Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises icon

Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises




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2. /Module1. General questions of Hygiene and Ecology/Lectures/Health and Environment.rtf
3. /Module1. General questions of Hygiene and Ecology/Lectures/Introduction to hygine.rtf
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Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises
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Determination of atmospheric pressure
Research of the factor of infra-red radiation
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Topic № 5


METHODS OF DETERMINATION AND HYGIENIC ASSESSMENT OF ARTIFICIAL ILLUMINATION IN DIFFERENT PREMISES


1.1. Learn the role and the meaning of the rational artificial illumination as the means of lengthening the activity period of the people, and the disease and fatigue prevention.

1.2. Master the methods of the measurement and hygienic assessment of artificial illumination in different premises with the help of a luxmeter and calculation methods. Determination of the surface brightness.


2. Basics

2.1. You should know:

2.1.1. Physical basis of illumination, concepts and measurement units for light.

2.1.2. Physiological functions of the visual analyzer, their dependence on illuminance.

2.1.3. Hygienic requirements and significance of artificial illumination in different premises.

2.1.4. Types of artificial illumination and their comparison (advantages and disadvantages).

2.1.5. Factors that influence the level of artificial illumination.

2.1.6. Methods of artificial illumination assessment and the principles of its hygienic regulation.


2.2. You should have the following skills:

2.2.1. To measure the illuminance and brightness, and other indices using instrumental and calculating methods.

2.2.2. To give a comprehensive hygienic assessment of the artificial illumination of the premises and workplaces, considering the type of visual work and premises’ function.

2.2.3. To draw the motivated conclusions and make recommendations concerning the optimization of the artificial illumination.


3. Self-training questions


3.1. Hygienic significance of artifitial illumination as an environmental factor in the modern world.

3.2 Influence of artificial illumination on the functional state of the central nervous system and on the work capacity.

3.3. Influence of artificial illumination on human vision.

3.4. Basic light engineering and technical concepts and units of their measurement.

3.5. Comparative hygienic assessment of different sources of artificial illumination (the advantages and disadvantages of incandescent and luminescent lamps).

3.6. Basic parameters of illumination and the factors that influence the level of illuminance.

3.7. Illuminance determination using the “Watt” calculation method, its essence and main calculation stages.

3.8. Methods of the determination of the illumination evenness, its hygienic significance.

3.9. Methods of the determination of the surface brightness, its hygienic significance.

3.10. Legislative documents that regulate natural and artificial illumination in different premises and other objects of different purpose.


4. Self-training assignments


4.1. Using the “Watt” method, calculate and assess the illumination in a 40 m2 classroom, illuminated by 6 incandescent lamps (each lamp is 200 Wt).

4.2. The illumination levels in two different points, 0.75m away from each other, are 450 and 275 luxes. Calculate the coefficient of illumination evenness (the ratio between the minimum and the maximum) and assess the results hygienically.

4.3. Calculate the brightness of an operative field if the illumination is 4 000 luxes. The reflection coefficient of the wound is 0.35. Will such brightness cause a visual discomfort?

4.4. An incandescent lamp 1.5 m away produces the illumination of 150 luxes on the workplace. How will the illumination level change if the lamp is moved to 3 meters away?

4.5. The 20 m2 manipulation room is illuminated by 6 direct lamps, 40 Wt each. Calculate the approximate illumination using the “Watt” method. Tell, if that is enough.


5. Structure and content of the lesson


It’s a practical lesson, held in the laboratories with the dark curtains, drawn over the windows. After the knowledge examination each student is given his individual task and necessary devices. Each student measures the parameters of artificial illumination in the laboratory (according to the scheme that is given below (see the appendix). Students do the necessary calculations using the results. They write them down into the protocols, draw the luxmeter scheme there, and draw the motivated conclusions and recomendations. The results of the work are reported during the last lesson. The level of students’ final knowledge is checked by questioning and protocol examination.


6. Literature

6.1. Principal:

6.1.1. Загальна гігієна. Пропедевтика гігієни. / Є.Г.Гончарук, Ю.І.Кундієв, В.Г.Бардов та ін. / За ред. Є.Г.Гончарука. – К.: Вища школа, 1995. С. 199-207.

