Medicine

INTRODUCTION TO HYGIENE

INTRODUCTION TO HYGIENE. METHODS OF HYGIENIC RESEARCH. ORGANIZATION OF EDUCATIONAL AND SCIENTIFIC RESEARCH.

HYGIENE AIR ENVIRONMENT. DEFINITION AND HYGIENIC EVALUATION OF TEMPERATURE, HUMIDITY, ATMOSPHERIC PRESSURE, DIRECTION AND SPEED OF AIR MOVEMENT. HYGIENIC REQUIREMENTS FOR HEALTH IMPROVEMENT PHARMACIES.

HYGIENIC ASSESSMENT OF ILLUMINATION. HYGIENIC REQUIREMENTS FOR HEALTH IMPROVEMENT PHARMACIES.

 

Health - is defined as a state of complete physical, mental and social well-being and not merely absence of disease or infirmity.  

Health is the functional and/or metabolic efficiency of an organism, at any moment in time, at both the cellular and global levels. All individual organisms, from the simplest to the most complex, vary between optimum health and zero health (dead).

Perfect health is an abstraction, which may not be attainable but is essential for an individual or a family or a group or a community's strivings. Optimum Health is the highest level of health attainable by an individual in his/her ecological settings. Positive health means striving for preservation and improve­ment of health. Negative health means scientific ef­forts for prevention and cure of diseases. To promote and maintain a state of positive health an individual needs the following prerequisites:

·        Supply of fresh air and sunlight

·        Safe and potable water supply

·        Balanced diet

·        Healthful shelter

·        Adequate clothing hygienic environmental sanitation

·        Protection from communicable and other avoidable afflictions

·        Complete sense of protection and security both socially and economically

·        A congenial social and cultural atmosphere.

·        In addition an individual should have a regulated way of life with proper rest and relaxation and good and simple habits.

All these factors help to maintain a normal balance of body and mind, which is must for positive health. The study of all these factors constitutes a branch of medicine designated as preventive and social medicine. Any imbalance or deviation in the above factors is likely to cause a state of illness, when curative aspect of medicine comes into picture.

Hygiene -  is a basic preventive science in medicine. It generalizes all dates of theoretical and clinical disciplines in the field of prophylaxis, integrates knowledge’s about complex influence of an environment for health of the man, work out principles and systems of preventive measures.

 The word Hygiene is derived from the Greek word (Hygeia) Hygieia — the goddess of health.

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In Greek mythology, Hygieia (Roman equivalent: Salus) was a daughter of Asclepius. She was the goddess of health, cleanliness and sanitation (and later: the moon), and played an important part in her father's cult (see also: asklepieion). While her father was more directly associated with healing, she was associated with the prevention of sickness and the continuation of good health.

Hygiene is defined as the science and art of preserving and improving health. Hygiene deals both with an individual and a community as a whole. Personal Hygiene is the term used for improvement of hygiene of an individual or a person. Social Hygiene is usually the term used for dealing with problems of sex especially for control of venereal diseases. Similarly other terms like mess hygiene, milk hygiene, hygiene of feeding, hygiene of clothes, hygiene of infant feeding etc., are self-explanatory

Hygiene and Good Habits are commonly understood as preventing infection through cleanliness. In broader call, scientific terms hygiene is the maintenance of health and healthy living. Hygiene ranges from personal hygiene, through domestic up to occupational hygiene and public health; and involves healthy diet, cleanliness, and mental health.

What is pollution.htm

Environmental Sanitation

The word Sanitation -  is derived from the Latin word Sanitas which means a state of health. Environ­mental Sanitation means the control of all those fac­tors in man's surroundings, which cause or may cause adverse effects on his health. The sanitarian directs his efforts towards hygiene of water and food supply, hygienic disposal of human wastes, hygiene of hous­ing and control of vectors and rodents etc.

The following definition now is accepted: «Hygiene is a science, which investigates regularities of influence of the environment on the organism of the man and public health with the purpose of the substantiation of the hygienic norms, sanitarian rules and measures, realization of which will ensure optimum conditions for vital activity, improving of health and preventing of diseases ».

The principal topics of the subject are:

·      Hygiene of atmospheric air

·      Water supply hygiene

·      Hygiene of nutrition

·      Occupational hygiene

·      Radiological hygiene

·      Hygiene of children and teenagers

·      Hospital hygiene

·      Hygiene of extraordinary situation

·      Tropical hygiene

 

Hygiene is a science of preserving and promoting the health of both the individual and the community.

    It has many aspects:

Ø     personal hygiene (proper living habits, cleanliness of body and clothing, healthful diet, a balanced regimen of rest and exercise);

Ø      domestic hygiene (sanitary preparation of food, cleanliness, and ventilation of the home);

Ø     public hygiene (supervision of water and food supply, containment of communicable disease, disposal of garbage and sewage, control of air and water pollution);

Ø      industrial hygiene (measures that minimize occupational disease and accident);

Ø     mental hygiene (recognition of mental and emotional factors in healthful living) and so on.

2. THE AIM AND TASKS OF HYGIENE

Basic aim of hygiene

Preservation and improving the health of the man is a basic aim of hygiene.

In this occasion the English scientist E.Parce has told, that the hygiene has a great and generous purpose: «...To make development of the man most perfect, life most intense, wasting least fast, and death most remote».

The tasks of a hygienic science:

    1. Study of the natural and anthropogenesis factors of the environment and social conditions which influence on health of the man.

    2. Study regularities of influence the factors and conditions of an environment on an organism of the man or population.

    3. Scientific substantiation and working out of the hygienic norms, rules and measures, which help use maximum positively influencing on an organism of the man the factors of an environment and elimination or restriction up to safe levels unfavourable operating ones.

    4. Introduction in practice of public health services and national economy developed hygienic recommendations, rules and norms check of their effectiveness and perfecting.

    5. Prediction of the sanitarian situation for the nearest and remote perspective in view of plans of development of the national economy. Definition of appropriate hygienic problems, which implying from prognostic situation and scientific working out these problems.

3. BASIC METHODS OF HYGIENIC RESEARCHES

    During the development the hygiene used many methods of study an environment and its influence on the health of the population.

Methods of hygiene

1. Methods of environment studying.

2. Methods of studying of environmental influence on human organism and health

 1. Methods of environment studying

Methods of sanitary examination with further sanitary description

 Speaking about methods of the research the exterior factors, first of all it is necessary point at method sanitarian description, which for a long time being almost only. It did not lost the value and now.

Specific hygienic method is method of sanitary examination and describing which is used for studying the environment.

     Sanitary examination and describing is carried out according to special programs (schemes), which contain questions. Answers to these questions characterize the object, which is being examined hygienically. As a rule it is usually supplemented by laboratory analyses (chemical, physical, microbiological and other), which allows characterizing environment from the qualitative side.

Instrumental and laboratory methods With the help of physical methods we can study microclimatic conditions, electrical conditions of air, all aspects of radiant energy, mechanical and electromagnetic oscillation, carry out the spectroscopic analysis and much other.

    By chemical methods we can determine peculiarities of a natural structure of all elements of an environment, the quantitative and qualitative indexes of it contamination, enable to make conclusion about sanitarian troubles of the investigated object.

     The biological methods, first of all bacteriological researches, for example, definition of a credit of the Esherichia colli, have much value for conclusion about epidemiological safety of the potable water.

THE METHOD OF DETERMINATION AND HYGIENIC ESTIMATION OF AIR TEMPERATURE  AND  ATMOSPHERIC  PRESSURE

Air temperature is a measure of how hot or cold the air is. It is the most commonly measured weather parameter. More specifically, temperature describes the kinetic energy, or energy of motion, of the gases that make up air. As gas molecules move more quickly, air temperature increases.

Why is Air Temperature Important?

Air temperature affects the growth and reproduction of plants and animals, with warmer temperatures promoting biological growth. Air temperature also affects nearly all other weather parameters. For instance, air temperature affects:

  • the rate of evaporation

  • relative humidity

  • wind speed and direction

  • precipitation patterns and types, such as whether it will rain, snow, or sleet.

How is Air Temperature measured?

Temperature is usually expressed in degrees Fahrenheit or Celsius. 0 degrees Celcius is equal to 32 degrees Fahrenheit. Room temperature is typically considered 25 degrees Celcius, which is equal to 77 degrees Fahrenheit.

A more scientific way to describe temperature is in the standard international unit Kelvin. 0 degrees Kelvin is called absolute zero. It is the coldest temperature possible, and is the point at which all molecular motion stops. It is approximately equal to -273 degrees Celcius and -460 degrees Fahrenheit.

 

TEMPERATURE SCALES

Temperature is a physical quantity that is a measure of hotness and coldness on a numerical scale. It is a measure of the local thermal energy of matter or radiation; it is measured by a thermometer, which may becalibrated

 

 in any of various temperature scales, Celsius, Fahrenheit, Kelvin, etc., etc.

Much of the world uses the Celsius scale (°C) for most temperature measurements. It has the same incremental scaling as the Kelvin scale used by scientists, but fixes its null point, at0°C = 273.15K, approximately the freezing point of water (at one atmosphere of pressure).[note 1] The United States uses the Fahrenheit scale for common purposes, a scale on which water freezes at 32 °F and boils at 212 °F (at one atmosphere of pressure).

