What type of radiation does HF belong to? Non-ionizing electromagnetic fields and radiation General information about non-ionizing radiation and fields

The concept of "non-ionizing radiation"

It is well known from the physics course that the propagation of energy occurs in the form of small particles and waves, the process of emission and propagation of which is called radiation.

There are 2 main types of radiation based on their effects on objects and living tissues:

1. Ionizing radiation. These are streams of elementary particles formed as a result of the fission of atoms - radioactive radiation, alpha, beta, gamma, x-rays. This type of radiation includes gravitational radiation and rays Hawking;
2. Non-ionizing radiation. At their core, these are electromagnetic waves with a length greater than $1000$ nm and released energy less than $10$ keV. Radiation occurs in the form of microwaves, releasing light and heat.

Non-ionizing radiation unlike the first, it does not break the bonds between the molecules of the substance it affects. But, it must be said that there are exceptions here, for example, UV rays can ionize substance. Electromagnetic radiation includes high-frequency X-rays and gamma rays, only they are more rigid and ionize substance.

Other electromagnetic radiations are non-ionizing and cannot interfere with the structure of matter, because their energy is not enough for this. Visible light and UV radiation are also non-ionizing, and light radiation is often called optical. It is formed when bodies are heated and its spectrum is close to infrared rays.

Infrared radiation widely used in medical practice. It is used to improve metabolism, stimulate blood circulation, and disinfect food. However, excessive heating leads to drying of the mucous membrane of the eye, and the maximum radiation power can destroy the DNA molecule.

Ability to ionization may have ultraviolet radiation close to x-rays. UV rays can cause various mutations, burns of the skin and cornea of ​​the eyes. Medicine synthesizes vitamin D3 in the skin using UV rays. With their help, water and air are disinfected and equipment is sterilized.

Non-ionizing electromagnetic radiation are of natural and artificial origin. Natural the source is the Sun, which sends out all types of radiation. They do not reach the surface of the planet in full. Thanks to the Earth's atmosphere, the ozone layer, humidity, and carbon dioxide, their harmful effects are mitigated. Lightning and space objects can become natural sources of radio waves. Any body heated to the required temperature is capable of emitting thermal infrared rays, despite the fact that the main radiation comes from artificial objects. In this case, the main sources include heaters, burners, and incandescent lamps found in every home.

Since radio waves are transmitted through any electrical conductors, all electrical appliances become artificial sources.

Impact force electromagnetic radiation depends on wavelength, frequency and polarization. Longer waves transfer less energy to an object and are therefore less harmful.

Impact on humans non-ionizing radiation has $2$ sides - long-term exposure brings harm health, moderate doses can be useful.

Impact of electromagnetic fields on humans

Electromagnetic fields, one way or another, have an effect on humans.

This impact is due to:

1. electric and magnetic field strength;
2. energy flux density;
3. vibration frequency;
4. irradiation mode;
5. size of the irradiated body surface;
6. individual characteristics of the body.

Compounding the danger of exposure to radiation is the fact that the human senses cannot detect it. A person is exposed to an electrostatic field (ESF) in the form of a weak current of several microamps passing through him, without observing electrical injuries. But, people may have a reflexive reaction to electric current, in this case it is possible mechanical injury, for example, you can hit structural elements located nearby. The central nervous system, analyzers, and cardiovascular system are quite sensitive to electrostatic fields. Irritability, headache, sleep disturbances are the manifestations that are observed in people working in the area exposed to ESP.

Magnetic fields(MF) can operate continuously or intermittently, the degree of impact of which depends on how strong the field is in space near the magnetic device. The dose received depends on where the person is located in relation to the MP and his work schedule. Visual sensations are noted during action alternating magnetic field, but with the cessation of exposure these sensations disappear. Serious violations occur in conditions of chronic exposure to MPs exceeding the maximum permissible levels. In this case, dysfunction of the central nervous system, cardiovascular and respiratory systems, and digestive tract is observed, and changes occur in the blood. The rhythm is disrupted and the heart rate slows down with constant exposure to industrial frequency EMF.

The human body, consisting of atoms and molecules, is polarized under the influence of electromagnetic fields in the radio frequency range, and the following occurs:

1. Polar molecules, for example, water molecules, are oriented in the direction of propagation of the electromagnetic field;
2. After exposure, ionic currents appear in electrolytes, and these are the liquid components of tissues and blood;
3. Human tissues heat up, which is caused by an alternating electric field. This occurs both due to the variable polarization of the dielectric and due to the emerging current conductivity.

The consequence of absorption of electromagnetic field energy is thermal effect. With increasing tension and exposure time, these effects become more pronounced.

Electromagnetic fields have a stronger and more intense effect on organs containing a large amount of water and will be approximately $60$ times higher compared to the effect on organs with a low water content. If the length of the electromagnetic wave is increased, then the depth of its penetration increases. Tissues are heated unevenly as a result of differences in dielectric properties, macro and micro thermal effects with temperature differences occur. An underdeveloped vascular system will experience shock, which will manifest itself in insufficient blood circulation to the eyes, brain, kidneys, stomach, gallbladder, and bladder.

One of the few specific lesions that are caused by electromagnetic radiation are the eyes and the possible development of cataracts. This lesion is caused by electromagnetic radiation of radio frequencies in the range of $300$ MHz...$300$ GHz at an energy flux density above $10$ mW/sq. see. Characteristic of long-term exposure to EMFs of various wavelength ranges are considered to be functional disorders in the central nervous system with often pronounced changes in endocrine metabolic processes and blood composition; performance, as a rule, decreases. The changes are reversible only at an early stage.

Non-ionizing electromagnetic fields

Charged particles are characterized electromagnetic interaction. The energy between these particles is transferred by photons of the electromagnetic field.

In the air length electromagnetic waveλ(m) is related to its frequencyƒ(Hz) ratio λƒ = с,,Where With– speed of light, m/s.

The spectrum of oscillations with a frequency of $10$ $17$ Hz has non-ionizing electromagnetic fields, while ionizing– from $10$ $17$ to $10$ $21$ Hz.

Non-ionizing electromagnetic fields, having a natural origin, are a constantly operating factor. Their sources are atmospheric electricity, solar and galactic radio emission, and the electric and magnetic fields of the planet.

Sources of magnetic fields most often associated with sources such as high-voltage power lines and those used in industrial enterprises industrial frequency electromagnetic fields.

In areas close to electrified railways, the resulting magnetic fields represent significant danger. Even buildings located close to these areas exhibit high-intensity magnetic fields.

Note 1

At the household level to sources electromagnetic fields and radiation include televisions, microwave ovens, radiotelephones and a number of other devices operating in a wide frequency range. When the humidity is less than $70$%, electrostatic fields are created by rugs, capes, curtains, etc. Household appliances such as an industrial microwave oven are not dangerous. But, if their protective screens are faulty, the leakage of electromagnetic radiation increases. TV and display screens, even with prolonged exposure to humans, will not pose a danger as sources of electromagnetic radiation, provided that the distance from the screen is more than $30$ cm.

St. Petersburg State University
Faculty of Applied Mathematics – Control Processes
Abstract on the course
"Ecology"
subject:
"Non-ionizing radiation"
Completed by: student of group 432

Checked by: professor

Saint Petersburg
year 2014

Content.
Introduction
Classification
Effect on health
History of research
Biological effects of electromagnetic fields
EMF parameters affecting biological response
Consequences of EMF effects on human health
The role of EMF modulation in the development of bioeffects
Combined effect of EMF and other factors

Main sources of EMF
Household electrical appliances
Power lines
Personal Computer
Radars
cellular
Satellite connection

