Industrial dust is particles of solid matter suspended in the air. According to its physicochemical properties, it belongs to the category of aerosols.

In industrial conditions, the sources of aerosols entering the air of working premises are a variety of technological processes: crushing and grinding of solid materials, sifting, drying, loading and unloading of bulk substances, grinding, turning, polishing of metal and other surfaces, sandblasting, mining and drilling operations, carding - scattering work in textile factories and many others. All these production operations are accompanied by the release of industrial dust, which, according to the method of formation, belongs to the category of disintegration aerosols. On the other hand, the sources of aerosol formation can be the processes of melting and sublimation of certain substances, as a result of which vapors of these substances are released, which, when the air is oversaturated with them, condense into tiny solid particles suspended in the air (for example, zinc oxide in copper foundries), called aerosols condensation

The wide variety of types of industrial dust has led to the need to classify it. It is generally accepted to classify dust by origin and divide it into two groups: organic and inorganic. Organic dust includes: plant dust (linen, wood, flour, etc.), animal dust (wool, bristle, horn, etc.) and artificial (plastic); to inorganic - mineral (quartz, asbestos, talc, gypsum, etc.) and metal (iron, cast iron, steel, copper, etc.). Often there are mixed dusts containing particles of different groups (for example, coal and soil in coal mines, metal and mineral during processing metal products on sanding wheels, etc.).

The dust content in the air of industrial enterprises depends mainly on two factors: the amount of dust generated and its stability, i.e., on the duration of its stay in the air in suspension. While the amount of dust generated depends on the nature of the technological process, the stability of dust in the air is associated mainly with its physicochemical properties: the degree of particle dispersion and their electrical charge.

The degree of dust dispersion depends on the conditions of its formation during the technological process. It has been established that in production premises There are mainly particles up to 10 μ in size, and of this number, 60-70% of dust has sizes up to μ.

The electric charge of particles arises during grinding due to friction against machine parts, during mutual friction of particles against each other, or due to the adsorption of ions from the air. Dust particles with opposite charges attract each other, thereby turning into particles larger size, and settle faster, and those with charges of the same name, on the contrary, repel and remain in a suspended state longer. Thus, the smaller the particle size and the greater the number of particles with the same charge, the greater the stability of dust in the air.

A number of other factors also influence the stability of dust in the air. In industrial conditions, due to the movement of people, the operation of machines, convection currents, etc., the air is in constant motion. This delays the settling of dust, as a result of which particles smaller than 2 μ in size (i.e., which are the largest in the air) practically do not settle.

The combination of all these factors determines the degree of dust in the air, which, like gas pollution, is assessed by the value of its concentration.

Naturally than more concentration dust, the more likely it is to enter the respiratory tract. At the same time, not only the amount of dust entering the body is significant, but also the depth of its penetration and the degree of retention in the body. In these processes, the main role belongs to the dispersion of particles and the protective properties of the body.

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Introduction

Industrial dust is the most common harmful factor in the working environment. It damages equipment, reduces the quality of manufactured products, reduces visibility in the production area and causes occupational diseases that have chronic consequences.

There are types of dust that can spontaneously ignite and even explode, so dust should be considered not just a harmful, but also a very dangerous production factor.

The air in all production areas is always polluted with dust. Even those areas that are considered clean and dust-free contain dust in small quantities (sometimes it can be seen with the naked eye on sunlight). But in many industries, due to the peculiarities of the technological process, the production methods used, the nature of raw materials, intermediate and finished products and many other reasons, intensive formation of dust occurs, polluting the air in these enterprises. This puts workers in these areas at risk. In such cases, dust becomes one of the factors in the production environment that determines working conditions. pneumoconiosis industrial dust

Therefore, the fight against industrial dust has recently become one of the main hygienic and socio-economic tasks.

But it is worth noting that such types of dust as sugar, flour, cement, soda are valuable as a product of production, so its loss causes serious economic damage.

Industrial dust is classified according to the method of formation, dispersion and method of origin. In this work we will consider each of the classifications in detail. We will also find out how dust affects the human body, discuss some occupational diseases and methods of their prevention.

Chapter 1. Industrial dust

1.1 The concept of industrial dust and its classification by education

Industrial dust (or aerosols) are small solid particles of organic or mineral origin that are in the air of a work area and gradually settle. The size of one speck of dust can reach from 0.0001 to 0.1 mm in diameter.

Manufacturing operations that generate dust are very diverse. These include the process of crushing and grinding solids, sifting, drying, grinding, polishing various surfaces, working with bulk materials. The dust released during these operations, according to the method of formation, belongs to the category of disintegration aerosols. Therefore, industries with intense dust generation include enterprises in the mining, coal, porcelain and earthenware, textile and flour milling industries.

Dust can also form during the melting and sublimation of some substance. As a result, vapors of this substance will be released, which, when air interacts with them, will begin to condense into small solid particles. According to the method of formation, such dust belongs to condensation aerosols.

1.2 Types of dust

There are so many types of industrial dust that it became necessary to classify it. The classification according to the method of aerosol formation is generally accepted.

1. Organic:

· vegetable (grain, etc.);

· animal (wool, etc.);

· protein (production of protein-vitamin concentrates).

2. Inorganic:

· mineral (silica, etc.);

metal (iron dust, etc.);

3. Mixed:

· mineral-metallic (a mixture of iron dust and silicon compounds, etc.);

· a mixture of organic and inorganic (dust from cereals and soil, etc.).

