Medicine

METHODS OF HYGIENIC ESTIMATION OF PHYSICAL FACTOR AT WORKPLACE. METHODS OF HYGIENIC ESTIMATION OF CHEMICAL FACTORS AT WORKPLACE. PROFESSIONAL DISEASES

METHOD DETERMINATION OF DUSTINESS AND CHEMICAL CONTAMINATIONS OF AIR IN OCCUPATIONAL ENVIRONMENTAL. METHOD OF HYGIENICAL ESTIMATION OF NOISE AND VIBRATION

                                    

Dangerous industrial hazards

(Abstract from State Standard 12.0.003 - 74)

 

According to this standard all dangerous industrial hazards are divided into 4 groups: physical, chemical, biological and psycho-physiological.

Industrial physical hazards are:

-       movable machines, mechanisms, unprotected movable elements of production equipment, feedstock, materials, goods that move, other mechanical agents;

-       hot or cold microclimate of the working zone, high levels of infrared radiation (hot shops in metallurgy industry, boiler shops etc.), hot water or steam;

-       increased or decreased barometric pressure and its leaps;

-       high noise level, vibration, infra- and ultra-mechanical fluctuations of air or hard surfaces;

-       high levels of radio region electromagnetic oscillations, electric magnetic fields of commercial frequency, static electricity;

-       high levels of ionizing radiation (X-radiation, gamma-radiation, corpuscular radiation);

-       insufficient or excessive illumination of work places, low contrast, high luminosity, its dazzle, unevenness, pulsation of the light, stroboscopic effect;

-       high dust content in the air, fuel and explosive gases (methane in the coal mines).

 

Group of chemical dangerous industrial hazards includes:

-       according to their action on organism - irritant, general toxic, sensibilizing, carcinogenic, mutagenic and teratogenic;

-       according to their penetration route into organism: through respiratory tract, digestive system, skin (chemical burns);

-       according to their tropism: pneumo-, neuro-, hepato-, hemato-, nephro-, dermato- and polytropic;

-       according to level of toxicity: extremely toxic (MAC in the air < 0.1 mg/m3 ), highly toxic (MAC 0.1 – 1.0 mg/m3), medium toxic (MAC 1.0 – 10.0 mg/m3), low toxic (MAC > 10,0 mg/m3).

 

Group of biological dangerous industrial hazards includes those biological objects, which impact on the workers causes diseases, poisonings and injuries:

-       zoonotic bacterial, viral, fungal infections (anthrax, foot-and-mouth disease, Bovine Spongiform Encephalophaty (BSE), tularemia), invasions, allergies (from animal and plant dust) etc.;

-       plant toxins and venoms (like snake hunters) etc.;

- biological production objects: antibiotics, protein-vitaminous concentrates, growth agents, bioactive preparations etc.

 

Group of psycho-physiological industrial hazards includes:

-       excessive physical activities: static (hold of heavy loads); dynamic (lifting and displacement of heavy loads and their intensity); hypodynamia, forced body position, overstrain of some organs;

-       neuropsychic overstrains: mental overstrains, overstrains of attention and analyzers, very rapid change of production processes, information, work monotony, psychological and emotional overloads (like “chief- subordinate” interrelations).

According to the character and extent of energy expenditure, physical labour is characterized by its weight and intensity, and mental activity, like operator’s – by its intensity.

According to the State Standard 12.1.005 – 88 “General hygiene and sanitary requirements for air in the working zone” physical labour is divided into light one (energy expenditure – below 150 large calories per year), medium complexity (150 – 200 large calories per year), heavy one (200 – 250 large calories per year), and very heavy labour (> 250 large calories per year).

According to its tension, mental, operator’s work is divided into: non-tensioned, slightly tensioned, tensioned, super tensioned.

In accordance to the listed agents of industrial hazards “List of occupational diseases and instruction for its application” was approved by the Order № 23/36/9 from 2.02.1995 of the Ministry of Social Policy and Ministry of Labour.

Occupational diseases caused solely by industrial and occupational hazards, their consequences in the near and distant future as well as consequences of non-occupational diseases caused by occupational hazards (like arterial hypertonia caused by vibration) were put on the list.

Acute and chronic occupational diseases and poisonings are recognized.

Acute occupational disease (intoxication) begins suddenly, after only one impact of a relatively high concentration of toxic chemical agents (during one shift) in the air of the working zone or levels or doses of other hazards.

Chronic occupational diseases occur as the result of long-term exposure to low (but exceeding MAC, MAL, MAD) concentrations, levels and doses of occupational and industrial hazards.

According to approved “List…” occupational diseases are divided into 7 groups:

1.   diseases caused by chemical agents: acute and chronic intoxications of different tropism (neuro-, hemo-, hepato-, nephro-, poli-, dermatotropic, allergic etc.);

2.   diseases caused by industrial particulate pollutants: black-lung diseases, dust bronchitis, rhino-pharyngolaryngitis, allergies;

3.    diseases caused by physical agents: ionizing radiations (acute, chronic radiation sickness, local radiation injuries, long-term consequences – malignant tumors); non-ionizing radiations (laser, ultraviolet, infrared); decompression - caisson sickness; acute, chronic overheating; noise, vibratory diseases etc.;

4.   diseases caused by overload and overstrain of certain organs and systems: coordination neurosis (at milkmaidens, violin players, linotypers), radiculitis, tendovaginitis, arthrosis, bursitis, thrombophlebitis; laryngitis at singers, teachers, progressive myopia etc.;

5.    diseases caused by biological agents: infectious and parasitogenic diseases at stock-breeders, vets, infectiologists, bacterial laboratory assistants etc.;

6.        allergic diseases: conjunctivitis, rhinitis, bronchial asthma, dermatitis, eczema, urticaria etc., that occur when one works with corresponding agents of plant or animal origin;

7.        neoplasms – malignant tumors when working with carcinogenic substances of  physical (ionizing radiations, ultraviolet radiation) and chemical (3, 4-benzpyrene, resins etc.) origin.

 

Considering listed industrial hazards and occupational diseases and poisonings that they can cause, a task of the physicians – specialists in occupational hygiene, occupational pathologists, and physicians of different specialties of medical departments of industrial plants and patient care and preventive institutions is:

-       to study hazards of industrial environment, engineering processes and their compliance with hygienic regulations;

-       to study impact of different hazards of industrial environment, (engineering process, air of the working zone, raw materials, half-products, end products, accompany products, wastes and industrial emissions);

-       to study state of health of workers, their general occupational disease incidence;

-       diagnostics and treatment of occupational diseases and poisonings, prevention and medical examination, sanatorium-and-spa treatment of the workers, participation in the work of Medical and Social Commission of Experts (MSCE), Medical Controlling Commissions (MCC), Medical and Labour Commission of Experts (MLCE) etc., examination commission of occupational pathology, ascertainment of disability etc.

 

Preventive medical measures must include:

-       participation in development of technical and engineering sanitation of working conditions (airing, packaging, automation, mechanization, remote control etc.);

-       scientific development of hygienic regulations, different sanitary legislation; Industrial Engineering (IE). (see appendices 3.1 -  3.7);

-       preventive and running check by sanitary inspectors;

-       health education and preventive work in the work collective (teaching sanitary regulations, use of overalls and personal protectors, clinical and preventive nutrition, water consumption schedule).

Methods and means of measurement of industrial hazards and working conditions (microclimate, noise, vibrations, natural and artificial illumination, electromagnetic radiation etc.) were learnt by students in the corresponding hygiene sections, therefore they are just mentioned in this lecture.

Methods and indications of environmental impact on organism and health were learnt by students in the previous sections of hygiene and physiology, pathologic physiology, biochemistry, lectures of clinical chairs, therefore in this lesson they are just listed.

Personal protective equipment of body, respiratory tract, eyes and ears are considered in “Personal hygiene” section.

Extract from State Standard12.1.005-76 «Air of the working zone.

General hygienic and sanitary requirements»

 

1.1.                     Optimal standards of temperature, relative humidity and air movement in the working zone of workshops

 

Season

Work category

Temperature, оС

Relative humidity, %

Air movement, m/sec

Cold and transitional seasons

Light – І

Moderate– ІІ а

Moderate–ІІ b

Hard - ІІІ

20-23

18-20

17-19

16-18

60-40

60-40

60-40

60-40

0.2

0.2

0.3

0.3

Warm season

Light – І

Moderate– ІІ а

Moderate–ІІ b

Hard - ІІІ

22-25

21-23

20-22

18-21

60-40

60-40

60-40

60-40

0.2

0.3

0.4

0.5

 

1.2.                     Allowable standards of temperature, relative humidity and air movement in the working zone of the workshops during cold and transitional seasons

 

         

Air temperature, оС

Relative humidity, %

Air movement, m/sec

Air temperature outside workplace

оС

Light – І

Moderate– ІІ а

Moderate–ІІ b

        Hard - ІІІ                       

19 – 25

17 – 23

15 – 21

13 - 19

75

75

75

75

0.2

0.3

0.4

0.5

15 – 26

13 – 24

13 – 24

12 - 19

 

3.3. Allowable standards of temperature, relative humidity and air movement in the working zone of the workshops at clear heat excess in warm season

Work category

Air temperature in premises, оС

Relative humidity, % in premises

Air movement, m/sec

higher at higher temperature and lower at lower temperature

 

with little surplus of clear heat

with considerable surplus of clear heat

with little surplus of clear heat

with considerable surplus of clear heat

Light – І

At most 3о above average outdoor air temperature at 13.00 of the most hot month but below 28о

At most 3о above average outdoor air temperature at 13.00 of the most hot month but below 28о

At most, at the cor-responding temperature

28 о – 55%

27 о– 60%

26 о – 65%

25 о– 70%

24 о– 75%

0.2 – 0.5

0.2 – 0.5

Moderate– ІІ а

0.2 – 0.5

0.3 – 0.7

Moderate–ІІ b

At most 3о above average outdoor air temperature at 13.00 of the most hot month but below 26о

At most 3о above average outdoor air temperature at 13.00 of the most hot month but below 26о

At most, at the cor-responding temperature

26 – 65%

25 – 70%

24 – 75%

0.3 – 0.7

0.5 – 1.0

Heavy -ІІІ

0.3 – 0.7

0.5 – 1.0

 

3.4. Air temperature outside permanent work places, оС, indoor

with little surplus of clear heat

with considerable surplus of clear heat

At most 3о above average outdoor air temperature at 13.00 of the hottest month

At most 5о above average outdoor air temperature at 13.00 of the hottest month

 

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

 

Substance

Value of

MAC, mg/m3

Class of hazard

Alumina – condensation aerosol

2

4

Alumina – disintegration aerosol

(Argil, fused corundum)

 

6

 

4

Boron carbide

6

4

Dolomite

6

4

Crystal silicon dioxide:

-       content in dust - above 70%

-       content in dust  - within 10 – 70%

-       content in dust - within 2 – 10%

 

1

1

4

 

3

3

4

Copper-nickel ore

4

4

Plant and animal origin dust with silicon oxide additive content of more than 10%

 

2

 

4

Industrial black soot with 3.4- benzpyrene additive content of less than 35 mg/kg

 

4

 

4

Content of natural and artificial asbestos in dust - more than 40%

2

4

Glass and mineral fiber

4

4

Cement, clay

6

4

Oil coke, shale coke, pitch coke

6

4

Coal with silicon oxide content of less than 25 %

10

4

Fused corundum with steel, chromium

6

4

 

3.6. Maximum allowable concentrations of hazardous substances in the air of working zone (selectively)

 

Substance

Value of

MAC, mg/m3

Class of hazard

Aggregative state *)

Nitric oxides converted to NO2

5

2

f

Amino plastics (molding powders)

6

3

а

Аmmonia

20

4

f

Arsenic anhydride

0.3

2

а

Selenium anhydride

0.1

1

а

Chrome anhydride

0.01

1

f

Anilin

0.1

2

f

Barium carbonate

0.5

1

а

Benzol

5

2

f

Beryllium and its compounds

0.001

1

а

3.4- benzpyrene

0.00015

1

а

Bromine

0.5

2

f

Gamma-hexachlorocyclohexane

0.05

1

а + f

Diethyl

0.005

1

f

Ethyl mercurous chloride (according to mercury)

0.005

1

а + f

*) а – aerosol; f – fumes and (or) gases; а + f – mixture of fumes and aerosol.

 

                                     Classification of a dust behind an origin and way of formation.