Organizational measures for protection against EMF
Engineering and technical measures to protect the population from EMF
Treatment and preventive measures
Conclusion
Bibliography
Introduction
In the modern world, we are surrounded by a huge number of sources of electromagnetic fields and radiation. The frequency spectrum of electromagnetic oscillations reaches 1021 Hz. Depending on the energy of photons (quanta), it is divided into the region of non-ionizing and ionizing radiation. In hygienic practice, non-ionizing radiation also includes electric and magnetic fields. Radiation will be non-ionizing if it is not capable of breaking the chemical bonds of molecules, that is, it is not capable of forming positively and negatively charged ions. Because radiation and its source are very closely related, then when we talk about electromagnetic fields, we will mean, where appropriate, the effect of non-ionizing radiation.
First, let's define what an electromagnetic field is.
In practice, when characterizing the electromagnetic environment, the terms “electric field”, “magnetic field”, “electromagnetic field” are used. Let us briefly explain what this means and what connection exists between them.
An electric field is created by charges. For example, in all the well-known school experiments on the electrification of ebonite, an electric field is present.
A magnetic field is created when electric charges move through a conductor.
To characterize the magnitude of the electric field, the concept of electric field strength is used, symbol E, unit of measurement V/m (Volts-per-meter). The magnitude of the magnetic field is characterized by the magnetic field strength H, unit A/m (Ampere-per-meter). When measuring ultra-low and extremely low frequencies, the concept of magnetic induction B is also often used, the unit T (Tesla), one millionth of a T corresponds to 1.25 A/m.
An electromagnetic field is a special form of matter through which the interaction between electrically charged particles occurs. The physical reasons for the existence of an electromagnetic field are related to the fact that a time-varying electric field E generates a magnetic field H, and a changing H generates a vortex electric field: both components E and H, continuously changing, excite each other. The EMF of stationary or uniformly moving charged particles is inextricably linked with these particles. With the accelerated movement of charged particles, the EMF “breaks off” them and exists independently in the form of electromagnetic waves, without disappearing when the source is removed (for example, radio waves do not disappear even in the absence of current in the antenna that emitted them).
Electromagnetic waves are characterized by wavelength, symbolized by λ (lambda). A source that generates radiation, and essentially creates electromagnetic oscillations, is characterized by the concept of frequency, symbolized by f. The international classification of electromagnetic waves by frequency is given in the table.
International classification of electromagnetic waves by frequency
Name of the frequency range Range limits Name of the wave range Range limits
Extreme low, ELF 3 - 30 Hz Decamegameter 100 - 10 mm
Ultra-low, VLF 30 - 300 Hz Megameter 10 - 1 mm
Infra-low, INF 0.3 - 3 kHz Hecto-kilometer 1000 - 100 km
Very low, VLF 3 - 30 kHz Myriameter 100 - 10 km
Low frequencies, LF 30 - 300 kHz Kilometer 10 - 1 km
Medium, MF 0.3 - 3 MHz Hectometric 1 - 0.1 km
High frequencies, HF 3 - 30 MHz Decameter 100 - 10 m
Very high, VHF 30 - 300 MHz Meter 10 - 1 m
Ultra-high, UHF 0.3 - 3 GHz Decimeter 1 - 0.1 m
Ultra-high, microwave 3 - 30 GHz Centimeter 10 - 1 cm
Extremely high, EHF 30 - 300 GHz Millimeter 10 - 1 mm
Hyper-high, HHF 300 - 3000 GHz Decimillimeter 1 - 0.1 mm
An important feature of EMF is its division into the so-called “near” and “far” zones.
In the "near" zone, or induction zone, at a distance from the source r< λ ЭМП можно считать квазистатическим. Здесь оно быстро убывает с расстоянием, обратно пропорционально квадрату r -2 или кубу r -3 расстояния. В "ближней" зоне излучения электромагнитная волне еще не сформирована. Для характеристики ЭМП измерения переменного электрического поля Е и переменного магнитного поля Н производятся раздельно. Поле в зоне индукции служит для формирования бегущих составляющей полей (электромагнитной волны), ответственных за излучение.
The “far” zone is the zone of the formed electromagnetic wave, starting from a distance r > 3 λ. In the “far” zone, the field intensity decreases in inverse proportion to the distance to the source r -1.
In the “far” zone of radiation, a connection is established between E and H:
E = 377H,
where 377 is the wave impedance of the vacuum, Ohm.
Therefore, as a rule, only E is measured. In the Russian practice of sanitary and hygienic supervision at frequencies above 300 MHz in the “far” radiation zone, the electromagnetic energy flux density (PEF), or the Poynting vector, is usually measured. Abroad, PES is usually measured for frequencies above 1 GHz. Denoted as S, the unit of measurement is W/m2. PES characterizes the amount of energy transferred by an electromagnetic wave per unit time through a unit surface perpendicular to the direction of propagation of the wave.
The elementary concepts introduced in this section about the nature of EMF, its components and units of measurement are sufficient for the perception of the material presented below by a reader who is not a specialist in electromagnetic fields.
Classification
So, non-ionizing radiation includes:
electromagnetic radiation (EMR) in the radio frequency range,
constant and variable magnetic fields (PMF and PeMF),
electromagnetic fields of industrial frequency (EMF),
electrostatic fields (ESF),
laser radiation (LR).
Often the effect of non-ionizing radiation is accompanied by other industrial factors that contribute to the development of the disease (noise, high temperature, chemicals, emotional and mental stress, light flashes, visual strain).
Because The main carrier of non-ionizing radiation is EMR; most of the abstract is devoted to this type of radiation.