For practical purposes of scientific temperature measurement, the International System of Units (SI) defines a scale and unit for the thermodynamic temperature by using the easily reproducible temperature of the triple point of water as a second reference point. The reason for this choice is that, unlike the freezing and boiling point temperatures, the temperature at the triple point is independent of pressure (since the triple point is a fixed point on a two-dimensional plot of pressure vs. temperature). For historical reasons, the triple point temperature of water is fixed at 273.16 units of the measurement increment, which has been named the kelvin in honor of the Scottish physicist who first defined the scale. The unit symbol of the kelvin is K.

Absolute zero is defined as a temperature of precisely 0 kelvins, which is equal to −273.15 °C or −459.67 °F.

One of the earliest temperature scales was devised by the German physicist Gabriel Daniel Fahrenheit. According to this scale, at standard atmospheric pressure, the freezing point (and melting point of ice) is 32° F, and the boiling point is 212° F. The centigrade, or Celsius scale, invented by the Swedish astronomer Anders Celsius, and used throughout most of the world, assigns a value of 0° C to the freezing point and 100° C to the boiling point.

 http://www.ux1.eiu.edu/~cfadd/1360/19Temp/Absolute.html

In scientific work, the absolute or Kelvin scale, invented by the British mathematician and physicist William Thomson, 1st Baron Kelvin, is used. In this scale, absolute zero is at -273.16° C, which is zero K, and the degree intervals are identical to those measured on the Celsius scale. The corresponding “absolute Fahrenheit” or Rankine scale, devised by the British engineer and physicist William J. M. Rankine, places absolute zero at -459.69° F, which is 0° R, and the freezing point at 491.69° R. A more consistent scientific temperature scale, based on the Kelvin scale, was adopted in 1933.

An absolute temperature scale invented in the 1800's by William Thompson, Lord Kelvin. It places the zero point of the scale at absolute zero, the temperature which scientists believe is the lowest possible. All molecular motion would stop there. A Kelvin degree is the same size as a Celsius degree, so the two scales simply have a constant offset.

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Temperature.

An instrument called thermometer ascertains this.

Name of

thermometer

Boiling     

point

Freezing

point

Fahrenheit

32

212

Centigrade (Calcius)

0

100

Reaumur

0

80

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                            Generally mercury or alcohol is used in the thermometers. Mercury is used in thermometers meant for recording high temperatures on account of its uniformity in expansion at different temperatures, easy visibility, high boiling point and low vapor pressure. Alcohol is used in thermometers for recording low temperatures, because it does not freeze even at low temperatures. Several kinds of thermometers are used

 These are:

(1)Standard or Dry Bulb Thermometer. It is an ordinary thermometer.

(2)Maximum Thermometer. It is used for registering the highest temperature attained in the day or any other period. The thermometer is laid in a horizontal position. In the stem of the thermometer, part of the mercury column is separated by air. When the temperature rises the mercury expands and pushes this broken column forward. But this column does not recede when the temperature falls and the main mercury column contracts. The reading taken indicates the maximum temperature attained during the day.

(3) The Minimum Thermometer. It is used for recording the lowest temperature during the night or during the early hours of morning. A small glass index is enclosed in the spirit, which fills the bulb and a part of the stem. When setting the instrument, the index is first brought to the top of the column of the spirit and the instrument is placed in a horizontal position.   When the temperature rises, the spirit expands and flows past the index, but when the temperature falls, the spirit contracts and carries the index along with it. The lowest temperature is thus registered. The instrument can be readjusted by tilting. 

 (4) Six's Maximum and Minimum Thermometer. It is a combination of maximum and minimum thermometers and gives a double reading. It is however, not a very accurate instrument and is therefore no more being used now in Indian Meteorological observatories.

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Methods of temperature measure

On value of temperature regime on the room measure do in difference place on a vertical.

 First measure of temperature is done on 10 cm from the floor and characterizes air on foot level.

 Second measure do on 1,5 meter from the floor – in respiration zone of man.

Third place is on 50 cm from ceiling and characterizes convection in the room. In hospital the second place is situated on level of bad. Measuring of temperature in horizontal line is done in three points: from external angle to internal angle on 20 cm. Change of temperature in time is measured by thermograph. It’s done in three places on  1,5 cm from the floor.

Thermometer

It is instrument used to measure temperature. The invention of the thermometer is attributed to Galileo, although the sealed thermometer did not come into existence until about 1650. The modern alcohol and mercury thermometers were invented by the German physicist Gabriel Fahrenheit, who also proposed the first widely adopted temperature scale, named after him.

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Types of thermometers

Wide variety of devices are employed as thermometers. The primary requirement is that one easily measured property, such as the length of the mercury column, should change markedly and predictably with changes in temperature.

Electrical resistance of conductors and semiconductors increases with an increase in temperature. For thermistor of given composition, the measurement of specific temperature will induce specific resistance. This resistance can be measured by galvanometer and becomes measure of the temperature. With proper circuitry, the current reading can be converted to a direct digital display of the temperature.

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Very accurate temperature measurements can be made with thermocouples in which small voltage difference (measured in millivolts) arises when two wires of dissimilar metals are joined to form a loop, and the two junctions have different temperatures.

Optical pyrometer is used to measure temperatures of solid objects at temperatures above 700° C (about 1300° F) where most other thermometers would melt. At such high temperatures, solid objects make so-called glow color phenomenon. The color at which hot objects glow changes from dull red through yellow to nearly white at about 1300° C (about 2400° F). The pyrometer contains a light bulb type of filament controlled by a rheostat (dimmer switch) that is calibrated so that the colors at which the filament glows corresponding to specific temperatures.

Another temperature-measuring device, used mainly in thermostats, relies on the differential thermal expansion between two strips or disks made of different metals and either joined at the ends or bonded together.

Special types of thermometers

Thermometers may also be designed to register the maximum or minimum temperature attained.

Maximum thermometers.A mercury-in-glass clinical thermometer, for example, is maximum-reading instrument in which trap in the capillary tube between the bulb and the bottom of the capillary permits the mercury to expand with increasing temperature, but prevents it from flowing back unless it is forced back by vigorous shaking.

Minimum thermometers. Inside capillary tube is alcohol with glass pin. When temperature increase ethanol moves pin. When temperature decrease ethanol paces pin for a minimal temperature.

Thermograph.

Thermograph consists of vertical pen, bimetallic laminas and clack mechanism. Perceiving part of instrument is bimetallic laminas, which change it curvature by change of temperature. By means system of levers which passes changing curvature of bimetallic laminas by righting pen and we have graphical illustration of temperatures on paper of clack mechanism.

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Table of Equivalent Temperatures by Celsius and Fahrenheit scales

C = (F - 32) х 100/180;

F = (C х 180/100) + 32.

Measuring Maximum and Minimum temperature

If possible it is best to record the daily maximum and minimum temperature as well as that which you record at a specific moment in time when you make your observations. You can simply use your normal thermometer. With this you need to record temperatures at about 14:00 where the daily maximum usually occurs, or very early morning when the temperature is similar to the overnight minimum. These are good times to take your am/pm measurements.

Studying the temperature condition of the indoor air

The temperature is measured in 6 or more points to fully characterize the temperature conditions of premises.

Thermometers (mercurial, alcohol, electric or psychrometer dry thermometers) are placed onto support racks at three points 0.2 meter high above the floor, at three points 1.5 meters high (points t2, t4, t6 and t1, t3, t5 respectively) and at 20 cm from the wall along the diagonal section of the laboratory according to the diagram:

The thermometer data are fixed after 10 minutes of the exposition at the point of measurement.

The air temperature parameters in premises are calculated using following formulas:

а) the average temperature in the premises:

а) taver.= ,

b) the vertical variation of the air temperature:

D

c) the horizontal variation of the air temperature:

D

Diagrams and calculations are written down into the protocol, the hygienic assessment is made. It is necessary to consider the following data: the optimal air temperature must be from +18 to +21оС in residential and class-room premises, wards for somatic patients, the vertical temperature variation must be no more than 1.5-2.0оС, horizontal - no more than 2.0-3.0оС. The daily temperature variations are determined using the thermogram, prepared in laboratory using the thermograph. The daily temperature variation must be no more than 6оС.

The allowable and optimal standards of the temperature, presented in the table 1 are the hygienic assessment criteria for residential and public premises.

Table 1

The temperature standards for residential, public and administrative premises

Season

Temperature

Optimal

Allowable

Warm

20-22оС

23-25оС

No more than 3оС higher than the estimated outdoor air temperature*

Cold and transitional

20-22оС

18 – 22оС**

Comment:

 * the allowable temperature is no more than 28оС for public and administrative premises, which are permanently inhabited, for regions with the estimated outdoor air temperature of 25оС and above – no more than 33оС.

** the allowable temperature is 14оС for public and administrative premises where the inhabitants are wearing their street clothes.

The standards were established for people that are continuously staying in the premises for 2 hours or more.

The temperature standards for the workplace air of industrial areas are set in the State Standard #12.1.005-88 “General sanitary and hygienic requirements to the workplace air”, depending on the season (cold, warm) and work category (easy, moderate and hard).

The optimal temperature standards for the cold season are set from 21 to 24оС during the physically easy work and from 16 to 19оС during the physically hard work. These temperature ranges correspond to 22-25оС and 18-22оС during the warm season. The allowable maximum temperature is no more than 30оС for the warm season, the allowable minimum temperature for the cold season is 13оС.

Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. This process is one aspect of homeostasis: a dynamic state of stability between an animal's internal environment and its external environment (the study of such processes in zoology has been called ecophysiology or physiological ecology). If the body is unable to maintain a normal temperature and it increases significantly above normal, a condition known as hyperthermia occurs. For humans, this occurs when the body is exposed to constant temperatures of approximately 55 °C (131 °F), and any prolonged exposure (longer than a few hours) at this temperature and up to around 75 °C (167 °F) death is almost inevitable. Humans may also experience lethal hyperthermia when the wet bulb temperature is sustained above 35 °C (95 °F) for six hours. The opposite condition, when body temperature decreases below normal levels, is known as hypothermia.

The radiant temperature and the wall temperature determination

The spherical thermometers are used for the radiant temperature determination in premises, wall thermometers – for the wall temperature determination (see fig. 6.1 а, b)

The spherical thermometer consists of the thermometer located inside the hollow sphere 10-15 cm in diameter and covered with porous polyurethane foam layer. This material has similar coefficients of the infrared radiation adsorption as the human skin.

The radiant temperature is also determined at 0.2 and 1.5 meters above the floor.

The device has the considerable inertia (up to 15 min.), that is why the thermometer data must be taken no earlier than after that time.

The spherical thermometer data at the height of 0.2 and 1.5 m must not vary by more that 3оС in comfortable microclimate conditions.

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Fig. 6.1. Thermometers for the radiant temperature determination

a – the section of the spherical black thermometer 

(1 – 15 cm diameter sphere covered with dull black paint; 2 – thermometer with the reservoir at the center of the sphere)

b – Wall thermometer with the flat turbinal reservoir

(1 – thermometer; 2 – base cover (foam-rubber); 3 –sticky tape)

The values of the radiant temperature below are recommended for different premises (see table 2).

Table 2

Standard values of radiant temperature for different premises

Type of premises

Radiant temperature, оС

 

Residential premises

20

Classrooms, laboratories

18

Lecture-rooms. halls

16-17

Gymnasiums

12

Bathrooms, swimming pools

21-22

Hospital wards

20-22

Doctors’ consulting rooms

22-24

Operating room

25-30

Special thermometers with the flat turbinal reservoir are used for the wall temperature determination. These thermometers are attached to the wall with special putty (wax with colophony addition) or alabaster. The wall temperature is also determined at 0.2 and 1.5 meters above the floor. In some cases it is necessary to determine the temperature of coldest parts of the wall.

The high levels of infrared irradiation in especially hot manufacture areas are measured using actinometers (solar radiation instrument) and are expressed in mcal/(сm2×min).

Water vapor

The person during all life is exposed to water vapor. Its quantity in air permanently changes: it decreases or increases. When in air a lot of water vapor is stored, the conditions for evaporation of moisture are worse. In air such quantity of water vapor can be stored, that it resilience equals resilience of liquid that evaporates, - and then the evaporation ceases.

The evaporation depends on temperature of air, the above last, the implements evaporation fan-in harder. There fore evaporation as though goes after temperature of air; temperature of air - is increased the evaporation is increased also; temperature of air is lowered, the evaporation is lowered also.

Air humidity

Humidity is moisture content of the atmosphere. The atmosphere always contains some moisture in water vapor; the maximum amount depends on the temperature. The amount of vapor that will saturate the air increases with temperature rise. At 4.4° C (40° F), 454 kg (1000 lb) of moist air contain maximum 2 kg of water vapor; at 37.8° C (100° F), the same amount of moist air contains maximum 18 kg of water vapor. When the atmosphere is saturated with water, the level of discomfort is high because the evaporation of perspiration, with its attendant cooling effect, is impossible.

Humidity is specified in several different ways. The weight of water vapor contained in a volume of air is known as the absolute humidity and is expressed in grams of water vapor per cubic meter.Relative humidity, given in weather forecasts, is the ratio between the actual content of the air vapor and the content of the air vapor at the same temperature saturated with water vapor.

The maximum damp is measured by that quantity of a water pair in grammas, which one saturates completely 1m3 of air at given temperature

         The relative humidity is an attitude of absolute humidity to maximum at given temperature, expresses in percentage, that is:

R=A / F х 100,

Where R - relative humidity;

A- absolute humidity;

F - maxime humidity.

         The relative humidity interests us because its characterize  saturation of air by a pair, its dryness. For example, if we speak, that relative humidity 60 %, from this number it is visible, that 40 % of a moisture does not suffice to saturation of air, that is, it has a capability to receive a moisture. At relative humidity 80 % we could say, that in this case elasticity of a pair in atmosphere is higher, at her the liquid evaporates worse. At 90 % - it is even worse.

 Knowing absolute humidity it is possible to definite dew point, that is that temperature, at which one the absolute humidity becomes maximum and the air humidity will begin to be condensate and to precipitate by the way of drops of water. Let's consider such example. What the temperature this damp will begin to saturate air? It also means to find dew point.

         The air humidity can be described as deficit of saturation. The deficit of saturation is a difference between maximum and absolute humidity at same temperature. Together with it there is also concept a physiological deficit of saturation. It - difference between maximum damp at the temperature of bodies of the person 36,5 degree and absolute humidity of air.

The most commonly used measure of humidity is relative humidity. Relative humidity can be simply defined as the amount of water in the air relative to the saturation amount the air can hold at a given temperature multiplied by 100. Air with a relative humidity of 50% contains a half of the water vapor it could hold at a particular temperature. 

Figure -1 illustrates the concept of relative humidity.

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 The following illustration describes how relative humidity changes in a parcel of air with an increase in air temperature. At 10° Celsius, a parcel of dry air weighing one kilogram can hold a maximum of 7.76 grams of water vapor

Physiological relative humidity

Hygiene uses also concept of physiological relative humidity. It is attitude of absolute humidity at given temperature of air to maximum at 36,5 degree, expressed in percentage. Physiological relative humidity characterizes capability of air to accept damp that evaporates at body temperature. It enables more precisely to evaluate effect of moist air.

Air humidity can be described as deficit of saturation. The deficit of saturation is difference between maximum and absolute humidity at same temperature.

There is also a concept of physiological deficit of saturation. It is difference between maximum damp at body temperature person 36,5 degree and absolute humidity of air. The physiological deficit of saturation lets us define how many grams of water the person can spend by evaporation in given conditions.

Air humidity is very relevant hygienic factor because it influences thermo exchange of the person. At low temperatures in moist air the feeling of cold is stronger than in dry air at the same temperature.

It is by outcome that the moist air has large heat conductivity and thermal capacity. From the same reason in wet clothes it is much more cold: pores of tissues charged with moisture, and its well carries out heat.

Human body permanently loses moisture either by water vapor or by liquid water. It is established that in quiet condition at room temperature the person loses by skin approximately 20% of moisture, mild - 15 %, remaining part - urine and feces. Therefore, in these conditions approximately 35% of water is lost by evaporation and 65% - in liquid with feces and urine. By activity and heat of air – in the contrary: 60% of water is lost by evaporation from skin and mild and much less by urine and feces.

Normal relative air humidity in dwelling apartments is 30-60%. A great range of normal air humidity is explained fluctuations by the fact , that its influence on the organism depends on a number of conditions. In peace when the air temperature is 16-200С with a light air motion the optimum humidity will be 40 - 60%. During physical work when the air temperature is above 200С or below 150С air humidity must not be more than 30-40%, and when the temperature above 25 0С desirable to bring relative humidity down to 20%.

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Air humidity determination methods

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Humidity is determined by psychrometes and hygrometers. Hygrographs determine humidity fluctuations for a day or a week. Absolute air humidity is determined by psychrometes (from greek psychros - cold).Psychrometes are of August and Assman types.

August psychrometer consists of  two identical mercury thermometers fixed on a support. By temperature difference on dry and humid thermometers we can define absolute air humidity with a help of table or formula.

Assman psychrometer consists of dry and humid thermometer situating in metal casing that protects from radiation temperature. There is a ventilator in the upper part of the device. Ventilator is wound up and during 5 minutes in summer (15 minutes in winter) registers a temperature difference.

Relative humidity is measured by hygrometer. It consists of metal frame in the middle of which a fair defatted woman’s hair is lightened. When humidity is low the hair becomes shorter, when it is high it becomes longer.

Instruments to Measure Humidity

A whirling psychrometer is a type of hygrometer which can be whirled around like a football rattle to take readings. You can directly read off the percentage relative humidity. It is a good idea to wrap it in a damp cloth for a while and then set the dial to read 100 %. Like paper, human hair stretches when moist and shrinks when dry. Humidity recorders use this principle, and you can make a simple hygrometer using this method.

http://www.piercecollege.com/offices/weather/psychrometer.html

Psychrometer Assmana

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The Psychrometer measures the wet and dry bulb temperature and under natural evaporation conditions the state of a given mass of air can be described by its temperature and vapor pressure. If water is allowed to evaporate in an isolated mass of unsaturated air , it latent heat content increases and its sensible heat content decreases. The process will stop when the air becomes saturated at the wet bulb temperature ( Tw). The change in latent heat must equal the change in sensible heat. http://weather.nmsu.edu/Teaching_Material/soil698/psych.html

Psychrometer

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A pair of thermometer placed parallel inside the screen with a bare bulb on the right indicating the air temperature and is called dry bulb thermometer. Another thermometer on the left whose blackened globe is covered with a moistened muslin wick is called wet bulb thermometer. Since they are usually using in a pair, therefore, we normally call them psychrometer. 