Dusts are solid particles generated by handling, crushing, grinding, and disintegrating organic and inorganic materials, such as rocks, ore, metal, coal, wood, and grains. The exposure of man to dusts can lead to a wide variety of respiratory diseases, including pulmonary fibrosis, obstructive lung disease, allergy and lung cancer. Toxic dusts may produce systemic poisoning after inhalation, or act as skin irritants to produce dermatitis, allergic reactions and cancer.

For the origin the dust is divided into such groups:

         1) Organic (vegetative, animal);

         2) Inorganic (mineral, metal);

         3) Mixed (artificial, plastic).

There are classifications of the dust from dispersing and ways of formation, according that distinguish aerosol of disintegration and aerosol of condensation. Aerosol of disintegration formation in cleavage or drilling (boring) any firm substance and consist, in general, from the metal steam and their combination, which in cooling turn in firm particles (for example, condensate of metal steam in electric welding).

         For the disperse the dust is visible – the size of speck of dust is >10 nm, microscopic – the size is 10 - 0,25 nm, and ultramicroscopic – the size is < 0,25 nm.

2. On what properties the harmful action of a dust on organism depends?

The harmful action of a dust on organism depends on next properties:

- from the morphology of dust particles (wooden dust, mineral dust, metal dust, glass dust);

- from the forms particles of a dust;

- from the solubility of dust  particles in water .

3. Kinds of harmful action of a dust on organism.

Dust influences on:

-        system of breath and causes such specific illness like  silicosis, antracosis, and others  pneumoconiosis, pneumonias, and influences on the top respiratory ways; not specific illness like cancer, tuberculoses;

-        on skin (irritation, damage, pollution);

-        on eyes (irritation, injure, pollution).

Dust is everywhere! It seems to enter from fissures and cracks and then settles out on almost everything in sight. A few days without dusting are enough for one to be able to observe fine dust deposited everywhere, especially on the dark furniture.. With time, the dust will become thicker and more noticeable. For people who are particularly sensitized or allergic to dust, certain kinds of dust can cause asthma and even bronchitis. However, for the amateur microscopist who is always looking for samples to observe, dust can be a fascinating area of study, especially when the focus is on the nature and origin of airborne particles.

Samples of dust can be collected in many different environments where they will exhibit different compositions. For example, on an open surface in a natural environment within continental Europe, you can expect to find fragments of plants, moulds, insects, pollen, spores, microorganisms and mineral dust. You may even find dust from the Sahara desert or micrometeoric dust from outer space. In a forested area, biological detritus is common, while in a desert environment, the mineral particles is more prevalent. In urban environments near cities, you will mainly find particles from the emissions of motorized vehicles and from the power plants. While the quantities are minute, you will also find particles released from the wearing of brake linings and rubber tires as well as mineral particles. In the floor sweepings you collect from a dinning room with a broom, you will likely find bread crumbs, sand grains including human and pet hairs. In the dust collected on a bookcase you should find textile fibers and thin fragments of biological and mineral material. In a bedroom, dust should be richer of textile fibers, but you may also find dust mites and their dreaded excrements. In machine shops, laboratories and factories the composition and the nature of the dust particles will vary according to the type of activities conducted there.

1.    Origin of the dust

 

1.1.     The dust sources in the air may be:

-            volcanic eruptions;

-            cosmic dust (meteorite combustion in the atmosphere);

-            dust stormswood ibet, China), soil, sand;

-            agricultural dustfrom 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.

 

2.    Classification of the dust

 

2.1.     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);

2.2.     By influence on organism:

-       indifferent;

-       toxic;

-       dermatotropic;

-       pneumotropic;

-       allergenic;

-       cancerogenic and others.

2.3.     By form of the particles:

-       amorphous;

-       fibrous;

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

2.4.          By size of the particles:

-       aerosuspensionsparticles with size more than 100 micrometers;

-       aerosols:  large dispersiblesizes 100-10 μm. (proper dust)

medium dispersiblesizes 10 –0.1 μm. (cloud)

small dispersiblesizes 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);

-         pneumoconiosesfibrous 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 cancerunder 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.

 

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 sedimentators 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 methodthe 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. Thedust formulais 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).

 

 

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;

  V0the 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

 

 

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 DIAPASONSput in position 1. Plug the device into the electrical supply network. The device is grounded automatically with the tripolar plug. The OPERATING MODEtumbler must then be put in theCALIBER position. The microampermeter pointer on 50 scale division is set up with CALIBRATIONhandle.

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

 

 

HOW TO COLLECT DUST

How do you collect dust samples to observe with a microscope? If the dust has settled on a smooth surface, you can collect it with a clean finger, or you can transfer it onto a microscope slide with a small brush. Perhaps, the best way is to use a pipette to apply water on the dusty surface and then collect your sample using the pipette . You can repeat this operation several times using the same water until you have collected a sufficient quantity of dust suspended in the water. Another method is to place a microscope slide in a selected location and wait until enough dust has settled on it. Obviously, you should not be in a hurry if you are going to use this method of sampling! If the quantity of available dust you want to collect is small and you do want to avoid contaminating it, you can use an adhesive tape to collect your sample.

Yet another method consists in using a vacuum cleaner with a filter placed over the intake of the hose. If the filter causes too much of a restriction, this can strain the motor of the vacuum cleaner and eventually burn it out. To avoid damaging your vacuum cleaner, you should use a porous filter media, or allow some air to bypass the filter. It is possible to find vacuum cleaners on the market that are equipped with a specially liquid chamber to filter the air. If you have one of these units, after cleaning your carpets, you can collect a sample of the water collected in the filter unit and observe the particulate material in suspension in the water.

To collect dust outfall in the open air, you can use a flat surface. To prevent the wind from blowing your sample away, this surface must be shielded by protective baffles. To accomplish this, a small plastic aquarium is suitable. To avoid collecting rain, you can place a lid at about 40 cm above the container. In any event, such a lid, you will not allow you to collect micrometeors. To do so you can observe the particles that collect in the water spout of your house. Bear in mind that dust can also contain bacteria and other microorganisms. So, when you are handling samples of dust, whether dry or humid, you should always observe proper hygiene measures like wearing latex or rubber gloves and washing your hands after handling any potentially contaminated dust or materials.
SOME OBSERVATIONS

To take these pictures I used an Optech Biostar B5 microscope and a Nikon Coolpix 800 digital camera with the resolution of 1600x1200 px. For the purpose of this publication, I reduced them to 400x300 px.

   

Figure 1 - Unstained sample of dust. 250                                                                          Figure 2 - Sample of dust stained with eosin.

To distinguish between biological and mineral materials, I collected a second sample of dust and stained it by soaking it in an eosin solution for two minutes. To remove the excess eosin, I used a pipette with water and allowed some drops of water flow between the slides. This surely removed many of the finer particles but there were enough particles remaining to observe under the microscope. This staining technique demonstrated that the scaly material on my bookshelf was for the most part biological in origin. Because the bookcase is near a door that opens onto a garden, it is likely that a good part of the biological material was vegetable in origin. According researchers, a large part of the dust that collects on the furniture in a house is composed of dead skin cells and dandruff. But how do you distinguish vegetable material from animal tissue? Usually, the vegetable cell have cellular walls that are thicker than animal cells.

Figure 3 - Textile fibers. The different colour of these filaments indica-
tes their origin from different fabrics. Sample stained with eosin. 250 X.

Figure 4 - A thorny filament of unknown origin. 250 X..

Figure 5 - Unknown fragment. 250 X.

Figure 6 - Fragment of vegetable tissue. 250 X.

Figure 7 - Tuft of vegetable filaments. 250 X.

Figure 8 - Scale of a butterfly wing. 400 X.

Figure 9 - Tuft of vegetable filaments, textile fibers and
biological fragments.
Sample stained with eosin. 250 X.

Figure 10 - Vegetable tuft. Sample stained with eosin. 250 X.

Figure 11 - Mushroom spores stained with eosin. 400 X.

Figure 12 - Cotton fibers after staining with eosin. 250 X.

In the samples of dust collected in the bookcase, I found different materials that required further investigation. The textile fibers are comparatively easy to identify. This is generally the case with wool, cotton and artificial fibers. In addition, several fibers of different shapes of uncertain origin were also noted. I noticed that the cotton-like fibers didn't take the colour of eosin very well or not at all. To determine if these were indeed cotton fibers, I took a little cotton batten and a fragment of optical paper, which are both composed of cellulose. I immersed both samples in eosin for two 2 minutes. After rinsing them, the staining disappeared. My observation through the microscope confirmed that the cellulose had not been stained by the eosin as shown in Figure 12.

AEROSOLS

The discussion so far has focused on dust, which consists of relatively coarse particles. These particles eventually settle out under of their own weight. There are also very tiny particles of liquids or solids, which tend to be airborne and stay suspended in the air for long periods of time. These are called aerosols. Actually, airborne dust contains extremely minute particles that are so small that you cannot even see them under microscope in addition to the particles already visible with a microscope, like the pollen. In fact most of dust is made up by particles that are coarse enough to settle out in relatively short periods of time, while the material that is much finer tends to stay suspended in the air. With the optical microscope, only the larger particles can be observed, while the smallest ones are only visible with a scanning electron microscope (SEM). The study of aerosols is actually quite an important area of interest that there is an entire branch of research dedicated to their study.

Some of the fields of study related to aerosols are as follows:

·                    industrial applications of the aerosols like industrial painting systems, atomizers for agriculture, cosmetics, etc.

·                    influence of the aerosols on the atmosphere due to particles in suspension due the human activities, forest fires and volcanoes eruptions reflect part of the sunlight and influence the climate of the Earth;

·                    influence of the aerosols on the human organism.

The size of the particles suspended in air is important. Our nose is able to stop the bigger particles suspended in air, but those smaller than 10 μm, called pm10 (from: "particulate matter"), are able to reach the pulmonary alveolus where the exchange oxygen/carbon dioxide occurs. The presence and the accumulation of these particles on the lungs can originate diseases.

Aerosols also occur in human environments. Fog, for example, is an aerosol. It is harmless, but some types of aerosols can be harmful to living organisms. Toxic compounds in the form of aerosols can be found in industrial environments like paint shops, steel foundries and construction sites. Outdoor environments like flowery meadows and woods will usually have airborne pollen particles and spores which may cause allergies and asthma for some sensitive individuals. Moreover, in some circumstances aerosols may contain bacteria and viruses.

Often, the indoor air quality of our homes can be affected by aerosols. Kitchens, in particular, may produce aerosols composed of extremely small particles of cooking oils and unburnt gas. Vacuum cleaners, which we use to collect dust, are used to collect larger particles, but they can also release the most minute and more harmful particles. To minimize the spreading of aerosols, the vacuum cleaners can be equipped with high efficiency filters at the outlet. These are called HEPA filters. Whenever you are sweeping or using a vacuum cleaner, it is a good practice to wear a mask. Vacuum cleaners equipped with water filters, in which the aspirated air is sparged through water, release smaller quantities of fine airborne particles. In the bedrooms where people use wool or down feather in their mattress, pillows or blankets, it likely that you will find dust mites. Dust mites produce excrements which may cause allergic reactions for certain individuals who are particularly sensitive to these allergens. Carpets may also spread dust mite excrements and fine particles when people simply walk over them.

DUST PATHOLOGY

Silica

Free silica (SiO2) in the form of quartz, tridymite, or cristobalite, can cause silicosis, whereas silicates do not usually present a significant health hazard. Drilling, crushing, grinding or handling quartz sand produces quartz dust. Occupational exposure occurs in mines and quarries, not only where quartz is mined but also in metal mines where the rock between the veins of ore contains free silica. Exposure may also occur in factories where quartz sand is used, e.g., in steel works and iron foundries, and in the ceramics and glass industries.

Entry into the body is by inhalation. Particles larger than 5 microns in size are generally deposited in the upper respiratory tract and bronchi, and are gradually removed by the ciliary’s epithelium (lung clearance). Smaller particles are deposited in the alveoli of the lungs and then gradually transported to the corresponding lymph nodes. The proportion of the dust that remains in the lungs does so for life, since quartz particles are practically insoluble; connective tissue is then formed around the particles so that nodules are produced. The mechanism whereby this occurs is not fully understood. The nodules may gradually aggregate and massive pulmonary fibroses may develop later and progress over a number of years, leading to emphysema with gradual impairment of lung function. Subjective symp­toms, which develop rather late, include cough and shortness of breath (dyspnoea) at effort. Silicosis is often combined with tuberculosis. The disease is gradually progressive and death occurs from right heart failure or from pulmonary tuberculosis.

