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

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 — the goddess of 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.

In India and other countries, the terms Hygiene and Public Health have been replaced by Preventive and Social Medicine. In fact the term incorporates all the con­cepts discussed under Hygiene, Public Health, Preventive Medicine and Social Medicine. InHygiene and Public Health, there was more em­phasis on classical public health. In Preventive and Social Medicine, the emphasis is more on total health care programmes for individuals, families, groups as well as communities through integration of medical, public health and social welfare services.


Prevention is better than cure is an old saying. Preventive medicine deals with the measures to protect the individuals from the diseases, and to keep them in a state of positive health. For this we have to ensure all the above-mentioned prerequisites required for the maintenance of positive health. The environments must be hygienic, with supply of fresh air, safe potable water and balanced diet. This aspect of preventive medicine started gaining more importance from 18th century onwards with the discovery of various vaccines and sera for the protection against various diseases like small pox, cholera, plague, whooping cough, tetanus, tuberculosis, poliomyelitis etc

Ecology is constituted by the total environment of man. The environment of modern man is partly natural and partly man-made. It consists of physical, mental and social factors, which are dynamic and interacting both within themselves and with the life process in the internal environment of men. The im­portant physical factors are air, water, food, build­ings, their contents and multiple devices produced by man to adjust the physical environment around him. The important biological factors are pathogens, other microorganisms as well as living beings, vec­tors, plants, etc., which have implications on health and disease. The important social factors are cus­toms, beliefs, laws, peculiarities and modes of living of human beings with their implications on health and disease.

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.

Thefollowingdefinitionnowisaccepted: «Hygieneis a science, whichinvestigatesregularitiesofinfluenceoftheenvironmentontheorganismofthemanandpublichealthwiththepurposeofthesubstantiationofthehygienicnorms, sanitarianrulesandmeasures, realizationofwhichwillensureoptimumconditionsforvitalactivity, improvingofhealthandpreventingofdiseases ».

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.


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.


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

1.     Methods of environment studying


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 Esherichiacolli, have much value for conclusion about epidemiological safety of the potable water.


1. Methods of experimental investigation

A studyresponseofanorganismonvariousexterioractionsplaysthemajorrolefordevelopmentofmodernhygiene. Theexperimentonthe warm-bloodedanimalsnowisleadingforallitsareas. So, toxico-hygienicresearchesarecompulsoryforevaluationoftoxicityofpoisonoussubstances, whichusesinindustryandagriculture. Notlesswidelythereareusesinmunicipalhygieneforanalysisofindustrialwastewater, inhygieneoffoodsforthedefinitionofharmfulimpurities, andinotherareasofhygiene. Theskilfulrealisationoftheseresearchesallowsreceivingdatesfordevelopmentoftheappropriatehygienicnorms, methodsofearlydiagnosticsofprofessionaldiseasesandforevaluationofeffectivenesspreventivemeasures.

2. Methods of natural observation

Much value is represented by clinical observations of the people, which are exposed of the defined exterior factors. In particular, defined value has working out materials of periodic medical examinations of working harmful trades. Comparing these observations with dates of the research of an industrial medium, it is possible form a correct estimate of the recommended hygienic norms.

    Also, in hygiene is widely applied the method of a sanitary - statistical analysis, with the help of which may form a true notion about positive and negative influence on health of the population: it physical development, morbidity, mortality, average life expectancy etc.

There are widely used different kinds of hygienic experiments:

1 Experiment with simulation of natural conditions.They are used for examining and predicting processes which are going on in the surrounding world (for example, for examining, the influence of chemical admixtures on the processes of self-clearing of water in reservoirs).

2. Laboratory experiment on animals.It helps to study influence of factors of environment on the organism which meets the goal to substantiate hygienic norms. In the process of this experiment the following methods are used:physiological,biochemical, immunological, histological, microscopic, radiobiological, genetic and others.

3. Chamber experiment on people.It is used to study the influence of some factors on the human organism and determine the norms. This method is used to study such factors as microclimate, illumination, noise, neural-psychic strain, etc.

 Natural experiment”which helps to study influence of factors of environment on the human health in real conditions of the life For example, studying health of people (especially children) who live at different distance from enterprises throwing out into the atmosphere toxic gaseous substances. Natural experiment allows to check-up hygienic norms which were determined in the experiment on animals.

The health of individuals is studied by way of medical examinations with the usage of anthropometric, clinical, physiological, biochemical, immunobiological, roentgenological and other methods of examinations. Their participation in labour and other types of activity must be taking into account.

The health of a certain group of people or of all population of the populated area (region, republic, etc.) is studied with the help of sanitary - statistic method. There are different criteria which characterize physical development, demographical peculiarities (birth-rate, death-rate, average life span and others), morbidity and pathology of studied group.

Epidemiological method is close to sanitary - statistic method. It is used for studying of spreading of this or that disease (hypertension, coronary disease, diabetes, ulcerous disease, etc.). They are studied during certain period (during. a year, month), on the certain territory (different regions of the city, republic), among different groups of population (which differ one from another by age, gender, occupation, conditions of water and food supply, conditions of life and others). Analysis of these data is used for determining of causes and conditions which favor the development of disease, for liquidation of disease as regional pathology, for planning prophylactic measures.

Methods of mathematical statistics and modelling are widely used.

Hygienic standardization:

Environmental standards are definite ranges of environmental factors, which are optimal, or the least dangerous for human life and health. In Ukraine basic objects of hygienic standardization are:

§        MAC – maximum admissible concentration (for chemical admixtures, dust and other hazards)

§        MAL – maximum admissible level (for physical factors)

§        LD – dose limit (for ionizing radiation)

§        Optimum and admissible parameters of microclimate, lighting, solar radiation, atmospheric pressure and other natural environmental factors.

§        Optimum and admissible daily requirements in food and water.



Let's study the methodical scheme of hygienic norms of substantiation using, the example of MAC for some toxic substance.The first stage is stud physical and chemical properties of the substance, elaboration of methods of quantitative determination of this substance in different subjects, determination of its regimen of action on the human (duration, interruption, changes of intensity), ways of getting into the organism, study migration in different elements of the surrounding, mathematical prediction of duration of existence in different surroundings.