Effect on health
History of research
In the USSR, extensive research into electromagnetic fields began in the 60s. A large amount of clinical material has been accumulated on the adverse effects of magnetic and electromagnetic fields, and it was proposed to introduce a new nosological disease “Radio wave disease” or “Chronic microwave damage.” Subsequently, the work of scientists in Russia established that, firstly, the human nervous system, especially higher nervous activity, is sensitive to EMF, and, secondly, that EMF has the so-called. informational effect when exposed to a person at intensities below the threshold value of the thermal effect. The results of these works were used in the development of regulatory documents in Russia. As a result, the standards in Russia were set very stringent and differed from American and European ones by several thousand times (for example, in Russia the MPL for professionals is 0.01 mW/cm2; in the USA - 10 mW/cm2).
Subsequently, a Soviet-American group was formed from scientists from the USSR and America, which operated from 1975 to 1985. This group organized joint biological research that confirmed the correctness of the concept of Soviet scientists and, as a result, standards in the United States were lowered.
In the late seventies and eighties, in order to improve hygienic standards in Russia, a set of experimental studies was carried out on the influence of EMF in a wide frequency range on various body systems. Conditions that modify the bioeffects of EMF were studied, and data were accumulated to substantiate the standard levels of EMF in different frequency ranges, according to the mechanism of the biological action of EMF.
Currently, research into the biological effects of EMF is ongoing.
Biological effects of electromagnetic fields
Experimental data from both domestic and foreign researchers indicate high biological activity of EMF in all frequency ranges. At relatively high levels of irradiating EMF, modern theory recognizes a thermal mechanism of action. At a relatively low level of EMF (for example, for radio frequencies above 300 MHz it is less than 1 mW/cm2), it is customary to talk about the non-thermal or informational nature of the impact on the body. The mechanisms of action of EMF in this case are still poorly understood.
EMF parameters affecting biological response
The options for the impact of EMF on bioecosystems, including humans, are varied: continuous and intermittent, general and local, combined from several sources and combined with other unfavorable environmental factors, etc.
The following EMF parameters influence the biological response:
EMF intensity (magnitude);
radiation frequency;
duration of irradiation;
signal modulation;
combination of EMF frequencies,
frequency of action.
The combination of the above parameters can give significantly different consequences for the reaction of the irradiated biological object.
Consequences of EMF effects on human health
In the vast majority of cases, exposure occurs to fields of relatively low levels; the consequences listed below apply to such cases.
Numerous studies in the field of biological effects of EMF will allow us to determine the most sensitive systems of the human body: nervous, immune, endocrine and reproductive. These body systems are critical. The reactions of these systems must be taken into account when assessing the risk of EMF exposure to the population.
The biological effect of EMF under conditions of long-term exposure accumulates over many years, resulting in the development of long-term consequences, including degenerative processes of the central nervous system, blood cancer (leukemia), brain tumors, and hormonal diseases.
EMFs can be especially dangerous for children, pregnant women (embryos), people with diseases of the central nervous, hormonal, and cardiovascular systems, allergy sufferers, and people with weakened immune systems.
Effect on the nervous system.
A large number of studies carried out in Russia, and the monographic generalizations made, give grounds to classify the nervous system as one of the most sensitive systems in the human body to the effects of EMFs. At the level of the nerve cell, structural formations for the transmission of nerve impulses (synapse), at the level of isolated nerve structures, significant deviations occur when exposed to low-intensity EMF. Higher nervous activity and memory change in people who have contact with EMF. These individuals may be prone to developing stress reactions. Certain brain structures have increased sensitivity to EMF. Changes in the permeability of the blood-brain barrier can lead to unexpected adverse effects. The nervous system of the embryo exhibits particularly high sensitivity to EMF.
Effect on the immune system
Currently, sufficient data have been accumulated indicating the negative impact of EMF on the immunological reactivity of the body. The results of research by Russian scientists give reason to believe that when exposed to EMF, the processes of immunogenesis are disrupted, more often in the direction of their inhibition. It has also been established that in animals irradiated with EMF, the nature of the infectious process changes - the course of the infectious process is aggravated. The occurrence of autoimmunity is associated not so much with a change in the antigenic structure of tissues, but with the pathology of the immune system, as a result of which it reacts against normal tissue antigens. According to this concept, the basis of all autoimmune conditions is primarily immunodeficiency in the thymus-dependent cell population of lymphocytes. The influence of high-intensity EMF on the body’s immune system is manifested in a suppressive effect on the T-system of cellular immunity. EMFs can contribute to nonspecific inhibition of immunogenesis, increased formation of antibodies to fetal tissues and stimulation of an autoimmune reaction in the body of a pregnant female.
Effect on the endocrine system and neurohumoral response.
In the works of Russian scientists back in the 60s, in the interpretation of the mechanism of functional disorders under the influence of EMF, the leading place was given to changes in the pituitary-adrenal system. Studies have shown that under the influence of EMF, as a rule, stimulation of the pituitary-adrenaline system occurred, which was accompanied by an increase in the content of adrenaline in the blood and activation of blood coagulation processes. It was recognized that one of the systems that is early and naturally involved in the body's response to the influence of various environmental factors is the hypothalamic-pituitary-adrenal cortex system. The research results confirmed this position.
Effect on sexual function.
Sexual dysfunction is usually associated with changes in its regulation by the nervous and neuroendocrine systems. Related to this are the results of work on studying the state of gonadotropic activity of the pituitary gland under the influence of EMF. Repeated exposure to EMF causes a decrease in the activity of the pituitary gland
Any environmental factor that affects the female body during pregnancy and affects embryonic development is considered teratogenic. Many scientists attribute EMF to this group of factors.
Of primary importance in teratogenesis studies is the stage of pregnancy during which EMF exposure occurs. It is generally accepted that EMFs can, for example, cause deformities by acting at different stages of pregnancy. Although there are periods of maximum sensitivity to EMF. The most vulnerable periods are usually the early stages of embryo development, corresponding to the periods of implantation and early organogenesis.
An opinion was expressed about the possibility of a specific effect of EMF on the sexual function of women and on the embryo. A higher sensitivity to the effects of EMF of the ovaries than the testes was noted.
It has been established that the sensitivity of the embryo to EMF is much higher than the sensitivity of the maternal body, and intrauterine damage to the fetus by EMF can occur at any stage of its development. The results of epidemiological studies will allow us to conclude that the presence of contact of women with electromagnetic radiation can lead to premature birth, affect the development of the fetus and, finally, increase the risk of developing congenital deformities.
Other medical and biological effects.
Since the beginning of the 60s, extensive research has been carried out in the USSR to study the health of people exposed to electromagnetic fields at work. The results of clinical studies have shown that prolonged contact with EMF in the microwave range can lead to the development of diseases, the clinical picture of which is determined, first of all, by changes in the functional state of the nervous and cardiovascular systems. It was proposed to identify an independent disease - radio wave disease. This disease, according to the authors, can have three syndromes as the severity of the disease increases:
asthenic syndrome;
astheno-vegetative syndrome;
hypothalamic syndrome.
The earliest clinical manifestations of the consequences of exposure to EM radiation on humans are functional disorders of the nervous system, manifested primarily in the form of autonomic dysfunctions, neurasthenic and asthenic syndrome. Persons who have been in the area of ​​EM radiation for a long time complain of weakness, irritability, fatigue, weakened memory, and sleep disturbances. Often these symptoms are accompanied by disorders of autonomic functions. Disorders of the cardiovascular system are manifested, as a rule, by neurocirculatory dystonia: lability of pulse and blood pressure, tendency to hypotension, pain in the heart, etc. There are also phase changes in the composition of peripheral blood (lability of indicators) with the subsequent development of moderate leukopenia, neuropenia , erythrocytopenia. Changes in the bone marrow are in the nature of a reactive compensatory stress of regeneration. Typically, these changes occur in people who, due to the nature of their work, were constantly exposed to EM radiation with a fairly high intensity. Those working with MF and EMF, as well as the population living in the area affected by EMF, complain of irritability and impatience. After 1-3 years, some people develop a feeling of internal tension and fussiness. Attention and memory are impaired. There are complaints about low sleep efficiency and fatigue.
Considering the important role of the cerebral cortex and hypothalamus in the implementation of human mental functions, it can be expected that long-term repeated exposure to maximum permissible EM radiation (especially in the decimeter wavelength range) can lead to mental disorders.
The role of EMF modulation in the development of bioeffects
In recent years, publications have appeared that contain very important indications about the presence of the so-called. resonance effects when exposed to EMFs on biological objects, the role of some forms of modulation in bioeffects. The presence of the so-called is shown. frequency and amplitude windows, which have high biological activity at the cellular level, as well as when exposed to EMF on the central nervous and immune systems. Many works point to the “information” mechanism of the biological action of EMF. Data have been published on inadequate pathological reactions of people to modulated electromagnetic fields.
However, the current hygienic standards, based only on the regulation of the energy load, composed of the intensity and time of contact with EMF, do not allow the extension of the MRL to conditions of exposure to EMF with complex physical characteristics, in particular in relation to specific modulation modes.
Combined effect of EMF and other factors
The available results indicate a possible modification of the bioeffects of EMF of both thermal and non-thermal intensity under the influence of a number of factors of both physical and chemical nature. The conditions of the combined action of EMF and other factors made it possible to identify the significant influence of ultra-low intensity EMF on the body's reaction, and with some combinations a pronounced pathological reaction can develop.
Diseases caused by exposure to non-ionizing radiation
Acute exposure occurs in extremely rare cases of gross violation of street safety regulations servicing powerful generators or laser installations. Intense EMR first of all causes a thermal effect. Patients complain of malaise, pain in the limbs, muscle weakness, increased body temperature, headache, redness of the face, sweating, thirst, and cardiac dysfunction. Diencephalic disorders may be observed in the form of attacks of tachycardia, tremors, paroxysmal headaches, and vomiting.
During acute exposure to laser radiation, the degree of damage to the eyes and skin (critical organs) depends on the intensity and spectrum of the radiation. The laser beam can cause clouding of the cornea, burns of the iris and lens, followed by the development of cataracts. A retinal burn leads to scar formation, which is accompanied by a decrease in visual acuity. The listed eye injuries caused by laser radiation do not have specific features.
Skin lesions caused by a laser beam depend on the radiation parameters and are of a very diverse nature; from functional changes in the activity of intradermal enzymes or mild erythema at the site of irradiation to burns reminiscent of electrocoagulation burns due to electric shock, or rupture of the skin.
In modern production conditions, occupational diseases caused by exposure to non-ionizing radiation are considered chronic.
The leading place in the clinical picture of the disease is occupied by functional changes in the central nervous system, especially its autonomic parts, and the cardiovascular system. There are three main syndromes: asthenic, asthenovegetative (or neurocirculatory dystonia syndrome of the hypertensive type) and hypothalamic.
Patients complain of headaches, increased fatigue, general weakness, irritability, short temper, decreased performance, sleep disturbances, and pain in the heart. Arterial hypotension and bradycardia are characteristic. In more severe cases, autonomic disorders are associated with increased excitability of the sympathetic part of the autonomic nervous system and manifested by vascular instability with hypertensive angiospastic reactions (instability of blood pressure, pulse lability, brady- and tachycardia, general and local hyperhydroe). The formation of various phobias and hypochondriacal reactions is possible. In some cases, a hypothalamic (diencephalic) syndrome develops, characterized by so-called sympathetic-adrenal crises.
Clinically, an increase in tendon and periosteal reflexes, tremor of the fingers, a positive Romberg sign, depression or increase in dermographism, distal hypoesthesia, acrocyanosis, and a decrease in skin temperature are detected. When exposed to PMF, polyneuritis can develop; when exposed to electromagnetic fields of microwaves, cataracts can develop.
Changes in peripheral blood are nonspecific. There is a tendency towards cytopenia, sometimes moderate leukocytosis, lymphocytosis, and decreased ESR. An increase in hemoglobin content, erythrocytosis, reticulocytosis, leukocytosis (EPPC and ESP) may be observed; decrease in hemoglobin (with laser radiation).
Diagnosis of lesions from chronic exposure to non-ionizing radiation is difficult. It should be based on a detailed study of working conditions, analysis of the dynamics of the process, and a comprehensive examination of the patient.
Skin changes caused by chronic exposure to non-ionizing radiation:
Actinic (photochemical) keratosis
Actinic reticuloid
Diamond-shaped skin on the back of the head (neck)
Poikiloderma Siwatt
Senile atrophy (flabbiness) of the skin
Actinic [photochemical] granuloma
Other skin changes caused by chronic exposure to non-ionizing radiation
Skin change caused by chronic exposure to non-ionizing radiation, unspecified
But the prognosis is favorable. If there is a decrease in working capacity and rational employment, a referral to VTEK is possible. It is necessary to improve technologies, observe sanitary rules and safety precautions.
Main sources of EMF
Household electrical appliances
All household appliances that operate using electric current are sources of electromagnetic fields.
The most powerful are microwave ovens, convection ovens, refrigerators with a “no frost” system, kitchen hoods, electric stoves, and televisions. The actual EMF generated, depending on the specific model and mode of operation, can vary greatly among equipment of the same type (see Figure 1). All data below refers to a magnetic field of industrial frequency 50 Hz.
The magnetic field values ​​are closely related to the power of the device - the higher it is, the higher the magnetic field during its operation. The values ​​of the electric field of industrial frequency of almost all electrical household appliances do not exceed several tens of V/m at a distance of 0.5 m, which is significantly less than the maximum limit of 500 V/m.

Fig.1. Average levels of the industrial frequency magnetic field of household electrical appliances at a distance of 0.3 m.
Table 1 presents data on the distance at which a magnetic field of industrial frequency (50 Hz) of 0.2 μT is detected during the operation of a number of household appliances.
Table 1.
Propagation of industrial frequency magnetic field from household electrical appliances (above the level of 0.2 µT)
Source Distance at which a value greater than 0.2 µT is recorded
Refrigerator equipped with a “No frost” system (during compressor operation) 1.2 m from the door; 1.4 m from the back wall
Regular refrigerator (during compressor operation) 0.1 m from the motor
Iron (heating mode) 0.25 m from the handle
14" TV 1.1 m from the screen; 1.2 m from the side wall.
Electric radiator 0.3 m
Floor lamp with two lamps of 75 W 0.03 m (from the wire)
Electric oven 0.4 m from the front wall
Air fryer 1.4 m from the side wall