Asbestos

Asbestos is a mixture of magnesium and iron silicates in fibrous form. It appears as dust in the form of fine fibres in the air.

Occupational exposure occurs in asbestos mines and wherever asbestos products are used, for instance, in handling asbestos-cement products used in the building industry (roofing sheets, wallboard and pipes). Exposure may also occur in the textile industry in the manufacture of fireproof materials, such as asbestos clothes or brake linings for motor vehicles. Asbestos is also used for insulation and fire protection purposes in shipbuilding, house building, and in the under sealing of cars.

Asbestos enters the body by inhalation, and fine dust, containing fibres of diameter less than 5 microns and length greater than 5 microns may be deposited in the alveoli. The fibres are insoluble. The dust deposited in the lungs causes fibrosis, pleural plaques, mesothelioma and lung cancer.

Asbestosis results in impaired lung function after five to ten years. The symptoms are shortness of breath, chest pain, and later bronchitis with increased sputum and clubbing of the fingers. Radiography of the lungs shows certain characteristic changes. Mesothelioma Lawyers: Malignant Asbestos Mesothelioma Help

 

4. Pneumoconiosis, a general term for any one of several lung diseases caused by breathing dust from industrial occupations like coal mining, sand blasting, and stone cutting. Years of continual exposure to industrial dust can cause the formation of spots (macules), lumps (nodules), or fibrous growths in lung tissue, causing permanent damage or destruction of these tissues. Smoking can complicate or worsen the conditions. Symptoms of the disease include shortness of breath, labored breathing, coughing, and production of phlegm (mucus secreted in the respiratory system when infections are present). Other, often fatal, illnesses such as cancer, tuberculosis, emphysema, or heart disease may also develop.

Both inorganic dust (from minerals) and organic dust (from plants) can produce pneumoconiosis. For example, inhalation of inorganic irritants such as coal dust, particularly from mining hard coal, or anthracite, causes the condition known as black lung disease, coal worker’s pneumoconiosis, or anthracosis. Silica dust from quarrying, mining, or sand blasting causes the disease silicosis. The fine particles and dust from asbestos, a fibrous material commonly used in construction and insulation until its use was curtailed by the Environmental Protection Agency in 1989, causes asbestosis and mesothelioma, a cancer of the chest lining. The inhalation of organic irritants most often found in textile mills such as the dusts of cotton, flax, hemp, and jute causes byssinosis, or brown lung disease. Another type of pneumoconiosis takes the form of hypersensitivity to irritants, fumes, and vapours in the workplace from substances like cadmium, beryllium, chlorine, and fluorine.

Treatment can only relieve the symptoms of pneumoconiosis. Treatment options include medication, removal of the patient from the workplace, providing dust control through added ventilation, or the use of personal protection devices like dust masks.

5. Methods of definition dusting of air of industrial rooms and atmospheric air.

             1) aspirative method;

             2) sedimentative method;

         3) Konimetrie method - sedimentative, morfometria

The hygienic estimation of a dust includes the quantitative and qualitative characteristic.

During a quantitative estimation of the dust factor use the aspirative (weight) and sedimentative methods of sampling of air.

Aspirative method is based on a delay of a dust from known volume of air on the filter, which then weigh.

Sedimental method consists that the dust settling from air gathers for the certain period of time with a strictly defined surface. Usually 1-5… 20 cm are applied to this purpose and height 25... 30 cm, and also special devices – glass sedimentators, faience or vinil jars with diameter of an aperture, allowing to isolate the certain volume of researched air to besiege (halt) on glass a dust and to count up motes under a microscope.

6. Devices for definition of a dust content air are electrical aspirator.

Electrical aspirator, which consist of:

1)     the socket for connection;

2)     cord to the device;

3)     the toggle – switch of inclusion;

4)     the precautionary valve;

5)     handles of the gate for regulation  speed of aspiration;

6)     reometer;

7)      the plag of grounding;

8)     unions for connection of pipe to allonge.

 

7. Preventive measures for the prevention of harmful influence of an industrial dust.

All preventive measures for the prevention of harmful influence of an industrial dust divide on general and personal.

  General preventive measures are:

        1) Technical: 

               a) Change of technological process;

      b) Replacement of materials, which have quartz;

      c) Work in a damp premise (room);

      d) Mechanical ventilation;

2) Medical-preventive;

3) Sanitary-technical.

Personal preventive measure:

 1) Use of respiratory mask;

    2) Periodic medical reviews;

    3) Personal hygiene.

 

8. Extreme admitted (extreme allowed, extreme allowable) equal dusting of industrial premises (rooms).

According to standard, established border permissible concentration dust of air in work's rooms, which depending from character and content in it SiO2

Kind of dust

Content of free SiO2 %

MAC (maximum admissible concentration ), mg/m3

Coal-dust

10-70

2

Coal-dust

5-10

4

Anthracite

to 5

6

Stone coal, brown coal

to 5

10

 

Dust meter

The device is used for calculating concentration of dust in the closed room if amount of dusty in air is from 0,1 to 500 mg/dm3.

The device consists of airtaking and electronic parts. Last one consists of amplifier, detector, stabilizer of energy, supply block and accumulating block.

The principle of work is based on electrification of dust parts in the field of changeable negative short discharges with next calculating of their common store of energy and that inductive point at the walls of cylinder-measuring airtaking camera. Measured common store of energy is directly proportionally to concentration of aerosol that goes through chargeable camera.

 

Fig. Filter

  

   Fig. Apparatus  for measure gas

 

Asbestos

Asbestos (Greek a-,“not”; sbestos, “extinguishable”), the fibrous form of several minerals and hydrous silicates of magnesium. The name may also be applied to the fibrous forms of calcium and iron. Asbestos fibers can be molded or woven into various fabrics. Because it is nonflammable and a poor heat conductor, asbestos has been widely used to make fireproof products such as safety clothing for fire fighters and insulation products such as hot-water piping. The first recorded use of the word asbestos is by Pliny the Elder in the 1st century ad, although the substance itself was known as early as the 2nd century bc. The Romans made cremation cloths and wicks from it, and centuries later Marco Polo noted its usefulness as cloth.

Asbestos is of two principal classes, the amphiboles and the serpentines, the former of relatively minor importance. Chrysotile, in the serpentine class, constitutes about 95 percent of the world supply of asbestos, of which three-fourths is mined in Quebec. Other large deposits exist in South Africa. In the United States, California, Vermont, and Arizona are the leading asbestos-producing states; however, the majority of United States deposits are of no commercial value.

Asbestos is obtainable by various underground mining methods, but the most common method is open-pit mining. Only about 6 percent of the mined ore contains usable fibers.

The fibers are separated from the ore by crushing, air suction, and vibrating screens, and in the process are sorted into different lengths, or grades. The most widely used method of grading, the Quebec Standard Test Method, divides the fibers into seven groups, the longest in group one and the shortest, called milled asbestos, in group seven. The length of the fibers, as well as the chemical composition of the ore, determines the kind of product that can be made from the asbestos. The longer fibers have been used in fabrics, commonly with cotton or rayon, and the shorter ones for molded goods, such as pipes and gaskets.

Asbestos has been used in building-construction materials, textiles, missile and jet parts, asphalt and caulking compounds and paints, and in friction products such as brake linings. Exposure to asbestos fibers and dust, however, can cause asbestosis, a disease of the lungs caused by the inhalation of asbestos particles, and, after a latent period of up to 30 years and more, various cancers, especially lung cancer and mesothelioma, which is an inoperable cancer of the chest and abdominal lining. At present no wholly satisfactory substitutes are available for asbestos in many of its applications; because of health risks posed by asbestos use, however, research into replacements has been accelerated. In 1986 the Environmental Protection Agency proposed an immediate ban on the major uses of asbestos and a complete ban on all asbestos products within the next decade. This proposal was partially overturned by the U.S. Court of Appeals, which limited the ban to asbestos flooring and new products using asbestos.

Mesotheliona Symptoms and Diagnosis

Mesothelioma Symptoms

The most common symptoms of pleural mesothelioma are difficulty in breathing, chest pain, or both. Occasionally, a patient may not have mesothelioma symptoms at diagnosis. Other less common symptoms include weight loss, fever, night sweats, cough, and a general feeling of not being well. Mesothelioma symptoms of peritoneal mesothelioma may include swelling, pain due to accumulation of fluid in the abdomen cavity, weight loss, and a mass in the abdomen. Other mesothelioma symptoms of peritoneal mesothelioma may include bowel obstruction, blood clotting abnormalities, anemia (a lowered red blood cell count), and fever.

Mesothelioma Diagnosis

It can be difficult to diagnose mesothelioma because many of the mesothelioma symptoms are similar to those of a number of other conditions, including lung cancer and other types of cancers. At the time of diagnosis, your doctor will first do a physical examination and complete a medical history, including asking about the possibility of prior exposure to asbestos.

Although there is no early detection test for mesothelioma, there are several tests that can be used to help in making the diagnosis of mesothelioma, including a chest x-ray, a CT scan, or an MRI scan. A chest x-ray yields an image of the lungs that will show many types of abnormal changes.

A CT
scan (computed tomography) is a type of x-ray, but it uses a computer rather than film to create detailed images. An MRI scan (magnetic resonance imaging) uses magnetism, radio waves, and a computer but does not utilize radiation to create a clear image. These tests help your doctor differentiate mesothelioma from other lung tumors as well as determine where the tumor is and its size.

Doctor may need to remove a tissue sample from the tumor (a biopsy) or draw fluid (aspirate) from it to confirm it to confirm the diagnosis. This can be done in several ways.The simplest way to obtain tissue samples involving making a small incision and placing a flexible tube in the area of the tumor. This is called a thoracoscopy if it is done in the chest area. A laparoscopy is the same procedure, but done in the abdominal cavity. A tube that is that is attached to a video camera is placed so that the doctor can look inside the body. A tissue sample may be taken at the same time. Sometimes, however, a more extensive surgical procedure may be advisable. A thoracotomy can be done to open the chest to take a tissue sample and, if feasible, to remove most or all of the visible tumor. If this procedure is done in the abdominal cavity, it is called a laparotomy.

At other times, a mediastinoscopy may be done in which a very small incision is made just above the sternum (breast bone) and a tube inserted just behind the breast bone. This lets the doctors look at lymph nodes. This are small, bean-shaped structures that are an important part of the body's immune system, and they contain cells that help your body fight infection as well as cancer. This test will give the doctor more information on the type of cancer and whether it has spread to other areas. The tissue samples taken in these procedures are analyzed by looking at them under a microscope in order to determine whether the tumor is a mesothelioma or some other type of cancer.

Asbestos - Wikipedia, the free encyclopedia

Asbestos | Basic Information | Indoor Air | Air | US EPA

Coal dust

 http://www.nlm.nih.gov/medlineplus/ency/imagepages/1603.htm

As coal is blasted, shredded, and hauled in a mine, large amounts of coal dust are produced. Coal dust is extremely flammable, and if ignited it can be more violently explosive than methane. Miners can reduce the buildup of coal dust by injecting pressurized water into coal beds before the coal is blasted or cut. Other methods to reduce coal dust include washing the dust from mining surfaces with water or covering it with dust from incombustible (nonflammable) rock.

Miners who inhale coal dust over a prolonged period can damage their lung tissue. Often, these miners develop spots, lumps, or fibrous growths in their lungs, a condition known as pneumoconiosis, or black lung disease. Furthermore, black lung disease can develop into other, often fatal illnesses, including heart disease, emphysema, and cancer. To protect miners from black lung, many mines are equipped with coal-dust filtering units.

Coal, solid, dark-colored fuel found in deposits of sedimentary rock. Coal is burned to produce energy and is used to manufacture steel. It is also an important source of chemicals used to make pharmaceuticals, fertilizers, pesticides, and other products. Coal comes from ancient plants buried over millions of years in the earth’s crust. Coal, petroleum, natural gas, and oil shale are all known as fossil fuels because they come from the remains of ancient life buried deep in the earth.

Dust, fine particles of organic and inorganic substances suspended in the atmosphere. The substances include animal and vegetable fibers, pollen, silica, bacteria, and molds. In some cities atmospheric dust also contains a large number of smoke particles and tarry soot particles. In an industrial city the air may contain more than 3 million particles per cu cm (more than 50 million per cu in), but above the middle of the ocean or in high mountains the count may be just a few thousand per cu cm. The size of dust particles varies from about half a micrometer (0.00002 in) to several times this size. The particles remain suspended in the air for long periods of time and may be carried great distances.

