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Methods of determination and hygienic assessment of the dust content in the air




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Лекция на тему: Здоровье детей и подростков как гигиеническая проблема. Физиолого-гигиенические
Лекция на тему: «Окружающая среда и здоровье»
Health (who) it is a state of complete physical, mental and social well-being, and not merely the absence of diseases or infirmity
Lecture “ Nutrition as a health factor”
Лекция на тему «Труд и здоровье»
Вода и здоровье” ( лекция для англоязычных студентов 3- го курса ммф ) Лекцию подготовил доцент кафедры гигиены и экологии Клименко А. И
Theme Hygienic assessment of the complex microclimate influence to the human organism
Тopic 8 methods of hygienic assessment of complex effects of the microclimate on the human heat exchange
Theme: methods of hygienic assessment of the dust and chemical admixtures level in atmospheric air
The methods of air sampling
Methods of determination and hygienic assessment of the dust content in the air
Theme: Food poisoning prevention
Theme: the complex assesment of individual health of children and adolescents
Hygienic assessment of conditions and organization of education in comprehensive school
Hygienic estimate of insolation regimen, daylight and candlelight of hospital apartments
Theme: Methods of hygienic investigations and assessment natural illumination and insolating regime in premises Purpose
Solar radiation and its hygienic importance
Topic №4 methods of determination and hygienic assessment of natural lighting in different premises
Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises
Theme: Methods of the hygienic investigation and assessment of the artificial illumination in premises Purpose
The adequacy of the individual nutrition study according to the daily energy intake
Hygienic importance of the air movement in premises
Determination of atmospheric pressure
Research of the factor of infra-red radiation
Тopic №6 Method of determination of temperature and humidity conditions indoors and their hygienic assessment
Method of determination and hygienic assessment of the air movement direction and speed
Methods of determination of со
Microclimate of premises
Theme: Hygienic assessment of the noise and vibration as occupational hazards
Topic №18 method of hygienic assessment of soil according to sanitary examination of the land parcel and results of laboratory analysis of samples
The hygienic estimation of quality of potable water according to inspection and to results of the laboratory analysis
Umanskiy, А. N. Bessmertniy hygienic regulation of water quality. Basic methods of water treatment
Theme: Hygienic assessment of occupational hardness and intensity
Theme: Methods of determination of the ultraviolet radiation intensity as such as preventive dose of it’s irradiation and use it for diseases prevention and air disinfection in premises

Тopic № 12

METHODS OF DETERMINATION AND HYGIENIC ASSESSMENT OF THE DUST CONTENT IN THE AIR





  1. Learning objective


1.1. Master and complete the students’ knowledge about the dust as the environmental factor and its influence on the human health.

1.2. Master the methods of determination and hygienic assessment of the dust content in the air.


2. Basics


2.1. You should know:

2.1.1. Origin, classification and characteristics of the domestic, street, industrial and agricultural dust.

2.1.2. Dust impact on the human health. Diseases caused by the dust content in the air.

2.1.3. Classification and characteristics of the methods of determination of the dust content in the air. Criteria of the hygienic assessment of the dust content in the air.

2.1.4. Methods and facilities of the domestic, public, industrial and atmospheric air protection from the dust.


2.2. You should have the following skills:

2.2.1. To perform the sanitary inspection of the object, determine the place, goal and method of the air sampling to determine the dust content.

2.2.2. To convert the value of the air volume to its value in standard conditions using the temperature and atmospheric pressure data during the air sampling.

2.2.3. To weigh the samples (filters, sediment) using the analytical or torsion balance.

2.2.4. To perform the measurement of the dust particles size using microscope with ocular and objective micrometers.

2.2.5. To assess the results of the dust content in the air measuring.

2.2.6. To determine the general and individual methods and measures for prevention of the harmful influence of the dust on the human health.


3. Self-training questions


3.1. Sources and hygienic significance of the dust content in the domestic, public, industrial and atmospheric air.

3.2. Classification of the dust by origin, chemical composition, dispersion, formation mechanism. Aerosuspensions, aerosols of disintegration and condensation origin. Principles of their behaviour in the air (Jibs-Stokes laws).

3.3. Physical and chemical characteristics of the dust, the harmful influence on human organism depending on them. Anatomical structure of the respiratory tract and physical laws on which the respiratory tract protection from unfavourable dust influence is based.