6.1.2. Общая гигиена. Пропедевтика гигиены. / Е.И.Гончарук, Ю.И.Кундиев, В.Г.Бардов и др. – К.: Вища школа, 2000. – С. 242-254.

6.1.3. Загальна гігієна. Посібник для практичних занять. / І.І.Даценко, О.Б.Денисюк, С.Л.Долошицький та ін. / За ред. І.І.Даценко – 2-ге вид. – Львів: „Світ”, 2001. – С. 95-104.

6.1.4. Габович Р.Д., Познанский С.С., шахбазян Г.х. Гигиена. К.: Вища школа, 1983. – С. 132-133.

6.1.5. Lecture materials.


6.2. Additional:

6.2.1. Минх А.А. Методы гигиенических исследований. – М.: Медицина, 1971. – С. 258-269, 278-280.

6.2.2. Даценко І.І., Габович Р.Д. Основи загальної і тропічної гігієни. – К.: Вища школа, 1995. – С. 298-301.

6.2.3. СНиП ІІ-4-79. Строительные нормы и правила. Естественное и искусственное освещение. Нормы проектирования. – М.: 1980. – С. 20-25.


7. Equipment required for the lesson


1. The U-16, U-116 luxmeter.

2. Measuring tape.

3. Examples of artificial illumination sources: incandescent lamps, gas and luminescent lamps etc.

4. Samples of the illumination fixture (5 types, for different light directions).

5. Curtains for the window blackout.

6 Tables: - Standards for the artificial illumination of the residential areas and classrooms;

- Standards for the artificial illumination of industrial areas;

- The maximum horizontal illuminance with 10 Wt/m2 lamp specific capacity.

7. Student’s task on the laboratory artificial illumination assessment.


Appendix 1


Physical characteristics of artificial illumination


1. The artificial illumination (same as natural) is characterized by:

- light intensity (I)- the light source capacity, measured in candles (Cd). It’s a light intensity, that generates the monochrome radiation of the 540∙1012 Hz frequency in certain direction, with radiant intensity in that direction of 1/683Wt/steradian;

- light flow (luminous flux) (F) - the density of light, measured in lumens (lm) - light flow, radiated by the individual source with intensity of 1 cd in the solid angle of 1 steradian. The solid (spatial) angle is the cone, which, if its top is considered to be in the center of the sphere, cuts the surface, equaling to the squared radius of that sphere from it;

- illuminance (E)- the amount of light falling on a surface (surface density of the light flow) , where S is the illuminated surface area, m2. The illuminance is measured in luxes. 1 lux is the illuminance of the 1 m2 surface, illuminated by the light flow of 1 lumen;

- brightness (B) –light intensity, at which the light is radiated or reflected from the surface in certain direction. , where is the angle between the light direction and the perpendicular to the surface.

The unit of brightness is cd/m2 - the brightness of the surface with the area of 1m2, radiating or reflecting the light with the intensity of 1cd;

- reflection coefficient (β) - the ratio of the reflected light flow (Fref) to the light flow received by the surface (Frec). It is calculated using the following formula .

The β value is 0.9 for fresh snow, 0.7 – for white paper and 0.35 – for untanned skin.

- optical transmission coefficient (τ) is the light flow, which goes through the (Fthrough.) medium, divided by the light flow, which falls on that medium .



This coefficient allows assessing the quality and the cleanness of the window glass and the glass parts of different lighting fixtures.

- luminosity (M) – surface density of the light flow, expressed in lm, which is radiated from the 1m2 surface (lm/m2).


  1. Human vision


- visual acuity (the recognition ability) is the ability of the visual analyzer to recognize the smallest elements of the object. It’s determined by the smallest angle, under which the two adjacent spots are recognized as separate. The visual acuity is conventionally considered to equal to one angular minute. The visual acuity grows proportionally to the illuminance until it reaches 130-150 lux. When the illuminance is above that point, the visual acuity growth slows down.

