150 Kilocalorie per hour (174 w).

Easy physical work divides into Category Ia - energy consumption up to 120

kilocalorie per hour (139 W) and Category Ib - energy consumption is 121-150

kilocalorie per hour (140-174 W).

Category Ia includes work in sitting or standing position what takes slight

physical exertion (work applied in precise instrument-machine engineering,

clothing manufacture, offices etc.).

Category Ib includes work in sitting, standing position or walking what

takes some physical exertion (work applied in printing industry, communication

service, checkers, experts in any industry etc.);

Normal physical work (Category II) is activity with energy consumption

151-250 kilocalorie per hour (175-290 W).

Normal physical work divides into Category IIa - energy consumption is

151-200 kilocalorie per hour (175-232 W) and Category IIb - energy consumption

is 201-250 kilocalorie per hour (233-290 W).

Category IIa includes work with constant walking, moving small things (up

to 1 kg weight) sitting or standing and takes some physical exertion (work applied

in mechanical workshops, in machine engineering, spinning factory etc.).

Category IIb includes work with constant walking, moving and carrying

weights up to 1 kg and takes moderate physical exertion (work applied in foundry,

rolling, forge, heat and welding workshops etc.).

Hard physical work (Category III) is activity with energy consumption over

250 kilocalorie per hour (290 W).

Category III includes work with constant walking, moving and carrying

heavy weights (over 10 kg) and takes great physical effort (work applied in

forge workshops with manual ramming and casting in machine engineering and

metallurgical works etc.).

The calendar year is divided into two periods: warm period having average

daily temperature of external air +10 deg C and higher; and cold period - average

daily temperature of external air below +10 deg C.

17. METEOROLOGICAL MONITORING

Mercury and alcohol thermometers are used to measure air temperature. The

mercury thermometers are more precise in temperatures -35 ...+357 deg C. Alcohol

thermometers are less precise and applied in low temperatures (under -130 deg C).

The alcohol boils at temperature over 78.3 deg C.

Mercury thermometer indicates actual temperature at position of the upper

part of meniscus, the alcohol - at the lower one.

Measuring air temperature in the area with the source of heat radiation they

take pair-thermometer what’s made up from two thermometers. The surface of

one of the mercury bulb is covered by black paint, and the other one is silver. The

actual temperature is calculated taking both indications by the formula

ta = tb - k(tb-ts) ,

(8)

where tb - indication of thermometer with black bulb, deg C; k - instrument

constant; ts - indication of thermometer with silvered bulb.

Time rating air temperature is read by thermograph.

Psychrometers are applied to measure air humidity. It consists from two

thermometers - dry and wet one. The bulb of wet thermometer is covered with wet

fabric; vaporizing from the bulb absorbs the heat, therefore the wet thermometer

indication is lower than the dry one.

The most simply model of psychrometers is August psychrometer what’s

made up from two alcohol thermometers - dry and wet one. The bulb of wet

thermometer is covered by cambric the end of which is dipped into glass with

distil water, which vaporizing from the bulb absorbs the heat, therefore the wet

thermometer indication is lower than of the dry one.

More precise measurements use aspiration psychrometer (Asman

psychrometer). It also consists from two thermometers the bulbs of which are

in the metal sleeves, what prevents additional heating of thermometers by heat

radiation. Protective sleeves connect to the pipe with aspiration ventilator set on its

upper part.

Difference in thermometers’ indications is used to find humidity by

psychrometeric table 1, or by formula.

f − α ⋅ (t 1 − t 2 )⋅ P

K=

100

M

,

(9)

where f - partial pressure of saturated vapor at the temperature of wet thermometer,

millimeters of mercury column (mm.mr.cl.) (table A.3); α - psychrometerical

coefficient, grad-1 (for psychrometers «M-34» and «MB-4M» α = 0.0007 grad-

1); t and t - indications of dry and wet thermometers accordingly, deg C; P

1

2

- barometric pressure, mm.mr.cl.; M - partial pressure of saturated vapor at the

temperature of dry thermometer, mm.mr.cl.