There is also a classification of dust by dispersion:

1. Visible (?10 µm);

2. Microscopic (from 10 to 0.25 microns);

3. Ultramicroscopic (? 0.25 microns).

By origin, dust is divided into:

1. Soluble (sugar, etc.);

2. Insoluble (bleach dust).

1.3 Factors influencing dust formation

Dust formation depends on 2 factors:

· Amount of dust

Dust stability

The amount of dust that is generated at the enterprise mainly depends on the nature of the technological process. And the stability of aerosols in the air is related to their physicochemical properties: the degree of particle dispersion and their electrical charge. The degree of dust dispersion is affected by the conditions of its formation. It was revealed that dust particles up to 10 microns in size predominate in the indoor air at the enterprise. An electrical charge on particles occurs during grinding due to friction against machine parts, due to friction between particles, and also due to the adsorption of ions from the air. Dust grains with opposite charges are attracted and become larger in size, which contributes to their rapid settling. On the contrary, dust particles with the same charges are repelled and remain in the air longer. It turns out that the smaller the size of the dust grain and the greater the number of particles with the same charge, the greater the stability of the dust in the air.

Other factors also influence dust formation. In production, air is always in constant motion; as a result, aerosols settle much more slowly, and dust particles smaller than 2 microns remain suspended almost all the time. The degree of dust in the air is determined by its concentration. That is, the higher the concentration of dust, the more likely it is to enter the human body. But in addition to the number of aerosols entering the respiratory tract, the depth of their entry and the degree of retention in the body are of great importance. In these processes, the main role belongs to the dispersion of dust and the protective properties of the body.

Chapter 2. Hygienic importance of various types of dust

2.1 Exposure to dust

A person working at any enterprise is exposed to both external and internal exposure to aerosols. Dust in the air of the working area gets on the worker’s skin, on his mucous membranes, upper respiratory tract, and the dust is also swallowed with saliva and enters the lungs when inhaled.

External exposure to dust is not dangerous for humans, because it is simply washed off from the skin and mucous membranes or shaken off altogether. That is, a worker, leaving the enterprise at the end of a work shift or leaving a place with intense dust formation, stops contact with dust. Plus, the skin does not allow most types of dust to pass through and is not exposed to them.

Dust that gets into the digestive tract also does not pose any threat. In fact, inhalation of aerosols is more dangerous, in which most of them enter the body and are not exhaled. As a result, there is prolonged contact of residual dust in the respiratory tract with their mucous membrane, which is most susceptible to aerosols.

As mentioned above, the degree of danger of dust on the worker’s body is determined mainly by the concentration of dust in the air and its dispersion.

2.2 Dust concentration and dispersion

Dust concentration is the weight content of suspended dust per unit volume of air. This value is expressed in milligrams of dust per 1 cubic meter. meter of air (mg/m 3), sometimes it is expressed in the number of dust particles per unit volume of air (see Appendix 1). It has been established that the main importance is not the number of dust particles, but their mass, so a weight method was adopted for the hygienic assessment of dust content in the air. Consequently, the higher the dust concentration, the greater the amount of it that affects a person during working hours.

Dust dispersion is the degree of its grinding. It is expressed as the percentage of individual dust fractions relative to the total number of dust particles (see Appendix 2). To find out the hygienic assessment of aerosol dispersion, it is divided into small groups: up to 2 microns, 2 - 4 microns, 4 - 6 microns, 6 - 8 microns, 8 - 10 microns and above 10 microns. For some research work, dispersion is divided into smaller or larger fractions.

2.3 Physico-chemical characteristics of dust

The size of the dust is of great hygienic importance - the smaller it is, the deeper the dust particles penetrate into the respiratory system. While large dust particles remain in the upper respiratory tract during breathing and are expelled from the body through expectoration, fine dust penetrates the lungs, settles there and affects the lung tissue. In addition, with the same mass, it has a large surface of contact with the lung tissue, therefore it is the most active.

At various enterprises you can find dust of varying degrees of dispersion. There are substances (for example, zinc) that, in the form of coarse dust, have a neutral effect on the human body, but when they take on a finely dispersed state, they become toxic. This is evidenced by the chemical composition of the dust; based on this criterion, it is divided into 2 categories:

Toxic (if such dust enters the body, acute or chronic poisoning will occur)

· Non-toxic (being in the body does not cause poisoning even in large quantities and for an unlimited period of exposure)

The biological effect of toxic dust is greatly influenced by its solubility. Dust, which is highly soluble, when it enters the body, is quickly absorbed into mucus, blood, lymph, and spreads throughout the body, causing a toxic effect. And dust, poorly soluble or insoluble, enters the body mainly during breathing, remains at the site of deposition and has a local effect.

The shape of dust particles also has a direct hygienic significance, since it affects the character local action dust and to some extent on penetration ability. Dust particles with sharp edges (crystalline dust, lamellar dust, etc.) are very irritating to the mucous membranes of the eyes and upper respiratory tract. For example, fiberglass dust particles can penetrate the pores of the skin and the surface of the mucous membranes, causing irritation and mechanical damage.

From the above, we can conclude that different types of dust, having different physical and chemical properties, act on the body differently and, therefore, pose a danger to workers.

Chapter 3. Effects of dust on the human body

3.1 Effect of dust on the body

Dust has both direct and indirect effects on the human body.