- contrast sensitivity is the ability of the visual analyzer to perceive the minimum difference between the brightness of the object and the background. It reaches its highest level when the illuminance is 1 000-2 500 luxes;

- visual perception speed is the time, required to recognize the details of the object. This speed grows until the illuminance reaches 150 luxes. After that point, the growth slows down unproportionally to the illuminance growth;

- visibility is the integral function of the visual analyzer, which is the combination of its main functions – visual acuity, contrast sensitivity, visual perception speed;

- clear vision stability is the time, during which the object can be clearly seen to the total time of the object examination. Physiologically this function of the visual analyzer based on the destruction of the visual purple (rhodopsin) under the influence of the light and formation of the protective black pigment on those parts of the retina, where the picture is the brightest. This function reaches its optimal value at the illuminance of 600-1 000 luxes. Its reduction is the evidence of the visual analyzer fatigue;

- color recognition function. White, black, grey – achromatic colours are only characterized by brightness and light flow intensity. Chromatic colours (monochromatic) are characterized by brightness and chromaticity. Vision is the most sensitive to the yellow and green part of the visual spectrum and the least sensitive to the violet light. During the twilight or under the artificial illumination (especially with incandescent lamps) the visual analyzer’s colour recognition reduces and may distort;

- adaptation is visual analyzer’s ability to reduce its sensitivity during the change from low to high illumination (light adaptation), (achieved very quickly, (in 2-3 minutes) and is caused by the visual purple conversion into the protective black pigment in the retina), and to increase it again when the illumination changes from high to low level (adaptation to darkness), which takes much longer – up to 40-60 minutes and is caused by the restoration of the visual purple in the retina;

- accommodation is the ability of the eye to regulate the visual acuity depending on the distance to the examined object and illumination due to the changes in the light refraction in the optic system of the eye, which is mostly caused by the chrystalline lens curvature change. The curvature will increase when the illumination is less than 100-75 luxes. So, in such circumstances the object must be closer to the eye for the proper recognition;

The insufficient illumination leads to the overstrain of accommodation system, overstrain of the visual analyzer, and for children and adolescents (their eye has not yet formed completely) it may cause the myopia (short-sightedness) especially if they have the congenital disposition;

- critical flicker frequency is determined by the time, during which the afterimage remains in the visual analyzer: the image of an object, which has disappeared from the visual field still remains visible for some time depending on the object brightness. This visual function is based on the same processes of visual purple destruction and restoration. The cinema, one of the most important human inventions, is based on it. The frequent change of the frames and the almost similar objects (25 frames per second), and the darkening of the screen provides dynamic and continuous picture.


The sources of artificial illumination may be electric and non-electric. Non-electric sources are kerosene, carbide lamps, candles and gas lamps. Their use nowadays is mostly limited to the field conditions and emergency situations. The electric sources of artificial illumination may be arc lamps (in searchlights, floodlights, spotlights etc), incandescent lamps, gas-discharge lamps and luminescent lamps.

The disadvantage of incandescent lamps is the spectrum parallax in the yellow-red direction, the distortion of the color perception, the dazzling (blinding) effect of direct rays.

The luminescent lamps have the spectrum, almost similar to the day light with modifications, depending on the luminophor, that covers the internal surface of the glass tube and transforms the ultraviolet luminescence of mercury vapour in the tube into the visible light. There are the daylight lamps (DL), white light lamps (WL), warm white light lamps (WWL) etc.

The disadvantage of luminescent lamps is the stroboscopic effect - the flickering of moving objects.

One of the disadvantages of both the direct sunlight and bright sources of artificial illumination is their ability to cause the dazzling effect. We protect ourselves from the bright sunlight using the curtains and jalousies, dark-toned windows, the sun glasses.

The lighting fixtures (also used for the aesthetic purpose), are used for protection from the dazzling effect of artificial light sources.

The lighting fixtures are divided onto 5 types according to light flow formation (see fig. 5.1):

- direct light type, directing the whole light flow into one hemisphere (the table lamp with the opaque lamp-shade, spotlights, floodlights, and other fixtures used in photo and movie shooting);

- evenly-diffusing the light (dim or light-white sphere);

- reflected light (when the lamp with the opaque lamp-shade directs the light flow towards the upper hemisphere);

- directed-diffused light type, when the main light flow is directed towards the lower hemisphere through the aperture in the lamp-shade and the other part is diffused to the upper hemisphere through the lamp-shade made of plastic, dim or light-white glass;

- reflected-diffused light type, when the main light flow is directed towards the upper hemisphere and is reflected from the ceiling but a part of it is diffused to the lower hemisphere through the lamp-shade with dim or light-white glass.


