The air in the working area is strictly controlled hygiene standards included in the relevant GOSTs, which are mandatory. There is a table with MPC indicators and recommendations for control measures. To better understand the importance of this work, one should know how harmful substances affect human health.
What you need to know
Employers are required by law to provide employees with safe conditions labor (Article 212 of the Labor Code of the Russian Federation). An important indicator is MPC of harmful substances in the air of the working area.
With its help, the employer has the opportunity to minimize the harmful effects of toxic substances on the health of employees.
The level of influence of hazardous elements is determined by their concentration in the air that surrounds people in the workplace. To eliminate the negative impact, MPCs have been established for most hazardous elements and substances.
MPC harmful substances in the air working area- this is the content of toxic substances that, during an eight-hour working day (excluding weekends), does not have a detrimental effect on people and their future descendants.
Normative acts reflect MPC in mg/m3. The working area is a space equal to 2 m from the floor level.
Varieties of harmful substances
There are about 1,200 regulated substances that can harm human health. They are divided into classes according to the level of danger:
- Extremely dangerous - less than 0.1 mg / m3 (for example, lead and mercury).
- Highly dangerous - 0.1-1.0 mg/m3 (sulfuric acid, chlorine).
- Moderately dangerous - 1.0-10.0 mg/m3 (methyl alcohol).
- Low-hazard - more than 10.0 mg/m3 (acetone, ammonia).
According to the principle of exposure, the substance is divided into:
- narcotic (acetone);
- suffocating (carbon oxide);
- irritants (chlorine, ammonia);
- somatic (lead, arsenic);
- allergens (aldehydes);
- general toxic (mercury);
- mutagenic (formaldehyde, lead, manganese).
IMPORTANT! The division into hazard classes plays a big role. The higher the class, the less substance will have a detrimental effect on human health. Therefore, this problem must be approached with all seriousness, because the health and even the lives of people are at stake.
How is pollutant concentration measured?
In industries with harmful conditions, the employer is obliged to organize measures to control the purity of the air. These tasks are performed by employees of labor protection departments.
If substances of the 1st hazard class are present at the enterprise during production, then monitoring is carried out continuously. For this, special recording devices have been developed. When the MPC is exceeded, they give an audible signal.
But such devices are not always possible to apply. In such cases, air sampling is carried out at a distance of 0.5 m from the face of the worker (breathing zone). In production with heightened danger samples are taken at least 5 times per shift.
When there are several unidirectional substances in the air, the concentration will be equal to 1. These are such substances:
- various alcohols;
- hydrogen fluoride and hydrofluoric acids;
- hydrochloric acid and formaldehyde;
- sulfuric and sulfurous anhydride;
- various forms of aromatic hydrocarbons;
- carbon disulfide and methyl bromide.
If there are several hazardous substances in the air in different directions, then when calculating the volume of air for ventilation, the hazardous substance, which requires the largest amount of air, is taken into account.
- the conditions under which the hazardous substance appears;
- toxicity and hazard level with a single contact with the substance;
- state of aggregation;
- physical characteristics;
- chemical structure.
Watch the video: Atmosphere, its composition and main pollutants
MPC of harmful substances in the air are summarized in the table
| No. p / p | harmful substance | Maximum content in the working area mg/m3 |
| 1 | MPC nitrogen dioxide | 5,0 |
| 2 | Carbon dioxide MPC in the air of the working area | 9000,0 |
| 3 | Sulfur dioxide MPC in the air of the working area | 10,0 |
| 4 | Oil hydrocarbons MPC in the air of the working area | 300,0 |
| 5 | MPC of oil vapors in the air of the working area | 10,0 |
| 6 | MPC of carbon monoxide in the air of the working area | 20,0 |
| 7 | MPC ammonia | 20,0 |
| 8 | MPC phenol | 5,0 |
| 9 | MPC benzene | 5,0 |
| 10 | MPC chlorine | 1,0 |
| 11 | MPC ethanol | 1000,0 |
| 12 | Non-toxic dust | 6,0 |
| 13 | MPC nitrogen oxides in terms of NO2 | 5,0 |
| 14 | MPC nitric acid HNO3 | 2,0 |
| 15 | MPC gasoline (solvent, fuel) | 100,0 |
| 16 | MPC boric acid | 10,0 |
| 17 | MPC butane | 300,0 |
| 18 | MPC hexane | 300,0 |
| 19 | MPC iron | 10,0 |
| 20 | MPC iron trioxide | 6,0 |
| 21 | MPC ash C10H14 | 4,0 |
| 22 | MPC iodine | 1,0 |
| 23 | MPC potassium chloride | 5,0 |
| 24 | MPC ozone | 0,1 |
| 25 | MPC mercury | 0,01/0,005 |
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The impact of hazardous substances in the air of the working area on human health
A harmful substance is an element or compound that causes occupational diseases or results in industrial injuries as a result of security violations.
Health disorders can also be caused, manifested in the process of work and in the remote period of life of the living and subsequent generations.
The optimal composition of air for a person (in% by volume):
- nitrogen - 78.08;
- oxygen - 20.95;
- inert gases - 0.93;
- carbon dioxide - 0.03;
- other gases - 0.01.