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The absolute humidity is calculated using the Regnault formula:

А = f – a · (t - t1) · B,

where, А – the air absolute humidity at the current temperature in Hg mm;

            f – maximum pressure of water vapour at the wet thermometer’s temperature (see the table of saturated water vapours, table 3);

            а – psychrometric coefficient is 0.0011 for enclosed spaces;

            t – temperature of the dry thermometer;

            t1 – temperature of the wet thermometer;

            В – barometric pressure during the humidity determination, Hg mm.

The relative humidity is calculated using the following formula:

P = ,

where,  Р –the value of relative humidity to be found, %;

            А – absolute humidity, Hg mm;

             F – maximum pressure of water vapour at the dry thermometer temperature, Hg mm (see the table of saturated water vapours, table 3).

Table 3

Psychrometric tables for the August psychrometer are used for the relative humidity (RH) determination (if the air velocity is 0.2 m/sec.). The value of RH is found at the point of the dry and wet thermometers data intersection, table 4.

The psychrometer operation is based on the fact that the rate of the water evaporation from the surface of dampened psychrometer’s reservoir is proportional to the air dryness. The drier the air – the lower is the wet thermometer’s result in comparison to the dry thermometer due to the latent evaporation.

Determination of the air humidity using the Assmann aspiration psychrometer

The significant disadvantage of August psychrometer is its dependence on the air velocity. The air velocity influences the evaporation intensity and the device’s wet thermometer cooling.

This disadvantage has been eliminated in Assmann psychrometer due to the usage of the ventilator. The ventilator produces the constant air movement at the 4 m/sec speed near thermometers’ reservoirs. As a result data does not depend on the air velocity either inside or outside of the premises. Furthermore, thermometers;’ reservoirs of this psychrometer are protected with reflecting cylinders around psychrometer’s reservoirs from the radiant heat.

The cambric of Assmann aspiration psychrometer wet thermometer is dampened using the pipette, the spring of the aspiration devise is set or the psychrometer with electrical ventilator is plugged in. After these procedures the psychrometer is hung up onto the support at the determination point. The data of wet and dry thermometers are taken 8-10 minutes later.

The absolute air humidity is calculated using the Sprung formula:

,

where: А – absolute air humidity in Hg mm;

            t – maximum pressure of water vapour at the wet thermometer temperature (see the table of saturated water vapours, table 3);

           0.5 – constant psychometric coefficient;

            t – temperature of the dry thermometer;

            t1 – temperature of the wet thermometer;

            В – barometric pressure at the determination moment in Hg mm.

Relative humidity is determined using the following formula:

,

where: Р –the value of relative humidity to be found, %;

           А – absolute humidity, Hg mm;

           F – maximum humidity at the dry thermometer temperature, Hg mm

Relative humidity is determined using the psychrometric tables for aspiration psychrometers. The value of the relative humidity is found at the intersection point of the dry and wet thermometer data (see table 5).

Hair or membrane hygrometers are used for the determination of the relative humidity of the air. These devices measure the relative humidity directly. The hygrometer operation is based on the facts, that the degreased hair lengthens, and the membrane/diaphragm weakens when it’s damp, and vice-versa when they are dry (see fig. 6.2-c).

Table 5

The relative humidity standards for residential, public and administrative premises (abstract from Building Norms and Rules 2.04.05-86)

Season

Relative humidity, %

Optimal

Allowable

Warm

30-60

65*

Cold and transitional

30-45

65

Note:* Allowable humidity is 75% for regions with the estimated outdoor air relative humidity more than 75%.

Standards are set for people who continuously stay in premises for more than 2 hours.

Humidity deficit (the difference between the maximum and absolute air humidity) is determined using the table of saturated water vapours. The absolute air humidity, calculated using Regnault or Sprung formulas is subtracted from the value of maximum air humidity according to the dry psychrometer’s thermometer.

Physiological humidity deficit (the difference between the maximum air humidity at 36,5оС body temperature and absolute air humidity) is determined using the same table of saturated water vapours (see table 3).

Dew point (temperature when the absolute air humidity is maximum) is determined using the same table of saturated water vapours (see table 3) in reverse direction. The temperature when the absolute air humidity is equivalent to the maximum, is found using the value of absolute humidity.

The scheme shows, that the rise of temperature provokes the maximum humidity increase in geometric progression, the absolute humidity – in arithmetical progression. When the air temperature rises, the relative humidity is decreases. As a result the amount of water in the air (absolute humidity) is essentially lower in cold seasons than in summer, but is closely related to saturation (maximum humidity). That is why the relative humidity is high in cold seasons and low in summer usually.

The daily temperature, the air humidity and the atmospheric pressure variation are determined using the thermograph, hygrograph and barograph respectively

 

The role of earth surface type in appearing of winds

Wind is air in motion. It is caused by horizontal variations in air pressure. The greater the difference in air pressure between any two places at the same altitude, the stronger the wind will be. The wind direction is the direction from which the wind is blowing. A north wind blows from the north and a south wind blows from the south. The prevailing wind is the wind direction most often observed during a given time period. Wind speed is the rate at which the air moves past a stationary object.

Measuring of wind speed

Plenty of instruments can measure wind.

Wind vane measures wind direction. Most wind vanes consist of a long arrow with a tail that moves freely on a vertical shaft. The arrow points into the wind and gives the wind direction.

Описание: Описание: Описание: anemometer 1Описание: Описание: Описание: cup anemometer

Anemometers measure wind speed. Most anemometers consist of three or more cups that spin horizontally on a vertical post. The rate at which the cups rotate is related to the speed of the wind. The cup of anemometer has measuring borders from 1 to 50 m/sec, the wing one – from 0,5 to 15 m/sec.

Cathathermometer – alcohol thermometer with cylindrical or globular reservoir and a capillary tube, dilated upwards, can measure air motion speed from 1,5 to 2 m/sec.

Anemometer -

A cup anemometer has metal cups which rotate in the wind.

A swinging-arm anemometer records the force of the wind against a single ball or plate. With a ventimeter wind blows into a hole at the bottom of a tube and raises a plate up it.

A Dwyer wind meter similarly uses a ball. You can easily make a simple anemometer.

Usage of "wind rose" in preventive sanitary control for settlements, industrial enterprises, resting-places building.

The direction of a wind is determined by that part of horizont from where it blows. A direction and force of wind is taken into account for need of construction and planning of cities. As the direction of a wind is constantly changed, therefore it is necessary to know, what winds dominate in this district. For this purpose all directions of winds on stretch of season or year are taken into account. On this data they create the schedule named "rose of winds". Thus, "rose of winds" represents a graphical image of recurrence of winds.

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Wind scale

Classification of Wind Speed

Wind speed can be given according to the Beaufort Scale mainly used to report weather at sea, "a force 9 gale" for example. On land, various indicators such as the movement of smoke or branches, enable the wind speed to be estimated with reasonable accuracy.

Force 1: 3 km/h (2 mph) smoke drifts

Force 2: 9 km/h (5 mph) leaves rustle

Force 3: 15 km/h (10 mph) flags flutter

Force 4: 25 km/h (15 mph) small branches move

Force 5: 35 km/h (21 mph) small trees sway

Force 6: 45 km/h (28 mph) large branches move

Force 7: 56 km/h (35 mph) whole trees sway

Force 8: 68 km/h (43 mph) twigs break

Force 9: 81 km/h (50 mph) branches break

Force 10: 94 km/h (59 mph) trees blow down

Force 11: 110 km/h (69 mph) serious damage

Force 12: 118 km/h (74 mph) hurricane damage

Wind Projects and Activities

      There are lots of projects related to wind speed and direction. You can build a lot of the instruments yourself (look at things to do). Investigate why the wind does what it does!

In enclosed spaces the running speed of air is determined in meters for one second. The more air in a location varies, it is purer and health. But to admit of high speeds of motion of air in a location it is impossible, as flows of cold air, which one acts in a location, can derivate draughts. Is established, that the draught can call in the person or offensive feels or sometimes catarrhal diseases. The feel of a draught is at a running speed of air of 0,5m/sec and above.

Therefore at cooling locations it is undesirable to make motion of air with speed of 0,5m/sec and more, specially in a cold season.

The motion of air near to temperature and damp it influences heat output by an organism and, means, on thermo exchange of the person.

Let's consider such example. Let's allow, that temperature of air high, or is little bit lower from temperature of a human body. The relative humidity is high also. Under such circumstances heat output by a body of the person becomes difficult, as also temperature of air high. Close up to temperature of a human body. The stay of the person in such conditions conducts to an overheating.

Atmospheric pressure

http://www.physicalgeography.net/fundamentals/7d.html

What is Pressure?

Air or atmospheric pressure, is the force exerted on the Earth, by the weight of the air above. That depends on how high the column of air is, so the higher the surface, the less the pressure. That is why you set your barometer to the height of your house or school above sea-level to get correct readings. Air pressure basically refers to the volume of air in a particular environment, with greater volumes creating higher pressures. On the earth's surface, for example, it is known as "atmospheric pressure" and refers to the weight of the earth's atmosphere pressing down on everything. Changes in pressure can impact the temperature, weather patterns, and cause physiological problems for people and animals. This pressure can even impact the performance of a basketball or similarly inflated object.

Atmospheric Pressure

 On the earth, the average air pressure at sea level is 1.03 kilograms per square centimeter (kg/cm2) or 14.7 pounds per square inch (psi); this is commonly measured in bars, in which atmospheric pressure is about 1 bar. This means that hundreds of pounds of pressure are pressing on everyone from all sides, at all times.  Humans and other animals are able to survive this pressure because their bodies evolved on the surface where it is natural.  If the pressure increases or decreases, it can result in discomfort or even death.