The allowable values of dazzling at the workplace are:

-20 cd/m2 for types 1 and 2 of the visual work;

-40 cd/m2 for the types 3-5 of the visual work;

- 60 cd/m2 for the types 6 and 7 of the visual work.



Fig.5.1. Types of lighting fixtures

(1 - direct light type, 2 - directed-diffused light type; 3, 4 - evenly-diffused light type;

5 - reflected-diffused light type)

Appendix 2


The scheme of the artificial illumination assessment in different premises


Descriptive data:

  • name and function of premises;

  • system of illumination (local, general and combined);

  • number of lights, their types (incandescent, luminescent and other lamps);

  • their capacity, Wt;

  • type of lighting fixture, light flow direction and formation (direct, evenly-diffused, directed-diffused, reflected, diffused-reflected);

  • height of the lamps above the floor and the work plane;

- illuminated area;

- reflection ability (brightness) of ceiling, walls, windows, floor, furniture and other surfaces.


Illumination determination using the ‘Watt’ calculation method:

  1. the area of the premises is determined, S, m2;

  2. the total capacity of all the lamps, Wt, is determined;

  3. the specific capacity, Wt/ m2, is calculated;

  4. the illuminance at the specific capacity of 10 Wt/m2 can be found from the table 1 of minimum horizontal illuminance values;

  5. for the incandescent lamps the illuminance is calculated according to the following formula:





where, P – is a specific capacity, Wt/m2;

Etab - illuminance at 10 Wt/m2, (from table 1);

K – which equals to 1.3, is the reserve coefficient for residential and public premises.


Table 1


The (Etab) minimum horizontal illuminance values at the specific capacity (P) of 10 Wt/m2

The electric lamp capacity, Wt

The direct light

Half-reflected light

Voltage, V

100…127

220

100…127

220

40

26

23

16.5

19.5

60

29

25

25

21

100

35

27

30

23

150

39.5

31

34

26.5

200

41.5

34

35.5

29.5

300

44

37

38

32

500

48

41

41

35

This formula may be applied for the illumination calculation if all the lamps have the same capacity. The calculations are done separately if there are lamps with different capacity. Their results are added up. The received illumination value by the “Watt” method is compared to the normative values (table 2).


Table 2


Standards of the general artificial illumination (BNaR II-69-78 and BNaR II-4-79)


Premises

The smallest illumination, lux

Luminescent lamps

Incandescent lamps

Rooms and kitchens of dwelling houses

75

30

Classrooms

300

150

Rooms of technical drawing

500

300

School workshops

300

150

Public reading halls

300

150

Operating and sectional rooms




200

Delivery room, dressing ward, manipulation room

400

200

Pre-operative room

300

150

Surgeon’s, obstetritian-gynecologist’s, pediatrician’s, infectionist’s, dentist’s room

500

200

X-ray room

-

150

Functional diagnostics room

-

150

Wards for newly-born babies, postoperative rooms

150

75


For the luminescent lamps with 10 Wt/m2 specific capacity the minimum horizontal illumination is 100 luxes. The minimum horizontal illumination for other specific capacities is calculated proportionally.

For the industrial areas, according to BNandR II-4-79, all activities are divided into seven types of work, based on the linear dimensions of the smallest object, worked with at the distance of 0.5 m from the eye. The first 5 types are divided into 4 sub-types (a, b, c, d), based on the contrast between the examined object and the background, and the background luminosity. For example, during the especially accurate work (type 1, the object size is less than 0.1 mm), the illumination at the workplace must be 1 500 luxes if the contrast with the background is low; 1 000 luxes if the contrast is medium and 400 luxes if the contrast is high. When the work is of low accuracy (type 4, object size is 1.0-10 mm ), the illumination must be 150, 100, 75 luxes respectively.

The above mentioned method is not fully precise as it doesn’t take the illumination in each point, lamp location and some other factors into the account, but is often used for the classes, wards and other areas illumination assessment.

To determine the illumination at the definite workplace, the lamp specific capacity (P) must be multiplied by the coefficient (e), which shows the amount of luxes, given by the 1 Wt/m2 specific capacity: E = P×e. This coefficient for the premises of 50 m2 area and the lamp capacities of less than 110 Wt is 2, 110 Wt and more – 2.5 (see table 3) and 12.5 for the luminescent lamps.