Atmospheric dust has two important physical properties: its ability to scatter light of short wavelengths and its ability to serve as nuclei for the condensation of water vapor. Mist, fog, and clouds would never occur but for the presence of dust particles in the air.

The heavy concentration of dust in the air over large cities is a serious pollution problem. In places such as flour and sugar mills and coal mines a concentration of flammable particles constitutes an explosion hazard. Silica particles in dust are destructive to machinery because of their hardness; they can also be injurious when inhaled.To obtain dust-free air, filters have been devised using either cloth or water. Dust and smoke may be removed from exhaust stacks of industrial plants by such devices as the Cottrell precipitator.

 

http://www.humanillnesses.com/original/Pan-Pre/Pneumoconiosis.html

Gases

Because coal and natural gas form by similar natural processes, methane (a principal component of natural gas) is often trapped inside coal deposits. Gases trapped in deeper coal beds have a harder time escaping. Consequently, high-grade coals, which are typically buried deeper than low-grade coals, often contain more methane in the pores and fractures of the deposit. As coal miners saw or blast into a coal deposit, they can release these methane pockets, which may explode spontaneously, often with deadly results. Miners use a technique called methane drainage to reduce dangerous releases of methane. Before mining machinery cuts into the wall face, holes are drilled into the coal and methane is drawn out and piped to the surface.

Coal miners also risk being exposed to other deadly gases, including carbon monoxide, a poisonous by-product of partially burned coal.

Carbon monoxide is deadly in quantities as little as 1 percent. It is especially prevalent in underground mines after a methane explosion. In the early 1800s, after a gas explosion, coal miners used canaries to test for carbon monoxide. If the canary died, the miners increased ventilation in the mine to remove the carbon monoxide. The miners then conducted the same test with another canary and repeated the process until a bird survived. Miners also tested for carbon monoxide and methane with a small flame. If the flame’s size increased, methane was present in the air; if the flame went out, carbon monoxide was present.

Other dangerous gases locked inside coal deposits include hydrogen sulfide, a poisonous, colorless gas with an odor of rotten eggs, and carbon dioxide, a colorless, odorless gas. To prevent injury from inhaling these gases, underground coal mines must be sufficiently ventilated. Often, the total weight of air pumped through the mine exceeds the total weight of coal removed.

Air-Conditioning

A number of manufacturing processes, such as those used in the production of paper, textiles, and printed matter, require air conditioning for the control of conditions during manufacture. Air conditioning of this kind usually is based on adjusting the humidity of the circulated air. When dry air is required, it is usually dehumidified by cooling or by dehydration. In the latter process it is passed through chambers containing adsorptive chemicals such as silica gel. Air is humidified by circulation through water baths or sprays. When air must be completely free of dust, as is necessary in the manufacture of certain drugs and medical supplies, the air-conditioning system is designed to include some type of filter. The air is passed through water sprays or, in some filters, through a labyrinth of oil-covered plates; in others, dust is removed electrostatically by means of precipitators (see Electrostatic Precipitator).

Centralized air-conditioning systems, providing fully controlled heating, cooling, and ventilation, as required, are employed widely in theaters, stores, restaurants, and other public buildings. Such systems, being complex, generally must be installed when the building is constructed; in recent years, these systems have increasingly been automated by computer technology for purposes of energy conservation. In older buildings, single apartments or suites of offices may be equipped with a refrigerating unit, blowers, air ducts, and a plenum chamber in which air from the interior of the building is mixed with outside air. Such installations are used for cooling and dehumidifying during the summer months, and the regular heating system is used during the winter. A smaller apparatus for cooling single rooms consists of a refrigerating unit and blower in a compact cabinet that can be mounted in a window.

The design of an air-conditioning system depends on the type of structure in which the system is to be placed, the amount of space to be cooled, the number of occupants, and the nature of their activity. A room or building with large windows exposed to the sun, or an indoor office space with many heat-producing lights, requires a system with a larger cooling capacity than an almost windowless room in which cool fluorescent lighting is used. The circulation of air must be greater in a space in which the occupants are allowed to smoke than in a space of equal capacity in which smoking is prohibited. In homes or apartments, most of the cooled or heated air can be recirculated without discomfort to the occupants; but in laboratories or factories employing processes that generate noxious fumes, no air can be recirculated, and a constant supply of cooled or heated fresh air must be supplied.

Air-conditioning units are rated in terms of effective cooling capacity, which properly should be expressed in kilowatt units. Usage still supports the term ton of refrigeration, which implies the amount of heat that would have to be absorbed to melt a ton of water-ice in 24 hours, or 12,000 Btu/hour equal to 3.5 kw—a Btu is the amount of heat removed from 1 lb (0.45 kg) of water when its temperature is lowered by 1° F (5/9° C). Horsepower ratings were formerly used for small air conditioners, but the term is misleading because a horsepower (or 0.746 kw) represents work power and not cooling. It came into use because under usual summer conditions a motor of one horsepower could support 3.5 kw of cooling, the equivalent of a ton of refrigeration.

Ventilation hygiene inspection, air duct cleaning equipment

DuctControl Maxi

A remote controlled video/digital camera system using a built-in mini tractor, which can be used for visually monitoring cleaning quality and microbial and other sampling methods and accessories.

  Temperature measurement

  Airflow measurement

  Relative Humidity

  Dust sampling

  Instant display gas meters

DuctControl Mini

A light hand cotrolled version for vertical ducts by which it is possible to survey cleaning needs, and check the quality of cleaning afterwards.

 

 

 

 

 

Special Cleaner 20
Electrically driven cleaning equipment with a wide range of accessories.
Ideal for small ducts.

Hydmaster
Powerful remote controlled hydraulically driven cleaning equipment with optional integration of video camera to the brush unit for real time control of cleaning quality.
Hydmaster has a wide range of accessories

HepaClean 4000
A low-pressure vacuuming unit that is adaptable to the maintenance opening or air valve site of the ventilation duct. The other valves are then covered. First the branches of the duct are cleaned using a rotary brush. Powerful airflow (10 – 20 ms/s) is needed to carry the loosened dirt into the collecting filter bag of the low pressure vacuum unit. Then the filtered exhaust air is conducted outside the building. A High Efficiency Particulate Air (HEPA) filter is used when there is not a possibility to conduct the air out of the facility.

 

The ventilation system in general

Inspections of the cleanliness of ventilation ducts have normally been done by taking samples and making sensory inspections via the inspection hatches and at the incoming or outgoing air valves. The ducts have not normally been inspected throughout their whole length, and post-cleaning quality assurance inspections have normally been done from the inspection hatches only.

Lifa Air Ltd has done, and continues to do, much innovative development work to ensure that cleanliness inspections of the ventilation system are done thoroughly and well. Lifa Air Ltd has developed remote-controlled video camera robots and systems by which it is possible to survey cleaning needs, and check the quality of cleaning afterwards.

40 % of the contaminants in indoor air come with the incoming air via the ventilation system. The distances between filters in these incoming air ducts are often too long, and impure air may flow past them. Regardless of the filters in the ventilation system, some particulate contaminants from the outdoor air will enter the system and accumulate on the inner surfaces of the ventilation equipment or flow with the incoming air into the ventilated spaces themselves. And that's not all. Contaminants may accumulate during the manufacture, transport, storage and installation of the ventilation equipment, and thus lower the quality of the incoming air. The contaminants originating from equipment manufacture include oil residues in the ducts. Equipment which is transported and stored in unprotected form may collect contaminants from the outdoor air and the ground. During installation, particulate contaminants such as cement dust and metal powder may also accumulate.

The dirt that collects in ventilation equipment and on duct walls and in various heat recovery, refrigerating, humidifying and air distribution equipment may act in humid conditions as a fertile soil for microbes.

The different kinds of indoor air problems derive mainly from a lack of regulations and maintenance, and partly from poor planning. Almost anything can be found in ventilation ducts that have not been cleaned - ranging from building waste to bird carcasses and excrement. Air inlets polluted by organic waste may become colonies of microbiological compounds which spread with the ventilation system throughout the whole building.

Ventilation system contaminants

Examples of various contaminants which are found in ventilation ducts or equipment and in cooling systems.

The particulate contaminants accumulated on the surfaces of ventilation systems, their sources and period of accumulation.

Contaminant

Organic dust
Bacteria
Fungi
Pollen
Algae
Plant parts & insects
Protozoa
Viruses

Inorganic dust
Inorganic dust from ground
Coal dust
Flue dust
Soot
Heavy metals
Cement dust
Metal dust
Oil
Inorganic fibres
Lubricants & grease

Contaminant Source

Organic nature
Industrial processes
Birds
Cooling towers
Water systems
Air humidifiers
Damp, wet materials
Excrement of arachnids

Industrial traffic
The raw materials of sheet metal
Sound and heat insulation made of mineral fibre
Motors, gears and lubricants of fans

When accumulated

Use of ventilation system.
Storage, transport and installation of ventilation equipment.

Use of ventilation system.
Installation of ventilation system.

Is our present knowledge enough to identify all the effects of ventilation system contaminants on people's living environment and health? For example, if bird droppings get into the ventilation system, they may contain Histoplasma and Cryptococcus fungi or other excrement-based fungi and bacteria. What is the risk to a hospital, if these fungi, when inhaled, lead to infections in patients with immunity deficiencies?

Regulations on cleaning ventilation ducts

Until now, ventilation systems have been cleaned voluntarily in Finland. The regulations affecting ventilation systems have been drawn up to cater for fire safety, and thus they seldom relate to incoming air ducts. On the other hand, the dust and grease that accumulate in the exhaust air ducts of buildings have been regarded as a fire risk, and their cleaning is therefore officially regulated.

According to the regulations of Finland's Ministry of Internal Affairs, ventilation equipment must be cleaned at least once per year for the sake of fire safety in the following types of premises:

·                    premises for professional food preparation

·                    industrial premises in which air ducts accumulate much flammable material

·                    premises where flammable liquids are used or made

Ventilation equipment must be inspected at no longer than 5-year intervals in:

  nursing, service and penitentiary institutions

  places of public accommodation and/or catering (hotels, restaurants, etc.)

Finland's Indoor Air Society has defined cleanliness classes for ventilation systems. Two classes, C1 and C2, are used for new ventilation systems. Class 1 signifies the best possible level that can be installed in work and residential premises, while class 2 is a level that meets the official requirements.

 

 

PHYSICAL AGENTS AND CONDITIONS

The hazardous physical agents and conditions considered here are the following: noise, vibration; unsatisfactory lighting conditions; ultraviolet radiation; and heat and cold.

NOISE

Noise it is sound vibrations of a different frequency and different loudness.

Noise, in physics, an acoustic, electric, or electronic signal consisting of a random mixture of wavelengths. In information theory, the term designates a signal that contains no information. In acoustics, “white” noise consists of all audible frequencies, just as white light consists of all visible frequencies. Noise is also a subjective term, referring to any unwanted sound. Noise pollution is a serious environmental problem, particularly as sound levels above a certain intensity can be physically damaging.

Noise Pollution or Sound Pollution, exposure of people or animals to levels of sound that are annoying, stressful, or damaging to the ears. Although loud and frightening sounds are part of nature, only in recent centuries has much of the world become urban, industrial, and chronically noisy

Sound intensity is measured in units called decibels. The decibel scale is logarithmic and climbs steeply: An increase of about three decibels is a doubling of sound volume. In the wilderness, a typical sound level would be 35 decibels. Speech runs 65 to 70 decibels; heavy traffic generates 90 decibels. By 140 decibels, sound becomes painful to the human ear, but ill effects, including hearing loss, set in at much lower levels.

         Sound intensity is measured in units called decibels. The decibel scale is logarithmic and climbs steeply: An increase of about three decibels is a doubling of sound volume. In the wilderness, a typical sound level would be 35 decibels. Speech runs 65 to 70 decibels; heavy traffic generates 90 decibels. By 140 decibels, sound becomes painful to the human ear, but ill effects, including hearing loss, set in at much lower levels.

Automobile Traffic In addition to adversely impacting urban air quality, heavy automobile traffic pollutes cities in another way: it creates seemingly unbearable noise pollution. Traffic noise is particularly severe in urban centers of countries that do not require mitigative measures, such as sound-deadening mufflers at the base of automobile exhaust pipes.