Fig.2. Change in the level of the magnetic field of industrial frequency of household electrical appliances depending on the distance
Sanitary and hygienic standardization of EMF of household appliances
The main document establishing the requirements for the EMF of household appliances is “Interstate sanitary standards for permissible levels of physical factors when using consumer goods in domestic conditions”, MSanPiN 001-96. For certain types of goods, their own standards have been established: “Maximum permissible levels of energy flux density created by microwave ovens” SN No. 2666-83, “Maximum permissible standards for the electromagnetic field strength created by induction household ovens operating at a frequency of 20 - 22 kHz” SN No. 2550 -82. The EMF MPL values ​​for household appliances are given in Table 2.
table 2
Maximum permissible electromagnetic field levels for consumer products that are sources of EMF
Source Range Value Remote Control Note
Induction furnaces 20 - 22 kHz 500 V/m
4 A/m Measurement conditions:
distance 0.3 m from the body
Microwave oven 2.45 GHz 10 μW/cm2 Measurement conditions:
distance 0.50 ± 0.05 m from any point, with a load of 1 liter of water
Video display terminal PC 5 Hz - 2 kHz Epdu = 25 V/m
Vpdu = 250 nT Measurement conditions:
distance 0.5 m around the PC monitor
2 - 400 kHz Epdu = 2.5 V/m
Vpdu = 25 nT
surface electrostatic potential V = 500 V Measurement conditions:
distance 0.1 m from the PC monitor screen
Other products 50 Hz E = 500 V/m Measurement conditions:
distance 0.5 m from the product body
0.3 - 300 kHz E = 25 V/m
0.3 - 3 MHz E = 15 V/m
3 - 30 MHz E = 10 V/m
30 - 300 MHz E = 3 V/m
0.3 - 30 GHz PES = 10 μW/cm2
Possible biological effects
The human body always reacts to the electromagnetic field. However, in order for this reaction to develop into a pathology and lead to disease, a number of conditions must coincide - including a sufficiently high field level and duration of irradiation. Therefore, when using household appliances with low field levels and/or for a short period of time, the EMF of household appliances does not affect the health of the majority of the population. Potential danger can only be faced by people with hypersensitivity to EMFs and allergy sufferers, who also often have increased sensitivity to EMFs.
In addition, according to modern concepts, a magnetic field of industrial frequency can be dangerous to human health if prolonged exposure occurs (regularly, at least 8 hours a day, for several years) with a level above 0.2 microtesla.
Recommendations
When purchasing household appliances, check in the Hygienic Report (certificate) the mark on the product’s compliance with the requirements of the “Interstate Sanitary Standards for Permissible Levels of Physical Factors when Using Consumer Goods in Domestic Conditions”, MSanPiN 001-96;
use equipment with lower power consumption: industrial frequency magnetic fields will be lower, all other things being equal;
Potentially unfavorable sources of a magnetic field of industrial frequency in an apartment include refrigerators with a “no-frost” system, some types of “warm floors”, heaters, televisions, some alarm systems, various types of chargers, rectifiers and current converters - the sleeping place should be at a distance at least 2 meters from these objects if they work during your night rest;
When placing household appliances in your apartment, follow the principles shown in Figure 3.

Rice. 3a. Option for incorrect placement of household electrical appliances in an apartment

Rice. 3b. Option for the correct placement of household electrical appliances in the apartment
microwaves
The question is often asked regarding the danger - safety of microwave ovens, so we provide information about them separately.
A microwave oven (or microwave oven) uses an electromagnetic field, also called microwave radiation or microwave radiation, to heat food. The operating frequency of microwave radiation of microwave ovens is 2.45 GHz. It is this radiation that many people are afraid of. However, modern microwave ovens are equipped with fairly advanced protection that prevents the electromagnetic field from escaping beyond the working volume. At the same time, it cannot be said that the field does not penetrate at all outside the microwave oven. For various reasons, part of the electromagnetic field intended for the chicken penetrates outward, especially intensely, usually in the area of ​​the lower right corner of the door.
To ensure safety when using ovens at home, Russia has sanitary standards that limit the maximum leakage of microwave radiation from a microwave oven. They are called “Maximum permissible levels of energy flux density created by microwave ovens” and have the designation SN No. 2666-83. According to these sanitary standards, the energy flux density of the electromagnetic field should not exceed 10 μW/cm2 at a distance of 50 cm from any point of the stove body when heating 1 liter of water. In practice, almost all new modern microwave ovens meet this requirement with a large margin. However, when purchasing a new stove, you need to make sure that the certificate of conformity states that your stove meets the requirements of these sanitary standards.
It must be remembered that over time the degree of protection may decrease, mainly due to the appearance of microcracks in the door seal. This can happen both due to dirt and mechanical damage. Therefore, the door and its seal require careful handling and careful maintenance. The guaranteed durability of protection against electromagnetic field leaks during normal operation is several years. After 5-6 years of operation, it is advisable to check the quality of protection and invite a specialist from a specially accredited laboratory for monitoring electromagnetic fields.
In addition to microwave radiation, the operation of a microwave oven is accompanied by an intense magnetic field created by an industrial frequency current of 50 Hz flowing in the oven's power supply system. At the same time, a microwave oven is one of the most powerful sources of a magnetic field in an apartment. For the population, the level of the industrial frequency magnetic field in our country is still not limited, despite its significant effect on the human body during prolonged exposure. In domestic conditions, a single short-term switching on (for a few minutes) will not have a significant impact on human health. However, now a household microwave oven is often used to heat food in cafes and in similar other industrial settings. In this case, a person working with it finds himself in a situation of chronic exposure to a magnetic field of industrial frequency. In this case, mandatory control of the industrial frequency magnetic field and microwave radiation is necessary at the workplace.
Power lines and human health
The wires of a working power line create electric and magnetic fields of industrial frequency in the adjacent space. The distance over which these fields extend from the line wires reaches tens of meters.
The range of propagation of the electric field depends on the voltage class of the power line (the number indicating the voltage class is in the name of the power line - for example, a 220 kV power line), the higher the voltage, the larger the zone of increased electric field level, while the size of the zone does not change during the operation of the power line.
The range of propagation of the magnetic field depends on the magnitude of the current flowing or on the line load. Since the load on power lines can change repeatedly both during the day and with changing seasons, the size of the zone of increased magnetic field level also changes.
Electric and magnetic fields are very strong factors influencing the state of all biological objects falling within the zone of their influence.
For example, in the area of ​​influence of the electric field of power lines, insects exhibit changes in behavior: for example, bees show increased aggressiveness, anxiety, decreased performance and productivity, and a tendency to lose queens; Beetles, mosquitoes, butterflies and other flying insects exhibit changes in behavioral responses, including a change in the direction of movement towards a lower field level.
Developmental anomalies are common in plants - the shapes and sizes of flowers, leaves, stems often change, and extra petals appear.
A healthy person suffers from a relatively long stay in the field of power lines. Short-term exposure (minutes) can lead to a negative reaction only in hypersensitive people or in patients with certain types of allergies. For example, the work of English scientists in the early 90s is well known, showing that a number of allergy sufferers, when exposed to the power line field, develop an epileptic-type reaction.
With prolonged stay (months - years) of people in the electromagnetic field of power lines, diseases can develop, mainly of the cardiovascular and nervous systems of the human body. In recent years, cancer has often been cited as a long-term consequence.
Studies of the biological effect of EMF IF, carried out in the USSR in the 60-70s, were focused mainly on the effect of the electrical component, since no significant biological effect of the magnetic component was experimentally discovered at typical levels. In the 70s, strict standards were introduced for the population according to EP, which are still among the most stringent in the world. They are set out in the Sanitary Standards and Rules “Protection of the population from the effects of the electric field created by overhead power lines of alternating current of industrial frequency” No. 2971-84. In accordance with these standards, all power supply facilities are designed and built.
Despite the fact that the magnetic field throughout the world is now considered the most dangerous to health, the maximum permissible magnetic field value for the population in Russia is not standardized. The reason is there is no money for research and development of standards. Most power lines were built without taking this danger into account.
Based on mass epidemiological surveys of the population living in conditions of irradiation by magnetic fields of power lines, a magnetic induction flux density of 0.2 - 0.3 µT.
The basic principle of protecting public health from the electromagnetic field of power lines is to establish sanitary protection zones for power lines and reduce the electric field strength in residential buildings and in places where people can stay for a long time by using protective screens.
The boundaries of sanitary protection zones for power transmission lines on existing lines are determined by the criterion of electric field strength - 1 kV/m.
Boundaries of sanitary protection zones for power lines according to SN No. 2971-84
Power line voltage 330 kV 500 kV 750 kV 1150 kV
Size of sanitary protection (security) zone 20 m 30 m 40 m 55 m

Boundaries of sanitary protection zones for power lines in Moscow
Power line voltage<20 кВ 35 кВ 110 кВ 150 -220 кВ 330 - 500 кВ 750 кВ 1150 кВ
Size of sanitary protection zone 10 m 15 m 20 m 25 m 30 m 40 m 55 m