Changes in Pressure and Weather

Atmospheric pressure varies slightly over the earth's surface, and variations in pressure are responsible for various types of weather.  Low pressure systems are associated with storms, tornadoes, and hurricanes.  Sometimes the air pressure at sea level can drop as low as 870 millibars, which is about 85% of average air pressure.  This only happens during the most severe storms.  Pressure variations on the earth's surface cause wind: as high pressure air moves toward low pressure areas, creating gusts.

Various Pressures at Different Altitudes

On the top of Mt. Everest, the tallest mountain on earth, the air pressure is just about a third of what it is at sea level. Humans at high altitudes often experience discomfort, such as ear popping, due to differences in their internal and external pressures.  At 16 kilometers (km) or almost 10 miles above the surface, slightly higher than the cruising altitude of a typical jet liner, pressure is only 1/10th what it is at sea level.  Because low air pressure can be very unpleasant for humans, due to low oxygen content, all areas of aircraft that contain passengers are artificially pressurized. In the event of a rupture in an airplane's fuselage, unsecured items may be "sucked" out of the craft as the high pressure air within it rushes out into the low pressure environment outside.

Higher Altitudes and Outer Space

At 31 km  or about 19 miles above the earth's surface, in the stratosphere, the air pressure is only 1/100th what it is at sea level.  From this level on, the atmosphere quickly deteriorates into nothingness.  Above 100 km or just over 62 miles above the surface, the international definition for outer space, the pressure approaches zero and nearly becomes a vacuum. Humans cannot exist unprotected in such a low-pressure environment.

Why is it Important?

Different pressure regimes have different types of weather associated with them.

Barometer readings are plotted on a pressure chart. Points on a map that have the same air pressure are connected by lines known as isobars. By studying the patterns shown by isobars, forecasters can make predictions about how the weather will develop. We can identify "troughs" of low pressure and "ridges" of high pressure.

Barometer

 http://www.stuffintheair.com/barometermakes.html

Types of barometers

Mercury siphon barometer consists of long vertical tube.Instrument contains mercury. We get the result after summation of hailing mercury tube in long and short knee.

Описание: Описание: Описание: mercury barom

Mercury-cupping barometer consists of vertical glass tube which has mercury solder in upper part and open in lower part. Lower part is put into cup with mercury.

Metal barometer aneroid. Main part of this barometer is metal reservoir with cavity. When pressure changes, change volume and forms of reservoir with mercury. http://www.bom.gov.au/info/aneroid/aneroid

Описание: Описание: Описание: aneroidbarometer

Barograph.

Point of instruments connects with metallic aneroid. The recording barometer may be day and week periodical. To establish of the periodicals it is necessary to open the device’s case, to take down from the drum’s axis for the tape and on it’s lower part to see on what period well calculated clock mechanism. 747 Millimeter of a mercury column x 4/3 = 963 mB.This quantity we put on the tape instead of the beginning record time.

Описание: Описание: Описание: barograph

There is a scheme of an estimation of air behind damp: air name dry, when a water pair in this there are less than 55 %, slightly dry – at 56 up to 70 %, by slightly wet - from 71 up to 85 %, hardly wet - have more 86 % and saturated - 100 %.

The business in that in miscellaneous terrains prevalence a direction of winds happens miscellaneous. What the dominating direction of winds means? This is a direction, which one often repeats during one year or season.

On meteorological stations permanently registry can be defined a cosines speed of their motion and directions a direction of winds on 4-8 or 16 rhombs. E - Eastern wind, that is wind, that winds from east. W- Western wind; N - Northern wind; S – Southern, NE - Northern – Eastern. At a sanitarian estimation of the projects of settlements the availability on the schedule of a wind rose enables fast and simplly to orient and to evaluate a regularity of accommodation miscellaneous regions, objects. For example, the regularity of mutual accommodation of industrial firm, which one will flare air of habitation point.

Effects of low atmospheric pressure

Altitude training

At high altitudes (1500m and above), there is still approximately 21% of oxygen in the air, but due to the low atmospheric pressure (B < A), the partial pressure of oxygen is reduced. Due to the pressure gradient, significantly more energy is also required for the lungs to take in oxygen. Hence, to adapt to the difficulty of obtaining and lack of oxygen, the body will increase the mass of red blood cells and hemoglobin in the blood, as well as reduce muscle metabolism to enable a more efficient use of oxygen. This effect is able to last for up to 2 weeks after returning to lower altitudes giving altitude trained athletes a competitive advantage.

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Illnesses

When the atmospheric pressure drops, tissues expand. The expansion of tissues in and surrounding joints aggravates the nerves, causing pain. Thus, patients living in geographical locations with a higher atmospheric pressure tend to experience a greater severity of osteoarthritis (pain in the joints due to expansion of tissues).

Drops in atmospheric pressure also have an impact on headaches, particularly sinus headaches. When atmospheric pressure drops (such as in an ascending airplane or before a storm), gases in the sinuses and ears are at a higher pressure than those of the surrounding air. The air pressure tries to equalize, causing pain in the face and ears. Those that suffer from chronic sinusitis or have a cold have the most issues, as the air becomes trapped in the sinuses and is unable to equalize.

Effects of high atmospheric pressure

Illnesses

Increases in atmospheric pressure (such as in a descending airplane) results in a condition called “ear popping” where air particles rushes into the ears to balance out the pressure inside and outside of the ears. This may result in pain for some people.

Other health effects of high pressures such as that during diving could be found at Effects of Hydrostatic Pressure on the human bodympression Sickness

The formation of gas bubbles in the organism during ascent is called decompression sickness, known also as “the bends”.

Symptoms They occur 5 minutes to 1 hour after the ascent, sometimes after 2-4 hours. Symptoms range cough, itching, reddened skin or pains in the joints to serious respiratory, cardiac and mental damage (such as rapid pulse and heart beat, shortness of breath, pains in the chest and stomach, paralysis of limbs)

Treatment The only remedy to do away with decompression sickness is the chamber for recompression. The diver is exposed to the same pressure (at which he was before the beginning of bubbles’ formation), necessary to dissolve the bubbles. Afterwards, the pressure decreases on stages to avoid decompression sickness.

HOW DOES AIR PRESSURE AFFECT THE BODY?

 Air pressure is the force that is exerted on you by air molecules; the weight of tiny air particles. Atmospheric pressure is a measure of the force exerted by the atmosphere, so therefore at any point on the earth’s surface, there is a quantity of air sitting above your body. If that quantity of air is greater, there will be more pressure on the body; and if it is less, there will be less pressure on the body. This is traditionally measured in pounds per square inch (PSI). 1 PSI is the force of one pound applied to an area of one square inch.

At high altitudes the quantity of air is less, and the density of air is also less. As such, there is less air pressure and as a result, less oxygen in a given volume of air. To demonstrate this, If a person dives below the surface of water in scuba diving, their body has to contend with both the air exerting pressure on the surface of the water, and the water above that exerting further pressure, hence, the deeper you dive, the more pressure there is.

At sea level, we say atmospheric pressure is 1 atmosphere (this is equal to 14.7 psi). This arbitrary measurement provides a reference point from which we can determine air pressure at varying altitudes or depths.

For every 10 metres deep which you go in water, the pressure increases by 1 atmosphere. For example -at 10 metres it is 2 atmospheres; at 40 metres it is 5 atmospheres).

 

HOW DOES THE HUMAN ORGANISM LOSE A HEAT?

Major part of heat loses through the skin and mucous, other part goes on heating of food, water and breathes air. Through the skin loses main heat mass: for after one authors - 85-90%, after other - even 95%, so, only 4-6% loses on heating of food, breathe air and waters.

http://www.expeditionsamoyeds.org/Hypothermia.html

Because of that interestingly will learn how the heat is lost by skin. Appear, that skin loses a heat by three ways:

by radiation,

taking and

on evaporation of sweat moisture.

For data of Rubner, we can say, that man attached to light work in room conditions

loses by radiation about 40%,

taking - about 30% and

by evaporation - about 20% of heat.

These ciphers are directed for orientation, and really they consider vacillate dependency on conditions.

What is the heat losing way by radiation?

From physics we know, that any more heated body radiates more heat, than less heated. So, even not colliding with it, it gives to it its heat, while the temperatures of both bodies will not complete with each other.

Man in room conditions is usually circled by objects with more low temperature, than his body, that is why takes place heat losing by radiation.

Also heat is lost by installation. In this case a heat is lost by two ways - conduction and convection.

Conduction is a heat transition on the strength of contiguity of objects, and also air parts from more heated to less heated. Convection is a heat transmission on the strength of mediators - air, steam, liquid, the fractions of which, heating attached to contact with more warm body, bear off heat and return it attached to contiguity with more cold objects. On the strength of temperature difference in intermediate environment, for example, in air, the convectional streams are generated.

The third way of heat losing is evaporation of moisture.

A human skin is always covered by sweat, water of which evaporates. For this process it is necessary expenditure of warm /secretive evaporation temperature /.

http://ppo.tamuk.edu/ehs/Heat_Stress/heatstress.htm

Microclimate

 it is meteorological conditions in work zone, which characterized by complexes of factors that act on organism of peoples it is temperature, humidity and rate movement of air, and also radiation temperature and warm radiation. Temperature of air is favorable factors which influence on heat exchange. Radioactive temperature – it is the temperature that surround people of superficiality or intensive sun or another radiation.