Most noise pollution comes from machines, especially automobiles, trucks, and aircraft. Construction equipment, farm machines, and the din of machinery inside factories can be dangerously loud. Some home appliances, shop tools, lawnmowers, and leaf blowers can also be noisy, as are guns, firecrackers, and some toys. Even music, when played at very high volume, particularly through personal headphones, is as damaging to the ears as a roaring chain saw.

Fig. Noise meter “Noise-1SH”

Sound Intensities

 Sound intensities are measured in decibels (dB). For example, the intensity at the threshold of hearing is 0 dB, the intensity of whispering is typically about 10 dB, and the intensity of rustling leaves reaches almost 20 dB. Sound intensities are arranged on a logarithmic scale, which means that an increase of 10 dB corresponds to an increase in intensity by a factor of 10. Thus, rustling leaves are about 10 times louder than whispering.

The most significant health problem caused by noise pollution is hearing loss .Any noise appreciably louder than talking can damage the delicate hair cells in the cochlea, the structure in the inner ear that converts sound waves into auditory nerve signals. The initial damage to the cochlea may be temporary, but with repeated exposure, the damage becomes permanent. Loud noise deafens quickly—extremely loud sounds, such as gunshots at close range, can cause immediate hearing loss. But even sound levels of only 85 decibels will cause some hearing loss after prolonged exposure. Ten million Americans have some hearing loss due partly or wholly to exposure to loud sounds, and 20 million are at risk. In addition to deafness, many people with damaged ears are afflicted with tinnitus, or ringing in the ears.

Most hearing loss occurs in workplaces, where workers may be unable to avoid unhealthy noise, and where exposure may continue for years. Factory workers, construction workers, farmers, military personnel, police officers, firefighters, and musicians all have reason to be concerned about their occupational exposure to noise.

Even at levels below those that cause hearing loss, noise pollution produces problems. Noise makes conversation difficult, interferes with some kinds of work, and disturbs sleep. As a source of stress, it can promote high blood pressure and other cardiovascular problems, as well as nervous disorders. According to the National Institutes of Health, 65 million Americans are exposed to noise levels that can hamper their work or disrupt their sleep, and 25 million risk health problems due to noise.

Noise also puts stress on domestic animals and wildlife. In remote areas, helicopters and military aircraft often frighten animals. Aircraft noise in Alaska, for example, has been shown to reduce the survival rate of caribou calves. There is concern that increasing noise levels in the oceans may confuse the natural sonar that whales use to navigate, communicate, and locate food.

CONTROLS

Glass Enclosure in Automated Plant Most hearing loss occurs in workplaces, where workers are exposed to the incessant noise, such as that produced by automated production lines and factory equipment. A protective glass enclosure limits noise exposure, while still enabling a worker to oversee plant operations. Here, a worker observes robots in an assembly line as they perform repetitious duties in a steel plant.

Noise pollution is not a necessary price to pay for living in an industrial society. Much can be done to reduce the severity of the problem. For example, vehicles and other machines can be built to produce less noise. Four-cycle engines can replace much noisier two-cycle engines in such products as lawnmowers, motorboats, and jet skis. Labels that indicate the noise levels of appliances and tools can help consumers avoid noisy products and choose quieter alternatives.

Even after noise is generated, steps can be taken to reduce human exposure to it. At homes or in offices, insulation of walls and double-glazing of windows can muffle sound from traffic, neighbors, and other sources from the outside world. Sound walls along highways can shield nearby neighborhoods from traffic noise. Individuals should protect themselves with earplugs or mufflike ear protectors, particularly when noise levels exceed 85 decibels.

In the industrialized nations, governments have laws and policies to counter noise pollution. In the United States, at least six federal agencies are involved in controlling noise pollution. Since 1969 the Federal Aviation Administration (FAA) has monitored and controlled noise from airplanes. The agency requires that new aircraft meet specified noise standards and that old ones be retrofitted or retired. Local airport authorities, with FAA approval, reduce the impacts of noise pollution by routing flights over water or unpopulated areas on takeoff and landing, and by limiting traffic at night. The FAA also encourages airports and local governments to take steps on the ground, such as constructing sound barriers, insulating buildings, and restricting residential development in noisy areas. In extreme cases, airports have relocated people living under flight paths.

The Occupational Safety and Health Administration (OSHA) is charged with reducing noise in workplaces. Under OSHA regulations, no exposure above 115 decibels is permitted, exposure up to 115 decibels is limited to 15 minutes for an 8-hour shift, and average noise levels above 85 decibels are regulated. OSHA requires employers to measure noise levels, to muffle extremely noisy equipment, to provide ear-protection gear if necessary, and to offer regular hearing tests to workers who are regularly exposed to high sound levels. The Bureau of Mine Safety has comparable rules to protect miners. The Department of Housing and Urban Development and the Veterans Administration require noise-proofing in dwellings whose mortgages they finance. The Department of Defense even has noise standards for certain military situations.

In 1972 Congress passed a Noise Control Act establishing an Office of Noise Abatement and Control in the Environmental Protection Agency. The office conducted research, coordinated the work of other agencies, and directly set noise standards for trucks, motorcycles, air compressors, truck-mounted garbage compactors, and railroads. More standards would have followed, but in 1981 Congress cut off funding for this effort.

Some state and many local governments work to reduce noise pollution. State and local building codes include noise insulation requirements, and land-use planning is used to keep noise sources away from housing and offices. Local ordinances can ban the use of some equipment, such as leaf blowers, or limit use to certain times of day.

In the last 30 years, the United States and other countries have expended considerable efforts to control noise pollution. Most vehicles and many other noise producers are quieter than they used to be. On the other hand, there are more noise-making machines than ever, operating more of the time. In the United States, most of the rules governing noise pollution were established at least two decades ago, and critics are calling for new, stronger measures, as well as for better enforcement of the old ones. What is true of most other kinds of pollution is also true of noise: Our best efforts against it tend merely to keep matters from getting dramatically worse.

Fig. Apparatus measure of  noise and vibration ”VSHV-003” ,

Deafness

Deafness, most simply defined as an inability to hear. This definition, however, gives no real impression of how deafness affects function in society for the hearing-impaired person. Approximately 28 million United States residents have a hearing impairment. This condition affects all age groups, and its consequences range from minor to severe. Of these 28 million persons, more than 2 million are considered profoundly deaf. That is, they have a hearing loss so severe that they cannot benefit from mechanical amplification, whereas hard-of-hearing persons often can benefit, to varying degrees, from the use of such amplification.

Fig. Audiometer AP-02

Hearing loss

Four types of hearing loss may be described. The first, conductive hearing loss, is caused by diseases or obstruction in the outer or middle ear and usually is not severe. A person with a conductive hearing loss generally can be helped by a hearing aid. Often conductive hearing losses can also be corrected through surgical or medical treatment. The second kind of deafness, sensorineural hearing loss, results from damage to the sensory hair cells or the nerves of the inner ear and can range in severity from mild to profound deafness. Such loss occurs in certain sound frequencies more than in others, resulting in distorted sound perceptions even when the sound level is amplified. A hearing aid may not help a person with a sensorineural loss. The third kind, mixed hearing loss, is caused by problems in both the outer or middle ear and the inner ear. Finally, central hearing loss is the result of damage to or impairment of the nerves or nuclei of the central nervous system.

Deafness in general can be caused by illness or accident, or it may be inherited. Continuous or frequent exposure to noise levels above 85 dB can cause a progressive and eventually severe sensorineural hearing loss.

The sociocultural perspective regards mental illness as the result of social, economic, and cultural factors. Evidence for this view comes from research that has demonstrated an increased risk of mental illness among people living in poverty. In addition, the incidence of mental illness rises in times of high unemployment. The shift in the world population from rural areas to cities—with their crowding, noise, pollution, decay, and social isolation—has also been implicated in causing relatively high rates of mental illness. Furthermore, rapid social change, which has particularly affected indigenous peoples throughout the world, brings about high rates of suicide and alcoholism. Refugees and victims of social disasters—warfare, displacement, genocide, violence—have a higher risk of mental illness, especially depression, anxiety, and post-traumatic stress disorder.

Social scientists emphasize that the link between social ills and mental illness is correlational rather than causal. For example, although societies undergoing rapid social change often have high rates of suicide the specific causes have not been identified. Social and cultural factors may create relative risks for a population or class of people, but it is unclear how such factors raise the risk of mental illness for an individual.

Even healthy whales may now be unable to hear well in the sea. Underwater noise pollution is steadily increasing and may be drowning out the tremendous calls of the blue and fin whales. Whales could once heard across thousands of kilometers of ocean, but some researchers believe noise pollution is now interfering with this form of long-distance communication between animals. As we learn more about whales and the ecology of the ocean, we have new chances, and new motivations, to protect these magnificent animals.

Fig. Spectrogram

 

Decibel Scale

The decibel scale is used primarily to compare sound intensities although it can be used to compare voltages.

Decibels Typical sound

0 threshold of hearing

10 rustle of leaves in gentle breeze

10 quiet whisper

20 average whisper

20-50 quiet conversation

40-45 hotel; theater (between performances)

50-65 loud conversation

65-70 traffic on busy street

65-90 train

75-80 factory (light/medium work)

90 heavy traffic

90-100 thunder

110-140 jet aircraft at takeoff

130 threshold of pain

140-190 space rocket at takeoff

 

An ordinary conversation has a sound-level reading of about 70 dB; a jet-airplane noise, around 120 dB.

To evaluate the acoustical properties of rooms and materials, the acoustical scientist uses tools such as anechoic chambers and sound-level meters. The anechoic chamber is a room free from echoes and reverberations in which all sound is absorbed by glass-fiber wedges placed on the surfaces of the walls. A sound-level meter measures sound intensity, the rate of flow of sound energy, which is related to the loudness of a sound, and expresses the result in decibels (dB), a logarithmic unit. In a quiet residence the sound-level meter would read about 38 dB. An ordinary conversation would increase the sound-level reading to about 70 dB. The sound intensity of an air-raid siren could reach about 150 dB; a jet-airplane noise, around 120 dB. When perceived sound intensity is doubled, its power level increases by 10 times, or 10 dB. Loudness levels, which depend upon the judgment of the listener, are measured in sones and phons.

Vibration

Vibration, especially in the frequency range 10-500 Hz, may be encountered in work with pneumatic tools, such as drills, hammers, and chisels, in mines, quarries, foundries or the machine industry, or with other machines, such as those used in the shoe industry, and motor saws in forestry.

Vibration usually affects the hands and arms. After some months or years of exposure, the fine blood vessels of the fingers become increasingly sensitive to spasm, especially after exposure to the cold or to vibration (white fingers). Exposure to vibration may also produce injuries of the joints of the hands, elbows and shoulders. Such symptoms may be very common, e.g., among forestry workers. Vasospastic symptoms occur, however, more often when people are exposed to cold during leisure periods, rather than at work.

 

Fig. Apparatus for measure vibration

 

UNSATISFACTORY LIGHTING CONDITIONS

The assessment of lighting conditions at work must include not only the light intensity and distribution, but also other characteristics, such as shadows, glare, contrasts, and colour.

The levels of illumination needed for the performance of difficult tasks at work have been defined (Jones, 1959). The desirable quantity of light depends on the fineness of detail and the accuracy required in performance of the task. With regard to the quality of light, many complex factors are involved, such as glare, diffusion of light, direction, uniformity, and distribution.

Dim light associated with high visual demands may lead to eye strain and fatigue. Exposure to the dim light of inadequately illuminated workplaces, or to the partial darkness of a coal mine for eight hours a day over long periods, can cause both acute and chronic effects on health. The former include headache, eye pain, lachrymation, and congestion around the cornea, particularly if the exposure is associated with eye strain from trying to see small objects. The latter include miner's nystagmus.

Natural daylight appears to be best for visual comfort. Artificial lighting may also fulfil the demands of adequate visual performance, if care is taken to secure proper light distribution and to avoid glare. The latter is an important factor in vision. Distraction from visual tasks and loss of concentration may result from "direct glare"  This kind of glare is also associated with discomfort, annoyance, and visual fatigue. Intense direct glare may also result in temporary loss of visual ability, as in the case of drivers exposed to direct intense light from on-coming cars at night.

Other kinds of glare include the "indirect glare" from an intense light spot; it may cause blurring of vision. "Reflected glare" from shiny surfaces or dials can obscure details and prevent perception of visual displays. In the occupational environment, intense colours should be avoided as they may result in fatigue of certain retinal cones.