Harmful substances, getting into the air, change its composition, it will differ from atmospheric air.
During various technological processes, some solid and liquid fractions are released into the air, forming aerosols. Harmful substances enter the body through the respiratory tract, as well as through the skin or with food if the employee eats at the workplace.
When dust is inhaled, it settles on the lungs, causing diseases. pneumoconiosis. The most common is silicosis, which develops with constant inhalation of silicon oxide SiO2.
The influence of harmful substances can be considered using the example of carbon monoxide.
An important indicator of air purity - carbon oxide MPC of the working area is 20.0 mg/m3. Carbon monoxide CO is an odorless and colorless gas. It has a detrimental effect on human health, as it significantly reduces the ability of hemoglobin to carry and deliver oxygen to vital body systems.
Gas is formed during the combustion of coal, paper, wood, gasoline, oil in conditions of lack of oxygen or air. It is also called carbon monoxide.
Naturally, 90% of the total amount is formed in nature. 10% are of artificial origin:
- from exhaust gases;
- installations for catalytic cracking of oil;
- foundries;
- lime kilns;
- from the distillation of coal and wood;
- in the production of synthetic methanol;
- in the production of carbide and formaldehyde;
- during the operation of waste processing plants and others.
Processes during which incomplete combustion of organic matter takes place become a source of carbon monoxide. Therefore, carbon monoxide MPC in the air of the working area is so strictly controlled.
Carbon monoxide has become the most common cause of fatal poisoning. A huge number of workers are exposed to this danger every day at service stations, in garages, in the automotive industry.
Coke and blast furnace workers, miners, bakers, cooks, firefighters and many others are at serious risk.
Symptoms of poisoning are manifested in the form of nausea, headache and dizziness within 15 minutes. If exposure to carbon monoxide continues for 10 to 40 minutes, suffocation and death ensue.
By observing safety standards in the air of the working area, it is possible to significantly reduce the harmful effects of hazardous elements on human health.
Numerous studies show that the dust content of the air in working rooms varies widely depending on the nature of production, the technological process, the condition of the equipment, the nature of production operations, the state of technical measures to combat dust, etc.
Depending on the specified conditions in the air of working rooms, it is possible to detect the amount of dust from 1 mg/m 3 and less to tens and hundreds of milligrams in 1 m 3 air and from 200 to tens of thousands of microscopic dust particles per 1 cm 3 of air, and ultramicroscopic particles - up to several hundred thousand. However, it should be noted that, despite the intensification of production processes and, in connection with this, an increase in dust formation, the dust content of the air in working rooms is now much lower than it was 10-20 years ago. This is explained by the rationalization of technological processes and equipment, as well as the improvement and widespread use of special technical measures to combat dust.
Based on the established provision on the highest aggressiveness of quartz (SiO 2) dust, the following maximum permissible concentrations of dust in the air of working premises in weight units have been established in Russia: if the dust contains more than 70% free silicon dioxide - 1 mg / m 3, if its content is from 10 to 70% -2 mg / m 3, for asbestos dust and mixed dust containing more than 10% asbestos - 2 mg / m 3, for glass and mineral fiber dust - 4 mg / m 3. In total, more than 30 types of non-toxic dust are standardized, and for dust containing free silicon dioxide in an amount of less than 10%, limit values are set. allowable concentrations within 2-6 mg/m 3 , and for dust that does not contain free silicon dioxide, such as coal, etc., the maximum allowable concentration is 10 mg/m 3 . The maximum allowable concentrations of dust established in Russia are significantly lower than in other countries, in particular in the USA; besides there they are only recommendations, but not legislative norms. ["Sanitary standards for the design of industrial enterprises", SN-245-71.Yu Occupational health. 145]
1.4. Movement of dust in the body
Not all dust that enters the respiratory tract reaches the lungs: some of it lingers in the upper respiratory tract, primarily in the nasal cavity. Hairs of the nasal mucosa, winding passages, sticky mucus covering the membrane, ciliated epithelium of the nasal mucosa are excellent mechanisms that trap dust particles. Of great importance in the retention of dust in the nasal cavity are changes in the direction and speed of the air stream along the airways. The same kind of mechanisms that trap dust are present in the middle sections of the airways: a change in the cross section, a delay in the glottis, bifurcation and peristalsis of the bronchi, phagocytosis on the surface of the bronchial mucosa. The amount of trapped dust in the upper respiratory tract depends on the physical and chemical properties of the dust, the size of dust particles, the condition of the respiratory tract, etc.
A significant part of the trapped dust is released back when sneezing and coughing. According to different authors, the amount of emitted dust ranges from 10% to 70%. On average, it is considered that "about 50% of the dust reaches the lungs and lingers there.
Regardless of the physico-chemical properties, all types of dust particles initially have a mechanical effect on the lung tissue, which reacts to them as a foreign body with a proliferative cellular reaction. In the lungs, the process of phagocytosis of dust particles occurs, primarily by cells of the lung epithelium. Phagocytosis is a protective function of the body and helps to cleanse the lungs of dust. Cells that have absorbed dust particles, the so-called dust cells, seek to remove dust from the lungs in various ways. One of the ways is to remove dust along with sputum, the other is to remove dust along the lymphatic pathways of the lung to the bronchial glands and towards the pleura, where, accumulating, the dust causes a proliferative reaction. The activity of phagocytosis of various types of dust is not the same.