Microclimate is a thermal status of the limited space. It results from combined action of air temperature, radiation heat, air humidity and air movement velocity. Microclimate defines heat state of an organism. Microclimate is influenced by latitude, topography, human activities and vegetation as well as other factors. Sometimes they mean microclimate as variations of the climate within a given area, usually influenced by hills, hollows, structures or proximity to bodies of water. The warmth and humidity of the air in close proximity to a plant or heat/moisture source may differ significantly from the general climate of the premise.

Air treatment/air cooling differs from ventilation because it reduces the temperature of the air by removing heat (and sometimes humidity) from the air. Air conditioning is a method of air cooling, but it is expensive to install and operate. An alternative to air conditioning is the use of chillers to circulate cool water through heat exchangers over which air from the ventilation system is then passed; chillers are more efficient in cooler climates or in dry climates where evaporative cooling can be used.

Local air cooling can be effective in reducing air temperature in specific areas. Two methods have been used successfully in industrial settings. One type, cool rooms, can be used to enclose a specific workplace or to offer a recovery area near hot jobs. The second type is a portable blower with built-in air chiller. The main advantage of a blower, aside from portability, is minimal set-up time.

Another way to reduce heat stress is to increase the air flow or convection using fans, etc. in the work area (as long as the air temperature is less than the worker's skin temperature). Changes in air speed can help workers stay cooler by increasing both the convective heat exchange (the exchange between the skin surface and the surrounding air) and the rate of evaporation. Because this method does not actually cool the air, any increases in air speed must impact the worker directly to be effective.

If the dry bulb temperature is higher than 35°C (95°F), the hot air passing over the skin can actually make the worker hotter. When the temperature is more than 35°C and the air is dry, evaporative cooling may be improved by air movement, although this improvement will be offset by the convective heat.

When the temperature exceeds 35°C and the relative humidity is 100%, air movement will make the worker hotter. Increases in air speed have no effect on the body temperature of workers wearing vapor-barrier clothing. Heat conduction methods include insulating the hot surface that generates the heat and changing the surface itself. Simple engineering controls, such as shields, can be used to reduce radiant heat, i.e. heat coming from hot surfaces within the worker's line of sight. Surfaces that exceed 35°C (95°F) are sources of infrared radiation that can add to the worker's heat load. Flat black surfaces absorb heat more than smooth, polished ones.

Having cooler surfaces surrounding the worker assists in cooling because the worker's body radiates heat toward them. With some sources of radiation, such as heating pipes, it is possible to use both insulation and surface modifications to achieve a substantial reduction in radiant heat.

Instead of reducing radiation from the source, shielding can be used to interrupt the path between the source and the worker. Polished surfaces make the best barriers, although special glass or metal mesh surfaces can be used if visibility is a problem.

Shields should be located so that they do not interfere with air flow, unless they are also being used to reduce convective heating. The reflective surface of the shield should be kept clean to maintain its effectiveness.

HVAC (heating-ventilation-air conditioning) system defines indoor microclimate.

A microclimate maintenance system (general HVAC system) created in several rooms gives a possibility to use an economic decision, the idea of which consists in use of one outdoor unit and several indoor units (from two to four). It is explained by the fact that in adjacent room’s air-conditioners have to carry out similar functions of cooling or heating.

This makes it possible to use one outdoor unit for work with indoor units which carry out cooling, for example. As a result such a system has lower operating costs and lower power consumption and at the same time allows you to carry out air-conditioning in one or several rooms, where indoor units are installed.

HEAT BALANCE

Fundamentals of heat transfer Humans are homeothermic, which means they must maintain body temperature within a narrow range in varying environmental conditions. The normal deep body temperature (core body temperature) at rest is between 36-37.5 oC, although extremes in excess of 40 oC have been recorded in athletes and workers exposed to very severe environmental conditions. These temperatures are at the upper limit of human physiological tolerance, however they illustrate that people do get exposed to such conditions during their work practice. The variation of resting core body temperatures also demonstrates the individual diversity that may exist in a working population. This variation means that people may have different tolerances to working in the heat. Some people cannot tolerate mild increases in core body temperature whereas others, as illustrated, can continue to work at much higher temperatures. The factors that may account for this variation among workers are still, however, poorly understood.

Thermal homeostasis is maintained by achieving a balance between the various avenues of heat gain and heat loss from the body. There are two recognised sources of heat load;

a) Environmental, which may be positive or negative, that is, there may be a heat gain or a heat loss from the body.

b) Metabolic, which is generated by muscular activity.

ENVIRONMENTAL FACTORS AFFECTING THERMOREGULATION

The principal methods of heat exchange between the body and the external

environment are: convection, conduction, radiation and evaporation.

Convection

The rate of convective exchange between the skin of a person and the ambient air in close proximity to the skin, is dictated by the difference in temperature between the air and the skin temperature together with the rate of air movement over the skin.

When the air temperature is greater than the skin temperature, there will be a gain in body heat from the surrounding air, conversely when the skin is warmer than the air temperature there will be a loss of heat from the body. Because warm air rises (less dense than cool air) the warm air will rise from the body and cool air will come in to take its place. This process is then repeated. The process is called convection.

Radiation

The surface of the human body constantly emits heat in the form of electromagnetic waves. Simultaneously, all other dense objects are radiating heat. The rate of emission is determined by the absolute temperature of the radiating surface. Thus if the surface of the body is warmer than the average of the various surfaces in the environment, net heat is lost, the rate being directly dependent on the temperature difference. This form of heat transfer does not require molecular contact with the warmer object. The sun is a powerful radiator, and exposure to it greatly decreases heat loss by radiation. When the temperature of the objects in the environment exceeds skin temperature, radiant heat energy is absorbed from the environment. Under these conditions the only avenue for heat loss is by evaporative cooling.

Conduction

The difference between heat loss by conduction and radiation is that with conduction the body must be in contact with the object. In such circumstances the heat moves down its thermal gradient from the warmer to the cooler object, the heat energy being transferred from molecule to molecule. The warmer molecule slows down after it has lost some of its heat and the cooler molecules move faster having gained heat. The temperature transfer continues until eventually the temperature of the two objects equalises. The rate of the heat transfer through conduction depends on the difference in temperature between the two objects and the thermal conductivity of the two objects.

Evaporation

When water evaporates from the surface of the skin, the heat required to transform it from a liquid to a gas is dissipated from the skin, this acts to cool the body. Evaporative heat loss occurs from the respiratory tract lining as well as from the skin. There is a constant gradual loss of water from the skin that is not related to sweat glands. The skin is not fully waterproof and so some water is lost out through pores in skin, and lost by evaporation. This loss is not subject to physiological control and is termed insensible perspiration. Sweating is an active process requiring energy and controlled by the sympathetic nervous system. The rate at which this process proceeds can be controlled and therefore the amount of heat loss can be controlled.

Radiation and convection are insufficient to prevent warming up of the body during heavy manual work or at high surrounding temperatures. Under these circumstances heat loss is aided by evaporation of water. At environmental temperatures above about 36 oC, heat is lost exclusively by evaporation. At higher temperatures heat is taken up by the body from the environment by radiation, conduction and convection.

Sweating then becomes profuse in order to maintain the balance between heat uptake and heat loss by evaporation. In order to be effective, sweat must be evaporated from the skin. If sweat merely drips from the surface of the skin or is wiped away, no heat will be lost.

 METHODS OF DETERMINATION OF THE NATURAL LIGHTING INDICES IN DIFFERENT PREMISES

Descriptive data:

1.   External factors that influence natural lighting in different premises:

- the territory latitude and its climate (number of sunny and cloudy days);

- season of the year and time of the day, when the premises are being used, existence of objects producing shadow (buildings, trees, hills, mountains).

2. Internal factors:

- name and function of premises;

- window orientation, floor;

- type of natural lighting, (light aperture location), (one-side, two-side, upper and combined);

- number of windows, their construction (one-framed, two-framed, combined);

- clarity and quality of glass, existence of objects producing shade (flowers and curtains);

- the window-sill height, distance from the window top edge to the ceiling;

- brightness (reflection ability) of the ceiling, walls, equipment and furniture

The above mentioned factors also influence the premises insolation regimen (the duration of exposure to the direct solar light). It can also be influenced by the windows’ orientation. (table 1).

Table 1

Types of premises isolation regimen

Premises insolation regimen

Orientation of windows

The duration of insolation, hours

The insolated area of the floor,%

Maximum

South-East, South-West

5-6

80

Medium

South, East, West

3-5

40-50

Minimum

North-East, North-West, West

less than 3

till 30

According to the hygienic norms the duration of insolation in residential areas, classrooms and other premises of similar functions must be not less than 3 hours.

The assessment of natural lighting in different premises using the geometric method:

1.   The lighting coefficient determination (the ratio of the glazed part area to the floor area, expressed in common fraction);

- the total area of the glazed window part is to be measured (S1), m2;

- the area of the floor is to be measured (S2), m2;

- the lighting coefficient is to be measured (LC=S1:S2=1:n) (n is calculated as S2 divided on S1 and approximated to the integer).

The received result is assessed according to the hygienic norms (table 2).

Table 2

The natural lighting norms for different premises

The type of premises

The daylight factor (DF)

The lighting coefficient (LC)

The angle of incidence (a)

The aperture angle (g)

The depth coefficient of premises

not less than

not less than

not less than

not less than

1.Classrooms

1.25-1.5%

1:4 – 1:5

27°

5°

2

2.Residential

1.0%

1:5 – 1:6

27°

5°

2

3. Wards

0.5%

1: – 1:8

27°

5°

2

4. Surgeries

2.0%

1:2 – 1:3

27°

5°

2

2. Determination of the angle of incidence a (the ABC angle at the furthest workplace from the window is formed by the horizontal line (or plane) AB from the workplace to the lower window edge (window-sill) and the line (plane) AC from the workplace to the upper window edge) (fig. 4.1).