The placement of ultra-high voltage overhead lines (750 and 1150 kV) is subject to additional requirements regarding the conditions of exposure to the electric field on the population. Thus, the closest distance from the axis of the designed 750 and 1150 kV overhead lines to the boundaries of populated areas should, as a rule, be at least 250 and 300 m, respectively.
Permissible levels of exposure to the electric field of power lines on the population
MPL, kV/m Irradiation conditions
0.5 inside residential buildings
1.0 on the territory of a residential development zone
5.0 in populated areas outside residential areas; (land of cities within the city limits within the boundaries of their long-term development for 10 years, suburban and green areas, resorts, lands of urban-type settlements within the village limits and rural settlements within the boundaries of these points) as well as in the territory of vegetable gardens and orchards;
10.0 at the intersections of overhead power lines with highways of categories 1–IV;
15.0 in uninhabited areas (undeveloped areas, at least frequently visited by people, accessible to transport, and agricultural land);
20.0 in hard-to-reach areas (inaccessible to transport and agricultural vehicles) and in areas specially fenced off to exclude public access.
Within the sanitary protection zone of overhead lines it is prohibited:
place residential and public buildings and structures;
arrange parking areas for all types of transport;
locate automobile servicing enterprises and oil and petroleum products warehouses;
carry out operations with fuel, repair machines and mechanisms.
The territories of sanitary protection zones are allowed to be used as agricultural land, but it is recommended to grow crops on them that do not require manual labor.
If in some areas the electric field strength outside the sanitary protection zone is higher than the maximum permissible 0.5 kV/m inside the building and higher than 1 kV/m in the residential area (in places where people may be present), they must measures should be taken to reduce tensions. To do this, on the roof of a building with a non-metal roof, almost any metal mesh is placed, grounded in at least two points. In buildings with a metal roof, it is enough to ground the roof in at least two points.
In personal plots or other places where people are located, the power frequency field strength can be reduced by installing protective screens, for example, reinforced concrete, metal fences, cable screens, trees or shrubs at least 2 m high.
Personal computer and human health
Emissive characteristics of the monitor
electromagnetic field of the monitor in the frequency range 20 Hz-1000 MHz
static electric charge on the monitor screen
ultraviolet radiation in the range 200-400 nm
infrared radiation in the range 1050 nm - 1 mm
X-ray radiation > 1.2 keV
Computer as a source of alternating electromagnetic field
The electromagnetic field created by a personal computer has a complex spectral composition in the frequency range from 0 Hz to 1000 MHz. The electromagnetic field has electric (E) and magnetic (H) components, and their relationship is quite complex, so E and H are assessed separately. An example of the spectral characteristics of a PC in the range of 10 Hz - 400 kHz is shown in Figure 4.

Fig.4. Spectral characteristics of monitor radiation in the range 10 Hz–400 kHz
The presence of several computers with auxiliary equipment and a power supply system in a room creates a complex picture of the electromagnetic field. Figure 5 illustrates a typical example of the distribution of a power frequency magnetic field in a computer room. It is obvious that the electromagnetic environment in rooms with computers is extremely complex, the distribution of fields is uneven, and the levels are high enough to indicate the danger of their biological effects.

Rice. 5. An example of a typical magnetic field distribution in the range from 5 Hz to 2 kHz in a room equipped with computers
Computer as a source of electrostatic field
When the monitor is operating, an electrostatic charge accumulates on the kinescope screen, creating an electrostatic field (ESF). In different studies, under different measurement conditions, EST values ​​ranged from 8 to 75 kV/m. At the same time, people working with the monitor acquire electrostatic potential. The spread of electrostatic potentials of users ranges from -3 to +5 kV. When ESTP is experienced subjectively, the user's potential is the deciding factor in the occurrence of unpleasant subjective sensations.
A noticeable contribution to the total electrostatic field is made by the surfaces of the keyboard and mouse, which are electrified by friction. Experiments show that even after working with the keyboard, the electrostatic field quickly increases from 2 to 12 kV/m. At individual workplaces in the area of ​​the hands, static electric field strengths of more than 20 kV/m were recorded.
Impact of computer electromagnetic fields on user health
The first significant comprehensive study of the possible adverse effects of electromagnetic fields on the health of users was conducted in 1984 in Canada. The reason for the work was numerous complaints from employees of the accounting department of one of the hospitals. To identify causative factors, all types of radiation were measured and a questionnaire covering all types of health effects was distributed. The report based on the results of the work established an unambiguous connection between morbidity and one of the leading factors of external influence - the electromagnetic field generated by the computer monitor.
According to generalized data, in those working at a monitor from 2 to 6 hours a day, functional disorders of the central nervous system occur on average 4.6 times more often than in control groups, diseases of the cardiovascular system - 2 times more often, diseases of the upper respiratory tract - 1.9 times more often, diseases of the musculoskeletal system - 3.1 times more often. As the time spent on a computer increases, the ratio of healthy to sick users increases sharply.
According to the US Bureau of Labor Statistics, between 1982 and 1990, there was an eightfold increase in user disability. It has also been established that frequent exposure to electromagnetic radiation from monitors leads to abnormal pregnancy outcomes.
Studies of the functional state of a computer user, conducted in 1996 at the Center for Electromagnetic Safety, showed that even with short-term work (45 minutes), significant changes in the hormonal state and specific changes in the biocurrents of the brain occur in the user’s body under the influence of electromagnetic radiation from the monitor. These effects are especially pronounced and persistent in women. It was noticed that in groups of people (in this case it was 20%), a negative reaction of the functional state of the body does not manifest itself when working with a PC for less than 1 hour. Based on the analysis of the results obtained, it was concluded that it is possible to form special professional selection criteria for personnel using a computer in the process of work.
According to a number of researchers, an electrostatic field of a VDT with a intensity of 15 kV/m during a one-hour exposure to teenagers playing on a computer enhances excitatory processes in the central nervous system and shifts autonomic homeostasis towards sympathetic predominance.
Research into the general patterns of the human body’s reaction to the effects of an EMF monitor is being conducted in Ukraine. The results indicate that among other disorders in the functional state of the body, the most pronounced disorders are those of the hormonal and immune systems. Deviations in the immune status, equally both immunodeficiency and autoimmunity, are fundamental in the discoordination of processes that maintain homeostasis in the body as a whole.
A study of 1,583 women conducted in Oakland, California, USA by the Kaiser Medical Center found that women who used computer terminals more than 20 hours a week had an 80% higher risk of miscarriage in early and late pregnancy than women who used computer terminals more than 20 hours a week. which do the same job without display terminals. According to Swedish scientists, there is a 90% chance that VDT users are 1.5 times more likely to have miscarriages and have 2.5 times more children with birth defects than women in other professions.
The New York City Board of Occupational Safety and Health believes that women who are pregnant or intending to become pregnant should be transferred to jobs that do not involve the use of video terminals.
Of course, listing these facts does not limit the adverse impact of EMF in the workplace on the health of the user. For this exposure situation, all other biological effects of the electromagnetic field are possible.
Remote control of the electromagnetic field and surface electrostatic potential of a computer monitor
Field type Frequency range Unit of measurement Remote control
magnetic field 5Hz-2kHz nT 250
magnetic field 2-400 kHz, nT 25
electric field 5Hz-2kHz V/m 25
electric field 2- 400 kHz V/m 2.5
equivalent (surface) electrostatic potential V 500
According to a number of experts, it is also advisable for women who intend to become pregnant to refuse to work with a computer, since the embryo in the early stages of development is extremely sensitive to the electromagnetic field.
Radars and human health
Radar stations are usually equipped with mirror-type antennas and have a narrowly directed radiation pattern in the form of a beam directed along the optical axis.
Radar systems operate at frequencies from 500 MHz to 15 GHz, but individual systems can operate at frequencies up to 100 GHz. The EM signal they create is fundamentally different from radiation from other sources. This is due to the fact that periodic movement of the antenna in space leads to spatial intermittency of irradiation. Temporary intermittency of irradiation is due to the cyclical operation of the radar on radiation. The operating time in various operating modes of radio equipment can range from several hours to a day. So, for meteorological radars with a time intermittency of 30 minutes - radiation, 30 minutes pause, the total operating time does not exceed 12 hours, while airport radar stations in most cases operate around the clock. The width of the radiation pattern in the horizontal plane is usually several degrees, and the duration of irradiation over the viewing period is tens of milliseconds.
Metrological radars can create a PES of ~100 W/m2 for each irradiation cycle at a distance of 1 km. Airport radar stations create PES ~ 0.5 W/m2 at a distance of 60 m. Marine radar equipment is installed on all ships; it usually has a transmitter power an order of magnitude lower than that of airfield radars, so in normal mode scanning PES created at a distance of several meters, does not exceed 10 W/m2. A comparison of the levels of fields created by radars with other microwave sources is shown in Figure 6.
An increase in the power of radars for various purposes and the use of highly directional all-round antennas leads to a significant increase in the intensity of EMR in the microwave range and creates long-distance zones with a high energy flux density on the ground. The most unfavorable conditions are observed in residential areas of cities within which airports are located: Irkutsk, Sochi, Syktyvkar, Rostov-on-Don and a number of others.

