur pollutants in the atmosphere mainly include H2S, SO2, SO3, CS2, H2SO4 and various sulfates. They mainly come from the waste gas discharged from the combustion of coal and petroleum fuel, the smelting of sulfur-containing ores and the production of sulfuric acid and other chemical products. As one of the main indicators of air pollution, sulfur dioxide is widely distributed in all kinds of air pollutants and has the greatest impact. Therefore, sulfur dioxide is often represented in the detection of sulfur oxides. The determination of nitrogen oxides in the atmosphere can be divided into chemical method and instrumental method. Salcman method (GB/T 15435-95), acidic potassium permanganate solution oxidation method and chromic trioxide-quartz sand oxidation method are the most commonly used chemical methods. Among them, the Salcman method is only suitable for the determination of nitrogen dioxide content, and the acid potassium permanganate solution oxidation method and chromium trioxide-quartz sand oxidation method can detect the total amount of nitrogen oxides in the atmosphere. 2.3 Comprehensive improvement of air pollution Comprehensive improvement planning is to divide functional areas according to the present situation and development trend of urban air quality, and calculate the maximum allowable emissions and reductions of each functional area according to the proposed environmental objectives, so as to formulate pollution control plans. The treatment of air pollution should determine the primary pollutants according to the energy structure and traffic conditions of the city, that is, pollutants with high concentration, wide range and great harm. It is convenient for targeted treatment and the right medicine. At present, air pollution in most cities in China is mainly caused by coal burning and automobile exhaust, and the primary pollutants are sulfur dioxide and total suspended particulate matter. Therefore, the long-term goal of the plan should be to improve the backward coal-burning mode, improve the combustion efficiency, try to use gas fuel, briquette, solar energy, geothermal energy and other pollution-free or less polluting energy sources, implement regional central heating, eliminate small chimneys of thousands of households, improve the road hardening rate, and create a smoke-free control area by strengthening pollution control and improving pollution control technology. Adjust the industrial layout and make scientific and convenient use of atmospheric environmental capacity according to the law of atmospheric self-purification; Strengthen pollution source control and reduce pollutant discharge; Reduce automobile exhaust pollution through technical and administrative means; Improve the urban greening rate, select tree species with good pollution resistance, and vigorously develop plant purification. 2.4 Using meteorological conditions to prevent air pollution In the case of relatively stable changes in pollution sources, air pollution mainly depends on meteorological conditions. The dilution and diffusion of pollutants in the atmosphere are obviously controlled by meteorological conditions. Therefore, it is a realistic and effective method to control air pollution by using meteorological conditions, and the prediction of pollution meteorological conditions is the key. The role of meteorological department in the prevention and control of urban air pollution. It is not only limited to providing air pollution forecast, but also provides scientific basis for government planning departments to do a good job in the rational layout of urban construction and urban environmental planning. Fog is one of the important meteorological conditions that aggravate air pollution, and precipitation can wash away pollutants in the atmosphere. Therefore, meteorological departments can purify the atmosphere and eliminate pollution through artificial precipitation, snow and fog elimination. Conclusion At present, China's per capita energy consumption level is still very low, only14 of the world's per capita, and energy consumption will show an obvious upward trend. In the near future, China's energy structure will still be dominated by coal, and the increase of coal consumption will aggravate the degree of urban air pollution in China, but it is difficult to significantly increase the investment in urban air pollution control. Therefore, the development trend of atmospheric environmental quality in China is not optimistic. According to China's many years of environmental protection experience, before the pollution from industrial pollution sources or stationary sources is fundamentally controlled, the control of urban air pollution in China must be based on mandatory control and laws and regulations. With the establishment and perfection of China's market economy, environmental economic means is undoubtedly the development direction of China's environmental policy. References [1] Tong Zhiquan, Chen,. Pollution control and utilization of industrial waste gas [M]. Beijing: Chemical Industry Press, 1989. [2] Qin. 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