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Fig. 4.1. Diagram for determination of the angle of incidence and the angle of aperture

The aperture angle calculation:

tg a=BC/AB (see table of tangents), a - the angle of incidence;

tg b=BD/AB (see table of tangents), b - the angle of shading;

Conventional marks:

BC- the height from the upper window edge to the work plane level, m;

AB- the distance from the window to the furthest work place, m;

BD- the distance from the projection of the shadowing object’s top onto the window glass to the level of the worktop, m.

As this angle together with the window glass line form the right triangle, it must be determined by tangent – the ratio of the window height above the workplace level (BC) (opposite cathetus of the triangle) to the distance from the window to the workplace (AB) (adjacent cathetus of the triangle). The angle of incidence a is found by the tangent value using the table.

3. The aperture angle g  determination (CAD angle, under which the part of the sky can be seen from the working place). This angle can be determined as the difference between the angle of incidence a and angle of shading b (DAB angle at the workplace between the horizon and the plane connecting the workplace and the shading object’s top (buildings, trees, mountains) (see the diagram, fig. 4.1).

To determine the angle of shading you must find the point D, where the line (plane) connecting the workplace and the top of the shading object comes through the window, divide the BD cathetus by AB (find the tangent of the shading angle), and find the value of the angle of shading b from the table.

4. The determination of depth coefficient in different premises - the ratio of the distance from the window to the opposite wall (EF, m) to the upper window edge height above the floor (CE, m). According to the hygienic norms this coefficient must not be higher than 2 for residential areas, classrooms and other similar premises.

The lighting engineering method of natural lighting assessment in different premises consists in determination of daylight factor (DF).

The daylight factor (DF) is defined as the ratio of the actual illuminance at a point in a room (lux) and the illuminance available from an identical unobstructed sky:

The indoor and outdoor lighting is measured by luxmeter (see the instruction, appendix 2 and fig. 4.2).

Описание: Описание: Описание: 4

Fig. 4.2. Luxmeter U-116 (Ю-166)

(1 – measuring device (galvanometer); 2 – light receiver (selenium photo-cell); 3 – changing light filters)

The part of the sky can be hidden behind the tall buildings and trees in the cities or by mountains in highlands. That’s why the curves of the regional lighting climate are used in practice (fig. 4.3). 

The curves, shown on the fig.4.3, include months, hours and the level of cloudiness. The ordinate axis has lighting indicators, marked in thousands of lux.

The natural lighting of factory sections may be side (one-side, double-side), upper (light apertures in the ceilings) and combined.

According to the Building Norms and Rules (BNandR)-4-79, the daylight factor (DF) is calculated:

- in case of one-sided lighting – at the distance of 1 m from the opposite wall;

- in case of double-sided lighting - in the middle of the section;

- in case of the combined lighting, the average of the several lighting measurings, performed using the “envelope” method is calculated (table 4).

TRAINING INSTRUCTION

on lighting determination using the luxmeter

The U-116 (Ю-116) or U-117 (Ю-117) luxmeter consists of selenium photo-cell with changing light filters and the galvanometer with the scale. When the light strikes the photo-cell surface, it produces the electric current, the strength of which is measured by the galvanometer. The galvanometer indicates the value of the researched light in luxes.

The front panel of the luxmeter also contains the switching buttons, and the scheme, that explains the effect of each button when using different light filters. There are two different scales at the device’s panel: the 0 – 100 scale, and the 0-30 scale. Each of them has the starting point of its measuring range marked: on the 0-100 scale that is 20, and on the 0-30 scale – 5. Also there is the screw-adjusted regulator for setting the device to zero.

The selenium photo-cell connected to the device with the plug is hidden in the plastic case. The spherical light filter, made of white light dispersing plastic and the opaque ring, is used with the photo-cell for more exact measuring. This filter is used simultaneously with one of the three changing filters. These changing filters have different attenuations (10, 100 and 1 000), and they extend the measuring range.

The process of the measuring consists of the following:

1)     The device is set to 0;

2)     By trying the different combinations of the pressed buttons and changing filters, the appropriate scale for the present light is found. When the button, next to which the ranges, divisible by 3 are written, the 0-30 scale is used. When the button with the ranges, divisible by 10 is pressed – the 0-100 scale is used;

3)     The measuring result in scale marks is then multiplied by the attenuation value of the filter used.

The U-116 (Ю-116) or U-117 (Ю-117) luxmeter is graded for measuring the light, produced by the incandescent lamps. The correcting coefficients are used for the other types of light. For the natural light its value is 0.8, for the fluorescent daylight lamps – 0.9, and for the white lamps – 1.1.

The general assessment of the natural lighting in different premises is made by comparing the results of all measurements with the hygienic norms. The accuracy of visual work is the base for these norms. It includes the sizes of the visual objects, their contrast against the background etc.

For the convenience the results of measurements and the hygienic norms are written into the table:

Figure

Results of determination

Hygienic norm

Assessment

1.

 

 

 

 

2.

 

 

 

 

To draw the final conclusion about the natural lighting of different premises it is necessary to compare the assessment of each result with the norm.  

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 5401012 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).

2.     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.

Описание: Описание: Описание: 5_1

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:

a)     the area of the premises is determined, S, m2;

b)    the total capacity of all the lamps, Wt, is determined;

c)     the specific capacity, Wt/ m2, is calculated;

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

e)     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.

 

The sources of artificial lighting.

There are two main sources of artificial lighting: incandescent bulbs and luminescent lamp. A bulb is very convenient source of light. Its deficiency is a very small light returning: on 1 Vat of expended electric energy one can receive 10-20 lm. The spectrum of its radiation differs from the spectrum of white daylight. It has less quantity of blue and violet radiation and more red and yellow one. That’s one taking into consideration psycho-physiological side this radiation is pleasant and warm.

Luminescent lamp consists from glass tube. The internal surface of this glass is covered by luminoforum. The tube is full of mercury steam. At the ends it has electrodes. When the lump is switched in the electric net on, the electric current creates between the electrodes. It generates ultraviolet radiation. Under ultraviolet radiation influence luminofor starts to shine. Thus choosing different kinds of luminofor one can made luminiscent lamps with different spectrum of visible radiation: lamps of day light, white light, warm-white light. The spectrum of day light lamp radiation is very clothing by spectrum of natural lighting of lodging, situated on the north. This light helps to get tired less, even if we look at very small subject. To deficiency of lamp one can attribute blue color at surroundings: skin… and so on.

Lighting appliance of bulbs.

There are lighting appliance of direct light, reflected light, half-reflected light, and diffused light. The lighting appliance of direct light directs over 90% of lamp light to the lighting place, providing its high lighting. But at the same time there is a great difference between the lighting and sun lighting places of lodging. Harsh shadows are created sometimes it can blind there person. Usually this kind of lighting appliance is used for lighting of auxiliary lodging and sanitary lodgings. The appliance of reflected light is characterised by the fact, that rays from lamp are directed to the ceiling and upper part to the walls. They are repulsed, and evenly, without shadows, are divided in lodging. Their light is soft and diffused. This kind of lighting appliance creates lighting, which exactly corresponds to hygienic norms. But it is not economic one. Because in this case 50% of light is lost. That’s for lighting of settlements, classrooms, wards more economic lighting appliance is used – appliance of diffused light. In this case a part of rays shine the lodging after coming through milk or mat glass, and part of rays shine the lodging after repulsing from ceiling and walls. Such lighting appliance creates satisfactory conditions of lighting, does not blind and doesn’t create harsh shadows.

Deficiencies of luminiscent lamps (compared with bulbs).

One of the deficiencies of luminiscent lamp is that the skin of people in this light looks very pale or grey. That’s why there lamps are not used in schools, wards and others lodging like these. Becides there are another deficiency. If lighting in case of using luminiscent lamps is power than 750-150 Lk, one can see “twilight effect”. That means lighting is insufficiently even to look at big object. That’s why while using luminiscent lamps, lighting should be not less than 75-150 Lk. Besides while looking at moving or rotating object in luminiscent lighting sometimes “stroboscope effect” can occur. That means creating of numerous contours of objects. When dossals are out of order luminiscent lamps radiate pulse light or create noise.

The spectrum of worm-white lamps is rich on yellow and rose rays. This can make the colour of face more pleasant. But at the same time these lamps decrease eye capacity for work. These lamps are used for lighting of railway station, hall, and cinemas, metro stations.

Advantages of luminiscent lamps compared with bulbs.

         The bulb cannot be used when one need to differentiate colours well. In this case one should use luminiscent lamp of daylight. Lamps of white light have spectrum rich on yellow rays. That’s why while using true lamps great capacity for eye work is presented, and skin colour looks great. That’s why lamps of white light are used in schools, lecture rooms, settlements, and wards of hospitals. Spectrum of lamps of warm-white light is rich on yellow and rose radiation. This fact makes less capacity for eye work, but makes the skin colour very pleasant. Variety of spectrum is one of the hygienic advantages of these lamps light returning of luminiscent lamps is in 3-4 times higher than light returning of bulbs. That’s why they are more economic. During numerous comparative investigations with bulbs on industrial plants, in schools, hospitals, lecture rooms objective induces, which characterise the nervous system state, weariness of eye, capacity for work almost in all cases prove hygienic advantage of luminiscent lamps. But for their wide usage we need professional help. It is necessary to choose the lamp correctly, according to its spectrum, taking into consideration purpose of the place.