The second stage is study direct influence on the organism. It is started from 'sharp' experiments the main goal of which is getting initial toxicometric data about the substance (determination of LD50, or LC50 threshold of strong action (LIMac) and other. With the knowledge of physical and chemical properties of t he substance, its initial toxicological characteristics and approximate level of MAC can be calculated.The third stage- is conduction of 'subsharp' experiment during l-2 months for determination of cumulating coefficient and the most vulnerable physiologic systems and organs specification of mechanisms of action and metabolism.

The fourth (basic)stage is carrying out chronic experiment which lasts 4-6 months in the case of modeling of working conditions, 8-12 - communal conditions, 24-36 - in study processes of aging or induction of tumours.

During the experiment integral parameters are studied. They reflect condition of animals, degree of strain of regulative systems, functions and structure of organs which take part in processes of metabolism (activity of enzymes), influence of functional loadings.

Numbers of MACs of toxic chemical substances in the Ukraine are various: for the air of working: zone - more than 800, water- 700, atmosphere air- 200, food-stuffs - more than 200, soil - more than 30.

Basic objects, which are under the hygienic norms setting, can be divided into two groups.

    The first groupcontains factors of anthropogenous origin, which are unfavorable for human being, and are not necessary for the normal life activity (dust, noise, vibration, ionizing radiation, etc.). MAC, MAL and LD are those parameters, which are set for this group of factors.

    The second groupcontains factors of natural surrounding which are necessary (in certain amount) for normal life activity (food-stuffs, solar radiation, microclimatic factors and others). For this group the following parameters must be set: optimum, minimum and maximum admissible parameters.

    In those cases when factors influence on the human not only directly (physiologically) but also indirectly (through the environment) all types of possible influence must be examined at hygienic norms setting. For example setting of hygienic norms for toxic substance in the water of natural reservoirs determination of maximum concentrations must be based on worsening of organoleptic properties of the water (organoleptic sign), toxic influence (sanitary - toxicological sign) and disturbance of processes of self-clearing of reservoirs (general sanitary sign). In this case MAC are set according that harmful parameter which is characterized by the lowest level of concentration Such parameter is called limiting.



Major and most complicated of all hygienic problems doubtlessly is the sanitarian protection of an environment. Arise with emerging of a large industry; it gains the increasing value in accordance with development of industry. The wastes of industrial firms pollute atmosphere, soil, and reservoirs; therefore the series of harmful substances can penetrate into an organism with an inhaled air, water and foodstuff.

The task of hygiene is next: development and opportune realisation of preventive measures to notify expressed contamination of an environment and its unfavourable influence on health of the population. Thus, the hygienic science has not only to be in time with engineering progress in all areas of national economy, but also in any measure to foresee it, preparing the appropriate norms and measures of preventive maintenance.

At last, the modern hygiene should give the most serious attention to preventing of development of some pathological conditions, which are now the basic causes of mortality among the adult population (cardio – vascular diseases, malignant tumours, heavy chronic bronchitis). It is especially necessary, because it is possibleto count proved connection of this diseases with unfavourable modifications of an environment.


As the basic preventive discipline, hygiene should be a conducting link in medicine, which in our country has uniform treatment-preventive direction.            Undoubtedly, that a generous duty of the doctor is recovery of the patient, saving his life, restoring of work capacity. However it is even more important not to admit the beginning of illness. Actually duration of life and duration of active blossoming age will depend on it, as even easy disease often can inflict imperceptible, but indelible damage to an organism.

It is necessary always to remember, that modern diagnostics and successful therapy can be ensure only if the doctor will be familiar with basic positions of hygiene and will acquire « a hygienic mode of thinking ». So, only knowing detailed professional anamnesis and the character of possible harmful action of an industrial medium, is possible correctly to solve the problem about aetiology of this or that occupational disease, to define peculiarities provision of employment, to individualise a hygienic condition of the patient and so on.

Naturally, that in works of medical institutions the preventive treatment play more and more important part.

    The major task of any medical worker is the protection and improvement of an environment, because its contamination, as is known, exercise negative influence on the health of the population.

    Doctor should give more attention to looking healthy people, preventing the development of arteriosclerosis, hypertension and malignant tumours.


Public health has been denned as the art and science of preventing disease, prolonging life, and promoting physical and mental health, sanitation, personal hygiene, control of infection, and organization of health services.

From the normal human interactions involved in dealing with the many problems of social life, there has emerged recognition of the importance of community action in the promotion of health and the prevention and treatment of disease; this is expressed in the concept of public health.

Comparable terms for public health medicine are social medicine and community medicine; the latter has been widely adopted in the United Kingdom, and the practi­tioners are called community physicians.

The practice of public health draws heavily on medical science and phi­losophy and concentrates especially on manipulating and controlling the environment for the benefit of the public. It is concerned therefore with housing, water supplies, and food.

Noxious agents can be introduced into these through farming, fertilizers, inadequate sewage disposal and drainage, construction, defective heating and ventilat­ing systems, machinery, and toxic chemicals. Public health medicine is part of the greater enterprise of preserving and improving the public health.

 Community physicians cooperate with such diverse groups as architects, builders, sanitary and heating and ventilating engineers, factory and food inspectors, psychologists and sociologists, chemists, physicists, and toxicologists.

Occupational medicine is concerned with the health, safety, and welfare of persons in the workplace. It may be viewed as a specialized part of public health medicine since its aim is to reduce the risks in the environment in which persons work.

WHO has defined normal health as follows. "Normal health means a state of complete physical, mental and social well-being of an individual i.e., a state of positive health." 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.

In medicine were formed the two associate and complementary each other sections: medical and prophylactic medicine. A sick man is the object of study of medical medicine. "The disease" is a philosophical category, which is describing general or individual disturbances of vital functions of organism, caused by action of the external and internal factors.

At everybody the illness flows with the individual features. This pathological condition of the separate man, that is reflecting infringement of dynamic balance between organism and environment, constancy of internal environment (homeostasis), has received the name of disease. Therefore basic purpose of medical medicine as the science is to study the laws of occurrence and current of disease and, on the basis of it, development of ways and remedies of treatment of the patient, restoration of his health.

The object of studding of preventive medicine or hygiene is both separate healthy man, and groups of the practically healthy people. A philosophical category, which is describing a condition of the practically healthy man or group of the healthy people, is "health".

