Dust

Dust is aerodisperse system consisting of airborne particles of solids of size of 0.1-100 MK. Airborne particulates less than 0.1 MK called smoke.
The origin of the dust is divided into terrestrial and space, natural and artificial mineral and organic plant and animal production, municipal and other Up to 75% of the total number of Peterhof, in the atmosphere, consists of inorganic substances. The main sources on, are the processes of weathering of rocks and soils and various plants, living and dead organisms and their residues; P. formed on the fires, and so on, Some of the ingredients are organic dust, such as pollen and flowers, spores, fungi, moulds, microorganisms and other, can serve as allergens and inhalation can cause in individuals allergic diseases.
In the cities the main sources of air pollution are: P. industrial enterprises (see below - Industrial dust) and boiler plants which emit through flue ash, soot, products of incomplete combustion of fuel in the form of soot and adsorbed on her resinous substances containing 3,4-benzpyrene; street P., rising into the air when the movement of people and especially transport. Dusty air worsens climate conditions, reduces solar illumination.
The amount of dust in the air of cities depends on the number and density of population, quantity and nature of the industrial enterprises and the degree of their equipment sewage treatment plants, the type of coatings of streets and level of treatment, the number and character of precipitation, time of year etc., the Maximum dust noted in the morning and evening hours. Duration of preservation of P. in the air and the possibility of its penetration into the lungs depends mainly on the size of dust particles, their weight and shape.
Dust particles adsorb on its surface various gases, vapours, radioactive substances, microorganisms, ions and free radicals (the latter have a very high chemical activity and increase the harmful effects P. on the body). Dust becomes especially dangerous when her particles adsorbed toxic and radioactive substances, pathogenic microorganisms and viruses. The severity of the impacts P. on the body depends on its reaction, chemical composition, quantities, dispersion, solubility and adsorbed on the surface of toxic substances, microorganisms (see below - Bacterial dust), and so on
In the respiratory delayed from 40 to 80% of dust depending on the degree of dispersion. The largest number of P., penetrating into the pulmonary alveoli, has a size from 0.1 to 10 MK. Exhaled air contains 5-10% of dust particles, the rest of dust partially out of ciliated epithelium, and much of it is being swallowed up and gets in the gastrointestinal tract. P. irritating to the skin, the organs of sight and hearing. Long breath in dust-Laden air can lead to frequent diseases (in particular, respiratory organs, especially children and adolescents.
Measures of struggle with dust content of atmospheric air - see Sanitary protection of atmospheric air. Radical way of dealing with P. is to create conditions under which eliminates or significantly reduces her education.

Dust - particles of solids suspended in the air. The origin of dust can be classified on the earth and space, natural and artificial, industrial and domestic mineral and organic plant and animal etc. In some cases, the dust may be radioactive (after testing of nuclear weapons, radiological accidents objects and so on).
Physical and chemical properties of the dust particles are determined by the size, weight, density, shape, hygroscopicity, solubility, pH, electrical charge, chemical composition, radioactivity. With hygienic assessment of dust great importance is the size of its particles, the dispersion. Particles with a diameter of 1 -10 MK easily penetrate into the lungs. Larger dust retained in the upper respiratory tract (nose, trachea) and ciliary epithelium of the bronchi. The nose of the person is deposited on the average about 50% of inhaled dust.
Prolonged inhalation of highly dusty air irritates the mucous membrane of the nose. In the pulmonary alveoli special cells (phagocytes) capture dust particles and dissolved or transferred into the bronchi or lymphatic system, thus removing from the lungs. A significant part of the detained dust is released when sneezing or coughing.
The main source of dust pollution of the air basin of the cities is the burning of solid and liquid fuel in boiler-houses, power plants, industrial furnaces, engines of internal combustion household heating installations.
Atmospheric air in industrial areas is characterized by the high dust levels, for a group of residential areas have a lower level of dust content of the air basin. On highways with intensive traffic is high dust content in the air throughout the year.
Measures of struggle with dust content of atmospheric air - see Sanitary protection of atmospheric air. For the organization of hygienic monitoring of atmospheric dust content air in some districts of the city set of stationary points of air sampling. The choice of these points is determined by the layout and urban development (industrial, residential, green, station area, line, and so on). Sampling is performed by means of automatic electric aspirator, who works for a given program without human intervention. There are also other methods of sampling of dust.
In some cases, atmospheric dust affects the human body as an allergen. Inhalation of dust, rich floral pollen, in the period of flowering plants in humans may occur hay rhinitis (hay fever). Sometimes allergic action has a dust from clothes, mattresses, pillows, etc.
On dust particles can be adsorbed microbes and viruses (bacterial, or microbial dust).
For bacterial dust, use ventilation, wet cleaning, disinfection with bactericidal substances and ultraviolet radiation. The dust can settle Ascaris eggs.
In the atmospheric air is constantly there are particles with radioactivity.
The sampling of atmospheric air with the purpose of definition of radioactive dust is produced using suction and sedimentation methods with subsequent measurement, sample activity in special units. In some cases produce the definition of separate isotopes (see) using radiochemical methods of investigation. For air purification from radioactive dust apply special methods (see Radioactive waste).
Industrial dust is the main hazards in the mining industry; it is formed during drilling and blasting work, when the work of coal combines and rock-loading machines for sorting of coal and others, the crushing and grinding of rocks at concentrating factories. At the enterprises of building materials industrial dust formed during crushing, grinding, prosea, mixing and transportation of dust-like products. In foundries of machine-building industry the dust emitted during the preparation of the molding of the earth, when cleaning the wheels and a number of other processes in the mechanical workshops with grinding and polishing of products. In the shops of the chemical enterprises dust formation is connected with the process of grinding of raw materials and finished product. In agriculture dust is formed in the process of tilling and fertilizing the soil, when using powdered pesticides, cleaning grain and seeds, cotton and flax. Education radioactive dust can occur when mechanical, metallurgical and chemical processing of radioactive substances. The formation of such dust associated with the various processes of treatment of materials, crushing, grinding, screening and other Radioactive dust is produced also in the production of svetoslavov continuous action (to cover dials hours, devices, and so on).

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