Direct exposure to dust should be divided into 3 categories:

1. Impact on the respiratory tract: if you breathe in dust for a long time, the effect it will have on the nasal mucosa can lead to chronic rhinitis. Also, during inhalation, dust enters the bronchi through the respiratory system, affecting them and causing bronchitis in a person. Dust entering the alveoli is instantly captured by phagocytes, accumulates and dies in huge quantities in the lumen of the alveoli, which leads to the proliferation of connective tissue. It begins to shrink, form scars and compress blood vessels. After which the body’s respiratory and circulatory function is disrupted, which leads to the disease pneumoconiosis;

2. Impact on mucous membranes: as a result of dust getting on mucous membranes, conjunctivitis, gingivitis, etc. may occur.

3. Impact on the skin: when it penetrates the skin and the openings of the sebaceous glands, dust can also cause various diseases: pyoderma, dermatitis. With indirect exposure, aerosols act on the human body through the environment. For example, dust affects the level of illumination in a room and the transparency of the air.

3.2 Pneumoconiosis

Pneumoconiosis is a chronic lung pathology that occurs during prolonged inhalation of industrial dust, causing the development of widespread fibrosis of lung tissue. During this time, a person is bothered by a dry cough, shortness of breath and chest pain. When diagnosing the disease, the employee’s professional experience and the harmfulness that provokes the lung tissue are taken into account.

Currently, pneumoconiosis is very well studied; Borshchevsky contributed a considerable share to this in 1974.

There are several types of pneumoconiosis, but the most common are:

· Silicatosis is a type of pneumoconiosis that develops when industrial dust contains silicon dioxide (SiO2) with another molecule (Mg, Ca, Al, Fe, etc.). Silicates can be found not only in nature, but also in enterprises. People working in such production are very susceptible to this disease. When extracting silicates, processing and using them, the worker inhales small particles of silicates, which, when entering the body, affect the ciliated epithelium of the respiratory tract. There are different types of silicatosis:

Asbestososis is the most common type of silicosis, in which inhalation of dust particles of asbestos occurs. It occurs among workers in the ship and machine industries, at construction sites and in aviation. For this disease to occur, work experience in these enterprises must be at least 5 years. Asbestos begins with bronchitis, which subsequently becomes chronic, then rhinitis and pharyngitis develop, asbestos particles are present in the sputum, and asbestos warts may appear on the skin;

Talcosis is a type of silicosis that occurs during prolonged inhalation of talc particles and is considered its mildest form. With this disease, a person develops mild bronchitis; complications can arise from inhaling cosmetic powder.

Cementosis is a respiratory disease that develops due to inhalation of cement particles. Accompanied by dry throat and nose, cough. In cement production workers with many years of experience, the mucous membrane becomes dry, becomes thinner and no longer retains dust that enters the body. Various chemical impurities added to cement have a great influence;

· Metalloconiosis is an occupational disease that occurs due to prolonged inhalation of metal dust (particles of aluminum, beryllium, barium, iron), resulting in the deposition of dust on the cells of the lung tissue;

· Anthracosis is a pathology that develops when inhaling dust particles with a high carbon content, resulting in damage to the respiratory tract. It takes a minimum of 15 years for an employee to become ill with anthracosis. This disease mainly affects people working in mines. There is a severe form of anthracosis - anthracosilicosis, which occurs when inhaling coal dust mixed with silicon dioxide. In this case, a malignant worsening of fibrosis of the lung tissue occurs;

3.3 Diagnosis of pneumoconiosis

Modern X-ray diagnostics plays a huge role in the diagnosis of pneumoconiosis. In the initial stages, this disease is very difficult to identify; in each individual case, many factors must be taken into account: from work experience to the individual characteristics of the body and previous diseases of the person being examined.

Various methods are used to diagnose pneumoconiosis:

· large fluorography;

· fluoroscopy - mainly used to identify stages 2 and 3 of pneumoconiosis, because small details are poorly visible;

· radiography - used to clarify the data that was obtained during fluorography. IN this method diagnostics, high-focus X-ray tubes are used to magnify 1.5-2 times small parts(vessels, nodules, bronchi).

There are other diagnostic methods for identifying some types of pneumoconiosis, but the ones listed above are the most basic.

The X-ray picture is greatly influenced by the degree of permeability of various aerosols.

3.4 Prevention and treatment of pneumoconiosis

It has been established that modern pneumoconiosis develops after approximately 10 years from the moment of starting work in dust production, therefore even completely healthy workers with such experience should be classified as at risk for the possibility of dust pathology.

The most important prevention of this disease is taking measures at enterprises to reduce dust levels. You won’t be able to get rid of all the dust, but you can minimize its formation. It is also important to use sealed or maximally closed equipment and communications to prevent dust formation. And when cleaning surfaces, it is important to use suction (aspiration), and not just blow off aerosols.

In places of intense dust formation, it is necessary to apply dust suppression measures: recently, a widespread method is irrigation, which contributes to the wetting of dust particles, their weighting and, consequently, settling. Sometimes the entire working area is irrigated; for this purpose, diffuse sources of dust emission are used. There are types of dust that do not interact well with water (for example, stone or coal). In such cases, special substances that wet dust particles are added to the water used for irrigation (mylonaphte, sulfonal, Petrov’s contact, DP, OP-7, etc.). Sometimes steam is used, but it does not properly moisturize the material used in the enterprise, so it is better to treat production equipment with it.

At some enterprises, due to technological processes, it is impossible to use irrigation or water vapor, then exhaust ventilation is used. It looks like a hood and is placed in places with intense dust formation.

