Industrial and economic development is usually accompanied by an increase in environmental pollution. Most large cities are characterized by a significant concentration of industrial facilities in relatively small areas, which poses a danger to human health.
One of the environmental factors that have the most pronounced effect on human health is air quality. Of particular danger at present are emissions of pollutants into the atmosphere. This is due to the fact that toxicants enter the human body mainly through the respiratory tract.
Air Emissions: Sources
Distinguish between natural and man-made sources of pollutants in the air. The main impurities that contain atmospheric emissions from natural sources are cosmic, volcanic and plant dust, gases and smoke generated by forest and steppe fires, products of destruction and weathering of rocks and soils, etc.
The levels of air pollution by natural sources are background. They change little enough with time. The main sources of pollutants entering the air basin at the present stage are man-made, namely industry (various industries), agriculture and motor vehicles.
Air emissions
The largest "suppliers" of various pollutants to the air basin are metallurgical and energy enterprises, chemical production, construction industry, and mechanical engineering.
In the process of burning various types of fuel, energy complexes emit large amounts of sulfur dioxide, carbon oxides and nitrogen, and soot into the atmosphere. Also in emissions (in smaller quantities) there are a number of other substances, in particular hydrocarbons.
The main sources of dust and gas emissions in the metallurgical industry are smelting furnaces, casting plants, pickling compartments, sintering machines, crushing and grinding equipment, unloading and loading of materials, etc. The largest share of the total amount of substances entering the atmosphere is occupied by carbon monoxide, dust, sulfur dioxide, Nitric oxide. Manganese, arsenic, lead, phosphorus, mercury vapor, etc. are emitted in slightly smaller amounts. Also, in the process of steelmaking, emissions into the atmosphere contain vapor-gas mixtures. They include phenol, benzene, formaldehyde, ammonia and a number of other dangerous substances.
Harmful atmospheric emissions from chemical industry enterprises, despite their small volumes, pose a particular danger to the environment and humans, since they are characterized by high toxicity, concentration, and significant diversity. Depending on the type of products, the mixtures entering the air may contain sulfur oxides, volatile organic compounds, fluorine compounds, nitrous gases, solids, chloride compounds, hydrogen sulfide, etc.
In the production of building materials and cement, atmospheric emissions contain significant amounts of various dusts. The main technological processes leading to their formation are grinding, processing of blends, semi-finished products and products in hot gas streams, etc. Pollution zones with a radius of up to 2000 m can form around plants producing various building materials. They are characterized by a high concentration of dust in the air containing particles of gypsum, cement, quartz, as well as a number of other pollutants.
Vehicle Emissions
In large cities, a huge amount of pollutants in the atmosphere comes from vehicles. According to various estimates, they account for 80 to 95%. Exhaust gases consist of a large number of toxic compounds, in particular nitrogen and carbon oxides, aldehydes, hydrocarbons, etc. (a total of about 200 compounds).
The largest volumes of emissions are observed in areas where traffic lights and intersections are located, where cars move at low speed and in idle mode. The calculation of atmospheric emissions shows that the main components of the emissions in this case are carbon monoxide and hydrocarbons.
It should be noted that, unlike stationary sources of emissions, the operation of vehicles leads to air pollution in city streets at the height of human growth. As a result, pedestrians, residents of houses located near roads, as well as vegetation growing in the adjacent territories, are exposed to harmful effects of pollutants.
Agriculture
Emissions of harmful substances into the atmosphere in rural areas are mainly the result of livestock farms and poultry farms. From rooms containing poultry and cattle, hydrogen sulfide, ammonia, and some other gases, spreading over considerable distances, enter the air. Dangerous toxicants also get into the air as a result of crop production activities when spraying pesticides and fertilizers in the fields, seed treatment in warehouses, etc.
Other sources
In addition to the above sources, air emissions of pollutants are produced by oil and gas refineries. This also occurs as a result of the extraction of mineral raw materials and their processing, during the emission of gases and dust from underground mining, burning of rocks in dumps, during the operation of incinerators, etc.
Human impact
According to various sources, there is a direct link between air pollution and a number of diseases. For example, the duration of the course of respiratory diseases in children who live in relatively contaminated areas is 2-2.5 times longer than in those who live in other areas.
In addition, in cities characterized by adverse environmental conditions, children noted functional deviations in the system of immunity and blood formation, violations of the compensatory-adaptive mechanisms to environmental conditions. Many studies have also identified a link between air pollution and human mortality.
The main components of emissions coming into the air from various sources are suspended solids, oxides of nitrogen, carbon and sulfur. It was revealed that zones with excess MPC for NO 2 and CO cover up to 90% of the urban area. The given macrocomponents of emissions can cause serious diseases. The accumulation of these contaminants leads to damage to the mucous membranes of the upper respiratory tract, the development of pulmonary diseases. In addition, elevated concentrations of SO 2 can cause dystrophic changes in the kidneys, liver, and heart, and NO 2 can cause toxicosis, congenital malformations, heart failure, nervous disorders, etc. Some studies have revealed a relationship between the incidence of lung cancer and concentrations of SO 2 and NO 2 in the air.