3.4. Ways and mechanisms of the harmful dust influence on the human organism. Diseases caused by the dust in the domestic, public and industrial air.

3.5. Pneumoconioses, their types, pathogenesis and prevention.

3.6. Hygienic standards of dust content in the air as a preventive measure of harmful dust influence on the human organism.

3.7. Classification and characteristics of the methods of determination of the dust content in the air. Aspiration and sedimentation methods. Determination of the dust dispersion. Dust formula.

3.8. Preventive measures for the domestic, public, industrial and atmospheric air protection from the dust pollution. Personal dust-protective equipment and its characteristics.


4. Self-training assignments


4.1. The air was tested for the dust content in the detail-polishing department of the machine-tool plant. The air was blown through the AFA-B-18 filter at the speed of 10 l per minute during 30 minutes using the electrical aspirator to assess the working conditions. The air temperature during the sampling was 210С, the atmospheric pressure – 755 Hg mm. The initial filter weight is 0.0920 g, weight after air sampling – 0.0933 g. Determine the dust concentration in the air and perform the assessment of the results.

4.2. The ocular-micrometer with scale interval of 3 μm was used for determination of the dust dispersion in the granite monument and headstones manufacture department air. Determination of the size of dust particles demonstrates, that 5 dust particles could fit one point of the ocular-micrometer; 10, 20, 4, 18, 21, 13, 9 dust particles could, respectively, fit 0.5, 1.5, 2.5, 3.5, 4.5, 5.5 6.5 points. Determine the size of dust particles, make up a “dust formula” and draw up a prognosis about possible adverse events on organism of the workers.


  1. Structure and content of the lesson


This is a laboratory lesson. At the beginning of the lesson students will have their knowledge of basics checked. Theoretical and practical issues are studied by questioning of the students, and the teacher’s explanations, if necessary, in accordance to the question list (point 3) and appendix 1. After that the students receive the individual tasks and materials (samples of the dust content in the air acquired by aspiration and sedimentation methods), determine the dust content by weighing of the samples and using the VKP-1 (ВКП-1) dust-meter. The air sampling is performed using the aspiration method in the laboratory.

Determine the dust dispersion in the air using the microscope with ocular and objective micrometers, make up the “dust formula”.

Assess the results, draw the appropriate conclusions and recommendations. The task should be written down in the protocol.



  1. Literature


6.1. Principal:

6.1.1. Гигиена: Учебник /Р.Д.Габович, Г.Х.Шахбазян, С.С.Познанский. – К. , 1983. – С. 211-217.

6.1.2. Загальна гігієна. Посібник для практичних занять / І.І.Даценко, О.Б.Денисюк, С.Л.Долошицький та ін. /За ред. І.І.Даценко. - 2-ге вид. – Львів: „Світ”, 2001. – С. 294-297.

6.1.3. Ю.П.Пироваров, О.Э.Гоева, А.А.Величко. Руководство к лабораторным занятиям по гигиене. – М., 1983. - С. 140-147.

6.1.4. Lecture materials.


6.2. Additional:

      1. Гігієна праці /А. М. Шевченко, О. П. Яворовський та ін. /За ред. А.М.Шевченка. – 2-ге вид.: Київ: „Інфотекс”, 2000, С. 209-228.

      2. Гігієна праці (методи досліджень та санепіднагляд). – За ред. А.М. Шевченка і О.П. Яворовського – Вінниця, „Нова книга”, 2005. – С. 232-243.

      3. Даценко І.І., Габович Р.Д. Профілактична медицина: загальна гігієна з основами екології/ 2-ге видання. – К.: Здоров’я, 2004. – С. 86-98.

      4. Минх А.А. Методы гигиенических исследований. - М., 1971. - С. 98-105.


7. Equipment required for the lesson


    1. Electrical aspirator.

    2. Filter holders with aerosol filters.

    3. Torsion scales.

    4. Microscope.

    5. Acetone in the dropper.

    6. Object-plates.

    7. Dust-meter VKP-1 (ВКП-1).

    8. Ocular and objective micrometers.

    9. Student’s task to determine the dust content in the air.

Appendix 1


  1. Origin of the dust




    1. The dust sources in the air may be:

  • volcanic eruptions;

  • cosmic dust (meteorite combustion in the atmosphere);

  • dust storms – wood (Тibet, China), soil, sand;

  • agricultural dust – from harvesting and crop processing;

  • industrial – manufacturing emissions and meltdowns;

  • road dust;

  • marine (salt).