Well-phagocytized dust, such as coal, is relatively easily removed from the lungs, while quartz dust, despite the high activity of phagocytosis, is slowly removed due to the rapid death of phagocytes and accumulates in the lungs. Dust transported by dust cells along the lymphatic pathways can linger in the places of bifurcation and bends of the lymphatic vessels, clog them, and cause lymphostasis, which contributes to the further development of connective tissue.
Part of the dust cells under the influence of the toxic effect of dust (quartz) is destroyed, dust particles in this case are retained in the alveoli, penetrate into the tissue of the interalveolar septa and cause a proliferative cellular reaction.
In the future, depending on the aggressiveness of the dust, the processes can proceed in two directions: the development of specific processes - the formation of pathological connective tissue, i.e. pulmonary fibrosis and the development of non-specific pathological processes, such as pneumonia, pulmonary tuberculosis, lung cancer, etc.
Content limit question dust in the air of working rooms has great importance. The most correct method for determining the permissible concentrations of dust in the air can be considered a method based on a comparison of long-term dynamic observations of dust pathology of various professional groups and dust external environment in which these groups operate. The level of dust content at which no specific dust pathology is noted could be considered as the maximum allowable. This principle is based on the maximum allowable concentration of 1-2 mg/m3 recommended by various researchers for all types of dust with a significant content of quartz (dust of quartz, sand, sandstone, granite, etc.) and asbestos dust.
For other types non-toxic dust its maximum permissible content in the working area can be increased from a hygienic point of view depending on the characteristics of the dust - its chemical composition, shape, consistency and other properties.
Our legislation provides for containing more than 10% quartz, the maximum allowable concentration is 2 mg/m3, for other types of non-toxic dust - up to 10 mg/m3. In accordance with the guidelines given in H 101-54, the maximum permissible concentrations of dust in the air of the working area are established by industry in relation to individual production processes in coordination with the Main State Sanitary Inspectorate of the Ministry of Health.
Main activities preventing entry into the air industrial premises dust, is the rationalization of the technological process and equipment, excluding the possibility of dust formation, mechanization and automation of production, ventilation.
Of great importance, in particular, pneumatic transport widely used in the preparatory workshops of cotton factories, in cement, tobacco, woodworking and some other industries. As an example, the figure shows a diagram of grinding and moving bulk materials using vacuum pneumatics. Ventilation devices on mill units are much less efficient.
Some finished products may not be produced in powders, but in the form of a paste (dyes) or tablets (white soot), which completely or to a large extent eliminates dust emission.
In foundries significant hygienic effect is provided by replacing sandblasting of castings with hydrocleaning (a water jet under the addition of up to 100 atm. sandblasting (wet sand jet) or when replacing sand with shot. In the same workshops, dust reduction is achieved by using pneumatic transport of burnt earth, mechanization and automation of the processes of molding and knocking out sand molds , stripping (peeling) of casting.
On the image shown device for hydro-dedusting during the transport of dusty materials. Water is sprayed from nozzles. In the mining and coal industry, the use of water in order to reduce the dust content of the air is, according to the current rules, mandatory for all those jobs in which significant dust formation occurs. Such works include drilling of holes with pneumatic hammers, cleaning operations with the help of mining combines, rock loaders, etc. However, the use of wet methods of processing with water usually fails to achieve the required dedusting efficiency. This is especially true for the most harmful fine dust particles up to 3–5 u in size suspended in the air.
Insufficient efficiency dedusting during wet working methods depends primarily on the poor wettability of dust with water, especially fine dust. To enhance the efficiency of dedusting in these cases, in the mining and coal industries, small amounts (0.1-0.25%) of substances that increase wettability are added to water. These wetting agents lower the surface tension of water at the interface with air. In addition, wetting agents have the ability to be adsorbed to some extent from an aqueous solution on solid surfaces.
raising dust holding capacity of water under the action of small additions of wetting agents, as Acad. P. A. Rebinder, precisely with these two of their properties. Various organic products have been proposed as wetting agents - soap naft, Petrov's contact, sulfanol, DB, OP-7, OP-10, sulfite-alcohol stillage (wetting agent with. s. b.), etc. Mylon naft is a by-product of oil refining; consists of sodium salts of naphthenic acids, mineral oil and water. Petrov's contact is obtained by cleaning diesel and spindle oils with sulfuric acid.
Wetting action render contained in contact in an amount of up to 50% sulfonic acid - sulfanol-a mixture of sodium salts of alkylbenzenesulfonates. DB - a mixture of polyethylene glycol monoalkylphenyl ethers; a product of the treatment of butylphenols with ethylene oxide. OP-7 and OP-10 are similar in chemical composition to the wetting agent DB; products of processing high molecular weight alkylphenols with ethylene oxide. Unlike DB wetting agent OP-7 has an unpleasant smell of rot. OP-10 has this odor to a lesser extent. Sulfite-alcohol bard (wetting agent with. with. b.) - waste in the production of cellulose.