 “Prevention is better than cure” is an old saying. Preventive medicine deals with the measures to protect the individuals from the diseases, and to keep them in a state of positive health. For this we have to ensure all the above mentioned prerequisites required for the maintenance of positive health. The environments must be hygienic, with supply of fresh air, safe potable water and balanced diet. This aspect of preventive medicine started gaining more importance from 18th century onwards with the discovery of various vaccines and sera for the protection against various diseases like small pox, cholera, plague, whooping cough, tetanus, tuberculosis, poliomyelitis etc. Edward Jenner discovered vaccination against small pox in 1796. The discovery of causative agents of the diseases by Louis Pasteur (1822-1895) and Robert Koch (1843-1910) gave a great fillip to the science of preventive medicine. Von Behring (1854-1917) brought up the principle of serum treatment and use of anti-sera in various diseases. The various disinfectants and insecticides played a great role in the gradual control and prevention of communicable diseases. The hazards of population explosion brought the family planning programmer into limelight. The infant and maternal mortality rates have been brought down with improvement in maternal and child health services. The other main aspects covered under the subject are noncommunicable diseases, school health services, occupational medicine, rural health services, health education, mental health, geriatrics, medical genetics and the public health administration. With advancement of medical science, its preventive aspects are also coming more and more to the fore. In short an ounce of prevention is worth a pound of cure.

If all etiological factors of not infectious nature, which can change a level of health of the population take as 100 %, the densities of each of them will be such as: the conducting meaning in formation of level of health of the population is a healthy or unhealthy way of life (49-53 %), the second place occupies the genetic factor (18-22 %), third one - factors of  pollution of an environment (17-20 %) and only fourth (8 -10 %) - medical etiological factors (out of time rendered medical aid, poor quality, inefficiency of preventive measures and etc). From these follows, that for all responsible for health people services of the country, including sanitary - epidiological, it is necessary to make basic emphasis formation of healthy way of life, and then on struggle with pollution of environment by substances, which can be potential mutagens receipt in organism of the man or influence on it, can promote occurrence of genetic defects, which is shown in first and the subsequent generations.

The basic law of hygiene is based on principles fixed in a basis of one of the conducting laws of the epidiology, which was formulated by the academician L.B. Gromashevski. According to this law the driving forces (conditions), that are determining epidemic process, are: a source of an infection – the sick man or contagious man, mechanism of transfer and susceptible to the given infection organism. At deenergizing even by one of these driving forces the occurrence of infectious disease or epidemics (epidemic process) is impossible.

The first law of hygiene

The first law of hygiene (about three driving forces of adverse influence of factors of an environment on health of the population) can be formulated as follows: the infringement of level of health of the people (disease, decreasing of the resistance, immunological status, adaptation-compensatory opportunities of organism), caused by physical, chemical, biological and psychogenic etiological factors, can arise only at presence of three driving forces: a source of insalubrity (polluting substance) or the complex of the insalubrities, factor (mechanism) of influence or transfer of this polluting substance and susceptible (sensitive to influence of the insalubrity) organism. At the absence of one of these conditions, the disturbances of health will not take place.

From the first law of hygiene follows, that it is necessary the presence of all three driving forces for the decreasing of health of the population. Hence, basic task of hygiene as the science should be the scientific substantiation of a complex of preventive measures directed on elimination or even on reduction (at the beginning) of role of one, two or all three driving forces of deterioration of health of the population.


Well, what is it? Stinky stuff?Muck?Poison? Yes, all those things... and more. It is difficult to give a simple, comprehensive definition of pol­lution. The word comes from the Latin pollutus, which means made foul, unclean, or dirty. Some is obvious like smoke which you can see but much of it is not obvious at all. Yet you're eating it and drinking it and breathing it most of the time. And what is worse is that all this muck affects all other life on Earth. You can find pollution made by people just about everywhere on the planet. Even remote places like the Arctic are badly polluted by nasty chemicals made by people. The polar bears and seals there have poisonous chemicals made by people in their bodies and so do the Inuit people who live with them. These nasty things kill many animals and make others sick -- including penguins in the Antarctic. They also kill people and make them ill too. There's nowhere on the planet left with no pollution; not even the bottom of the sea or high up in the air.

On a degree of danger distinguish four groups of chemical substances – pollutes: I - especially high toxic (middle death doze -DL - is lower than 50 mg/kg of weight of body); II - high toxic (DL = 50-200 mg/kg); Ш - middle toxic (DL = 200-1000 mg/kg); IV - low toxic (DL- more than 1000 mg/kg)

The concept about first driving force of process of change of level of health allows to study laws of change of polluting substances in an environment, their decomposition and transformation under influence of the physical and chemical factors of an environment at mutual amplification or decrease of harmful properties.

It is ideal, if the receipt of polluting substances in environment is absent, which is unreal in epoch of scientific and technical progress. Therefore presence of the first driving force and its role for health of the population cause necessity of the scientifically proved hygienic specifications of polluting substances, as on their basis the doctor - hygienist will argue the preventive measures on elimination or reduction of the first driving force of level of health. The basic purpose of these measures is the decreasing of concentration of polluting substances in an environment up to a level, which is safetee for health of the population, its residing and labour activity.

The concept about the second driving force of level of health is a concept about role of the factors of transfer mechanisms of the report of polluting substances up to susceptible organism, about densities of each factor, that allows to study ways of migration of polluting substances from a source of pollution to the man. Thus the polluting substance can enough long be in objects of an environment (atmospheric air, water of reservoirs, ground), but can’t be dangerous for the man. Only then it can render harmful influence, when it gets in the organism of the man with inhaled air, water, food in quantities exceeding hygienic norm.

Thus, the polluting substance can render damaging action on organism, if mechanism of transfer it in organism of man enclose or work by one of the ecological chains, for example for polluting chemical substances: polluting substance - air-man; polluting substance - water - man; polluting substance - soil - plant - animal - man.

If from ecological circuit to withdraw this or that factor (link) of transfer (polluted air, water, foodstuff), the mechanism of transfer will not work.

At last, the conception about the third driving force of the first law - about susceptible to the given polluting substance or complex of substances of organism, allowing to systematize our knowledge and to prove scientifically the preventive measures, directed on amplification of the imunological reactivity of organism, on disclosing and using of laws, determining ways and meanings of increasing of stability of organism to influence of the adverse factors of environment, amplification of mechanisms  of self regulating, adaptation and compensation.