Fig.6. Radar EMF levels compared to other microwave sources
Cellular communications and human health
Cellular radiotelephony is one of the most rapidly developing telecommunication systems today.
The main elements of a cellular communication system are base stations (BS) and mobile radiotelephones (MRT). Base stations maintain radio communication with mobile radiotelephones, as a result of which BS and MRI are sources of electromagnetic radiation in the UHF range.
An important feature of the cellular radio communication system is the very efficient use of the radio frequency spectrum allocated for the system’s operation (repeated use of the same frequencies, use of different access methods), which makes it possible to provide telephone communications to a significant number of subscribers. The system operates on the principle of dividing a certain territory into zones, or “cells,” with a radius of usually 0.5–10 kilometers.
Base stations
Studies of the electromagnetic situation in the territory adjacent to the BS were carried out by specialists from different countries, including Sweden, Hungary and Russia. Based on the results of measurements carried out in Moscow and the Moscow region, it can be stated that in 100% of cases the electromagnetic environment in the premises of buildings on which BS antennas are installed did not differ from the background characteristic of a given area in a given frequency range. In the adjacent territory, in 91% of cases, the recorded levels of the electromagnetic field were 50 times less than the maximum limit established for the BS. The maximum measurement value, 10 times less than the maximum limit, was recorded near a building on which three base stations of different standards were installed at once.
Available scientific data and the existing system of sanitary and hygienic control during the commissioning of cellular base stations make it possible to classify cellular base stations as the most environmentally and sanitary and hygienically safe communication systems.
Mobile radiotelephones
A mobile radiotelephone (MRT) is a small-sized transceiver. Depending on the phone standard, transmission is carried out in the frequency range 453 – 1785 MHz. The MRI radiation power is a variable value that largely depends on the state of the communication channel “mobile radiotelephone – base station,” i.e., the higher the BS signal level at the receiving location, the lower the MRI radiation power. The maximum power is in the range of 0.125–1 W, but in real conditions it usually does not exceed 0.05–0.2 W.
The question of the impact of MRI radiation on the user’s body still remains open. Numerous studies conducted by scientists from different countries, including Russia, on biological objects (including volunteers) have led to ambiguous, sometimes contradictory, results. The only undeniable fact is that the human body “responds” to the presence of cell phone radiation. Therefore, MRI owners are advised to take some precautions:
do not use your cell phone unless necessary;
talk continuously for no more than 3 – 4 minutes;
Do not allow children to use MRI;
when purchasing, choose a cell phone with a lower maximum radiation power;
In a car, use MRI in conjunction with a hands-free communication system with an external antenna, which is best located in the geometric center of the roof.
For people surrounding a person talking on a mobile radiotelephone, the electromagnetic field created by MRI does not pose any danger.
Satellite communications and human health
Satellite communication systems consist of a transceiver station on Earth and a satellite in orbit. The antenna pattern of satellite communication stations has a clearly defined narrowly directed main beam - the main lobe. The energy flux density (PED) in the main lobe of the radiation pattern can reach several hundred W/m2 near the antenna, also creating significant field levels at a large distance. For example, a 225 kW station operating at a frequency of 2.38 GHz creates a PES equal to 2.8 W/m2 at a distance of 100 km. However, energy dissipation from the main beam is very small and occurs most in the area where the antenna is located.
A typical calculated graph of PES distribution at a height of 2 m from the earth’s surface in the area where a satellite communication antenna is located is shown in Figure 7.

Fig.7. Graph of electromagnetic field flux density distribution at a height of 2 m from the earth’s surface in the area where a satellite communication antenna is installed
Height of the antenna on the ground, m 4.8
Antenna diameter, m 5.5
Power emitted by the antenna, W 134
Antenna tilt angle relative to the horizon, degree 10
Height of the energy flux density calculation line, m 2
Azimuth of the energy flux density calculation line, degree 0
There are two main possible exposure hazards:
directly in the area where the antenna is located;
when approaching the axis of the main beam along its entire length.
Protecting humans from the biological effects of EMF
Organizational measures for protection against EMF
Organizational measures for protection against EMF include: selection of operating modes of emitting equipment that ensures a radiation level not exceeding the maximum permissible, limiting the place and time of stay in the EMF action area (protection by distance and time), designation and fencing of areas with increased levels of EMF.
Time protection is used when it is not possible to reduce the radiation intensity at a given point to the maximum permissible level. The existing remote control systems provide for a relationship between the intensity of the energy flux density and the irradiation time.
Protection by distance is based on a drop in radiation intensity, which is inversely proportional to the square of the distance and is applied if it is impossible to weaken the EMF by other measures, including protection by time. Protection by distance is the basis for radiation regulation zones to determine the required gap between EMF sources and residential buildings, office premises, etc.
For each installation emitting electromagnetic energy, sanitary protection zones must be determined in which the intensity of the EMF exceeds the maximum permissible limit. The boundaries of the zones are determined by calculation for each specific case of placement of a radiating installation when operating at maximum radiation power and are controlled using instruments. In accordance with GOST 12.1.026-80, radiation zones are fenced off or warning signs are installed with the words: “Do not enter, dangerous!”
Engineering and technical measures to protect the population from EMF
Engineering and technical protective measures are based on the use of the phenomenon of shielding electromagnetic fields directly in places where a person stays or on measures to limit the emission parameters of the field source. The latter is usually used at the development stage of a product that serves as a source of EMF.
One of the main ways to protect against electromagnetic fields is to shield them in places where a person stays. Typically there are two types of shielding: shielding EMF sources from people and shielding people from EMF sources. The protective properties of the screens are based on the effect of weakening the tension and distortion of the electric field in space near a grounded metal object.
The electric field of industrial frequency created by power transmission systems is carried out by establishing sanitary protection zones for power lines and reducing the field strength in residential buildings and in places where people may stay for a long time by using protective screens. Protection from a power-frequency magnetic field is practically possible only at the stage of product development or facility design; as a rule, a reduction in the field level is achieved through vector compensation, since other methods of shielding a power-frequency magnetic field are extremely complex and expensive.
The basic requirements for ensuring the safety of the population from the electric field of industrial frequency created by power transmission and distribution systems are set out in the Sanitary Standards and Rules “Protection of the population from the effects of the electric field created by overhead AC power lines of industrial frequency” No. 2971-84. For more information on protection requirements, see the section "EMF sources. Power lines"
When shielding EMI in the radio frequency range, a variety of radio-reflecting and radio-absorbing materials are used.
Radio-reflective materials include various metals. The most commonly used materials are iron, steel, copper, brass, and aluminum. These materials are used in the form of sheets, mesh, or in the form of gratings and metal tubes. The shielding properties of sheet metal are higher than mesh, but mesh is more convenient from a structural point of view, especially when shielding inspection and ventilation openings, windows, doors, etc. The protective properties of the mesh depend on the mesh size and the thickness of the wire: the smaller the mesh size, the thicker the wire, the higher its protective properties. A negative property of reflective materials is that in some cases they create reflected radio waves, which can increase human exposure.
More convenient materials for shielding are radio-absorbing materials. Sheets of absorbent materials can be single or multi-layered. Multilayer - provide absorption of radio waves over a wider range. To improve the shielding effect, many types of radio-absorbing materials have a metal mesh or brass foil pressed onto one side. When creating screens, this side faces the direction opposite to the radiation source.
Despite the fact that absorbing materials are in many respects more reliable than reflective ones, their use is limited by high cost and narrow absorption spectrum.
In some cases, the walls are coated with special paints. Colloidal silver, copper, graphite, aluminum, and powdered gold are used as conductive pigments in these paints. Ordinary oil paint has a fairly high reflectivity (up to 30%), and a lime coating is much better in this regard.
Radio emissions can penetrate into rooms where people are located through window and door openings. For screening observation windows, room windows, glazing of ceiling lights, and partitions, metallized glass with screening properties is used. This property is given to glass by a thin transparent film of either metal oxides, most often tin, or metals - copper, nickel, silver and their combinations. The film has sufficient optical transparency and chemical resistance. When applied to one side of the glass surface, it attenuates the radiation intensity in the range of 0.8 - 150 cm by 30 dB (1000 times). When the film is applied to both surfaces of the glass, the attenuation reaches 40 dB (10,000 times).
To protect the population from the effects of electromagnetic radiation in building structures, metal mesh, metal sheet or any other conductive coating, including specially designed building materials, can be used as protective screens. In some cases, it is sufficient to use a grounded metal mesh placed under the facing or plaster layer.
Various films and fabrics with a metallized coating can also be used as screens.
Almost all building materials have radio-shielding properties. As an additional organizational and technical measure to protect the population when planning construction, it is necessary to use the property of “radio shadow” arising from the terrain and the bending of radio waves around local objects.
In recent years, metallized fabrics based on synthetic fibers have been used as radio-shielding materials. They are obtained by chemical metallization (from solutions) of fabrics of various structures and densities. Existing production methods make it possible to regulate the amount of applied metal in the range from hundredths to units of microns and change the surface resistivity of tissues from tens to fractions of Ohms. Shielding textile materials are thin, lightweight, and flexible; they can be duplicated with other materials (fabrics, leather, films) and are compatible with resins and latexes.
Treatment and preventive measures
Sanitary and preventive provision includes the following activities:
organization and monitoring of compliance with hygienic standards, operating conditions of personnel servicing EMF sources;
identification of occupational diseases caused by unfavorable environmental factors;
development of measures to improve the working and living conditions of personnel, to increase the resistance of workers’ bodies to the effects of adverse environmental factors.
Current hygienic control is carried out depending on the parameters and operating mode of the radiating installation, but as a rule, at least once a year. At the same time, the characteristics of EMF in industrial premises, in residential and public buildings and in open areas are determined. Measurements of EMF intensity are also carried out when changes are made to the conditions and operating modes of EMF sources that affect radiation levels (replacement of generator and radiating elements, changes in the technological process, changes in shielding and protective equipment, increase in power, change in the location of radiating elements, etc.) .
In order to prevent, early diagnosis and treatment of health problems, workers associated with exposure to EMFs must undergo preliminary upon entry to work and periodic medical examinations in the manner established by the relevant order of the Ministry of Health.
All persons with initial manifestations of clinical disorders caused by exposure to EMF (asthenic astheno-vegetative, hypothalamic syndrome), as well as with general diseases, the course of which may be aggravated under the influence of unfavorable factors in the work environment (organic diseases of the central nervous system, hypertension, diseases of the endocrine system , blood diseases, etc.), must be monitored with appropriate hygienic and therapeutic measures aimed at improving working conditions and restoring the health of workers.
Conclusion
Currently, there is an active study of the mechanisms of the biological action of physical factors of non-ionizing radiation: acoustic waves and electromagnetic radiation on biological systems of different levels of organization; enzymes, cells that survive slices of the brain of laboratory animals, behavioral reactions of animals and the development of reactions in chains: primary targets - cell - cell populations - tissue.
VNIISKhRAE is developing research to assess the environmental consequences of the impact on natural and agricultural cenoses of man-made stressors - microwave and UV-B radiation, the main objectives of which are:
studying the consequences of ozone layer depletion on the components of agrocenoses in the non-chernozem zone of Russia;
studying the mechanisms of action of UV-B radiation on plants;
study of the separate and combined effects of electromagnetic radiation of various ranges (microwave, gamma, UV, IR) on farm animals and model objects in order to develop methods for hygienic and environmental regulation of electromagnetic pollution of the environment;
development of environmentally friendly technologies based on the use of physical factors for various sectors of agricultural production (crop farming, livestock farming, food and processing industries in order to intensify agricultural production.
And at the Institute of Theoretical and Experimental Biophysics of the Russian Academy of Sciences in Pushchino, a study was conducted on the topic “Phase transition in synaptic membranes as a highly sensitive target of the thermal action of non-ionizing radiation.”
When interpreting the results of studies of the biological effects of non-ionizing radiation (electromagnetic and ultrasonic), the central and still poorly studied questions remain questions about the molecular mechanism, the primary target and thresholds of radiation action. Recently, a new molecular mechanism of synaptic transmission has been proposed based on the phase transition of the lipid membrane as the driving force for neurotransmitter release at synapses in the central nervous system. One of the most important consequences is that relatively small changes in local temperature in nervous tissue (from tenths to several degrees) can lead to a noticeable change in the rate of synaptic transmission, up to complete shutdown of the synapse. Such temperature changes can be caused by radiation of therapeutic intensity. From these premises follows the hypothesis of the existence of a general mechanism of action of non-ionizing radiation - a mechanism based on a small local heating of areas of nervous tissue.
Thus, such a complex and little-studied aspect as non-ionizing radiation and its impact on the environment remains to be studied in the future.