The surface of the walls and floors of the dust room should be lined with smooth material so that aerosols can be easily removed or washed off. It is very important to note that in a dusty room you should never smoke, use electric welding, and fire or the slightest sparks are not allowed.

Regarding medicine, it can be noted that for a person working in an industry with intense dust generation, periodic medical examinations play an important role.

The worker should adhere to a number of preventive measures:

· Nutritious food

· Correct mode work and rest

· Physical and breathing exercises

· Quitting smoking

· Ultraviolet radiation is provided for mine workers (20 sessions each in autumn and spring)

· Therapeutic inhalations (2 times a year for 15 procedures)

· Use of expectorants and mucolytics

No radical treatments have yet been found for the treatment of pneumoconiosis, but glutamic acid has been proven to have a positive effect in the treatment process.

Conclusion

So, to summarize, we can state the following: completely harmless dust does not exist.

At work, a person faces various types dust, which adversely affects health and reduces its performance. To prevent such exposure, technological processes, equipment, raw materials, by-products, etc. are studied. This makes it possible, to some extent, to prevent the development of dusty pathologies, because it is simply impossible from a technical point of view to completely eliminate the effects of dust on the body. Yes and in everyday life humans are exposed to dust emitted by natural sources.

It is always worth remembering that our health is what was given to us by nature from birth, so we need to make every effort and knowledge to preserve it.

Literature used

1. Bondin V.I., Lysenko A.V. Life safety, Rostov-on-Don: “Phoenix”. 2003. - 354 p.

2. Ivanov P.P. “Occupational hygiene. Industrial dust." Moscow, 2001

3. Pneumoconiosis: http://ilive.com.ua/health/pnevmokonioz

4. Industrial dust: http://ohrana-bgd.narod.ru/bgdps11.html

5. Encyclopedia Around the World: http://www.krugosvet.ru

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Industrial (industrial) dust

Dust (aerosol) is the name given to crushed or otherwise obtained small particles of solid substances that float (in motion) for some time in the air. This hovering occurs due to the small size of these particles (dust particles) under the influence of the movement of the air itself.

The air of all industrial premises is polluted with dust to one degree or another; even in those rooms that are usually considered clean and not dusty, there is still dust in small quantities (sometimes it is even visible to the naked eye in passing light). sunbeam). However, in many industries, due to the peculiarities of the technological process, the production methods used, the nature of raw materials, intermediate and finished products and many other reasons, intensive dust formation occurs, which pollutes the air of these premises to a large extent. This may pose a certain danger to workers. In such cases, dust in the air becomes one of the factors in the production environment that determines the working conditions of workers; it was called industrial dust.

Dusts are formed due to crushing or abrasion (disintegration aerosol), evaporation followed by condensation into solid particles (condensation aerosol), combustion with the formation of solid particles in the air - combustion products (smoke), a number of chemical reactions, etc.

In industrial conditions, the formation of dust is most often associated with the processes of crushing, grinding, sifting, turning, sawing, pouring and other movements of bulk materials, combustion, melting, etc.

Industrial dust is one of the unfavorable factors, affecting human health. The first information about the possibility of developing lung disease due to inhalation of dust during mining operations is found in ancient Greek and Roman literature. However, based on the descriptions presented at that time, it is still difficult to say what specific forms of dust lung diseases were discussed (we can assume that about pneumoconiosis, coniotuberculosis, chronic dust bronchitis).

Only since the middle of the last century have observations gradually begun to accumulate, which have now made it possible to identify individual nosological forms of dust lung diseases, such as mullitosis.

In various industries and agriculture Many manufacturing processes generate dust. This is the mining and coal mining industry; metallurgical, metalworking and machine-building enterprises; production building materials; electric welding works; textile enterprises; processing of agricultural products - grain, cotton, flax, etc.

Dust of various origins:

Cereal:

Maximum concentration limit = 4 mg/m³

MPCm.r.=0.5 mg/m³

MPC.s.=0.15 mg/m³

Flour, wood, etc.:

Maximum concentration limit = 6 mg/m³

MPCm.r.=1 mg/m³

MPCs.s.=0.4 mg/m³

Cotton, linen, wool, down:

Maximum concentration limit = 2 mg/m³

MPCm.r.=0.2 mg/m³

MPC.s.=0.05 mg/m³

Hazard class - 3 (Moderately hazardous substances)

Cement, limestone, chalk, sand, clay, ash:

Maximum concentration limit = 4 mg/m³

MPCm.r.=0.3 mg/m³

MPC.s.=0.1 mg/m³

Hazard class - 3 (Moderately hazardous substances)

Dust emissions from tobacco factories with nicotine content up to 2.7%

MPCm.r. =0.0008 mg/m³

MPCs.s. =0.0004 mg/m³

Hazard class - 4 (Low hazardous substances)

Polymetallic dust with a lead content of up to 1% (asbestos belongs to the same hazard class)

MPCcr.z.=0.005 mg/m³

MPCm.r.=not allowed

MPC.s.=0.0001 mg/m³

Hazard class - 1 (Extremely hazardous substances)

Separately, I would like to say a few words about dust. Yes, yes, about the most common ubiquitous dust. Did you know that it is a Group 1 carcinogen and there are very specific Maximum Permissible Concentrations for it?

Why is dust important? Why does dust control receive so much attention around the world?