Composition of wetting agents additives to water must be selected in each individual case, taking into account the mineralogical composition of the rock, water hardness, other local conditions and checked both in the laboratory and in production. In particular, soap naphth and other soaps in hard iodine lose their effectiveness under the influence of precipitation of calcium and magnesium soaps. With the right selection of wetting agents, their addition to water has a significant effect, especially in terms of reducing the amount of fine dust particles. In the mining industry, the best results were obtained with the wetting agent DB. General exhaust ventilation systems are ineffective in dust control.
Considering the deposition process dust on the floor, walls and equipment, it is necessary to carry out regular cleaning of work areas by sweeping and wiping the settled dust with a wet method, and in some cases by pneumatic suction. This is all the more important, the smaller the dust particles and the more easily they can rise again into the air by the currents that occur during cleaning in the room. It is important to remove dust deposited on central heating appliances - radiators and pipes: in medium or high pressure steam or water heating, dust deposited on appliances can burn and become a source of air pollution.
Dust is the smallest particles of solid substances that are capable of being in suspension for some time.
According to the impact on the body, dust can be toxic and non-toxic. Toxic refers to industrial poisons and acts similarly to toxic gases.
Productive dust is understood as non-toxic dust. Main occupational diseases under its action are pneumoconiosis, chronic bronchitis, diseases of the mucous membranes of the respiratory tract and skin.
The most severe pneumoconiosis is caused by the action of silicon dioxide (SiO 2) - silicosis, coal dust - anthracosis, asbestos dust - asbestosis. Many dusts of plant and animal origin have an allergenic effect (grass dust, grains, flour, straw, etc.).
The risk of damage is influenced by: particle shapes, dust dispersion, electrical, physico-chemical properties, solubility.
Aerosols of predominantly fibrogenic action (APFD)(dust) - physical factor it's the same chemical substances, occurring in nature or obtained by chemical synthesis, but for their control, the method of weight (gravimetric) analysis is used.
fibrogenic Such an action of dust is called, in which an overgrowth of connective tissue occurs in the lungs of a person, disrupting the normal structure and functions of the organ.
APFD are divided into:
Highly and moderately fibrogenic, with MPC ≤ 2 mg / m 3
Weakly fibrogenic MPC ˃ 2 mg/m 3
APFDs are identified as harmful and/or hazards only in workplaces where:
Mining in progress;
Enrichment;
Production and use in technological process dusting substances related to APFD;
Equipment is operated, the work on which is accompanied by the release of APFD (dust containing natural and artificial mineral fibers, coal dust):
GN 2.2.5.1313-03 "Maximum Permissible Concentrations (MPC) of harmful substances in the air of the working area" 2472 items, of which 125 are APFD, table. 4.10.
Table 4.10. MPC dust in the air of the working area
At workplaces, the concentration of dust must be measured in the breathing zone (at a height of 1.5 m from the floor when working standing and 1.0 m when working while sitting). sampling equipment is shown in fig. 4.3.
1) 
2)
Fig.4. 3 Air sampling equipment for APFD:
1 - air intake device, 2 - filters.
The effect of APFD on the body:
§ Difficulty breathing, causes coughing and sneezing;
§ toxic dust can lead to poisoning, suffocation, etc.;
§ impairs visibility, leads to irritation of the mucous membrane of the eyes and increased lacrimation;
§ causes skin irritation;
§ Reduced visibility increases the risk of injury.
Dust load calculation. When estimating to ie working conditions at non-stationary workplaces and (or) in case of intermittent direct contact of workers with APFD during the working week, in order to establish the class (subclass) of working conditions, the expected dust load for the year (PN 1 year) is calculated based on the expected actual number of work shifts , worked out under the influence of APFD:
Mon 1 year = K ss N Q ,
where: to cc– actual average shift dust concentration in the worker's breathing zone, mg/m 3 ;
N- the number of work shifts worked in calendar year under the influence of APFD;
Q- the volume of pulmonary ventilation per shift, m 3.
The volume of pulmonary ventilation, which depends on the level of energy consumption and, accordingly, the categories of work (according to SanPiN 2.2.4.548-96) is:
The obtained value of PI for 1 year is compared with the value of CIT for the year (total number of work shifts per year N year under the influence of APFD at the level of the average shift MPC, respectively
CIT 1 year = MPC ss × N year ×Q.
If the actual dust load corresponds to the control level (CLL 1 year), the working conditions are classified as an acceptable class of working conditions. The multiplicity of excess control dust loads indicates the class (subclass) of working conditions according to Table 4.11.
Table 4.11. Classes of working conditions depending on the content of APFD in the air of the working area, (multiplicity of excess of MPC and CPN)
4.5.1 Lighting units
Illumination (E)- surface luminous flux density, defined as the ratio of the luminous flux dF to the area of the illuminated surface (dS), the unit of illumination is lux (lx):
Background - it is the surface on which the discrimination of the object takes place. The object of distinction is understood as the minimum element of the subject under consideration. The background is characterized reflection coefficient (r)- the ability to reflect the light falling on it, it is defined as the ratio of the reflected light flux F neg to the incident F pad:
r = F neg / F down
The reflection coefficient varies from 0.02 - black velvet to 0.95 mirror. For r< 0,2 фон считается темным, при r = 0,2 – 0,4 – средним; при r >0.4 light.