 

Ultraviolet radiation

Occupational exposure to ultraviolet radiation occurs mainly in arc welding. Such radiation mainly affects the eyes, causing intense conjunctivitis and keratitis (welder's flash.) Symptoms are redness of the eyes and pain; these usually disappear in a few days. The welder himself is usually well protected against radiation from his own work. The worker affected by welder's flash will therefore often be found to have been standing next to a welder, and to have been wearing goggles that do not protect the sides of the eyes. No permanent disability appears to result from this occupational disease

Exposure to heat and cold

Exposure to heat is common in work-places in many branches of industry. Acute disorders may result either from excessive demands on, or failure of, the temperature control mechanism , or from a combination of the two. The complex interactions between temperature at the work-place, physical work and climatic conditions are such that each of these types of stress reduces the ability to tolerate the other two.

Little is known as to the long-term effects of hot work; no conclusive epidemiological investigations have been carried out to determine the effects of such work on cardiovascular and renal function.

It is known that heat may adversely affect alertness, reaction times, and psychomotor co-ordination; this would account for a higher accident rate among workers exposed to heat. Accidents are particularly frequent among workers who are not acclimatized.

Important hazards associated with cold work are chilblains, erythro-cyanosis, immersion foot, and frostbite as a result of cutaneous vaso-constriction. General hypothermia is not unusual. Although it has often been claimed that the frequency of rheumatism and bronchopulmonary disease is greater among those engaged in cold work, this has not been conclusively proved.

Both the reduction in the temperature of the hands and the wearing of protective gloves reduce dexterity and therefore increase the risk of mistakes and accidents.

 

Important chemical agents:

Lead

Lead appears as dust or fumes in the air of the work-place. Occupational exposure occurs in mines, but more commonly in lead smelters where lead is produced from lead ore or scrap, and in occupations when lead or lead compounds are used, such as the production and repair of storage batteries, and the polishing and welding of lead-coated or lead-painted materials. This may occur in shipyards, car factories, glass and ceramic factories, and printing and paint shops.

www.epa.gov/reg3wcmd/ lp-whyislead.htm

 www.henriettesherbal.com/. ../lead-pois.html

www.lead.org.au/ bblp/silent-epidemic.html

Solvents

Solvents include aliphatic and aromatic hydrocarbons, alcohols, aldehydes, ketones, chlorinated hydrocarbons and carbon disulfide. The vapours of organic solvents may be toxic.

Occupational exposure can occur in many different processes, such as the degreasing of metals in the machine industry, the extraction of fats or oils in the chemical or food industry, in dry cleaning, painting, the plastics industry, and in the viscose-rayon industry.

Solvent vapours enter the body mainly by inhalation, although some skin absorption may occur. The vapours are absorbed from the lungs into the blood, and are distributed mainly to tissues with a high content of fat and lipids, such as the central nervous system, liver, and bone marrow,

Most solvent vapours have an anaesthetic effect on the central nervous system. Some solvents may, in addition, cause damage to the liver and kidneys (carbon tetrachloride) or to the blood-forming organs (benzene), or contribute to early atherosclerosis. The action on the central nervous system causes nervous symptoms, such as fatigue, headache, and vertigo, Unconsciousness and death may result from short-term exposure to high concentrations. Toxicity to the liver and kidney may cause jaundice and uraemia. Prolonged exposure to benzene may cause leukopenia and anaemia. Carbon disulfide may contribute to a high incidence of atherosclerosis and possibly of ischaemic heart disease, and may also cause severe nervous symptoms, including psychoses.

 

Carbon monoxide

Occupational exposure occurs in mines after explosions, in the iron and steel industry, where carbon monoxide is used to reduce the iron oxide to iron, and in gas plants.

Carbon monoxide enters the body by inhalation, and is quickly absorbed in the blood, where it combines with the haemoglobin. Symptoms of poisoning include headache, dizziness, and unconsciousness. Death may occur within a few minutes on exposure to high concentrations.

 

Sulfur dioxide

Occupational exposure may occur in certain mines for sulfur or sulfur-containing ore, in smelters where sulfur-containing ore is roasted, in the paper and pulp industry, in factories manufacturing sulfuric acid, and in some chemical plants where sulfur dioxide is used for organic synthesis.

Sulfur dioxide is a water-soluble gas that acts as a powerful irritant to the mucous membranes of the eyes and the upper respiratory tract. It causes rapid acute irritation of the eyes with tears and redness; its action on the upper respiratory tract causes cough, shortness of breath, and spasm of the larynx.

 

Skin irritants

Occupational dermatoses may be caused by organic substances, such as formaldehyde, and solvents or inorganic materials, such as acids and alkalis, and chromium and nickel compounds. Skin irritants are usually either liquids or dusts.

Skin irritants may have a primary toxic effect, as with solvents, acids, and alkalis, or produce an allergic reaction after 3-4 weeks of exposure or longer (chromium and nickel compounds, formaldehyde). Dermatosis or eczema develops, mainly on the skin areas exposed at work, such as the hands and forearms, but also on other parts of the body as a result of contact with contaminated clothes. Exposure to fine arsenical powder in the handling of arsenic compounds causes the development of warts on the skin; these may become malignant.

Maximum Permissible Concentrations

One of the basic principles of the operation of an occupational health programme is that, despite the potential health risk inevitably associated with known poisonous substances, there is for each substance a definable and measurable level of human contact below which there is no significant threat to man's health. This acceptable level of contact, expressed in appropriate terms of magnitude and duration of exposure to the offending agent, is variously called the threshold limit value (TLV), the maximum allowable concentration (MAC), or the permissible dose. Since, in most instances, significant contact with toxic substances is by inhalation of airborne dust, fumes, vapours, and gases, these permissible levels are given in terms of atmospheric concentrations, mg/m3, particles per m3 (for mineral dusts), or parts per million of air. Although there are certain differences of detail in the terms given above, all the terms have the same primary purpose: to identify and locate a point on the scale of dose of the offending agent, above which there is increasing probability of injury, overt illness, and even death, but below which the risk is so limited as to impose no serious threat to health, however long the exposure is continued.

Toxicologists seeking stringent criteria on which to base permissible levels, and endeavouring to ensure adequate safety factors in the face of many unknowns, have approached the problem from different directions. One approach has been to start from the higher levels of demonstrable ill effect and work downwards, using increasingly sensitive measures of preclinical, physiological, biochemical, and functional disturbance, but always subjecting these to a critical test of usefulness in terms of their significance as predictors of ill health. Another approach is to start from a known safe level in a healthy animal (or man), and work upwards, including highly sensitive measures of behavioural or other responses; the permissible limit is established just under the lowest level of exposure needed to induce any statistically significant deviation from the normal state of the organism. Two basically different concepts and criteria of health are involved here. In the first case, no serious threat to health is considered to exist so long as the level of exposure does not induce a demonstrable disturbance in the organism of a kind predictive of potential ill health; in the second, a potential for ill health is said to exist as soon as the organism undergoes the first detectable change of whatever kind from its normal state.

In consequence of the differences in approach, it is not at all surprising that the recommended permissible levels in various parts of the world sometimes differ by a facter of 10 or even more.

The Joint ILO/WHO Committee on Occupational Health (1969) proposed a classification of biological effects of occupational exposure to airborne toxic substances, as follows:

 

Category A: (safe exposure zones):

Exposures that do not, as far as is known, induce any detectable change in the health and fitness of exposed persons during their life-time.

Category B:

Exposures that may induce rapidly reversible effects on health or fitness, but that do not cause a definite state of disease.

Category C:

Exposures that may induce a reversible disease.

Category D:

Exposures that may induce irreversible disease or death.

MAXIMUM ALLOWABLE CONCENTRATION OF SOME HARMFUL SUBSTANCES IN VARIOUS COUNTRIES, IN mg/m3

Substance

USSR (1970-71)

USA (1971-72)

Czechoslovakia (1970-71)

Poland (1970)

Federal Republic of Germany (1971-72)

United Kingdom (1972)

Switzerland (1971)

Acetone

200

2400

800

200

2400

2400

2400

Xylene

50

435

200

100

870

435

437

Xylidine

3

25

5

-

25

25

25

Methanol

5

260

100

50

260

260

260

Lead

0.01

0.15

0.05

0.05

0.2

0.15

-

Styrene

5

420

200

50

420

420

420

Toluene

50

375

200

100

750

375

380

Trichloroethylene

10

535

250

50

260

535

260

Carbon dioxide

-

9000

9000

-

9000

9000

9000

Carbon monoxide

20

55

30

30

55

55

55

Vinyl chloride

30

770

-

300

260

770

260

Difficulties may be expected in deciding how to classify certain substances encountered in industry in terms of the suggested categories. This is certainly the case with carcinogenic and mutagenic substances where dose/response relationships are not clear. The TLVs set by the American Conference of Governmental Industrial Hygienists (ACGIH) and the MACs prescribed by the health legislation of the USSR are the permissible limits most widely accepted in other countries. In the USA, the most recent list of threshold limit values for airborne contaminants and physical agents contains permissible limits for almost 600 chemical agents, and thresholds in exposure to particulate matter and to physical agents including noise, non-ionizing radiation, and heat stress.

The list of MACs of toxic gases in the air of the working environment adopted in the Soviet Union (USSR Ministry of Health, 1970) contains almost as many substances, but in many cases there are wide variations in the permissible limits prescribed in the two countries. Other countries have adopted different levels again (see accompanying table), and it does not seem that international agreement will be possible for many years to come. The Joint ILO/WHO Committee noted that a comparison of the limits established by the USSR and the ACGIH showed close agreement (difference of less than a factor of two) for 24 industrial and/or agricultural chemicals. The Committee recommended safe concentration zones for international adoption for these 24 substances, as follows:

 

Substance

Safe concentration zone (mg/m3)

Hydrogen chloride (hydrochloric acid)

5-7

Phosgene

0.4-0.5

Hydrogen sulfide

10-15

Sulfur dioxide

10-13

Sulfuric acid and sulfuric anhydride

1

Ozone

0.1-0.2

Ammonia

20-35

Arsine

0.2-0.3

Ethanol

1000-2000

Methyl acrylate

20-35

Nitrobenzene

3-5

Dinitrobenzene

1

Dinitrotoluene

1-1.5

Trinitrotoluene

1-1.5

Parathion

0.05-0.1

Iodine

1

Beryllium and compounds (as Be)

0.001 - 0.002

Molybdenum, soluble compounds, dust (as Mo)

4-5

Vanadium (as V2O5):

 

dust

0.5

fume

0.1

Ferrovanadium

1

Zinc oxides (fumes)

5

Zirconium and compounds (as Zr)

5

Chlorinated derivatives of diphenyl

1

Chlorinated derivates of diphenyloxide

0.5

 

Regional and international technical bodies are taking a special interest in maximum permissible concentrations in different parts of the world. These bodies include a technical committee in the Economic Commission for Europe, a subcommittee of the Permanent Commission and International Association on Occupational Health, and the International Union of Pure and Applied Chemistry.

Experience in occupational toxicology and the extensive information derived from laboratory and field studies of industrial toxic agents provide useful background data for criteria and guides, not only for industry and agriculture but also for the community at large.

PHYSICAL CHARACTERISTICS AND CLASSIFICATION OF NOISE

 

From physical point of view noise represents chaotic elastic air vibrations of different frequency, intensity and rhythm. (Music represents harmonious elastic air vibrations).

From hygienic point of view noise represents various sounds that hinder a person to work, rest, and sleep, and has negative, irritating effect on him.

Sound or vibration frequency is expressed in Hertz (Hz) – quantity of vibrations per second, and by octave – audio band, the upper level of which is 2 times bigger than the lower one (16-32 Hz; 100-200 Hz etc.). Perceived by human ear frequency is in the range of 16-20000 Hz that is enclosed in 10 octaves.

According to frequency noise is classified into: low frequency, medium frequency, high frequency, sonic frequency (when one single frequency sounds), narrow-band frequency (1-3 octaves sound), wideband frequency (4-6 octaves sound) and “white noise” (all frequencies sound).

Sound intensity depends on amplitude of air vibration and in sound pressure it is expressed by energy units and is measured in Newton per square meter (N/m2). Human ear perceives sound pressure in the range of 2-10-5 - 2-101,5 N/m2, includes about 1 million of those units and makes their use impossible for noise intensity measurement in practice.

Therefore, the level of intensity or sound pressure intensity – the ratio of given sound intensity in N/m2 (Р) to its threshold value Р0, equal 2-10-5 and express in decibels (dB) – tenth part of logarithm (exponent) of sound pressure is used. Thus, level of upper (pain) threshold of sound pressure (L) is:

L = 20 lg = 20 lg6.5 = 20×6.5 = 130 dB

 

Thus, if level of sound pressure increases by 2 dB, sound pressure in N/m2 increases 2 times as much, by 3 dB - 3 times as much, by 7 dB - 7 times as much etc.