Dust is small solid particles of organic or mineral origin. Dust includes particles of average diameter from fractions of a micron to a maximum of 0.1 mm. Particulate matter less than 0.1 microns suspended in the air is called smoke. Particles larger than 0.1 mm transform the material into the category of sand, which has sizes from 0.1 to 5 mm. Dust particles less than 10 microns in size constantly float in the air, particles from 10 to 50 microns settle gradually, and larger ones settle almost immediately. When exposed to moisture, dust usually turns into dirt.

By origin, dust is divided into terrestrial and cosmic, natural and artificial, mineral and organic, plant and animal, industrial, municipal, etc. Up to 75% of the total amount of dust in the atmosphere consists of inorganic substances. The main sources of dust are weathering processes of rocks and soil cover, various plants, living and dead organisms and their remains; dust is formed in fires, etc. A number of ingredients of organic dust, for example, plant and flower pollen, spores, fungi, molds, microorganisms, etc., can serve as allergens and, when inhaled, cause allergic diseases in individuals.

In cities the main sources of pollution are atmospheric air are: dust from industrial enterprises and boiler houses emitted through chimneys ash, soot, products of incomplete combustion of fuel in the form of soot and resinous substances adsorbed on it containing 3,4-benzpyrene; street dust rising into the air when people and especially vehicles move. Dusty air worsens climatic conditions and reduces sunlight.

Dust has many influences, but almost all of them are negative. The greatest danger comes from dust particles 10 microns (PM10) or less. As with inhalation in a clinic or at home, the drug is sprayed into droplets of just the right size (about 2-10 microns, depending on the type of inhaler), which ensures that these drugs penetrate very deeply into the body, and sometimes directly into the blood. There is no difference when inhaling air saturated with dust, only instead of medicines, anything gets into the body, heavy metals, soot with unburnt petroleum products, microbes...

Dust particles sorb on their surface various gases, vapors, radioactive substances, microorganisms, ions and free radicals (the latter have very high chemical activity and enhance the harmful effects of dust on the body). Dust becomes especially dangerous when toxic and radioactive substances, pathogenic microorganisms and viruses are adsorbed on its particles.

In our society, minimal attention is paid to the influence of dust on health, as well as to the environment in general. However, many studies have been conducted in Europe and the USA. One of the latest was carried out between 2002 and 2004 in 13 cities in Italy. PM10 dust values ranged from 26.3 µg/m³ to 61.1 µg/m³. The number of deaths caused by dust concentrations above 20 µg/m³ was 8220 per year, or 9% of the total number of deaths (excluding accidents), for residents over 30 years of age. These are mainly deaths from lung cancer (742 cases per year), heart attack (2562), stroke (329). And also cordially vascular diseases and respiratory diseases.
Detailed report on English available .
In this case, it is important to say that in Russia a document has appeared “Addition No. 8 to GN 2.1.6.1338-03 “Maximum permissible concentrations (MAC) of pollutants in the atmospheric air of populated areas””, according to which the permissible average daily concentration of dust of the PM10 fraction is 60 µg/ m³. According to EU Directive 2008/50/EC in Europe, the average daily maximum concentration limit for PM10 is 50 µg/m³, with an allowance that for approximately 35 days a year it can be up to 75 µg/m³. In Germany, everything is stricter: for PM10 - the limit is 40 μg/m³, with a tolerance of 35 days a year - 50 - μg/m³.
And in Lithuania, in addition to the data, there are the following recommendations: at PM10 concentrations in the range from 51 to 100, it is not recommended to engage in outdoor activities and use your own vehicles (so as not to further increase the dust concentration). Even in the range from 31 to 51 - children and elderly people are advised to avoid long walks along roads with busy traffic.

The respiratory organs retain from 40 to 80% of dust, depending on the degree of dispersion. The largest amount of dust penetrating into the pulmonary alveoli has sizes from 0.1 to 10 microns. Exhaled air contains 5 - 10% of dust particles, the rest of the dust is partially excreted by the ciliated epithelium, and most of it is swallowed and enters the gastrointestinal tract. Dust irritates the skin, eyes and ears. Prolonged breathing in dusty air can lead to an increase in diseases (in particular, respiratory diseases), especially in children and adolescents. In the pulmonary alveoli, special cells (phagocytes) capture dust particles and dissolve them or transport them to the bronchi or lymphatic ducts, thus removing them from the lungs. A significant portion of retained dust is released when sneezing and coughing.

In a tightly locked apartment with closed windows, about 12,000 dust particles settle per 1 cm² of floor and horizontal furniture surface in two weeks. Household dust may contain pet hair and dander, feather fragments, insect particles, human hair and skin, mold spores, nylon, fiberglass, sand, fabric and paper particles, and tiny fragments of materials from which walls, furniture and household items are made. This dust contains 35% mineral particles, 12% textile and paper fibers, 19% skin flakes, 7% pollen, 3% soot and smoke particles. The remaining 24% is of unknown origin and even cosmic dust. Do you think that I have already gone too far about cosmic dust? If you believe Wikipedia, 40,000 tons of cosmic dust settle on planet Earth every year. Most of the dust enters a person’s home along with the air, and not due to dirty shoes, clothes, etc.

By the way, dust can sometimes be useful! In addition to spraying in an inhaler medicines dust may contain beneficial sea salts and minerals. True, far from sources of such dust their content is negligible. The amount of dust in the atmosphere also has a great influence on the climate. Dust particles absorb part of solar radiation and also participate in the formation of clouds, being condensation nuclei.