Major condition of high stability of the organism to adverse factors of environment is healthy way of life, excluding the using of alcoholic drinks, smoking, other harmful habits, rational nutrition, rational mode of work and rest, observance of rules of personal hygiene, using of wide improving opportunities of physical culture and sports, self preparing. At performance of work in maintenance high resestention of organism the large meaning has the professional selection, preliminary and periodic medical control, preventive feeding, protective, preventive inoculations, industrial training, sanitary education, safety precautions, use of individual means of protection.


The second law of hygiene

The second law of hygiene is law of inevitable negative influence of  activity of the people on the environment.

During the process of live the man allocates in environment excrement (faces, urine), which are very dangerous in the epidemic and sanitary attitude. This danger grows if not to undertake of measures of immediate removal of excrements from the inhabited localities through the water drain with the further neutralization on clearing sewer structures.

Environmental pollution is the release of harmful environmental contaminants, or the substances so released. Generally the process needs to result from human activity to be regarded as pollution. It is difficult to give a simple, comprehensive definition of pol­lution. The major types of air pollution are:


Gaseous pollutants: A different mix of vapors and gaseous air pollutants is found in outdoor and indoor environments. The most common gaseous pollutants are carbon dioxide, carbon monoxide, hydrocarbons, nitrogen oxides, sulfur oxides, particulates, leadand ozone. A number of sources produce these chemical compounds but the major man-made source is the burning of fossil fuel.

 Indoor air pollution is caused by cigarette smoking, the use of certain construction materials, cleaning products, and home furnishings. The most commonly recognized type of air pollution is smog. Smog generally refers to a condition caused by the action of sunlight on exhaust gases from motor vehicles and factories.

The Greenhouse effect prevents the sun's heat from rising out of the atmosphere and flowing back into space. This warms the earth's surface causing the green house effect. While a certain amount of green house gases in the atmosphere are necessary to make the earth warm, activities such as the burning of fossil fuels are creating a gaseous layer that is too dense to allow the heat to escape. Many scientists believe this is causing global warming. Other gases contributing to the problem include cholrofluorocarbons (CFC), methane, nitrous oxides, and ozone.

Acid rain forms when moisture in the air interacts with nitrogen oxide and sulfur dioxide released by factories, power plants, and motor vehicles that burn coal or oil. This interaction of gases with water vapor forms sulfuric acid and nitric acids. Eventually these chemicals fall to earth as precipitation, or acid rain. Acid rain pollutants may travel long distances, with winds carrying them thousands of miles before they fall as dew, drizzle, fog, snow or rain.

Damage to the ozone layer is primarily caused by the use of chloroflurocarbons (CFCs). Ozone is a form of oxygen found in the earth's upper atmosphere. The thin layer of ozone molecules in the atmosphere absorb some of the sun's ultraviolet (UV) rays before it reaches the earth's surface, making life on earth possible. The depletion of ozone is causing higher levels of UV radiation on earth, endangering both plants and animals.

The third law of hygiene

The third law of hygiene – is the law of inevitable negative influence on an environment and health of the people of natural ecological accidents (flood, earthquake etc), natural both toxic biochemist provinces and toxic failures (on AES, enterprises, transport).


Some pollutants come from natural sources.

  • Forest fires emit particulates, gases, and VOCs (substances that vaporize into the atmosphere)

  • Ultra-fine dust particles created by soil erosion when water and weather loosen layers of soil, increase airborne particulate levels.

Volcanoes spew out sulfur dioxide and large amounts of pulverized lava rock known as volcanic ash Volcanoes spew out ash, acid mists, hydrogen sulfide, and other toxic gases. Sea spray and decaying vegetation are major sources of reactive sulfur com­pounds in the air. Forest fires create clouds of smoke that blan­ket whole continents. Trees and bushes emit millions of tons of volatile organic compounds (terpenes and isoprenes), creat­ing, for example, the blue haze that gave the Blue Ridge Moun­tains their name. Pollen, spores, viruses, bacteria, and other small bits of organic material in the air cause widespread suffering from allergies and airborne infections. Storms in arid regions raise dust clouds that transport millions of tons of soil and can be detected half a world away. Bacterial metabolism of decaying vegetation in swamps and of cellulose in the guts of termites and ru­minant animals is responsible for as much as two-thirds of the methane (natural gas) in the air.

In many cases, the chemical compositions of pollutants from nat­ural and human-related sources are identical, and their effects are insep­arable. Sometimes, however, materials in the atmosphere are considered in­nocuous at naturally occurring levels, but when humans add to these levels, overloading of natural cycles or dis­ruption of finely tuned balances in the environment can occur.


The fourth law of hygiene

The fourth law of hygiene – is the law of positive influence on environmental of human society.

However we must not think, that the environment is absolutely defenseless in front of the activity of the man. The nature has huge resources of self-preservation, self-updating, self-regulation, maintenance of ecological balance, self-cleaning, but these reserves are not boundless. So, due to solar radiation, temperature processes, occurring in an atmosphere, there are winds, that are promoting the moving and dispersion of smokes and gases, which are thrown out by an industry and vehicle. A ultra-violet part of a solar spectrum, dispersion, concretion, neutralization promotes decomposition of many chemical components of emissions, clearing of air of biological impurity.

The processes self cleaning of reservoirs (lakes, rivers, seas) pass due to the same solar radiation and its ultra-violet component, temperature mode, physical, chemical, biological processes, dilution of polluting substances, speed of current of water, aeration (saturation by air), oxidizing processes, action microflore, fito- and zooplankton etc.

Self-regeneration of soil results in destruction of organic compounds to the level of mineral salts: nitrites, sulfates, carbonates which can be consumed by plants. Pathogenic microflora perishes suppressed by the antagonistic soil microbes associations and the soil chemical aggression. Helminthes eggs are being destroyed by UV sun radiation, parching etc. Fitoncides produced by some plants are able to kill pathogenic microbes.

 The man influences on the elements of biosphere by the influencing positively on an environment, healthing it, warning its pollution, that promotes the increasing of level of health of the population. The degree of this influence depends on technical arming of a society, level of science, culture of the population, social structure, and political system of society.