Time rating air humidity is read by hygrograph.

Table 1

Psychrometeric table

Wet

Air humidity, % , at the difference of dry and wet thermometers

thermometer

indications, deg C

indication,

°C

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0

8

67 62 57 53 50 46 42 39 36 32 30 27 24

9

69 64 59 55 51 51 44 40 37 34 32 29 26

10

70 65 60 56 53 53 46 43 40 36 34 31 28

11

70 65 61 57 54 54 47 44 41 38 35 32 30

12

71 66 62 58 55 55 48 45 42 40 37 34 32

13

71 67 63 59 56 56 50 47 44 41 39 36 34

14

72 68 64 60 57 57 51 48 45 42 40 37 35

15

73 69 65 62 58 58 52 49 47 44 42 39 36

16

73 70 66 62 59 59 53 50 48 45 43 40 38

17

74 70 67 63 60 60 54 52 49 46 44 41 39

18

75 71 68 64 61 61 55 53 50 47 45 43 40

For measuring air circulation in the frames of 0.3 ... 5 mps revolving-vane

analyzer is applied. Its vane has light aluminium or micaceous vane placed into

wide metal ring. The worm-gearing transfers the vane revolution to counter. The

air circulation is defined by means of calibration graph taking the difference of

counter indication before and after the measuring divided by time of measuring in

seconds.

For measuring air circulation in the frames of 1 … 50 mps revolving-cup

analyzer is applied.

To measure very slight air circulation electro-anemometers and

catathermometer are used.

Catathermometer is alcohol thermometer with cylindrical or spherical bulb.

Cylindrical catathermometer scale is calibrated in frames 35 .. 38 deg , spherical

one - 33 .. 40 deg C.

The heat measured in milicalories, that 1 cm2 of bulb surface radiates for the

time the catathermometer cools down from 38 to 35 deg C is called device factor

F. It’s signed on the catathermometer capillary bore.

If to divide factor F by time a (in seconds), during which alcohol column of

heated catathermometer goes down from 38 to 35 deg C, we’ll get the total cooling

ability of air H:

F

H =

a.

(10)

If measuring is carried out in the temperature frames 40 .. 33 deg C, or 39 .. 34 deg

C

H=

F (t' −t' ' )

3a ,

(11)

where t’ - temperature at the beginning of measuring, deg C; t’’ - temperature at

the end of measuring, deg C.

 H − 0 .2 





V =  ∆t



0 .4







 ,

 H − 0.13 





V =  ∆t



0.47







 ,

2

(12)

2

(13)

where ∆t - difference between average temperature of catathermometer (36.5 deg

C) and air temperature in room.

Heat radiation is measured by actinometer.

18. ACOUSTIC CONTAMINATION

Noise produces negative effect on human organism and first of all on central

nervous system and cardio-vascular system. Long time exposure to noise may

bring to hearing worsening and sometimes to deafness. In occupational conditions

long noise exposure can cause accident, occupational disease, work capacity

lowering.

In noisy conditions work production lowers down to 60%, and errors grow

at 50%. Necessity to speak load effects mental activity. It’s a proven fact that for

30% of people noise is the cause of early aging.

For successful noise control it’s important to know its physical nature, its

generating and distribution.

Noise is a type of sound that tends to sound unpleasant.

As a physical phenomenon noise is chaotic composition made up of many

sounds with different unrelated frequencies and intensities.

The basic physical characteristics of noise are frequency, pressure and

intensity.

Sound frequency is number of sound wave oscillations per second measured

in hertz (Hz). Sound spectrum is divided into three diapasons:

-

infra sound with frequency lower 20 Hz;

-

sound with frequency within 20 - 20000 Hz;

-

ultra sound with frequency over 20000 Hz.

Human ear can respond to sound in frequency spectrum from 20 to 20000

Hz. This sound diapason is divided into:

-

low frequency – under 400 Hz;

-

medium frequency – from 400 to 1000 Hz;

-

high frequency – over 1000 Hz.