The contrast of the object with the background (K) is characterized by the ratio of the brightness or reflectance of the object in question and the background. The contrast between the object and the background is determined by the formula:
K = =
where L o and L f; r about and r f - respectively brightness (L) and reflection coefficients ( r) object and background.
The contrast is considered large at K> 0.5, medium - at K \u003d 0.2-0.5 and small - at K<0,2.
Pulsation factor (k p)- change in surface illumination due to periodic changes in time of the luminous flux of the light source:
k p \u003d [(E max - E min) / 2E cf ] 100%
where E max , E min and E cf - the maximum, minimum and average value of illumination for the oscillation period; for discharge lamps k p \u003d (25-65)%, for incandescent lamps - k p \u003d 7%, for halogen lamps - k p \u003d 1%.
Glare value (P 0)- criterion for assessing the blinding effect created by the lighting installation:
P 0 = 1000 (V 1 / V 2 - 1)
where V 1 and V 2 are the visibility of the object of distinction, respectively, with a shielded and unshielded light source.
4.5.2 Industrial lighting systems
Lighting of industrial premises is divided into natural and artificial.
Daylight- side (one- and two-sided) - through light openings in the outer walls; upper - through skylights, openings in the roof and ceilings and combined - a combination of top and side lighting.
artificial lighting can be general (uniform or localized) and combined (general and local).
According to the functional purpose, artificial lighting is divided into working, emergency and special, which can be security, duty, evacuation, erythema, bactericidal, etc.
Work lighting is mandatory for all production facilities.
Emergency lighting arranged to continue working in rooms where turning off the working lighting can lead to accidents. The minimum illumination should be 5% of the normalized working illumination, but not less than 2 lux.
emergency lighting- organized in places dangerous for the passage of people with more than 50 people working. The minimum illumination on the floor should be at least 0.5 lux indoors, and at least 0.2 lux in open areas.
security lighting arrange along the borders of territories protected by special personnel. The lowest illumination is 0.5 lx..
signal lighting used to fix the boundaries of hazardous areas; it indicates the presence of a hazard or a safe escape route.
Germicidal irradiation(lighting) is created for the disinfection of air, drinking water, food. The greatest bactericidal ability is possessed by ultraviolet rays with a length of (254-257) nm.
Erythematous exposure created in rooms where there is not enough sunlight (northern regions, underground structures). The maximum erythemal effect is exerted by electromagnetic rays with a wavelength of 297 nm. They stimulate metabolism, blood circulation, respiration and other bodily functions.
Artificial light sources are incandescent, fluorescent and LED lamps.
4.5.3 Lighting regulation
Illumination is normalized SP 52.13330.2011."Natural and artificial lighting"; and SanPiN 2.2.1/2.1.1.1278-03"Hygienic requirements for natural, (Tables 4.12 and 4.13). For artificial lighting, the normalized parameter is the minimum illumination (E min) on the working surface in a horizontal plane at a distance of 0.8 m from the floor.
All works are divided into VIII categories, and I - V are divided into sub-categories. E min is selected depending on the accuracy of visual work, the reflectance of the visual surface and the contrast with the background.
Illumination measurements are made using luxmeters with an error of no more than 10%. It consists of a galvanometer and a photocell, Fig.4.4.
When working in an open area only during the daytime, the working conditions at the workplace in terms of the illumination of the working surface are recognized as acceptable.
When the workplace is located in several working areas (indoors, in areas, in open areas), the assignment of working conditions to a class (subclass) of working conditions when exposed to a light environment is carried out taking into account the time spent in different working areas according to the formula (4.1):
Table 4.12. Normalized indicators of natural, artificial and combined lighting of the main premises of a public building, as well as the production premises accompanying them, in accordance with SP 52.13330.2011
| Premises | Working surface | Daylight | Combined lighting | artificial lighting | ||||||||
| and plane | KEO, % | KEO, % | ||||||||||
| standardization of KEO and illumination (G - horizontal, V - vertical) and the height of the plane above the floor, m | with overhead or combination lighting | with side lighting | with overhead or combination lighting | with side lighting | Illumination, lx | Discomfort index, M, no more | Illumination ripple factor, %, no more | |||||
| with combined lighting | in general lighting | |||||||||||
| Total | from the total | |||||||||||
| 1.Cabinets, workrooms, offices, representative offices | G-0.8 | 3,0 | 1,0 | 1,8 | 0,6 | |||||||
| 2. Design halls and design rooms, drawing offices | G-0.8 | 4,0 | 1,5 | 2,4 | 0,9 | |||||||
| 3. Premises for photocopying | G-0.8 | - | - | - | - | - | - | |||||
| 4. Model, carpentry, repair shops | G-0.8 | - | - | 3,0 | 1,2 | 15/20 | ||||||
| 5. Rooms for working with displays and video terminals, computer rooms | G-0.8 Monitor Screen: | 3,5 - | 1,2 - | 2,1 - | 0,7 - | - | - | |||||
| - | ||||||||||||
| Conference rooms, meeting rooms | G-0.8 | - | - | - | - | - | - | |||||
| Lobby (foyer) | G-0.0 | - | - | - | - | - | - | - | ||||
| Laboratories | G-0.8 | 3,5 | 1,2 | 2,1 | 0,7 | |||||||
Fig.4.4. Light meters: 1 - TKA-PKM, 2 - Testo - 540
Table 4.13. Assignment of working conditions by class (subclass) of working conditions when exposed to a light environment
where: UT- working conditions, expressed in points;
UT 1 , UT 2 , … , UT n– working conditions in the 1st, 2nd, n-th working areas, respectively, expressed in points relative to the class (subclass) of working conditions (permissible working conditions - 0 points; harmful working conditions (subclass 3.1) - 1 point; harmful working conditions (subclass 3.2) - 2 points);
t 1 , t 2 , t n- the relative time of stay (in fractions of a unit) in the 1st,
2nd, n-th working areas, respectively
Production noise
The frequency range of human auditory perception of sound vibrations is in the range from 16 to 20,000 Hz.