Methods of definition of artificial lighting.

Artificial lighting can be defined by means of calculate methods, for example the methods of middle horizontal lighting. The principle of the methods is the following: if we use 10 Vat of electro energy stress on each square meter of floor, we receive the middle horizontal lighting. It depends on the force of used lamps. While the same expenditure of energy on square unit lighting can be different. It can be explained by different lighting returning of lamps of different force. Using data about lighting while expending energy (10 Wt/m2 ) and taking into consideration that received lighting depends directly on expended energy, one can find artificial lighting. For this we use the quantity of lamps with certain power and quantity of chalendeliers with certain power, which it is necessary for certain lighting. For example, it is necessary to find middle horizontal lighting in classroom. Its floor’s square is 50 m2. . We also know that 6 chalendeliers are used. The force of each lamp is 200 Wt. The voltage in net is 120 V. Taking into concideration all the conditions, general electro energy force, which is used to shine the classroom is 200 x 6 =1200 Wt. On 1 m2 of floor we have 1200:50 = 24 Wt/m2.  For lamps 200 Vat in case of energy expenditure 10 Vat/m2 lighting E will be 35,5 Lk. The lighting will be higher in so many times, as the energy expenditure is higher then common on square unit:

        10/24=35,5/E; E = 85,2 Lk.

 

Proper power (Wt2) of general illumination

 

Height of hanging of lamps, м

Square of the apartment

м2

Level of illumination, lux

30

50

75

100

150

200

300

400

500

Luminescence lamp

2-3

10-15

-

-

8,6

11,5

17,3

23

35

46

58

15-25

-

-

7,3

9,7

14,5

19,4

29

39

49

25-50

-

-

6,0

8,0

12,0

16

24

32

40

50-150

-

-

5,0

6,7

10,0

13,4

20

27

34

150-300

-

-

4,4

5,9

8,9

11,8

17,7

24

30

More 300

-

-

4,1

5,5

8,3

11

16,5

22

27

Incandescent lamp (bulb lamp)

2-3

10-15

11

17

24,

31

45

61

-

-

-

15-25

9,2

14

20

25,5

37

50

-

-

-

25-50

7,8

12

17,3

21,5

31

42

-

-

-

50-150

6,5

10,3

14,7

18,5

27

36

-

-

-

150-300

5,6

9,2

12,9

16,3

24

32

-

-

-

More 300

5,2

8,2

12,3

15,3

22

29,5

-

-

-

 

Hygienically norms of artificial illumination

 

Room

Minimal illumination, lx

Luminescence lamp

Incandescent lamp

(bulb lamp)

Оperation  room

-

200

Doctors room

300 (200)

150 (100)

Room for patient

-

50

Study rooms, laboratory room

300

150

Corridor

100

50

 

Methods of determination of the natural lighting indices in different premises

 

Descriptive data:

1.  External factors that influence natural lighting in different premises:

- the territory latitude and its climate (number of sunny and cloudy days);

- season of the year and time of the day, when the premises are being used, existence of objects producing shadow (buildings, trees, hills, mountains).

2. Internal factors:

- name and function of premises;

- window orientation, floor;

- type of natural lighting, (light aperture location), (one-side, two-side, upper and combined);

- number of windows, their construction (one-framed, two-framed, combined);

- clarity and quality of glass, existence of objects producing shade (flowers and curtains);

- the window-sill height, distance from the window top edge to the ceiling;

- brightness (reflection ability) of the ceiling, walls, equipment and furniture

The above mentioned factors also influence the premises insolation regimen (the duration of exposure to the direct solar light). It can also be influenced by the windows’ orientation. (table 1).

 

Table 1

Types of premises isolation regimen

 

Premises insolation regimen

Orientation of windows

The duration of insolation, hours

The insolated area of the floor,%

Maximum

South-East, South-West

5-6

80

Medium

South, East, West

3-5

40-50

Minimum

North-East, North-West, West

less than 3

till 30

 

According to the hygienic norms the duration of insolation in residential areas, classrooms and other premises of similar functions must be not less than 3 hours.

The assessment of natural lighting in different premises using thegeometric method:

1.  The lighting coefficient determination (the ratio of the glazed part area to the floor area, expressed in common fraction);

- the total area of the glazed window part is to be measured (S1), m2;

- the area of the floor is to be measured (S2), m2;

- the lighting coefficient is to be measured (LC=S1:S2=1:n)(nis calculated as S2 divided on S1 and approximated to the integer).

The received result is assessed according to the hygienic norms (table 2).

Table 2

 

The natural lighting norms for different premises

 

The type of premises

The daylight factor (DF)

The lighting coefficient (LC)

The angle of incidence (a)

The aperture angle (g)

The depth coefficient of premises

not less than

not less than

not less than

not less than

1.Classrooms

1.25-1.5%

1:4 – 1:5

27°

5°

2

2.Residential

1.0%

1:5 – 1:6

27°

5°

2

3. Wards

0.5%

1: – 1:8

27°

5°

2

4. Surgeries

2.0%

1:2 – 1:3

27°

5°

2

 

2. Determination of the angle of incidence a (the ABC angle at the furthest workplace from the window is formed by the horizontal line (or plane) AB from the workplace to the lower window edge (window-sill) and the line (plane) AC from the workplace to the upper window edge) (fig. 4.1).

 

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Fig. 4.1. Diagram for determination of the angle of incidence and the angle of aperture

 

The aperture angle calculation:

tga=BC/AB (see table of tangents), a - the angle of incidence;

tgb=BD/AB (see table of tangents), b - the angle of shading;

Ðg=Ða-Ðb Ðg

Conventional marks:

BC- the height from the upper window edge to the work plane level, m;

AB- the distance from the window to the furthest work place, m;

BD- the distance from the projection of the shadowing object’s top onto the window glass to the level of the worktop, m.

 

As this angle together with the window glass line form the right triangle, it must be determined by tangent – the ratio of the window height above the workplace level (BC) (opposite cathetus of the triangle) to the distance from the window to the workplace (AB) (adjacent cathetus of the triangle). The angle of incidence a is found by the tangent value using the table 3.

Table 3

The trigonometric table

tangent

angle, 0

tangent

angle, 0

tangent

angle, 0

0

0

0.287

16

0.601

31

0.020

1

0.306

17

0.625

32

0.030

2

0.325

18

0.649

33

0.050

3

0.344

19

0.675

34

0.090

5

0.364

20

0.700

35

0.105

6

0.384

21

0.727

36

0.123

7

0.404

22

0.754

37

0.141

8

0.424

23

0.781

38

0.158

9

0.445

24

0.810

39

0.176

10

0.466

25

0.839

40

0.194

11

0.488

26

0.869

41

0.213

12

0.510

27

0.900

42

0.231

13

0.532

28

0.933

43

0.249

14

0.555

29

0.966

44

0.268

15

0.577

30

1.000

45

3. The aperture angle g  determination (CAD angle, under which the part of the sky can be seen from the working place). This angle can be determined as the difference between the angle of incidence a and angle of shading b (DAB angle at the workplace between the horizon and the plane connecting the workplace and the shading object’s top (buildings, trees, mountains) (see the diagram, fig. 4.1).

To determine the angle of shading you must find the point D, where the line (plane) connecting the workplace and the top of the shading object comes through the window, divide the BD cathetus by AB (find the tangent of the shading angle), and find the value of the angle of shading b from the table.

 

4. The determination of depth coefficient in different premises - the ratio of the distance from the window to the opposite wall (EF, m) to the upper window edge height above the floor (CE, m). According to the hygienic norms this coefficient must not be higher than 2 for residential areas, classrooms and other similar premises.

The lighting engineering method of natural lighting assessment in different premises consists in determination of daylight factor (DF).

The daylight factor (DF) is defined as the ratio of the actual illuminance at a point in a room (lux) and the illuminance available from an identical unobstructed sky:

 

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The indoor and outdoor lighting is measured by luxmeter (see the instruction, appendix 2 and fig. 4.2).

Описание: Описание: Описание: 4

 

Fig. 4.2. Luxmeter U-116 (Ю-166)

(1 – measuring device (galvanometer); 2 – light receiver (selenium photo-cell); 3 – changing light filters)

 

The part of the sky can be hidden behind the tall buildings and trees in the cities or by mountains in highlands. That’s why the curves of the regional lighting climate are used in practice (fig. 4.3). 

The curves, shown on the fig.4.3, include months, hours and the level of cloudiness. The ordinate axis has lighting indicators, marked in thousands of lux.

The natural lighting of factory sections may be side (one-side, double-side), upper (light apertures in the ceilings) and combined.

According to the Building Norms and Rules (BNandR)-4-79, the daylight factor (DF) is calculated:

- in case of one-sided lighting – at the distance of 1 m from the opposite wall;

- in case of double-sided lighting - in the middle of the section;

- in case of the combined lighting, the average of the several lighting measurings, performed using the “envelope” method is calculated (table 4).

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Fig. 4.3. Curves of light climate

Table 4

The DF values for the industrial premises

 

Category of work

Visual work characteristic

Minimum visual object size

The coefficient of the natural lighting

if combined lighting

if side lighting

I

The highest accuracy

0.15

10

3.5

II

Very high accuracy

0.15-0.3

7

4.2

III

High accuracy

0.3-0.5

5