Bibliography
1. Pavlov A.N. “The impact of electromagnetic radiation on life activity”, Moscow: HELIOS, 2003, 224 pp.
2. http://www.tesla.ru
3. http://www.pole.com.ru
4. http://www.ecopole.ru
5. http://www.botanist.ru/
6. http://www.fcgsen.ru/
7. http://www.gnpc.ru/
8. http://www.rus-lib.ru/

Non-ionizing electromagnetic fields and radiation. Electromagnetic interaction is characteristic of charged particles. The carrier of energy between such particles are photons of the electromagnetic field or radiation. The length of an electromagnetic wave (m) in air is related to its frequency f (Hz) by the relation λf = с, where With– speed of light.

Electromagnetic fields and radiation are divided into non-ionizing, including laser radiation, and ionizing. Non-ionizing electromagnetic fields (EMF) and radiation (EMF) have a spectrum of vibrations with a frequency of up to 10 21 Hz.

Non-ionizing electromagnetic fields of natural origin are a permanent factor. These include: atmospheric electricity, radio emissions from the Sun and galaxies, electric and magnetic fields of the Earth.

In non-ionizing man-made sources of electric and magnetic fields and radiation. Their classification is given in table. 2.9.

The use of man-made EMF and EMR of various frequencies is systematized in Table. 2.10.

The main sources of electromagnetic fields of radio frequencies are radio engineering facilities (RTO), television and radar stations (RLS), thermal shops and areas (in areas adjacent to enterprises). Industrial-frequency EMFs are most often associated with high-voltage power lines (OHLs), sources of magnetic fields used in industrial enterprises.

Table 2.9

Classification of non-ionizing man-made radiation

		Index
		frequency range	wavelength
Static field	Electrical	–	–
	Magnetic	–	–
Electromagnetic field	Power frequency electromagnetic field	50 Hz	–
	Radio frequency electromagnetic radiation (RF EMI)	10 kHz to 30 kHz	30 km
		30 kHz to 3 MHz	100 m
		3 MHz to 30 MHz	10 m
		30 MHz to 50 MHz	6 m
		50 MHz to 300 MHz	1m
		300 MHz to 300 GHz	1 mm

Zones with increased levels of EMF, the sources of which can be RTO and radar, have dimensions of up to 100–150 m. Moreover, inside buildings located in these zones, the energy flux density, as a rule, exceeds permissible values.

Table 2.10

Application of electromagnetic fields and radiation

EMF and EMI Frequency	Technological process, installation, industry
>0 to 300 Hz	Electrical appliances, including household ones, high-voltage power lines, transformer substations, radio communications, scientific research, special communications
0.3–3 kHz	Radio communication power transmission, induction heating of metal, physiotherapy
3–30 kHz	Ultra-long-wave radio communication, induction heating of metal (hardening, melting and soldering), physiotherapy, ultrasound installations
30–300 kHz	Radio navigation, communications with ships and aircraft, long-wave radio communications, induction heating of metals, electrocorrosion treatment, VDT, ultrasonic installations
0.3–3 MHz	Radio communications and broadcasting, radio navigation, induction and dielectric heating of materials, medicine
3–30 MHz	Radio communications and broadcasting, dielectric heating, medicine, plasma heating
30–300 MHz	Radio communications, television, medicine (physiotherapy, oncology), dielectric heating of materials, plasma heating
0.3–3 GHz	Radar, radio navigation, radiotelephony, television, microwave ovens, physiotherapy, plasma heating and diagnostics
3–30 GHz	Radar and satellite communications, weather location, radio relay communications, plasma heating and diagnostics, radio spectroscopy
30–300 GHz	Radars, satellite communications, radiometeorology, medicine (physiotherapy, oncology)

Magnetic fields arising in areas adjacent to electrified railways pose a significant danger. High intensity magnetic fields are found even in buildings located in close proximity to these areas.

In everyday life, sources of EMF and radiation are televisions, displays, microwave ovens and other devices. Electrostatic fields in conditions of low humidity (less than 70%) create rugs, capes, curtains, etc. Commercial microwave ovens are not dangerous, but failure of their protective shields can significantly increase the leakage of electromagnetic radiation. TV and display screens as sources of electromagnetic radiation in everyday life are not dangerous even with prolonged exposure to a person, if the distance from the screen exceeds 30 cm.

The electrostatic field (ESF) is completely characterized by the electric field strength E (V/m). A constant magnetic field (CMF) is characterized by magnetic field strength H (A/m), while in air 1 A/m is 1.25 μT, where T is tesla (unit of magnetic field strength).

The electromagnetic field (EMF) is characterized by a continuous distribution in space, the ability to propagate at the speed of light, and affect charged particles and currents. EMF is a combination of two interconnected alternating fields - electric and magnetic, which are characterized by the corresponding intensity vectors E (V/m) and H (A/m).

Depending on the relative position of the source of electromagnetic radiation and the location of the person, it is necessary to distinguish between the near zone (induction zone), the intermediate zone and the far zone (wave zone) or radiation zone. When radiating from sources (Fig. 2.11), the near zone extends to a distance λ/2π , i.e., approximately 1/6 of the wavelength. The far zone begins with distances equal to λ*2π, i.e. from distances equal to approximately six wavelengths. Between these two zones there is an intermediate zone.

Rice. 2.11.Zones arising around an elementary source

In the induction zone, in which a traveling electromagnetic wave has not yet formed, the electric and magnetic fields should be considered independent of each other, therefore this zone can be characterized by the electric and magnetic components of the electromagnetic field. The relationship between them in this zone can be very different. The intermediate zone is characterized by the presence of both an induction field and a propagating electromagnetic wave. The wave zone (radiation zone) is characterized by the presence of a formed EMF, propagating in the form of a traveling electromagnetic wave. In this zone, the electric and magnetic components change in phase and there is a constant relationship between their average values ​​over the period

where ρ in – wave impedance, Ohm; , ε – electrical constant; μ – magnetic permeability of the medium.

Oscillations of vectors E and H occur in mutually perpendicular planes. In the wave zone, the impact of EMF is determined by the energy flux density carried by the electromagnetic wave. When an electromagnetic wave propagates in a conducting medium, the vectors E and H are related by the relation

where ω – circular frequency of electromagnetic oscillations, Hz; v – specific electrical conductivity of the screen substance; z – penetration depth of the electromagnetic field.

When EMF propagates in a vacuum or in air, where ρ in = 377 Ohm, E = 377H. The electromagnetic field carries energy determined by the energy flux density (1 = EN (W/m2)), which shows how much energy flows in 1 s through an area of ​​1 m2 located perpendicular to the movement of the wave.

When emitting spherical waves, the energy flux density in the wave zone can be expressed in terms of the power P source supplied to the emitter:

Where R– distance to the radiation source, m.

Impact of electromagnetic fields on humans depends on the strength of the electric and magnetic fields, energy flow, oscillation frequency, the presence of accompanying factors, irradiation mode, size of the irradiated body surface and individual characteristics of the body. It has also been established that the relative biological activity of pulsed radiation is higher than continuous radiation. The danger of exposure is aggravated by the fact that it is not detected by human senses.

The impact of an electrostatic field (ESF) on a person is associated with the flow of a weak current (several microamperes) through it. In this case, electrical injuries are never observed. However, due to a reflex reaction to electric current (sharp removal from a charged body), mechanical injury is possible when hitting nearby structural elements, falling from a height, etc. A study of biological effects showed that the central nervous system, cardiovascular system, and analyzers are most sensitive to the electrostatic field. People working in the area exposed to ESP complain of irritability, headaches, sleep disturbances, etc.