Any sound that is undesirable for a person is called noise.
Noise disrupts the reception of information, which affects errors and injuries. It causes fatigue.
The impact of noise is reflected primarily on the hearing organs. There are three forms of exposure - hearing fatigue, noise injury and occupational hearing loss, which leads to hearing loss up to its complete loss.
At each point in the sound field, the pressure and propagation velocity change with time. The difference between the instantaneous value of the pressure formed in the medium during the passage of sound ( R cf) and atmospheric pressure ( R atm) is called sound pressure- marked with a letter R sv and is measured in Pascals (Pa) (Fig. 4.5).
Rice. 4.5. Sound pressure illustration
When a sound wave propagates, energy is transferred. The average energy flux related to the surface normal to the direction of wave propagation is called sound intensity I (W / m 2) at a given point.
The sound intensity is related to the sound pressure dependence
(4.2)
where ρ – medium density, kg/m2;
With is the speed of sound in this medium, m/s.
The magnitudes of sound pressure and the intensity of the sound to be dealt with are within wide limits. Thus, the minimum value of sound intensity perceived by a person at a frequency f = 1000 Hz is equal to I o\u003d 10 -12 W / m 2 is called hearing threshold. The maximum value is called pain threshold and is equal to Imax\u003d 10 2 W / m 2. In this case, the sound pressure range varies from R o\u003d 2 10 -5 Pa up to P max\u003d 2 10 2 Pa.
In the practice of measurements, the absolute values of the sound intensity and sound pressure are not used, but only the logarithmic (decibel) scale is used. This is due to the following reasons:
Firstly, the range of sound and sound pressure changes is extremely wide, the normal human ear is not able to perceive slight changes in sound pressure.
Secondly, the reaction of the human ear to different sound volumes has a logarithmic character. Therefore, Bel introduced the indicator intensity level (sound pressure level), which is determined by the formula
(4.3)
where Io is the sound intensity at the threshold of hearing (10 -12 W / m 2).
If we substitute in formula (2) instead of I the value of the intensity at the threshold of pain (I max =10 2 W/m 2), then we get the entire range of auditory perception (L I max , dB).
dB (4.4)
Since the sound intensity is proportional to the square of the sound pressure, then:
Industrial noise is characterized spectrum consisting of sound waves of different frequencies.
When studying noise, the audible range of 16 Hz - 20 kHz is divided into frequency bands ( noise spectrum) .
Frequency band whose upper limit is twice the lower limit, i.e. f 2 = 2 f 1 is called octave.
For a more detailed study of noise, one sometimes uses third-octave frequency bands for which f 2 = 2 1/3 f 1 = 1,26 f 1
The octave and one-third octave band is usually given by the geometric mean frequency: f cf = 
.
There is a standard series of geometric mean frequencies of octave bands in which noise spectra are considered ( f sg m in \u003d 31.5 Hz, f cg max = 8000 Hz), tab. 4.14.
By the nature of the spectrum noises are divided to tonal(single tones are expressed in the spectrum) and broadband(with a continuous spectrum of more than one octave).
By time characteristic - permanent(the sound level during the working day changes by no more than 5 dBA) and fickle(Sound level changes less than 5 dBA over a working day). The non-permanent, in turn, are divided into fluctuating in time, impulsive and intermittent.
The human ear reacts differently to sounds with different frequencies. Ear sensitivity (loudness) increases markedly at frequencies between 20 and 1000 Hz. The human ear has the highest sensitivity in the frequency range from 1000 Hz to 4000 Hz. 4.6.
Figure 4.6. Graph of curves of equal loudness: 1 - hearing threshold; 2 - pain threshold; 3 - area of speech transmissions; 4- area of musical programs.
To estimate the loudness level of noise at different frequencies, we use standard frequency response A approaching the sensitivity of the human ear. At the same time, they use corrections on the A scale(Table 4.15).