The fifth law of hygiene

The fifth law of hygieneis the law of inevitable negative influence of the muddyenvironment on health of the population.

People also become ill through exposure to hazards in the environment. Many diseases are linked to environmental problems such as polluted drinking water, poor waste disposal and air and exposure to mosquitoes and other carriers of disease. Some pollutants, such as pesticides, traffic emissions and industrial solvents, are created by human activities. Others, including arsenic or ultraviolet radiation, occur naturally in the environment, although exposure can be made worse by human activities.

These pollutants can undermine health in various ways, by causing diseases such as bronchitis or asthma, contributing to cancer or birth defects or perhaps by damaging the body's immune system, which makes people more susceptible to a variety of other health risks.

But changes in the way people live and work can also cause a sudden increase in old diseases or the emergence of new ones. Overcrowding and industrialisation affect the health of millions in the developing world. The emergence of some 30 new diseases in the past 20 years, including HIV, Ebola and haemorrhagic illnesses, has become a growing public health issue. Tobacco now kills over 11,000 people a day worldwide.

Population pressures

Many studies have shown links between pollution and health effects. Increases in air pollution have been linked to decreases in lung function and increases in heart attacks. High levels of air pollution according to the EPA Air Quality Index directly affect people with asthma and other types of lung or heart disease. Overall air quality has improved in the last 20 years but urban areas are still a concern. The elderly and children are especially vulnerable to the effects of air pollution.

The level of risk depends on several factors:

  • the amount of pollution in the air,

  • the amount of air we breathe in a given time

  • ouroverallhealth.

Other, less direct ways people are exposed to air pollutants are:

  • eating food products contaminated by air toxins that have been deposited where they grow,

  • drinking water contaminated by air pollutants,

  • ingestingcontaminatedsoil, and

  • touching contaminated soil, dust or water.


Air pollution can affect our health in many ways with both short-term and long-term effects. Different groups of individuals are affected by air pollution in different ways. Some individuals are much more sensitive to pollutants than are others. Young children and elderly people often suffer more from the effects of air pollution. People with health problems such as asthma, heart and lung disease may also suffer more when the air is polluted. The extent to which an individual is harmed by air pollution usually depends on the total exposure to the damaging chemicals, i.e., the duration of exposure and the concentration of the chemicals must be taken into account.

Examples of short-term effects include irritation to the eyes, nose and throat, and upper respiratory infections such as bronchitis and pneumonia. Other symptoms can include headaches, nausea, and allergic reactions. Short-term air pollution can aggravate the medical conditions of individuals with asthma and emphysema. In the great "Smog Disaster" in London in 1952, four thousand people died in a few days due to the high concentrations of pollution.

Long-term health effects can include chronic respiratory disease, lung cancer, heart disease, and even damage to the brain, nerves, liver, or kidneys. Continual exposure to air pollution affects the lungs of growing children and may aggravate or complicate medical conditions in the elderly. It is estimated that half a million people die prematurely every year in the United States as a result of smoking cigarettes.

Photochemical smog

         The so-called photochemical smog, which irritates sensitive membranes and damages plants, is formed when nitrogen oxides in the atmosphere undergo reactions with the hydrocarbons energized by ultraviolet and other radiations from the sun.

Acid Deposition

Most people in the world became aware of problems associated with acid precipitation (the deposition of wet acidic solutions or dry acidic particles from the air) within the last decade or so, but English scientist Robert Angus Smith coined the term "acid rain" in his studies of air chemistry in Manchester, England, in the 1850s. By the 1940s, it was known that pollutants, including atmospheric acids, could be transported long distances by wind currents. This was thought to be only an academic curiosity until it was shown that precipitation of these acids can have far-reaching ecological effects.

The sixth law of hygiene

The sixth law of hygiene is the law of positive influence of the factors of a natural environment on health of the population.The natural factors of an environmental, pure air, pure water, good-quality, high-grade food positively influence on health of the people, promoting its preservation and strengthening at reasonable using.

Ecology is constituted by the total environment of man. The environment of modern man is partly natural and partly man-made. It consists of physical, mental and social factors, which are dynamic and interacting both within themselves and with the life process in the internal environment of men. The im­portant physical factors are air, water, food, build­ings, their contents and multiple devices produced by man to adjust the physical environment around him. The important biological factors are pathogens, other microorganisms as well as living beings, vec­tors, plants, etc., which have implications on health and disease. The important social factors are cus­toms, beliefs, laws, peculiarities and modes of living of human beings with their implications on health and disease.

It is known, that without food the man can live about 50 days, without water - 5 day, without air - no more than 5 mines.

Air is vital to maintain life and serves to ensure a constant supply of life giving oxygen to the body through the process of respiration. One can refuse polluted food and water but not the polluted air. An unlimited, relatively clean air is necessary for comfortable and healthful living.

Good nutrition is a basic component of health. It is essential for the attainment of normal growth and development. Not only physical growth and development, but also the intellectual development, learning and behaviour are affected by malnutrition.In short, nutrition affects human health from birth till death.

The life of the man proceeds in air environment, which is characterized by conditions, which are favorable for normal functioning of his physiological systems. In a basis of positive influence of air environment on organism and health the physics-chemical properties of its factors lay. During evolutionary development the man has adapted to the certain factors of environmental natural environment - physical (solar radiation, temperature, humidity, speed of movement of air, atmospheric pressure, natural levels of radiation), chemical (chemical structure of air, water, food), biological (microorganisms, mushrooms etc).

All organic life of the Earth is obliged by the existence to solar radiation. The influence of solar radiation on organism and health is defined by his spectral structure: the seen radiation provides function of the visual analyzer, infra-red has thermal, ultra-violet - stimulating, biological, bacteriostatic action.

Rational using of solar radiation, sufficient insolation of dwellings and other premises promotes strengthening of health of the man, increasing of it reactivity and the stability to the adverse factors of environment. And on the contrary, at unsufficient insolation, is especial at ultra-violet deficiency, the level of health of the man is reduced. It becomes susceptible to infectious diseases, at children can appear rickets. In middle XX century it began to apply widely to increase resistension of organism artificial sources of ultra-violet radiation - bacteriocytic lamp. The solar radiation defines also weather conditions of this or that district, on which its microclimate - condition of air environment determined in temperature of air and environmental surfaces (radiating temperature), humidity and speed of movement of air also depend. The thermal balance of organism depends on a microclimate. This balance is provided with a quantitative dynamic parity.