The main sources of noise in cities and other settlements are motor

transport, railway and air transport and industrial plants. The motor transport

creates the noise level from 82 to 95 dBA on the streets. The street noise level is

determined by intensity, speed and character of traffic, and also depends on the

construction factors (structure of the streets, height and density of buildings), road

cover and green plantings. On the territory of industrial cities cars make significant

noise level, which spreading over the territory close to roads gets into dwellings.

There following methods for reduction of noise influence on environment are

recommended: decreasing of traffic speed and its restriction for some types of cars

on certain roads in definite time; motor transport development; improvement of

buildings soundproofing and construction of noise struggling screens along high-

ways.

Significant noise level is created by the railway transport: the electrotrain

- 93 dBA, passenger train - 91 dBA, freight train - 92 dBA on distance of 7,5 m

from the moving train. Noise levels in subway open lines reaches 70..80 dBA.

The most noisy among all the types of the city transport is tram. The moving tram

creates noise loading (10 dBA higher than car wheels) when engine is on and doors

operating. Reduction of tram noise level is possible improving condition of tram-

line, and also modification of car construction.

The air transport creates sound equivalent to levels of 80 dBA, and

maximum level reaches 108 dBA. For noise minimizing special piloting on takeoff

and landing, more steep trajectories, low power setting, rational organization of air

movement (take-off and landing strip not crossing localities), rational planning etc

are used.

Regulation of noise for city building is carried out with the noise standard.

For example, for apartments and rooms noise standard makes 30 dBA, class rooms

- 40 dBA. These standards are indicated for night time (from 11 p.m. to 7 a.m.),

and in day time standards are increased for 10 dBA.

City-planning measures on noise reduction include: increasing of distance

between protected object and source of a noise; using of acoustic screens - slopes,

walls, screen-structures; rational placing noisy and protected objects; using earth

relief, deepening of highways; using free building construction (places where

people stay temporarily: shops, dining rooms, ateliers serve as screen-building

situated in front of the streets and apartment houses are placed behind them); trees

planting.

19. ELECTROMAGNETIC CONTAMINATION

Intensity of electromagnetic radiation is measured in W/m2 and determined

by frequency.

Low frequency (0-300 kHz; 1-1000 km) radiated by all electro-devices,

cables, cords, power lines.

Center frequency (0.3-3 MHz; 100 m-1 km) – wireless connection (radio).

High frequency (3-30 MHz; 10 m-100 m) – radio.

Very high frequency (30-300 MHz; 1 m-10 m) – TV, radio.

Ultrahigh frequency (0.3-3 GHz; 10 cm-100 cm) – radio.

Superhigh (microwave) frequency (3-30 GHz; 1 cm-10 cm) – radiolocation,

satellite communication.

Extremely high frequency (30-300 GHz; 1 mm-10 mm) – radars.

Optical diapason:

- infrared radiation (0.1 mm – 0.76 microns): body with T>0;

- visible radiation (0.76 microns – 0.4 microns);

- ultraviolet radiation (0.4 microns – 0.2 microns): sun, daylight lamps;

- ionizing: radiation.

Biological effect is determined by force, intensity, size of exposed surface,

frequency as the higher frequency radiation penetrates deeper.

EMF polarizes body cells (water cells) forcing them to move in EMF

frequency. Exposure to EMF also causes ion-currents. Due to mentioned effects

EMF causes heating of the body. The heat absorbed by the body from EMF may

be backed away to some limit (10 mW/m2), or else it rises the temperature of the

body. It has the most adverse effect on organs that much water and poor blood

circulation, such as eyes, brain, kidneys, stomach, bladder. Blood circulation

system may be imagined as cooling one. Exposure of eyes causes clouding of the

crystalline lens, cataract, what appears after several days.