1.2. Domestic dust. The dust content in the air of living, industrial, public, educational, sport places may be caused by:

  • type and quality of the floor and furniture covering;

  • population density of the place;

  • character and quality of tidying up (dry, wet) and air exchange;

  • culture level of the inhabitants.

1.3. Industrial dust: the dust content in the industrial areas may be caused by:

  • type of industry;

  • mechanization level of the manufacture;

  • quality of dust-catching and ventilation facilities.




  1. Classification of the dust




    1. By chemical composition (origin):

  • inorganic (silicon oxide, asbestos, salt, minerals of ores, metals, soul and others);

  • organic (plant, animal, synthetic organic materials, polymers, plastics, gum, colorants (dye-stuff));

  • microbiological (microorganisms, fungi).

  • mixed (different particles of inorganic, organic and biological nature);

    1. By influence on organism:

  • indifferent;

  • toxic;

  • dermatotropic;

  • pneumotropic;

  • allergenic;

  • cancerogenic and others.

    1. By form of the particles:

  • amorphous;

  • fibrous;

  • pointy (spiky) and others (see fig. 12.1).

    1. By size of the particles:

  • aerosuspensions – particles with size more than 100 micrometers;

  • aerosols: large dispersible – sizes 100-10 μm. (proper dust)

medium dispersible – sizes 10 –0.1 μm. (cloud)

small dispersible – sizes less than 0.1 μm. (fume or smoke)

2.5. By formation mechanism:

  • disintegration aerosols (crashing and processing of the solid rocks and materials);

  • condensation aerosols (agglomeration of the atoms or molecules to dust particles)


3. Principles (rules) of aerosols and aerosuspensions behaviour in the air (Jibs-Stokes laws)


3.1. Aerosuspensions and large dispersible aerosols are accumulated from the air with acceleration: the gravity affects the dust particles greater than the air resistance.

3.2. Middle dispersible aerosols are accumulated from the air at the constant speed: gravity is in balance with the air resistance.

3.3. Small dispersible aerosols aren’t accumulated - they stay in the Brownian movement: the air resistance to the dust particle movement is greater than the gravity. Small dispersible particles conglomerate or absorb moisture on themselves, becoming heavier and only then accumulate.


4. Respiratory tract anatomy and physiological laws on which the respiratory tract protection from the dust in the air is based


The respiratory tract is quite well protected from the dust getting into lung alveoli. This protection consists of the respiratory tract curvature: three nasal meati with curved bone lamella; bronchial tree with its branching helps the air turbulence, and that is why the aerosuspensions and large dispersible dust particles, in accordance to the law of inertia (Newton’s law), are thrown away from the respiratory tract by the centrifugal force; and then the dust is removed due to the ciliary epithelium with bronchial mucus.

Middle dispersible aerosols penetrate deeper into bronchi. Small dispersible aerosols in accordance to the Brownian movement of the diminutive mass penetrate easily into alveoli with the air and may cause pneumoconiosis or other diseases. Some scientists have an opinion that a part of the small dispersible particles may be breathed away like the air molecules.


5. Adverse events and diseases caused by the dust influence on the human organism


5.1. The dust content in the atmospheric air reduces the lighting, ultraviolet radiation intensity, causes the dull weathers (the dust particles are the moisture condensation centers), fogs and smog.

5.2. The dust influence on the skin and mucous membranes appears as the obstruction of excretory ducts of sebaceous and sweat glands, development of skin and mucous membranes maceration, causes pyodermia and allergy. Lipotropic dust components may be absorbed into skin, causing the general toxic reactions. The dust reduces ventilating function and decreases the vapor conduction contaminating the clothes and influencing the heat exchange and skin breathing negatively.

5.3. The dust influence on respiratory track may cause different pathological states:

  • general toxic reactions: the dust dissolved in water is absorbed from the lungs and mucous membranes, gets into the blood vessels and may cause different pathology depending on the troposity of the toxic substance (lead or saturnism, zinc, strontium poisonings and others):

  • allergic diseases: dispnea or breathlessness, chronic bronchitis, rhinitis, pharyngitis, tracheitis, bronchial asthma (plant or woolen dust, soot and others);

  • infectious diseases with inhalation transmission (tuberculosis, pneumonic plague and others);

  • pneumoconioses – fibrous lung diseases, caused by the prolonged influence of some types of inorganic dust (silicosis is caused by the silicon oxide, siderosis – by iron dust, asbestosis, anthracosis and others);

  • lung cancer – under the chrome dust, radionuclides, 3,4-benzpyrene, 5,6-dibenzanthracene and other carcinogens influence.