The man feels the thermal comfort, if the temperature of air under clothes is in limits 32-34оС, humidity of air - within the limits of 40-60 %, speed of movement of air - 0,2-0,5 m/s, and radiating temperature on 1-2оС is lower than temperature of air. The fluctuation of parameters of a microclimate in limits of the adaptation opportunities of organism promotes increasing of stability of it, strengthening of health of the man, his hardening. And only significant deviations of these parameters (cooling or heating up microclimate) can result in infringement of health. In these cases to the aid of the man rational clothes, heating, air conditioning comes. The large importance has the hardening for expansion of borders of an optimality of a microclimate, especially to a cold.

The natural fluctuations of atmospheric pressure also positively influence on the health of the healthy man, rendering stimulating action on vascular system. However at the persons, suffering cardiovascular diseases, these fluctuations render negative influence, promoting development hypertension. Significant changes of atmospheric pressure in this or that party (caisson, the underwater works, raising on height) can cause kesonic or high-altitude (mountain) disease.

The positive influence on health of the man renders pure air containing about 21 % of oxygen, no more than 0,03 % of carbonic gas, and also sufficiently ionized (containing easy negative ions). At pollution of air the contents of carbonic gas is increased, the concentration of negative ions is reduced, on change with which there come heavy positive ions adversely influencing on organism.

The beneficial effect on health of the man of pure water is defined not only its mineral structure and physiological functions, but also direct and indirect hygienic functions. The physiological functions of water are defined by its necessity for maintenance plastic, transport, and excretive functions of organism, water both electrolythic exchange etc

Water from the hygienic point of view, alongside with solar radiation, fresh air, is widely used for strong organism, being by the powerful factor of increasing of it resestension. Using of water for maintenance of cleanliness of a body, clothes, dwelling and other objects, and also for removal of dross of household and industrial activity of the man (water drain) renders the large positive influence on health of the people.

The strongest positive action on a level of health of the people renders a balanced diet. The balanced diet is the balanced feed ensuring normal growth and development of organism, his high serviceability and stability to the adverse factors of an environment. Conditions of a balanced diet are: quantitative sufficiency of food (accordingly to the power inputs of the organism); qualitative full value, that is the presence in a diet of all necessary food substances (fibers, fats, carbohydrates, vitamins, mineral salts and microelements, flavoring substances, water) in optimum quantities and parity; a rational mode of a feed (accordingly to quantity and time of reception of food with biological rhythms of organism); high assimilated food (accordingly to the quality of food  opportunities of digestive system); epidemic safety (absence in food of activators of diseases) and toxic harmlessness of food (absence of poisonous substances in toxic concentration).

It is necessary to note, that the positive action of the factors of an environment on organism and health can be effective only at their complex influence. Using of a complex of the improving factors (sun, air, water, physical activity, high-grade feed) is a necessary condition of preservation and strengthening of health both individual and public.


 Concept about  biodoze.

Thebiologicalmethodiswidelyusedtomeasuretheintensityof ultra-violetirradiation. Theunitofmeasurementisbiodose.Itisthesmallestquantityof ultra-violetirradiation, provokinghardlyvisiblehyperaemiaofuntannedskinin 6-20 hoursaftertheirradiation. Theminimaldailyprophylacticaldose, preventingrachitisinmenwiththewhiteskin, is 1/8 ofbiodose. Theoptimaldosewiththeadaptagenousmeaningis 1/4 - 1/2 ofbiodose.  The measuring instrument is ultra-violetmeter (UVmeter).Ultra-violetmeteris a specialdevice, usedinmedicine. Ultravioletirradiationisabsorbedbyphotoelementandthegeneratedelectricalcurrentisregisteredbygalvanometer. Thescaleof galve-nometerisgraduatedbymcW/sm2. 1 biodoseisequalto 600-800 mcW/sm2.Consequently, minimalphysiologicalrequestofwhitemanis 100 mcW/sm2,optimal - 200-400 mcW/sm2. Theseindicesmake 250-500 and 500-2000mcW/sm2 correspondinglyforblackman. Theintensityof UV-irradiationmakes 15-20 mcW/sm2 permin.





Fig.Biodosemeter of Gorbachov


The lighting depends on distance between buildings  height and proximity of green plantations. A denseness of buildings in a district quarter and close disposition of houses to each other leads to a considerable loss of a solar radiation, especially in the lower levels.

The essential factor that influences on intensity and duration of daylight of rooms, is the size, form and disposition of windows. The upper edge of windows is necessary to higher as it is possible. The area of windows should correspond  to area of room. Therefore a widespread method of evaluate of a daylight is geometrical, at which one calculate light coefficient (LC), i.e. attitude of a glass area of windows to area of a floor of room. The more size of light factor, the better is lighting. For living rooms LC = 1:6 - 1:8, for hospital wards, the doctors cabinets, educational classes 1:5 - 1:6, for operational, birth wards, observation, dressing rooms, labs 1:3 - 1:4, for extra locations 1:10 - 1:12.

 The best in form are the rectangular windows, and the upper edge of the window should be placed from a ceiling on 20-30 cm., for maximum receipt of light to the depth of rooms.

At contamination of glasses the lighting in room decreases on 50-70  %.

The lighting in room is depend on coloring of a ceiling, floor, walls, furniture in the room. The dark colors swallow a plenty of light rays, therefore coloring of locations and furniture at schools, children's preschool and preventive establishments should be brighten. The white color and light tone are mirrored by sun rays on 70-90 %, yellow color - on 50 %, green - on 50-60 %, blue, violet - on 10-11%, black - on 1 %.

The basic lighting engineering parameter for a normalization of a daylight is coefficient of daylight (CDL).This attitude of lighting indoors to simultaneous lighting  outdoor, expressed in %. For living rooms CDL must be not less than 0,5 %, for hospital wards - not less than 1 %, for school classes - not less than 1,5 %, for operational - not less than 2,5 %.

The angle of incidence of light rays is an angle between a horizontal surface of a table, and line conducted from this surface to the upper edge of the window. The more erectly direction of light rays, i.e. the more angle, the lighting is more. For living rooms the angle of incidence in norm should be not less than 27°.