Table 4.15. Standard correction values for frequency correction on the A scale.
| Frequency | 31,5 | |||||||||
| Correction ∆L A, dBA | 26,3 | 16,1 | 8,6 | 3,2 | -1,2 | -1,0 | 1,1 |
The A-weighted sound pressure level, dBA, in the i-th octave band is calculated as:
∆L A i = L i - ∆L A i (4)
The total noise level (loudness level or sound level) with a complex spectral composition is determined by the sound level in all octave bands according to the formula:
L Σ =10 lg (10) 0.1Ll + 10 0.1L2 + …+ 10 0.1Ln), dBA (4.6)
L Σ = L 1 + Σ∆ L i (4.7)
For constant noise, remote controls are installed in octave bands with geometric mean frequencies: 31.5, 63, 125, 500, 1000, 2000, 4000, 8000 Hz. The sound level (dBA) can be used to estimate the noise level.
When an employee is exposed during a working day (shift) to noise with different temporal (permanent, non-permanent noise) and spectral (tonal noise) characteristics, the equivalent sound level is measured or calculated. To obtain comparable data, the measured or calculated equivalent sound levels of impulse and tonal noise are increased by 5 dBA, after which the result can be compared with the noise limit without making a down correction.
4.6.1 Calculation of the equivalent noise level
The equivalent noise level is calculated using formulas 4.8 or 4.9.
L cp = 10 lg (10 0.1 L 1 + 10 0.1 L 2 +10 0.1 L 3 +...+10 0.1 L n) - 10 lg n, dBA (4.8)
where: L 1 , L 2 , l 3 , ...L n - measured levels, dBA,
n is the number of measurements.
L cp =L sum - 10 lg n (4.9)
The summation of the measured levels according to formula 7 is carried out in pairs sequentially as follows. According to the difference between the two levels L 1 and L 2 according to the table. 4.16 determine the additive ΔL, which is added to a larger level L 1, resulting in a level l 1, 2 = L 1 + ΔL. Level L 1,2 is summed in the same way with level L 3 and get level L 1,2,3, etc. The final result Lsum is rounded up to the nearest decibel.
Table 4.16
At equal levels, i.e. with L 1 = L 2 = L 3 = ...=L n =L, Lsum can be determined by formula 4.10.
L sum =L 1 + 10 lg n , (4.10)
Table 4.17. Values 10 lg n depending on n.
When assessing working conditions by the noise factor, the exposure time of the factor is estimated and the equivalent value is determined according to table 4.18.
The equivalent sound pressure level is the sound pressure level averaged over time (unit - dBA)
Table 4.18. Noise Level Adjustment Depending on Exposure Time
| Time | in hours | 0,5 | 15 minutes | 5 minutes | ||||||||
| in % | ||||||||||||
| Correction in dB | about | -0,6 | -1,2 | -2 | -3 | -4,2 | -6 | -9 | -12 | -15 | -20 |
4.6.2 Noise measurement in workplaces
When taking measurements, cover all characteristic and repeated from day to day noise situations(it is important to identify all significant noise changes in the workplace, for example by 5 dB (dBA) or more).
Duration of measurements within each reference time interval:
§ for permanent no less noise 15 s;
§ for intermittent, including intermittent, noise, it must be equal to the duration of at least one repetitive working cycle or a multiple of several work cycles;
§ for intermittent noise, - 30 minutes(three measurement cycles of 10 min each);
§ for impulsive noise - not less than the transit time of 10 pulses (recommended 15 - 30 s).
Sound level meters are used for measurement, Fig. 4.7.
Table 4.19. Maximum permissible levels of sound pressure, sound and equivalent sound level at workplaces with a special assessment of working conditions
Production vibration
Vibration- oscillatory movements of elastic bodies, structures, structures near the equilibrium position. The impact of vibrations on a person is classified:
According to the method of transmitting vibration to a person;
In the direction of vibration action;
By duration of action.
According to the method of transmission to a person, general and local vibration are distinguished (Fig. 4.8).
 1
|  2
|
Fig 4.8. The direction of the coordinate axes under the action of the general (1): a) standing position; b) sitting position and local vibration (2): when covering: a) end; b) spherical surfaces.
The general vibration according to the source of its occurrence is divided into
movement speed - excavators, cranes, concrete pavers, floor industrial vehicles;
a) at permanent workplaces of industrial premises;
b) at workplaces in warehouses, canteens, amenity, duty rooms and other premises where there are no machines that generate vibration;
c) at workplaces in the premises of the plant management, design bureaus, laboratories, training centers, health centers and other premises for mental workers.
Local vibration is transmitted through the hands of a person. It includes the impact on the legs of a seated person and on the forearms in contact with vibrating surfaces.
According to the direction of action, the vibration is subdivided according to the direction of the orthogonal coordinate system.
According to the temporal characteristic, it differs:
constant vibration, for which the controlled parameter during the action changes no more than 2 times (by 6 dB);
intermittent vibration, for which these parameters change by more than 2 times (by 6 dB) during the observation time.
Under the action of vibration on a person, the vibration velocity (vibration acceleration), the frequency range and the time of exposure to vibration are evaluated.
The frequency range of perceived vibrations is from 1 to 1000 Hz. Oscillations with a frequency below 20 Hz are perceived by the body only as vibration, and with a frequency above 20 Hz - both vibration and noise.