Ear perceives sounds of different frequency differently: low-frequency sounds of the same level of sound pressure are quieter, and high-frequency sounds are louder. Therefore physiological value of sound perception was introduced by volume, measurement unit of which is phon (decibels of volume). For conversion of decibels into phons and vice versa, special diagrams of Robinson and Dotson are used. They are given in the corresponding manuals (fig. 33.1).

Fig. 33.1 Diagram of Robinson and Dotson.

(horizontal lines – sound pressure level in dB; curves – sound volume in phons)

 

To compare: if volume threshold at 1 000 Hz is taken for 0 dB, then at З0 Hz it is higher by 63 dB, and at 4 000 Hz it is lower by 10 dB.

Also hourly noise classification exists, according to which noise is divided into uninterrupted (continuous), interrupted (rhythmic and arrhythmic) and impulse-type (percussion).

According to their impact, sounds of the same volume attack organism in the same way, depending on frequency: low-frequency sounds are less harmful and high-frequency sounds are more harmful than ones of medium frequency (Standard, 1 000 Hz). Thus lower threshold of sound harmful effect at 1 000 Hz comes to 30 dB, and at 60 Hz – to 65 dB, at 8 000 Hz – to 23 dB.

Therefore, both control objects (streets, lodgings, offices, study, medical and manufacturing premises) and noise frequency spectrum are put into the basis of noise sanitary regulation (table 1).

For detection of level of noises in medium-octave bands either noise spectrum analyzer or noise and vibration dosimeter are used. (see Appendix 4)

Based on measurement results and standard levels from table 1, noise spectrogram is made (fig. 33.2). This spectrogram allows to determine frequencies, at which actual noise exceeds maximum allowable levels in controlled areas, and to make sound conclusions.

Table 1

Maximum allowable level of noise on workplaces

(extract from State Sanitary Rules 3.3.6.037-99)

Type of work activity, workplace

Sound pressure levels (dB) in octave bands with average geometric frequencies

Equi-valent sound levels (dBA)

31.5

63

125

250

500

1000

2000

4000

8000

Industrial premises, establishments and organizations

Creative, scientific activity, teaching and studying, premises of design offices, programmers, laboratories for theoretic activity and experiment data processing, reception of patients in medical posts

86

71

61

54

49

45

42

40

38

50

High-skill job, administrative activity and management, measuring and analytic work in laboratories

93

79

70

63

58

55

52

50

49

60

Work requiring permanent hearing control, operator and dispatcher work with voice connection by phone, observation cabins and distant control

96

83

74

68

63

60

57

55

54

65

Work requiring concentration, work with increased requirements to observation and remote control of manufacture, workplaces at observation and remote control cabins without voice connection by phone

103

91

83

77

73

70

68

66

64

75

All other types of work except listed above at permanent workplaces in industrial premises and on manufacture territory

107

95

87

82

78

75

73

71

69

80

Motor transport

Workplaces of bus-drivers

99

91

83

77

73

70

68

66

64

75

Workplaces of car-drivers

96

83

74

68

63

60

57

55

54

65

 

If there is no spectrum analyzer, then noise dosimeter is used for measurement (Appendix 3, fig. 33.3). The result is expressed using integral indices of noise level - decibels А (dBА) and evaluated according to last column of State Standard (Table 1).

Total noise level from different sources is calculated according to special formulas (Appendix 2).

 

Training Instruction

on the procedure of calculation of total noise level

 

1. Summing up noises of the same level is accomplished according to formula:

Іtotal = І0 + 10 lg n                                      (1.1.)

where: Іtotal – total noise level;

 І0 – noise level from one source;

 n – quantity of sources.

lg 2 = 0.3                                            lg 5 = 0.7

lg 3 = 0.5                                          lg 6 = 0.8

lg 4 = 0.6                                          lg 7 = 0.85

Example: There are three operating engines with amount of noise of 70 dB each
Іtotal0+10 lg n = 70+ l0 lg 3 = 70 + 10×0.5 = 75 dB

 

2. Summing up noises of different level is accomplished according to the following formula:

Itotal = Іmax + DL1 + DL2 + ... DLn                                     (2.1.)

where:  Іtotal – total noise level;

 Іmax – maximum noise level from one source;

 DL1,2 … n – maximum level’s complement amount is presented in the table as difference between maximum level of noise and noise from given source Ln:

 

Imax-In or І1-In

0

1

2

3

4

5

6

7

8

9

10

11

12

DL

3

2.5

2.1

1.8

1.5

1.2

1

0.8

0.6

0.5

0.4

0.2

0

 

Example: 4 machines are operating with definite amount of noise 1 – 94 dB; 2 – 86 dB; 3 – 84 dB; 4 – 70 dB.

Itotal = Іmax + DL1 + DL2 + ... DLn       

1. 94 – 86 = 8 (dB) acc. table DL1 = 0.6                         Іtotal 1 = 94.6 dB

2. 94.6 – 84 = 106 (dB) acc. table DL2 = 0.4                            Іtotal 2 = 95.0 dB

3. 95 – 70 = 25(dB) acc. table DL3 = 0.0                         Іtotal 3 = 95.0 dB

Result: Іtotal = 95.0 dB

 

3. Distance noise abatement is calculated according to the following formula:

І1 = І0 - 20 lg N/n,

where: І1 –noise level at the distance of N meters, which is to be determined;

 І0 – certain noise level at the distance of n meters.

 

Example: level of noise of working compressor at the distance of 5 meters equals 92 dBА.

What is amount of noise at the distance of 50 meters at the same conditions (without obstacles for sound waves’ transmission)?

І1 = 92 - 20 lg 50/5 = 92 - 20 × lg 10 = 92 - 20×1 = 72 dBА       (lg 10 = l).

 

4. Interdependence of sound energy flux density and sound intensity:

Difference between intensities (dB)

3

6

9

20

40

60

80

Respective difference between sound intensities (several times more)

2

4

8

10

100

1 000

10 000

 

 

TRAINING  INSTRUCTION

on the noise measurement by noise dosimeter ШУМ-1-М (SHUM-1-M) (see fig. 33.3)

Fig. Noise dosimeter „ШУМ-1М” (SHUM-1-M)

 

Setting-up procedures

1. An instrument is located close to the source of noise.

2. Capsule of microphone is screwed up on the electronic module.

3. Switch "Fast - Slow" is set in the position "Fast".

4. Required sound level is selected by switch "Band".

5. Switch «Operation mode» is moved to position «Battery» (needle must be located at the left side of the black sector, otherwise, battery should be replaced).

6. Switch «Operation mode» is set in the position of «Calibration» and with the help of button «Calibration» set a needle to the reference level of microphone capsule.

 

Measurements

7. Switch "Operation mode" is set to characteristic А (if necessary – on characteristic В or С).

8. Switch «Band»is turned to the left, or to the right, to place the needle in the range of 0 - 10 dB.

9. Measurement result is read as follows: add (if the needle on the scale of the instrument is located from the right of zero) or deduct (if the needle on the scale of the instrument is located from the left of zero) dB indication of the needle of the instruments’ scale to dB indication of the switch «Band». For example, 60 dB of switch «Band»+ 3.5 dB of scale = 63.5 dB.

10. On completion of measurements «Operation mode» switch is set to "Turn off" position.

 

Assignment of the instrument – This instrument is used for frequency analysis of noise and vibration parameters at scientific research works for permanent noise control according to SS 12.1.003-76 and for vibration control in the production areas.

Operational mode of the instrument. Dosimeter ВШВ-003 (NVD-003) is designed on the principle of conversion of sound and mechanical vibrations of the objects under investigation into proportionate to them electric signals that later on are amplifyed and metered.

Preparation of the instrument for noise and frequency measurement. Instrument ВШВ-003 (NVD-003) can be operated from cells 373 or from 220 V electric mains. In this case the instrument is earthed through socket І. The needle of the instrument is set on zero scale indication with the help of mechanical equalizer (if required).

Switch «Operation mode» is set to the position -||- for voltage control of power supply elements. |If voltage suffices the needle of the instrument must place between 7 and 10 scale divisions - + 10 (in lower scale divisions are marked by green strokes). Voltage presence is indicated by light of one of light-emitting diodes (LED) of the switch "Divider - dB 1, 2". Switch “Operation mode” is turned to positions F or S. The instrument is ready for operation.

Operation procedure. Before start of sound level measurement (and periodically in the process of measurement) electric calibration of the instrument ВШВ-003 (NVD-003) is carried out (according to special procedure).

Measurement of sound pressure levels at frequency characteristics of "Line", С. В. А:

- buttons "V", "І kHz", "Octave filters", "Н" must be switched off (unburied). Switch «Operation mode» is turned off.

- switches of the measuring instrument are set to position "Divider dB 1” - 80, "Divider dB II" - 50. Filters - to "Line", «Operation mode» - to F.

With this, a rightmost light-emitting diode lights up that corresponds to scale value 130 dB МІ01 (the upper on the board). The instrument warms up during 2 minutes.

During measurements preamplifier ПМ-3 (PM-3) (microphone) should be held on a stretched hand in the direction to the source of the sound. If the needle of the instrument is located at the beginning of the scale (the lower), then it is moved to sector - 10 of dB scale, first by switch «Divider dB 1", and then by switch «Divider dB II". If indicator "Overheat." lights up, «Divider dB 1" should be switched over to a higher level.

When measuring sound low-frequency compounds oscillations of the needle of the instrument can occur. In this case switch «Operation mode» should be moved from F position to S position.

For getting measurement results, it is necessary to sum indications of light-emitting diode according to scale dB МІ01 on the front board of the instrument and indications according to dB scale.

Sound pressure levels in octave bands of frequencies are measured only in frequency characteristic of "Line" (i.e., when switch "Filters" is positioned to "Line").

A button "Octave filters" is pressed. Required octave filters are switched on with the help of the switch "Octave filters", each time setting the needle of dB scale to the range of 0-10 dB with the help of switch «Divider dB П".

Switch «Divider dBІ" must remain in the same position that it was when total amount of sound was measured (at characteristic of "Line").

At sound pressure in wind conditions, when wind speed exceeds 1 m/sec, screen П-ІІ (for wind protection of capsule Ml01) should be used. Sound pressure is measured as described above.

Based on the results a spectrogram is drawn (or ready-made form with standard curve is used), actual results are put in and frequencies that exceed standard ones are evaluated (fig. 33.2)

 

TRAINING INSTRUCTION

on pure tone audiometry by polyclinic audiometer (AP) (see fig.)

 

Hearing loss because of in-plant noise, depending on its degree, is diagnosed as auditory fatigue, auditory adaptation, cochlear neuritis (noise disease), occupational deafness.

Hearing loss among the workers because of in-plant noise is determined by audiometry method according to SS 12.0.067-78 "Noise. Determination methods of hearing loss of a person".

For assessment of the state of the auditory analyzer, method of determination of temporary and permanent shift of sensitivity threshold (TSST and PSST correspondingly) is used.

For assessment of the functional state of the auditory analyzer audiometers are used: clinical (AC) – for detailed clinical examination; polyclinic (AP) – for examination of auditory function of a person in polyclinic; mass (AM) – for mass rough assessment of auditory functions. Besides, audiometers of other manufacturers are used: "Elsa", "AU-5", "AM-31", audiometer - "PA-31" etc.

 

 

Fig. 33.5 Audiometer АP-02

а – physical configuration;

(1 – power connection key; 2 – indicating light; 3 – operation mode switch; 4 – switch telephones of air sound conduction; 5 – switch of masking noise intensity; 6 – tone intensity switch; 7 – frequency switch; 8 – button for audiogram freeze; 9 – indicating lamp of patient’s replies; 10 – switch „ Conversation”; 11 – switch of tone feed break; 12 – button of tone feed break);

b – rear view;

(1 –plug for power connection; 2 – fuse box; 3 – bonding point; 4 – socket for connection of patient’s button; 5 – socket for telephones of bone sound conduction; 6 – socket for air conduction telephone; 7 – socket for microphone).