Fig.The angle of incidence of light rays


Coefficient of depth(CD ) of room - this is a attitude of distance from the upper edge of the window to a floor to distance from the window to the opposite wall. The hygienic norm CD is no more 2.


Description of natural illumination of workplaces



Coefficient of daylight (CDL)

not less 0,75 %

Light coefficient (LC)

not less 1/6-1/8

Angle of incidence of light rays

not less 27°

Angle of opening

not less 5°

 Coefficient of depth of room(CD)

no more 2


 The estimation of illumination is made on an illumination level of a horizontal surface on a job place with the help of a luxmeter. An accepting part of the instrument is the photo cell conversing a quantity of light in electrical. A recording part is the sensing galvanometer calibrated in luxs. The obtained result is compared to the established norms.


Appraisal of artificial lighting.

While appreciation of artificial lighting first of all sufficiently of light is measured by directly definition of lighting in lodging. The results are usually compared with well-known hygienic norms. Then one should characterize the light, in particular to indicate whether it is similar to the day light, whether is even, whether it has blinding effect and so on. For answering these questions we have to indicate the kind of light source, the system of lighting, the type of lighting device (chandelier of direct light, of diffused light, of repulsed light, the height of its location, the order of its location, the force of lamps, properties of protective stuff and its ability to make the brightness less. It is also important to establish the presence of shadows on working surface of table; the contact between brightness of working surface and surroundings. Also one have to find whether light sources have blinding effect at the expense of light repulsing from smooth and polishing surfaces and objects. The aim of creating of hygienic norms for lighting is to make the most favourable conditions for eye work. That provides its great working ability and minimal weariness. The functions of eye lights depend of lighting conditions. In sufficient lighting eye can perform its function without stress; on the contrary in irrational lighting eye gets tired very quickly.

Electric Lighting, illumination by means of any of a number of devices that convert electrical energy into light. The types of electric lighting devices most commonly used are the incandescent lamp, the fluorescent lamp, and the various types of arc and electric-discharge vaporlamps .

Neon Lights at Night Bright neon lights shine throughout the night in Las Vegas, Nevada. Neon lamps are used for art, advertising, and even airplane beacons. They are made by evacuating air from glass tubes, then filling them with neon gas. When the light is “on,” an electric current flows through the gas between two electrodes sealed within the tube. The neon forms a luminous band between the two electrodes. 

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 35,5Lk. 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.




Fig.Luxmeter U-116




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.

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 constantoffset.

Fahrenheit, Celsius and Kelvin temperature scales



An instrument called thermometer ascertains this.

Name of









Centigrade (Calcius)







         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.


Methods of temperature measure

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

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

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

Third placeis 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.



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.


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.


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 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.


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.

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 / Fх100,

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.

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%.


Air humidity determination methods

psychromassman psychrom

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 greekpsychros - cold).Psychrometes are of August and Assman types.

August psychrometerconsists 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.

Assmanpsychrometer 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 whirlingpsychrometer 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.


F:\lototska\Assman psychrom 2.files\psych.files\psycro.jpg

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.



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














(а - thermograph; б - hyhrograph; в - barograph)



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 – psychrometriccoefficient is 0.0011 for enclosedspaces;

            t – temperature of the dry thermometer;

 t1temperature 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 valueof 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

Maximum pressure of the air water vapor of premises


Air temperature, оС

Water vapour pressure, Hg mm

Air temperature, оС

Water vapour pressure, Hg mm














































































Psychrometrictablesfor 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 waterevaporationfrom 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 significantdisadvantageof 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 Assmannpsychrometer due to the usage of the ventilator (see fig. 6.2-b). 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;

  t1temperature 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 (see table 3).


Relative humidity is determined using the psychrometrictablesfor 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).


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



Relative humidity, %






Cold and transitional




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.

Humiditydeficit (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.

Interdependency between different air humidity indices can be seen on the diagram (see fig. 6.3).


Fig. 6.3. Interdependency between different air humidity indices


The scheme shows, that the rise of temperature provokes the maximum humidity increase in geometricprogression, 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 closelyrelatedto 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.

anemometer 1cup 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.



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 orbranches, 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

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.

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.


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.

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.



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.



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.

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.

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.



in physics, process by which energy in the form of heat is exchanged between bodies or parts of the same body at different temperatures. Heat is generally transferred by convection, radiation, or conduction. Although these three processes can occur simultaneously, it is not unusual for one mechanism to overshadow the other two. Heat, for example, is transferred by conduction through the brick wall of a house, the surfaces of high-speed aircraft are heated by convection, and the earth receives heat from the sun by radiation.

Heat Transfer Heat can be transferred by three processes: conduction, convection, and radiation. Conduction is the transfer of heat along a solid object; it is this process that makes the handle of a poker hot, even if only the tip is in the fireplace. Convection transfers heat through the exchange of hot and cold molecules; this is the process through which water in a kettle becomes uniformly hot even though only the bottom of the kettle contacts the flame. Radiation is the transfer of heat via electromagnetic (usually infrared) radiation; this is the principal mechanism through which a fireplace warms a room Microsoft Corporation. All Rights Reserved. 


This is the only method of heat transfer in opaque solids. If the temperature at one end of a metal rod is raised by heating, heat is conducted to the colder end, but the exact mechanism of heat conduction in solids is not entirely understood. It is believed, however, to be partially due to the motion of free electrons in the solid matter, which transport energy if a temperature difference is applied. This theory helps to explain why good electrical conductors also tend to be good heat conductors (see Conductor, Electrical). Although the phenomenon of heat conduction had been observed for centuries, it was not until 1882 that the French mathematician Jean Baptiste Joseph Fourier gave it precise mathematical expression in what is now regarded as Fourier's law of heat conduction. This physical law states that the rate at which heat is conducted through a body per unit cross-sectional area is proportional to the negative of the temperature gradient existing in the body.

The proportionality factor is called the thermal conductivity of the material. Materials such as gold, silver, and copper have high thermal conductivities and conduct heat readily, but materials such as glass and asbestos have values of thermal conductivity hundreds and thousands of times smaller, conduct heat poorly, and are referred to as insulators (see Insulation). In engineering applications it is frequently necessary to establish the rate at which heat will be conducted through a solid if a known temperature difference exists across the solid. Sophisticated mathematical techniques are required to establish this, especially if the process varies with time, the phenomenon being known as transient-heat conduction. With the aid of analog and digital computers, these problems are now being solved for bodies of complex geometry.