Ultraviolet radiation has the slight ionizing effect yet. They are divided into

three subgroups: UVA near the natural, UVB carcinogenic, UVC ionizing (shortest

waves, highest frequency). Among effects mentioned above malignant skin and

eyes effect. Safe distance to daylight lamp: 3 m, to welding work: 5 m.

20. CHARACTERISTICS OF IONIZING RADIATION

Ionizing radiation or briefly “radiation” is the emission or transfer of radiant

energy as:

- particles: alpha, beta, neutrons;

- electromagnetic waves: gamma rays, X-rays.

Alpha radiation: a helium nucleus emission (containing two neutrons and

two protons) with start speed 20,000 km per sec. It has greatest energy that’s why

causes major damage as cells and atom decay. However its penetrating capability

is the lowest among the other emissions. Paper sheet or clothing stop alpha

radiation completely. It travels only for 1 cm in the air.

Beta radiation: a high-speed electron or positron emission. It’s less

destroying power but greater penetrating capability as compared with alpha

particle. Metal shield or glass absorbs it completely, clothing – about 50%. It

travels for 11 cm in the air.

Gamma radiation: electromagnetic waves emitted as photons - portions of

electromagnetic radiation. Its destroying power is 100 times less than beta and

10000 times less than alpha radiation. However its penetrating capability is the

greatest what makes it major hazard of radiation exposure. Only anti-rad shelters

are effective to reduce gamma exposure.

Neutron radiation: neutrons stream with the start speed 20,000 km per sec.

Neutrons have zero charge and meet no resistance penetrating into cells and atoms.

Neutrons transfer much energy, which excites and decomposes cells and atoms.

The only protection from neutron exposure is anti-rad shelters.

Ionizing produced by radiation is the primary cause of its biological effect.

To ionize means to change or become changed into ions.

Radiation sickness: illness caused by overexposure of the body or a

part of the body to ionizing radiations from radioactive material or x-rays. It is

characterized by vomiting, diarrhoea, and in severe cases by sterility and cancer.

Radiation sickness degrees:

1. first-degree: Deq=100-200 rems. Symptoms: periodically headache, running

high temperature, nausea. Latent period: 2-3 weeks.

2. second-degree: Deq=200-400 rems. Symptoms: similar to 1st degree but they

are stable and strong. Latent period: 1 week.

3. third-degree: Deq=400-600 rems. Symptoms: unconsciousness, intradermal

and mucous membrane bleeding, vomiting. Latent period: a few hours.

4. fourth-degree: Deq=>600 rems. Without intensive medical treatment it’s fatal

within 2weeks.

Blood cell affection:

- reducing quantity of red blood cells erythrocytes, which transport oxygen

and carbon dioxide, combined with the red pigment haemoglobin, to and

from the tissues, causes oxygen insufficiency, hypoxia, disturbs blood

clotting.

- reducing quantity of white blood cells leucocytes, which fight viruses,

weakens immunity.

All tissues and organs are broken into three sensitivity groups:

1.Very sensitive: blood and lymphatic tissues, intestine, genital organs,

crystalline lens.

2. Poorly sensitive: kidney, lungs, liver, skin.

3. Stable: nervous system, heart, muscles, connective tissue.

Radiation exposure can be external or internal.

Background radiation dose reaches 100 mR.

On X-ray examination: photoroentgenography – 370 mR. Tooth – 3 R. 3 hrs

watching TV – 0.5 mR.

21. UNITS OF RADIATION

Becquerel: the derived SI unit of radioactivity equal to one disintegration

per second. Symbol: Bq [named after A. H. BECQUEREL]

Curie: a unit of radioactivity equal to 3.7 X 1010 disintegrations per second.

Symbol: Ci [named after Pierre CURIE]

Quantity of radiation exposure, which has a definite adverse effect, as

destroying or ionizing cells, is called radiation dose.

There’re two principally different doses: exposure dose and absorbed dose.

Exposure dose unit is Roentgen: a unit of dose of electromagnetic radiation

equal to the dose that will produce in air a charge of 0.258 X 10-3 coulomb on all