For the scale of all kinds of phobias, I will quote the following text: During its life, a pillow absorbs several tons of liquid that evaporates from our skin. Saprophytic mites living in it are arthropods 0.3 mm in size, causing the most severe forms of allergies, feeding on scales from our skin or microparticles of blood that are on feathers. An old feather pillow contains 10% mite excrement. In 1 gram of mattress dust live from 200 to 15 thousand saprophytic mites, and in a double bed there are 500 million of them. 70% of children with bronchial asthma have a tick allergy. In tick-borne bronchial asthma, exacerbations occur in the spring and autumn, especially at night. To date, about 150 species of mites have been found in house dust. They are called dermatophagoid or pyroglyphid mites.

And don’t be surprised later that you have allergies!

Fire and dust explosion hazards

Dust can burn, self-ignite, and form explosive mixtures with air, even in cases where the source material is non-flammable! The reason is an increase in the total surface area and free energy surface of the system, which increases chemical activity, in particular, the ability to oxidize with the release of heat.

Dust suspended in the air is explosive, and settled dust is a fire hazard! At the same time, when settled dust rises as a result of combustion or a local micro-explosion, impact, etc. it can become suspended and become a medium for a subsequent explosion or even a series of explosions.

Explosive and flammable dust is divided into 4 classes:

1st class - dust with a lower explosive concentration limit of less than 15 g/m³ . This includes dust substances such as anthracene, rosin, slag, ebonite, sulfur, peat, flaxseed, milk powder, sugar, cotton.

Class 2 - explosive dusts with a lower explosive limit at a concentration of 16 to 65 g/m³. An example of inorganic dust included here is aluminum powder. Organic substances in this category include sprayed gas soot, shale flour, wood flour, mill dust, wheat waste, peas, sunflower cake, starch and tea dust.

Class 3 - the most flammable dust that can spontaneously ignite at temperatures UP TO 250 ° C. This includes tobacco, zinc, and coal dust.

Class 4 - dust with a self-ignition temperature above 250 ° C, for example, sawdust.

Of course, not all types of dust are listed. The finer the dust, the more porous its structure, the more chemically active and explosive it is. The possibility of an explosion is facilitated by the presence of an electric charge on the dust particles, as well as the contact of the dust with a heat source (ignition), the formation of sparks, and contact with a flame. Naturally, only dusty air that contains a sufficient percentage of oxygen can explode and ignite.

The explosiveness of dust, as well as the force of the explosion and the temperature of self-ignition, are significantly influenced by the dispersion of particles. Thus, with a decrease in dispersion, the pressure at the explosion site increases, and the temperature of spontaneous ignition of dust decreases. The explosiveness of dust also depends on the presence of inert impurities, humidity and the release of flammable gases. For example, when the oxygen content in the air is less than 10%, dust does not ignite. However, the possibility of releasing volatile gases from dust dramatically increases the fire and explosion hazard!

Since dust explosions can occur in equipment, fans, air ducts, etc., explosion-proof equipment must be used.

To determine the amount of dust in the air, various methods are used: weight; conimetric, which determines the number of dust particles in the air; photometric, based on measuring the decrease in the intensity of light passing through dusty air, and others.

You can convert weight data into counting data. When translating, it is assumed that 1 mg/m³ corresponds to approximately 200 dust grains (from 0.4 to 2 μm in diameter) per 1 cm³ . In dust cleaning practice, it is necessary to take into account the dispersed composition and divide the dust into fractions according to particle size. The fractional composition of dust is expressed in microns and divided into fractions with sizes: 0-5; 5-10; 10-20; 20-40; 40-60 and more than 60 microns.

To assess the dust content of atmospheric air, it is often expressed by the amount of dust settling per unit surface over a certain time. To determine the amount of dust falling out of dust-contaminated atmospheric air (aerosol) over a certain time, a jar-sediment sampling method is used. Dust particles that randomly settle from the air are collected in cylindrical jars (made of plastic or earthenware) 25-30 cm high and 20-30 cm in diameter. The jars are installed on special poles 3 m high or on the roofs of houses. To protect the can from the wind, it is placed in an open top plywood box with an edge of 0.6 m. The cans are exposed for a period of 15 to 90 days. At the end of the period, the dust settled in the can is weighed and thus the amount of dust settled per unit of time per unit area is obtained. This value is expressed in grams per 1 m² or in tons per 1 km² per year. This method can determine the amount of dust settling at various distances from the source of air pollution.

Industrial dust refers to tiny particles of solids that can remain suspended in the air for a long time. Sources of dust formation in industrial conditions are all technological processes associated with crushing, abrasion, sifting, mixing, sorting, and transportation of crushed materials.

Dispersed system consisting of a mixture of gases and solid particles is called aerosol. The layer of dust particles deposited on the enclosing surface of industrial premises and equipment is called airgel.

According to the type of substance included in the dust grains, dust is divided into organic vegetable (wood, cotton, tobacco, etc.), animal (bone, down, wool) origin and plastics, inorganic(metallic, mineral) and mixed.

The nature of the effect on the human body varies toxic(quartz, lead, tobacco) and non-toxic(wood, flour, lime) types of dust. Some dusts, especially those of plant and animal origin, although non-toxic, can cause severe allergic reactions in the human body.

Based on the size of dust particles, dust is divided into:

· visible - particles larger than 10 microns;

microscopic - from 10 to 0.2 microns;

ultramicroscopic - finer than 0.2 microns.