Conduction occurs not only within a body but also between two bodies if they are brought into contact, and if one of the substances is a liquid or a gas, then fluid motion will almost certainly occur. This process of conduction between a solid surface and a moving liquid or gas is called convection. The motion of the fluid may be natural or forced. If a liquid or gas is heated, its mass per unit volume generally decreases. If the liquid or gas is in a gravitational field, the hotter, lighter fluid rises while the colder, heavier fluid sinks. This kind of motion, due solely to nonuniformity of fluid temperature in the presence of a gravitational field, is called natural convection. Forced convection is achieved by subjecting the fluid to a pressure gradient and thereby forcing motion to occur according to the law of fluid mechanics.

If, for example, water in a pan is heated from below, the liquid closest to the bottom expands and its density decreases; the hot water as a result rises to the top and some of the cooler fluid descends toward the bottom, thus setting up a circulatory motion. Similarly, in a vertical gas-filled chamber, such as the air space between two window panes in a double-glazed, or Thermopane, window, the air near the cold outer pane will move down and the air near the inner, warmer pane will rise, leading to a circulatory motion.

The heating of a room by a radiator depends less on radiation than on natural convection currents, the hot air rising upward along the wall and cooler air coming back to the radiator from the side of the bottom. Because of the tendencies of hot air to rise and of cool air to sink, radiators should be placed near the floor and air-conditioning outlets near the ceiling for maximum efficiency. Natural convection is also responsible for the rising of the hot water and steam in natural-convection boilers (see Boiler) and for the draft in a chimney. Convection also determines the movement of large air masses above the earth, the action of the winds, rainfall, ocean currents, and the transfer of heat from the interior of the sun to its surface.


Wilhelm Wien German physicist Wilhelm Wien won the 1911 Nobel Prize in physics. His discoveries in the field of radiation, including the laws that govern heat radiation, laid the foundation for the development of the quantum theory The Nobel Foundation 

 This process is fundamentally different from both conduction and convection in that the substances exchanging heat need not be in contact with each other. They can, in fact, be separated by a vacuum. Radiation is a term generally applied to all kinds of electromagnetic-wave phenomena. Some radiation phenomena can be described in terms of wave theory (see Wave Motion), and others can be explained in terms of quantum theory. Neither theory, however, completely explains all experimental observations. The German-born American physicist Albert Einstein conclusively demonstrated (1905) the quantized behavior of radiant energy in his classical photoelectric experiments. Before Einstein's experiments the quantized nature of radiant energy had been postulated, and the German physicist Max Planck used quantum theory and the mathematical formalism of statistical mechanics to derive (1900) a fundamental law of radiation (see Statistics). The mathematical expression of this law, called Planck's distribution, relates the intensity or strength of radiant energy emitted by a body to the temperature of the body and the wavelength of radiation. This is the maximum amount of radiant energy that can be emitted by a body at a particular temperature. Only an ideal body (blackbody,) emits such radiation according to Planck's law. Real bodies emit at a somewhat reduced intensity. The contribution of all frequencies to the radiant energy emitted by a body is called the emissive power of the body, the amount of energy emitted by a unit surface area of a body per unit of time. As can be shown from Planck's law, the emissive power of a surface is proportional to the fourth power of the absolute temperature. The proportionality factor is called the Stefan-Boltzmann constant after two Austrian physicists, Joseph Stefan and Ludwig Boltzmann, who, in 1879 and 1884, respectively, discovered the fourth power relationship for the emissive power. According to Planck's law, all substances emit radiant energy merely by virtue of having a positive absolute temperature. The higher the temperature, the greater the amount of energy emitted. In addition to emitting, all substances are capable of absorbing radiation. Thus, although an ice cube is continuously emitting radiant energy, it will melt if an incandescent lamp is focused on it because it will be absorbing a greater amount of heat than it is emitting.

Opaque surfaces can absorb or reflect incident radiation. Generally, dull, rough surfaces absorb more heat than bright, polished surfaces, and bright surfaces reflect more radiant energy than dull surfaces. In addition, good absorbers are also good emitters; good reflectors, or poor absorbers, are poor emitters. Thus, cooking utensils generally have dull bottoms for good absorption and polished sides for minimum emission to maximize the net heat transfer into the contents of the pot. Some substances, such as gases and glass, are capable of transmitting large amounts of radiation. It is experimentally observed that the absorbing, reflecting, and transmitting properties of a substance depend upon the wavelength of the incident radiation. Glass, for example, transmits large amounts of short wavelength (ultraviolet) radiation, but is a poor transmitter of long wavelength (infrared) radiation. A consequence of Planck's distribution is that the wavelength at which the maximum amount of radiant energy is emitted by a body decreases as the temperature increases. Wien's displacement law, named after the German physicist Wilhelm Wien, is a mathematical expression of this observation and states that the wavelength of maximum energy, expressed in micrometers (millionths of a meter), multiplied by the Kelvin temperature of the body is equal to a constant, 2878. Most of the energy radiated by the sun, therefore, is characterized by small wavelengths. This fact, together with the transmitting properties of glass mentioned above, explains the greenhouse effect. Radiant energy from the sun is transmitted through the glass and enters the greenhouse. The energy emitted by the contents of the greenhouse, however, which emit primarily at infrared wavelengths, is not transmitted out through the glass. Thus, although the air temperature outside the greenhouse may be low, the temperature inside the greenhouse will be much higher because there is a sizable net heat transfer into it.

In addition to heat transfer processes that result in raising or lowering temperatures of the participating bodies, heat transfer can also produce phase changes such as the melting of ice or the boiling of water. In engineering, heat transfer processes are usually designed to take advantage of these phenomena. In the case of space capsules reentering the atmosphere of the earth at very high speed, a heat shield that melts in a prescribed manner by the process called ablation is provided to prevent overheating of the interior of the capsule. Essentially, the frictional heating produced by the atmosphere is used to melt the heat shield and not to raise the temperature of the capsule (see Friction).

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 /.



 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.