Table 3


The values of the coefficient e


Lamp capacity, Wt

Voltage, V

110, 120, 127

220

less than 110

2.4

2.0

110 and more

3.2

2.5


Illuminance determination using the luxmeter.

The determination of horizontal illuminance at the workplace is done with the help of luxmeter (see topic 4, appendix 2). The 0.9 correction coefficient is used for the luminescent lamps of day illumination (LD); 1.1 - for the white lamps; 1.2 - for the mercury-discharge lamps, because the device has initially been intended for measuring of the illuminance, produced by incandescent lamps.

If the determination is done in the morning or in the afternoon, it’s necessary to determine the illuminance, produced by the mixed illumination (both natural and artificial). After that the determination is done when the artificial illumination is switched off. The difference between the received data is the value of illuminance, produced by the artificial illumination.

The illumination evenness is determined by the “Envelope method,” which means that illuminance is measured at 5 different points of the premises and evaluated by calculation of illuminance variety coefficient (minimum illuminance divided by the maximum illuminance at two different points, which are 0.75 m from each other, when the evenness is determined at the workplace, or 5 m from each other, if the evenness is determined in the whole room).


The calculation of the workplane brightness is made using to the formula:





where, B - is brightness, cd/m2;

E - illumination, lux;

C - coefficient of surface reflection

(0.7 - white; 0.5 - light-beige; 0.4 -brown; 0.1 - black).


The allowable brightness of general illumination lamps for residential and public premises is given in the table 4.


Table 4

The allowable brightness values of general illumination lamps for residential and public premises




The allowable brightness value, cd/m2

for incandescent lamps

for luminescent lamps

The main premises of dwelling and public buildings

15 000

5 000

Classrooms, training rooms, lecture-halls, reading-halls, libraries

5 000-8 000

5 000-8 000

Doctor’s room

15 000

5 000

Wards, special rooms of children institutions and boarding-schools

5 000

5 000


The height of the lamps above the floor and the working place, and the location of general light lamps in the horizontal plane of premises is of the great importance for creating the sufficient and even illumination, and for the protection from dazzling. When the illumination is general or combined, the lamps of general light are located evenly in the horizontal plane of the ceiling (when it is necessity to create sufficient illuminance in every point of premises), or they are locally concentrated (to create the high illuminance in certain parts of the room). The lamp height above the floor must be not lower, than values, given in the table 5 to minimize the dazzling effect of the lamps.

The best illumination conditions are created when the optimal ratio between the distance between the lamps in horizontal plane (L), and their height above the work-plane (H) is used. These ratios have been found as a result of the determination of the light distribution curves of different lamps. The optimal values are shown in table 6.


Table 5


The lowest height of the lamps above the floor (m)

Lamps characteristics

Incandescent lamps

Luminescent lamps (depending on the amount of lamps in the fixture)

200 Wt and less capacity

capacity more than 200 Wt

4 and less

more than 4

Direct light lamps

with diffusing reflectors:













a) protective angle from 10° to 30°;

3

4

4

4.5

b) protective angle more than 30°

not-restricted

-

3

3.5

Lamps of diffused light with the light diffusers transparency:













a) less than 55%

2.5

3

2.6

3.2

b) from 55 to 80%

3

4

3.5

4.0

Table 6


The optimal ratios between the distance between the lamps and their height above the work-plane (L/H)


The lamp type

L/H

“Universal” without a shade, with opal shade

1.8-2.5

Direct light “Lucetta”, enameled narrow angle fixture

1.6-1.8

Enameled narrow angle fixture

1.2-1.4

The sphere of light-white silicate or organic glass

2.3-3.2

Note: The first number is the optimal lamp location;

The second number is the allowable lamp location.




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Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises iconSafety assessment for prevention of heavy disasters on the plant

Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises iconThe Determination of the Optical Constants of the Plant Leaves with Polarized Emission Using

Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises iconThe Determination of the Optical Constants of the Plant Leaves with Polarized Emission Using
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Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises iconDetermination of optimum constructional data of feed device of friction modifier with pneumatic drive

Topic №5 methods of determination and hygienic assessment of artificial illumination in different premises iconDetermination of optimum constructional data of feed device of friction modifier with pneumatic drive

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