General vibration causes changes in the cardiovascular and central nervous systems, the appearance of pain in individual organs. Local vibrations affect the central nervous system, increasing blood pressure, causing narrowing of the capillaries in the fingertips, leading to loss of their sensitivity (vibrodisease), Fig. 4.9. Vibration disease from local vibration is manifested by bouts of whitening of the fingers, impaired sensitivity, and coldness of the hands. Reduced muscle endurance to physical activity. With the progression of the disease, there is a violation of sensitivity in the form of "high gloves" (from the elbow), swelling of the hands, stiffness in the joints of the hands in the morning, etc.
Rice. 4.9. Signs of local vibration disease
Under the influence of vibration, visual perception deteriorates, especially at frequencies (25-40) and (60 - 90) Hz. Vertical vibration is especially unfavorable for those who work in a sitting position, horizontal vibration - for those who work standing. The effect of vibration on a person becomes dangerous when the vibration frequency of the workplace approaches the frequency of natural vibrations of the human body organs: (4-6) Hz - vibrations of the head relative to the body in a standing position, (20-30) Hz - in a sitting position; 4-8 Hz - abdominal cavity; 6-9 Hz of most internal organs; 0.7 Hz - "rocking", cause seasickness.
4.7.1. Vibration regulation
Normalized and controlled vibration parameters, according to SN 2.2.4/2.1.8.566-96, use the root mean square values of vibration acceleration (a) or vibration velocity (V), as well as their logarithmic levels in decibels (dB).
The logarithm of the level of vibration velocity (Lv, dB) and vibration acceleration (L a , dB) is determined by the formulas:
, (1)
, (2)
where 5×10 -8 and 1×10 -6 - reference values of vibration velocity and acceleration.
The normalized frequency range is set:
For local vibration in octave bands with geometric mean frequencies (f 2 /f 1 =2) - 8, 16, 31.5, 63, 125, 250, 500, 1000 Hz;
For general vibration in octave and 1/3 octave bands with geometric mean frequencies (f 2 /f 1 \u003d V2) - 0.8, 1, 1.25, 1.6, 2.0, 2.5, 3.1, 4.0, 5.0,6.3,8.0, 10.0, 12.5, 16.0, 20.25, 31.5.40, 50, 63, 80 Hz.
In table. 4.20 - 4.24 allowable values for vibrations of various categories are given for a work shift of 8 hours.
Table 4.20. Maximum permissible levels of local vibration
| Geometric mean frequencies of octave bands, Hz | Maximum permissible levels along the axes X l, Y l, Z l | |||
| vibration velocity | vibration acceleration | |||
| m/s 10 -2 | dB | m/s 2 | dB | |
| 1,4 | ||||
| 1,4 | 1,4 | |||
| 31,5 | 1,4 | 2,7 | ||
| 1,4 | 5,4 | |||
| 1,4 | 10,7 | |||
| 1,4 | 21,3 | |||
| 1,4 | 42,5 | |||
| 1,4 | 85,0 | |||
| Adjusted, equivalent adjusted level | 2,0 | 2,0 |
Table 4.21. Maximum permissible vibration values for workplaces
| Hz | Maximum allowable values along the X, Y, Z axes | |||||||||||||||
| for vibration acceleration | for vibration velocity | |||||||||||||||
| m/s 2 | dB | m/s 10 2 | dB | |||||||||||||
| in 1/3 | in octave | in 1/3 | in octave | in 1/3 | octave | in 1/3 | in octave | |||||||||
| Z | X, Y | Z | X, Y | Z | X, Y | Z | X, Y | Z | X, Y | Z | X, Y | Z | X, Y | Z | X, Y | |
| 0,8 | 0,70 | 0,22 | 4,50 | |||||||||||||
| 1,0 | 0,63 | 0,22 | 1,10 | 0,40 | 10,00 | 3,5 | 20,0 | 6,30 | ||||||||
| 1,25 | 0,56 | 0,22 | 7,10 | 2,80 | ||||||||||||
| 1,6 | 0,50 | 0,22 | 5,00 | 2,20 | ||||||||||||
| 2,0 | 0,45 | 0,22 | 0,79 | 0,45 | 3,50 | 1,78 | 7,10 | 3,50 | ||||||||
| 2,5 | 0,40 | 0,28 | 2,50 | 1,78 | ||||||||||||
| 3,15 | 0,35 | 0,35 | 1,79 | 1,78 | ||||||||||||
| 4,0 | 0,32 | 0,45 | 0,56 | 0,79 | 1,30 | 1,78 | 2,50 | 3,20 | ||||||||
| 5,0 | 0,32 | 0,56 | 1,00 | 1,78 | ||||||||||||
| 6,3 | 0,32 | 0,70 | 0,79 | 1,78 | ||||||||||||
| 8,0 | 0,32 | 0,89 | 0,63 | 1,60 | 0,63 | 1,78 | 1,30 | 3,20 | ||||||||
| 10,0 | 0,40 | 1,10 | 0,63 | 1,78 | ||||||||||||
| 12,5 | 0,50 | 1,40 |