The degree of exposure to industrial dust on the body depends on:

· chemical composition and origin;

· concentration and exposure time;

· size and shape of dust particles;

· solubility in physiological fluids;

· radioactivity;

· electrical charge of dust particles;

· individual characteristics of the body;

· combination with the influence of other factors of working conditions.

Presence of dust in industrial atmosphere makes breathing difficult and causes accelerated fatigue of workers. Poor visibility in workplaces and increased dustiness of the atmosphere provoke the occurrence of traumatic situations. Contaminating the skin and mucous membranes of the eyes, dust causes occupational diseases of the skin (purulent abscesses, dermatitis, eczema) and visual organs (conjunctivitis). Industrial dust can cause the occurrence or exacerbation of diseases of the upper respiratory tract (bronchitis, rhinitis, tracheitis, bronchial asthma), which are precursors or the initial phase of more severe pulmonary diseases.

Penetrating into the lungs with inhaled air and accumulating in them, industrial dust causes a number of occupational pulmonary diseases, collectively called pneumoconiosis(Greek pheumoh - light and kohia - dust). Depending on the type of dust exposed, each form of pneumoconiosis has its own name. Thus, when inhaling mineral dust containing silicon dioxide, the most severe form of pneumoconiosis develops - silicosis. Dust containing bound silicon dioxide generates silicosis, iron oxide - siderosis, coal dust - anthracosis etc.

The mechanical and chemical effects of dust on the delicate alveolar tissue of the lungs cause its replacement with rough scar tissue (pulmonary fibrosis), stretching and rupture of pulmonary alveoli (pulmonary emphysema). At the same time, the lungs begin to lose their function of supplying the body with oxygen, and the dust disease becomes more severe - pneumosclerosis. At this stage, the body’s defense systems are significantly weakened and the disease is complicated by pneumonia, tuberculosis and others.

infectious diseases.

Dust diseases are predominantly chronic. In the initial stages, they can be treated quite successfully, while in the advanced phase they can lead to complete disability and death.

In the form of an airgel, dust from flammable materials exhibits fire hazardous properties, and in the form of an aerosol, it exhibits explosive properties.

Assessment of dust hazards. Dust protection

Dust is a harmful factor, as it negatively affects the human body. Under the influence of dust, diseases such as pneumoconiosis, eczema, dermatitis, conjunctivitis, etc. can occur. The finer the dust, the more dangerous it is for humans. The most dangerous particles for humans are considered to be particles ranging in size from 0.2 to 7 microns, which, when entering the lungs during breathing, are retained there and, when accumulated, can cause illness. There are three ways dust can enter the human body: through the respiratory system, gastrointestinal tract and skin. Dust of toxic substances (lead, arsenic, etc.) can lead to acute or chronic poisoning of the body. In addition, dust impairs visibility at construction sites, reduces the light output of lighting devices, and increases abrasive wear of rubbing products, machines and mechanisms. As a result, productivity and quality of labor decrease and the overall production culture deteriorates.

The harmfulness of dust depends on its chemical composition. The presence of substances with toxic properties in dust increases its danger. Particularly dangerous is silicon dioxide SiO2, which causes a disease such as silicosis.

The dust concentration in real production conditions can range from several mg/m3 to hundreds of mg/m3. Maximum permissible concentrations (MAC) of dust in the air of the working area have been established (GOST 12.1.005 - 88 “General sanitary and hygienic requirements for the air of the working area”).

MAC are concentrations which, when working daily for 8 hours or for another duration, but not more than 40 hours a week, during the entire working experience, cannot cause diseases or deviations in health that are detected by modern research methods during work or in certain periods of life of the present and subsequent generations.

Depending on the chemical composition of the dust, their maximum permissible concentrations range from 1 to 10 mg/m3:

Maximum permissible dust concentrations for the air environment of populated areas have also been established. The values of these concentrations are significantly less than in the air of the working area and for neutral atmospheric dust are 0.15 mg/m 3 (average daily MPC) and 0.5 mg/m 3 (maximum one-time MPC).

Measurements of dust concentration in the air are most often carried out using the gravimetric method, less often using the counting method.

Weight method is based on the principle of obtaining weight gain from an analytical filter by passing a certain volume of test air through it. Analytical filters made of non-woven filter material have a high dust retention efficiency (about 100%) and are considered “absolute”. To suck air through the filter, special devices are used - aspirators.

Counting method is based on the preliminary separation of dust from the air with its deposition on cover slips and subsequent counting of the number of particles using a microscope. Dust concentration in this case is expressed by the number of particles per unit volume of air. Used to determine the dispersed composition of dust.

The gravimetric method for determining dust concentration is the main one. It is standardized and used by sanitary inspection authorities to control air quality in industrial enterprises.

To prevent air pollution in industrial premises and protect workers from its harmful effects, it is necessary to carry out the following set of measures:

1. Maximum mechanization and automation of production processes. This measure makes it possible to completely eliminate or minimize the number of workers located in areas of intense dust emission.

2. The use of sealed equipment, sealed devices for transporting dust-producing materials. For example, the use of suction-type pneumatic transport installations makes it possible to solve not only transport, but also sanitary and hygienic problems, since it completely eliminates dust emissions into the indoor air. Hydrotransport solves similar problems.

3. Use of moistened bulk materials. More often, hydroirrigation is used using fine water spray nozzles.

4. Use of effective aspiration units. In factories for the production of building structures, such installations make it possible to remove waste and dust generated during the mechanical processing of aerated concrete, wood, plastics and other fragile materials. Aspiration units are successfully used in the processes of grinding, transporting, dosing and mixing building materials, in the processes of welding, soldering, and cutting products.