6. Hygienic standards of the dust content in the air


The measuring methods of the dust content in the air may be classified: by the sampling technique – sedimentation and aspiration, by research results definition – weighting and calculation.


Table 1


Maximum allowable concentration (MAC) of the aerosols with the fibrogenic activity


Substances

MAC, mg/m3

Threat category

Alumina as condensation aerosol

2

4

Alumina as disintegration aerosol (alumina, electro corundum)

6

4

Crystalline silicon dioxide and its portion in the dust:

more than 70%

from 10 tо 70%

from 2 tо 10%


1

2

4


3

4

4

Non-crystalline silicon dioxide as a condensation aerosol

1

3

The dust of plant and animal origin with silicon dioxide more than 10% addition

2

4

Silicates and silicate content dust:

asbestos

asbestos-cement, cement, apatite, clay (loam)

talc, mica, muscovite


2

6

4


4

4

4

Cast iron

6

4

Chamotte and graphite fire-proof materials

2

4

Electro corundum and alloyed steel mixture

6

4

Chromic electro corundum

6

4





Fig. 12.1 Morphology of dust particles.

A, B – wood dust; C – bristle dust; D – chamotte dust; G- hemp dust;

Н – conifers dust; J – coal dust; К – glassy dust; L – bronze dust; M – dust under foundry cleaning.


Appendix 2

Sedimentation methods


2.1. Sedimentation-weighting method is used to determine the quantity of the dust, that falls down from the atmospheric air onto the surface unit near the industrial areas, in the cities and others settlements.

The sampling is performed using: 1) flask method, the wide glassware (sedimentator) with distilled water is exposed on the open surface for 3-4 weeks or 2) sticky screen method (for radioactive aerosols collection), when the sedimentator’s bottom is lubricated with the glycerin or 3) snow sample method: the first snowfall date is noted and then, after 1.5-2 months, the snow block of certain area (e.g. 0.5 m2) is cut out to the clean layer of the first snowfall. Water, snow and glycerin fix the drop-out dust very well. The water from glassware or the snow water is evaporated to the solid residual after the exposition, the glycerin with fixed dust is collected with the ash-free tampon quantitatively. The solid residual is weighed (for radioactivity determination it is ashed) and is recalculated in g/m2, and then in t/km2. Several tons of dust per km2 per year fall down in the industrial regions, according to this method.

2.2. Sedimentation-weighting method – the dust deposition on the object-plate. The object-plate (slide) is greased with glycerin, vaseline or 2% Canada balsam solution in xylol from the 10 cm air column to determine the form and size of the dust particles using the microscope and “dust formula” calculation. The “dust formula” is portions of the dust particles of each size in the air volume in percentage. The aspiration methods are also widely used for this purpose. (see appendix 3).


Appendix 3


Aspiration methods for determination of the dust content in the air


3.1. Aspiration-weighting method consists of drawing the certain air volume through the aerosol filter using the Migunov’s electrical aspirator or the hoover (vacuum cleaner) with rheometer (device for the aspiration speed determination). The aerosol filter АFА-В-18 (АФА-В-18) from Petrianov’s non-woven synthetic filter fabric (PFF) is fastened to the special bailer allonge (adapter) (fig. 12.2)





Fig. 12.2 Cassettes and allonges (adapters) with filters for the air sampling.

1 – filter with fabric PFF; 2 – plastic allonge (adapter) with filter;

3 – metal allonge (adapter); 4 – cassette case; 5 – cassette screw; 6 – filler ring.


The filter (without fixed paper ring) is weighed using the analytical or torsion balance before and after the air aspiration.

The air sampling duration depends on the dust content in the air, the air aspiration speed during sampling, the necessary minimal dust weight on the filter and may be calculated using the following formula:

,

where: Т –the air aspiration duration, min.;

а – the necessary minimal dust weight on the filter, mg;

C – MAC of the investigated dust, mg/m3;

W – the air aspiration speed, l/min.

The maximum makeweight has to be not more than 25-50 mg if the own filter mass (to 100 mg) is not too big.