 

Pure tone audiometry procedure conducted by polyclinic audiometer (АP)

 

First of all it should be noted that audiometry must be conducted in the free-field room (a room, where a full silence is ensured). Procedure of pure tone audiometry measuring is as follows:

During the air conductivity examination, sounds of different levels are transmitted to the ear of the tested person through air telephone. Researches start from sound (tone) of frequency 1000 Hz transmission and sound energy flux density, which is much higher than hearing threshold is. Duration of tone sound transmission is about 1-2 seconds. Sound level is gradually being lowered until it becomes inaudible and then increased to the level of hardly heard. Thus audible sensitivity is determined at frequencies of 500, 200, 125, and later on ‑ of 2000, 4000, 8000 Hz.

To determine bone sound conductivity bone telephone-vibrator is used, which must be pressed to mastoid process. At the same time in order to prevent auditing by another (untestable) ear, masking flat (white) noise is transmitted to that ear by a special device.

Measurement order for hearing threshold at bone sound conductivity is the same as at the air one.

To determine resistance of hearing organ in intensive in-plant noise conditions Paser’s test is used. At the same time after hearing threshold through air and bone sound conductivity of the tone of 1000 Hz determination, the same tone of 1000 Hz and density of 100 dB is being transmitted through air conduction telephone to the ear during 3 minutes. After 15 seconds of sound loading, hearing threshold at the same frequency is determined once again. In an hour of rest the examination is repeated but sound loading of the same density and duration is transmitted through bone sound telephone. In 15 seconds after insonation, hearing threshold through bone sound conductivity of the tone of 1000 Hz is determined. Test results are assessed according to data of table 2.

Table  2

1.          Assessment of steadiness of hearing organs

 

Increase in hearing threshold

(dB after loading according to conductivity)

 

Assessment

air

 

bone

 

 

 

5

 

0

 

Resistant to noise

6 - 10

 

0

 

Inclined to suffering from noise

10

 

5

 

Hypersensitive to noise

 

2.    Degree of hearing loss

 

Degree of hearing loss

Value of hearing loss, dB

 

On speech frequencies

(500, 1 000, 2 000Hz)

On frequency 4 000 Hz

Signs of hearing organ noise effect

below 10 (500 Hz - 5; 1000 Hz - 10; 2000 Hz - 10 dB)

below 40

First stage (slightly diminished hearing)

10-20

60±20

Second stage (medium diminished hearing)

21-30

65±20

Third stage (considerably diminished hearing)

31 and above

70±20

 

Physical characteristic and classification of vibrations

 

Vibration is a rhythmic oscillation of solid bodies of different frequency and intensity, at which alternate relatively time increase and decrease of characterizing values take place.

Vibrations are characterized by amplitude of vibration, speed of vibration in mm/sec, vibration acceleration in m/sec2.

Vibration is distinguished as:

- transport vibration, which affects the operators of mobile machines and carriers for movement on the roads and locality;

- transport and process induced vibration, which affects operators of machines of limited motion in a workshop, mine opening etc.;

- process induced vibration, which affects the operators of stationary machines and carriers and other workers through the floor:

·        at permanent workplaces of industrial premises;

·        at workplaces in storages, eating establishments, alimentary and other premises without vibration sources;

·        at workplaces in plant management premises, medical posts … and other premises for mental work people.

According to mechanism of action, vibration is distinguished as:

- general vibration of workplace (floor, seat) that can be vertical ("up and down") and horizontal ("onward - backward", "lateral");

- local vibration of control mechanisms (scales, handles of instruments), which affects hands and legs, and often a chest when it is necessary to press instrument both by hands and the chest.

Vertical vibration acts along the axis of the body that is denoted by Z, and horizontal vibration, onward, backward and lateral ‑ by X and У.

Local vibration is expressed by letters ХL that corresponds the axis that runs through the place, an instrument, where a steering wheel is grasped and axes ZL  and УL  correspond to direction of hand’s force application.

According to frequency compound, vibration can be divided into low frequency (in the range of octaves of 2, 4, 8, 16 Hz), medium frequency (8, 16, 31.5, 63 Hz) and high frequency (31.5, 63, 125, 250, 500, 1 000 Hz).

Vibration is measured in three mutually perpendicular directions (according to 3 axes) with the help of the same instrument ВШВ-003 (NVD-003) (see fig. 33.4) according to the instruction of Appendix 7.

Hygienic assessment of local vibration is given in octave bands of medium- geometric frequencies of 8, 16, 31.5, 63, 125, 250, 500 and 1000 Hz, and assessment of general vibration is given in octave bands with frequencies of 1, 2, 4, 8, 16, 31.5, 63 Hz or in third-octave bands from 0.8 to 80 Hz. (table 3).

Table 3

Maximum allowable levels of vibration

(abstract from State Sanitary Rules 3.3.6.039-99)

 

1.                                                                                                                                                                                                                                                                  Standards for local vibration

Vibration speed,

Octave bands with average geometric frequencies, Hz

8

16

31.5

63

125

250

500

1000

m/sec∙10-2

2.8

1.4

1.4

1.4

1.4

1.4

1.4

1.4

dBA

115

109

109

109

109

109

109

109

Vibration acceleration

Octave bands with average geometric frequencies, Hz

8

16

31.5

63

125

250

500

1000

m/sec2

1.4

1.4

2.7

5.4

10.7

21.3

41.5

85.0

dBA

73

73

79

85

91

97

103

109

 

2.                                                                                                                                                                                                                                                                  Standards for general vibration

 

 

Average geometric frequencies, Hz

1

2

4

8

6

31.5

63

Transport vibration

Vibration speed

m/sec∙10-2

20.0

7.1

2.5

1.3

1.1

1.1

1.1

dB

132

123

114

108

107

107

107

Vibration acceleration

m/sec2

1.12

0.8

0.56

056

1.12

2.24

4.50

dB

71

68

65

65

71

77

83

Transport and processed induced vibration

Vibration speed

m/sec∙10-2

-

3.5

1.3

0.63

0.56

0.56

0.56

dB

-

117

108

102

101

101

101

Vibration acceleration

m/sec2

-

0.4

0.28

0.28

0.56

1.12

2.25

dB

-

62

59

59

65

71

77

Process induced vibration

a) at permanent work places in industrial premises

Vibration speed

m/sec∙10-2

-

1.3

0.45

0.22

0.20

0.20

0.20

dB

-

108

99

93

92

92

92

Vibration acceleration

m/sec2

-

0.14

0.10

0.10

0.20

0.40

0.80

dB

-

53

50

50

56

62

68

b) in storage, eating establishment, alimentary and other premises

Vibration speed

m/sec∙10-2

-

0.50

0.18

0.089

0.079

0.079

0.079

dB

-

100

91

85

84

84

84

Vibration acceleration

m/sec2

-

0.056

0.04

0.04

0.08

0.16

0.32

dB

-

45

42

42

48

54

60

c) at workplaces in plant management premises, medical posts … and other premises for mental work people

Vibration speed

m/sec∙10-2

-

0.18

0.063

0.032

0.028

0.028

0.028

dB

-

91

82

76

75

75

75

Vibration acceleration

m/sec2

-

0.02

0.014

0.014

0.028

0.056

0.112

dB

-

36

33

33

39

45

51

 

Table 4

Standard levels of vibration in residential premises

 

Average geometric frequencies of octave bands, Hz

2

4

8

16

31.5

63

Vibration speed, dB

79

73

67

67

67

67

Vibration acceleration, dB

25

25

25

31

37

43

Vibration displacement, dB

133

121

109

103

97

97

 

Long-term vibration influence on organism leads to vibration disease development. Main manifestation symptoms of this disease are the following: vasospasm of fingers (local vibration influence) or toes (general vibration influence), their temperature decrease, numbness sensation, losing of tactile (touch) and temperature sensation. Vasospasm is accompanied with severe pain. Then the muscle atrophy, contractures, finger deformations may develop.

 

Appendix 7

Instruction

on noise and vibration dosimeter ВШВ-003 (NVD-003) operation during vibration measurement

 

1. Instrument preparation

At the beginning of measurements electric calibration of the instrument is carried out. Type of detector of piezoelectric vibropack is selected: either ДН-3 (DN-3) (at frequencies of 10-4000 Hz and dynamic range of  5-10-3 – 103 m/s ), or ДН-4 (DN-4) (at frequencies of 10 - 10 000 Hz and dynamic range of 5-10-2 -103 m/s2).

Preamplifier ПМ-3 (PM-3) is connected to the instrument by cable (5 м) and adapter. Adapter input is connected to the socket 50 m of the measurement instrument by cable (0.5 m).

Electric calibration switches of the instrument are set at the positions: - «Divider І" - 40; «Divider P" - 5; "Filters" - "Line"; «Operation mode» - F (fast) or S (slow).

After pressing button «Calibration» in 2 min. After operation mode setting by potentiometer D the needle of the indicating device is moved to the scale mark of 0-10 according to table 7.2, which is given in the Certificate of the instrument.

 

1.    Vibration acceleration measurement

Initially, measurement of vibration acceleration in octave frequency bands is carried out based on general level on "Line" characteristic. At that, buttons "V" and "І kHz" are switched off.

Detector - vibropack ДН-3 (DN-3) or ДН-4 (DN-4), mounted and fixed by wax on the measuring surface is connected to the adapter and preamplifier ПМ-3 (PM-3).

Switch of the instrument is set in the position: - «Divider І" — 80; «Divider ІІ" - 50; "Filters" - "Line"; «Operation mode» - F or S.

Such position of the switch is indicated by LED opposite figure 10 m/sec2 for vibropack ДН-3 (DN-3). It means that at measurement of vibration acceleration reading should be done according to scale 0-10 taking into consideration given scale of measurement, i.e. 0-100 m/sec2. When needle of the indicator, for example, points to figure 8, acceleration equals 800 m/sec2. At operation it is necessary to use first «Divider І" switch, and then «Divider II" switch.

For convenience of values of vibration acceleration reading light indication of «Divider І" and «Divider II" is used. Simultaneously, it indicates both the scale and scale readings 0-10 or 0-31.6.

During work with vibropack ДН-4 (DN-4), technique of vibropack reading is analogous to one already described. At that, scale factor is multiplied by 10.

During work with vibropack ДН-3 or ДН-4 (DN-3 or DN-4), for gage probe indication the button "1 kHz" must be pressed.

When measuring vibration acceleration according to octave bands a switch "Octave filters" must be set on the required octave filter by pressing button "Hz". When operating with octave filters only switch «Divider II" is used, whereas «Divider І" stays in the position that is chosen on general level.

 

3. Vibration speed measurement

Before commence of vibration speed measurement the instrument is calibrated. Chosen vibropack ДН-3 (DN-3) (at frequency of 10-2800 Hz and dynamic range of 0.05 mm/sec, and at frequency of 10-16 Hz and dynamic range of 0.05-10 000 mm/sec), or ДН-4 (DN-4) (at frequency of 10-2800 Hz and dynamic range of 0.5-57mm/sec, and at frequency of 10-16 Hz and dynamic range of 05-10 000 mm/sec) is mounted and fixed on the tested object by wax and connected with preamplifier ПМ-3 (PM-3) through adapter "5F5.282.167.

Switches of the instrument are set in the positions: «Divider І" - 80; «Divider II" - 50; "Filters" - "Line"; «Operation mode» - S. In two minutes after operation mode setting first measurements of vibration speed on general level are taken by button "V" pressing. Later with the help of switch «Divider II" deflection is achieved in scale sector 0-10, and «Divider 1" is left in the position that was set for measurement of vibration speed on general.

For instrument reading in speed units mm/sec according to lit LED vibration speed scale is determined.

For example, for vibropack ДН-3 (DN-3) use LED opposite figure 0.3 on the scale mm/sec lights up. It means that at the needle position of the indicator on mark 2 of lower scale 0-31.6 value of vibration speed will be equal to 0.2 mm/sec.

During work with vibropack ДН-4 (DN-4), technique of vibration speed reading is analogous. At that, scale factor is multiplied by 10.

Measurements of vibration speed in frequency octave bands are taken similarly to vibration acceleration measurement.

When measuring vibration speed or vibration acceleration in dB it is necessary to summarize indications of LED on the scale dB and МІ01 with readings of the scale - + dB, and then to add to the received result or to deduct from it the following values in db:

- during measurement of vibration acceleration by vibropack ДН-3 (DN-3) 10 dB is added;

- during measurement of vibration acceleration by vibropack ДН-4 (DN-4) 10 dB is added;

- during measurement of vibration speed by vibropack ДН-3 (DN-3) 26 dB is added;

- during measurement of vibration speed by vibropack ДН-4 (DN-4) 46 dB is added;

 

4. Hygienic assessment of vibration