5. Thorough and systematic dust removal of premises using vacuum units . The greatest hygienic effect can be achieved by stationary installations, which, with high vacuum in the networks, provide high-quality dust collection of large industrial premises.

6. Cleaning ventilation air from dust when it is supplied to premises and released into the atmosphere. In this case, it is advisable to remove the exhaust ventilation air to the upper layers of the atmosphere in order to ensure its good dispersion and thereby reduce the harmful impact on the environment.

7. Use of respirators (petal, hose and others), goggles and dust-proof clothing as personal protective equipment against dust.

Methods for cleaning air from dust

Used to clean air from dust dust collectors and filters.

To filters These include devices in which dust particles are separated from the air by filtration through porous materials. Devices based on other principles of dust separation are usually called dust collectors.

Depending on the nature of the forces acting on dust particles in the gas to separate them from the gas flow, the following types of dust collecting apparatus are used:

5) dry mechanical dust collectors (suspended particles are separated from gas using external mechanical force);

6) wet dust collectors (suspended particles are separated from the gas by washing it with a liquid that captures the particles);

7) electric dust collectors (dust particles are separated from the gas flow under the influence of electrical forces);

8) filters (porous partitions or layers of material that trap dust particles when dusty air is passed through them);

9) combined dust collectors (different cleaning principles are used simultaneously).

By functional purpose Dust collection equipment is divided into two types:

1) for cleaning supply air in ventilation and air conditioning systems;

2) for cleaning air and gases released into the atmosphere by industrial ventilation systems.

The main technical and economic indicators characterizing the industrial operation of dust collectors and filters are:

performance (or throughput apparatus), determined by the volume of air that can be cleared of dust per unit of time (m 3 / h; m 3 / s);

· aerodynamic resistance of the apparatus to the passage of purified air through it (Pa). It is determined by the difference in total pressure at the inlet to the apparatus R in and getting out of it P out, that is

P = P in - P out;

10) overall coefficient cleaning or the overall efficiency of dust collection, determined by the ratio of the mass of dust collected by the apparatus G st to the mass of dust entering it with contaminated air G input and expressed in relative units or %:

η = G st / G in * 100;

11) fractional purification coefficient, i.e. dust collection efficiency of the device in relation to fractions of different sizes (in fractions of a unit or in %)

η fr = (F in – F out (1 – η))/F in;

Where F in, F out– content of the dust fraction in the air, respectively, at the inlet and outlet of the dust collector, %;

12) cost of air purification (rub. per 1000 m 3 of purified air)

The simplest devices in terms of design and operation are dust settling chambers, in which the separation of dust particles from the air occurs under the influence of gravity when air passes through the chambers. These devices are used for rough cleaning, their dust collection efficiency is 50 - 60%. The speed of air movement in the chamber is selected from the conditions for ensuring laminar movement and is usually 0.2 - 0.8 m/s. The aerodynamic resistance of the chambers is low and equal to 80 – 100 Pa. In order to increase the efficiency of dust collection of chambers, they are sometimes separated in height by shelves, which can be periodically shaken to clear settling dust. Labyrinth-type dust settling chambers are used for the same purpose.

Centrifugal dust separators - cyclones - are most widely used, since with a relatively simple design they provide a high degree of air dust removal (80 - 90%). Figure 3 - Centrifugal dust separator - cyclone.

The cyclone consists of a cylindrical body, to which the inlet pipe is connected tangentially; the lower conical part and the exhaust pipe located inside the housing. Entering the cyclone at a speed of 16 - 20 m/s, dusty air acquires rotational movement and goes down. In this case, dust particles, under the influence of inertial forces, are thrown towards the walls of the apparatus and, sliding down them, fall into the bunker. The purified air flow turns upward and exits the cyclone through the exhaust pipe.

The efficiency of dust collection increases with increasing air entry speed into the cyclone. The maximum air speed is usually taken to be no more than 20 m/s. The diameter of the cyclone is assumed to be no more than 1 m. The hydraulic resistance of cyclones ranges from 500 to 1100 Pa.

The most widely used cyclones are NIIOGAZ, SIOT, VTSNIIOT, LIOT, Giprodreva. The NIIOGAZ cyclone is used to collect non-stick and non-fibrous dusts. Cyclone SIOT is used in cases where there are size restrictions at height. The VTSNIIOT cyclone is recommended for use when collecting abrasive dust. Cyclone LIOT is used to collect dry, non-stick dust. The Giprodreva cyclone is used mainly to collect wood waste.

Bag filters are widely used in industry to capture dry, non-stick dust. The dust retention efficiency of bag filters is 90 – 99%. Of the industrially produced bag filters, the most widely used are filters of the types FVK, FVV, FRM, FTNS, etc.

Electrical filters are widely used in the construction industry for purifying air and industrial gases from dust. The dust collection efficiency of electric precipitators is high, reaching 99.9%. For various application conditions, the industry produces different types of electrostatic precipitators: UG, EGA, UTT, OGP, UB, UVV, PG, DM, etc.

Wet dust collectors They are deep cleaning devices and are characterized by high dust collection efficiency. Their use is advisable when the collected dust is well wetted with water, is not cemented and does not form hard, difficult-to-destruct deposits. The dust collection efficiency of cyclones with a water film is 99.0 – 99.5%. Foam dust collectors are also distinguished by high performance indicators.

Industrial dust. Characteristics of industrial dust. personal protective equipment

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