The dust concentration (mg/m3) may be calculated using the following formula:

,

where: С – the dust concentration, mg/m3;

q 1 – the filter mass before air aspiration;

q 2 – the filter mass after air aspiration;

V0 – the sample air volume in standard conditions which is calculated using Gay-Lussac’s formula.


3.2. Aspiration-calculating method is used in two modifications.

Filters AFA used for determination of the mass dust content in the air are applied with filter surface to the object-plate (slide) and are held under acetone vapors for several minutes. The filter fabric melts to the transparent film and fixed dust particles can be seen through the microscope.

Samples received by both sedimentation and aspiration methods are studied using the microscope with ocular micrometer. The ocular micrometer is a scale on the round glass with diameter which is equivalent to the internal diameter of the microscope’s ocular.

The meaning of the scale interval of the micrometer has to be assigned before determination of the dust particles sizes. For this purpose the ocular micrometer with intervals from 0 to 50 is put in the ocular of microscope. The objective micrometer with scale interval of 10 μm is fixed on the microscope’s stage. Intervals of the ocular micrometer are combined with any interval of the objective micrometer. The scale interval is determined by the number of the ocular micrometer intervals which fit into the certain intervals of the objective micrometer (see fig. 12.3).

For example, 12 intervals of the ocular micrometer scale coincide with one interval of the objective micrometer scale which is 10 μm. One interval of the ocular micrometer thus equals to = 0.83 μm.

The dust particle sizes are determined by the application of the slide with the dust instead of the object-micrometer to the same optical system. For example, the biggest dust particle coincides to three intervals of the ocular micrometer scale. That is why the dust particle size is 0.83×3 = 2.49 μm.

Sizes of 100-300 dust particles are determined by the microscope in different parts of its view and then dust particles are grouped in according to their sizes (the data are signed out in the table 2 and “dust formula” is calculated. The “dust formula” is the percentage of the dust particles of each size in the whole sample. The dust hazard rate for respiratory track may be estimated according to the “dust formula”: the greater the percentage of the small dispersible dust the greater the danger of pneumoconioses development and general toxic effect.

Table 2

Calculation of the “dust formula”


Size of the dust particles, μm

Number of the dust particles

Percentage

Less than 2







2…5







5…10







Above 10







Total




100 %




Fig. 12.3 Determination of the meaning of the scale interval of ocular micrometer.

1 – ocular micrometer scale; 2 – objective–micrometer


Appendix 4


Determination of the dust concentration with dustmeter VKP-1 (ВКП-1)


The device VKP-1 (ВКП-1) is used for the dust concentrations in the air of the heated indoor industrial areas from 0.1 to 500 mg/m3. The device function is based on the aerosol particles electrization in the negative alternative corona charge field, and the following determination of their total charge, induced on the walls of the cylindrical measuring camera of air-absorbing part of the device. Determined under this condition, the total charge is proportional to the aerosol concentration in the air which has passed through the charging camera.

Device (dustmeter) setup. The “OPERATING MODE” tumbler should be turned on, the tumbler “DIAPASONS” put in position 1. Plug the device into the electrical supply network. The device is grounded automatically with the tripolar plug. The “OPERATING MODE” tumbler must then be put in the “CALIBER” position. The microampermeter pointer on 50 scale division is set up with “CALIBRATION” handle.

Order of testing. The “OPERATING MODE” tumbler is put into the “MEASURE” position, the microampermeter data is read after 10 sec. The measuring sub-diapason should be taken into the account. The dust concentration in the air of the industrial areas is determined in accordance to the calibration characteristic. If it is necessary repeat the measuring in the different diapason.

Put the “OPERATING MODE” tumbler in “OFF” position and “DIAPASONS” tumbler in position “4” after finishing the measuring, unplug the device.

The results of measuring using the device VKP-1 (ВКП-1) are assessed in accordance to the table 3.


Table 3


Table for the assessment of results measured with device VKP-1 (ВКП-1)





Quantity of the dust particles in 1 cm3 of the air

Clean air

from ten to hundred

Comparatively clean air (room, laboratory)

from 120 tо 500

The low dust content in the air, allowable in the industrial areas (breathing zone)

from 500 to 1 000

The medium dust content in the air, allowable in the industrial areas (breathing zone)

from 1 000 to 5 000

The high dust content in the air, allowable in the industrial areas (breathing zone)

from 5 000 to 20 000



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