The impact of magnetic fields (MF) can be constant (from artificial magnetic materials) and pulsed. The degree of impact of the MF on workers depends on its maximum intensity in the space of the magnetic device or in the zone of influence of the artificial magnet. The dose received by a person depends on the location in relation to the MP and the work regime. When exposed to an alternating magnetic field, characteristic visual sensations are observed, which disappear when the effect ceases. When constantly working under conditions of chronic exposure to MFs exceeding the maximum permissible levels, dysfunctions of the central nervous system, cardiovascular and respiratory systems, digestive tract, and changes in the blood are observed. Long-term action leads to disorders that are subjectively expressed by complaints of headache in the temporal and occipital region, lethargy, sleep disturbance, memory loss, increased irritability, apathy, and pain in the heart.

With constant exposure to industrial-frequency EMFs, rhythm disturbances and a slowdown in heart rate are observed. Those working in industrial frequency EMF zones may experience functional disorders of the central nervous system and cardiovascular system, as well as changes in the composition of the blood.

When exposed to radiofrequency EMFs, the atoms and molecules that make up the human body become polarized. Polar molecules (for example, water) are oriented in the direction of propagation of the electromagnetic field; in electrolytes, which are the liquid components of tissues, blood, etc., after exposure to an external field, ionic currents appear. An alternating electric field causes heating of human tissues both due to the alternating polarization of the dielectric (tendon, cartilage, etc.) and due to the appearance of conduction currents. The thermal effect is a consequence of the absorption of electromagnetic field energy. The greater the field strength and exposure time, the stronger these effects appear. Excess heat is removed to a certain limit by increasing the load on the thermoregulation mechanism. However, starting from the value I = 10 mW/cm 2, called the thermal threshold, the body cannot cope with the removal of the generated heat, and the body temperature rises, which is harmful to health.

Electromagnetic fields most intensely affect organs with a high water content. At the same field strength, the absorption coefficient in tissues with a high water content is approximately 60 times higher than in tissues with a low water content. As the wavelength increases, the penetration depth of electromagnetic waves increases; the difference in the dielectric properties of tissues leads to uneven heating, the occurrence of macro- and microthermal effects with a significant temperature difference.

Overheating is especially harmful to tissues with an underdeveloped vascular system or with insufficient blood circulation (eyes, brain, kidneys, stomach, gallbladder and bladder). Irradiation of the eyes can lead to clouding of the lens (cataract), which is not detected immediately, but several days or weeks after irradiation. The development of cataracts is one of the few specific lesions caused by electromagnetic radiation of radio frequencies in the range of 300 MHz - 300 GHz with an energy flux density of over 10 mW/cm 2. In addition to cataracts, corneal burns are possible when exposed to EMF.

For long-term exposure to EMF of various wavelength ranges at moderate intensity (above MPL), the development of functional disorders in the central nervous system with mild changes in endocrine metabolic processes and blood composition is considered characteristic. In this regard, headaches, an increase or decrease in blood pressure, a decrease in heart rate, changes in conductivity in the heart muscle, neuropsychiatric disorders, and the rapid development of fatigue may appear. Possible trophic disorders: hair loss, brittle nails, weight loss. Changes in the excitability of the olfactory, visual and vestibular analyzers are observed. At an early stage, the changes are reversible; with continued exposure to EMF, a persistent decrease in performance occurs. Within the radio wave range, the greatest biological activity of the microwave (microwave) field has been proven. Acute disturbances when exposed to EMR (emergency situations) are accompanied by cardiovascular disorders with fainting, a sharp increase in heart rate and a decrease in blood pressure.

Non-ionizing radiation includes part of the spectrum of electromagnetic oscillations and laser radiation. The emergence of this factor in the human environment is associated with the development of radio electronics, electric power, and laser technology.

2.5.1. Electromagnetic radiation

Non-ionizing are those electromagnetic oscillations (EMVs) whose quantum energy is insufficient to ionize the molecules and atoms of a substance. A significant part of the spectrum of non-ionizing radiation consists of radiation in the radio wave range, and a smaller part - radiation in the optical range.

Electromagnetic radiation occurs when using electromagnetic energy: radio communications, television, radar, radio linear, space communications, radio navigation. Electromagnetic energy has found wide application in various industries. In metallurgy and mechanical engineering - for melting, heating, welding, metal spraying; in textile and light industry - for drying leather, textiles, paper, dielectric processing of materials, heating, welding and polymerization of plastics, in the food industry - for heat treatment of various food products. Electromagnetic energy is widely used in modern computing technology and in medicine for therapeutic and diagnostic purposes.

The main parameters of electromagnetic oscillations are wavelength l, frequency f and wave propagation speed V. In a vacuum, the speed of propagation of electromagnetic waves is equal to the speed of light, and in media it is determined

Where e- dielectric constant of the medium; m- magnetic permeability of the medium.

The region of propagation of electromagnetic waves is divided into three zones: near (induction zone), intermediate (interference zone) and far (wave zone). The near zone extends over a distance equal to approximately 1/6 of the wavelength (), where r- radius of the sphere whose center is the source, l- wavelength. The far zone begins at distances equal to 6-7 wavelengths. Between these two zones there is an intermediate zone.

Various parameters are used to assess the intensity of electromagnetic fields in these areas. In the induction zone, where the electromagnetic field has not yet been formed and the measured electromagnetic energy represents a certain reserve of reactive power, the radiation intensity is estimated by electrical ( E) and magnetic ( N) components. The unit of measurement for electric field strength is V/m, and the unit for magnetic field is A/m.

The interference zone is characterized by the presence of both an induction field and a field of a propagating electromagnetic wave. The energy indicator of this zone, as well as the near one, is the volumetric energy density, which is equal to the sum of the densities of the electric and magnetic fields.

The wave zone is characterized by the presence of a formed electromagnetic field propagating in the form of a traveling wave. In this zone, the field intensity is estimated by the energy flux density (EFD), i.e. the amount of energy incident on a unit surface. The energy flux density in the wave zone is related to the strength of the electric and magnetic fields by the relation P=E N. The unit of measurement of PES is W/m 2.

The effect of electromagnetic radiation on the human body. The biological effect of electromagnetic radiation is determined by:

Energy flux density;

Radiation frequency;

Duration of irradiation;

Irradiation mode (continuous, intermittent, pulsed);

The size of the irradiated surface;

The presence of other harmful and dangerous environmental factors;

Individual characteristics of the body.

From the point of view of the interaction of electromagnetic fields with a biological object, the entire frequency spectrum of electromagnetic radiation is divided into 5 ranges. The first range includes electromagnetic oscillations with a frequency from a few to several thousand hertz, the second - from several thousand hertz to 30 MHz, the third - from 30 MHz to 10 GHz, the fourth - from 10 GHz to 200 GHz, the fifth - from 200 GHz to 3000 GHz.

The first range is characterized by the fact that the human body, when interacting with a low-frequency electromagnetic field, can be considered as a fairly good conductor, so the depth of penetration of the field lines is insignificant. There is practically no field inside the body.

The second frequency range is characterized by a rapid increase in the amount of energy absorption with increasing frequency. The increase in absorbed energy is approximately proportional to the square of the frequency.

A feature of the third range is that at certain frequencies there are a number of maxima in the absorption of external field energy by the body. The greatest absorption of electromagnetic energy by humans is observed at a frequency close to 70 MHz. At higher and lower frequencies the amount of absorbed energy is significantly less. At the same time, at lower frequencies the energy is distributed evenly, and at higher frequencies, areas of maximum (so-called hot spots) appear in various structures of the body.

The fourth range is characterized by rapid attenuation of the electromagnetic field energy as it penetrates into the tissue. Almost all energy is absorbed in the surface layers of biostructures.

Electromagnetic vibrations of the fifth range are absorbed by the most superficial layers of the skin.

With constant exposure to low-frequency electromagnetic fields, headaches, lethargy, drowsiness, irritability, pain in the heart, as well as functional disorders of the central nervous and cardiovascular systems appear.

The mechanism of the biological action of electromagnetic fields is associated with their thermal effect, which is a consequence of the absorption of the energy of the electromagnetic field. Heat exposure is especially harmful to tissues with an underdeveloped vascular system or insufficient blood circulation (eyes, brain, kidneys, stomach, gall and bladder).

One of the specific lesions caused by exposure to electromagnetic radiation is the development of cataracts, which occurs as a result of heating the lens of the eye to temperatures exceeding permissible physiological limits. In addition to cataracts, when exposed to high-frequency electromagnetic radiation (about 35 GHz), keratitis can occur - inflammation of the cornea of ​​the eyes.

Operators are significantly exposed to electromagnetic radiation when working on displays. Found that radiation? created by the horizontal scan output transformer can reach 500 mW/cm, which corresponds to 1300 V/m. At a distance of 25 cm from the screen, the electric field at a frequency above 203 kHz reaches 80 V/m.

Hygienic standardization of electromagnetic radiation. Regulatory documents regulating the impact of electromagnetic radiation are:

GOST 12.1.006-84 "Electromagnetic fields of radio frequencies. Permissible levels in the workplace and requirements for monitoring";

Sanitary standards and rules for protecting the population from the effects of the electric field created by overhead power lines of alternating current of industrial frequency" N 2971-34;

Sanitary rules and regulations SanPiN 2.2.4/2 1.8.055-96 “Electromagnetic radiation in the radio frequency range (RF EMR).

GOST 12.1.006-84 establishes remote controls for electromagnetic radiation in workplaces, taking into account frequency ranges.

In the frequency range 60 kHz-300 MHz, the intensity of the electromagnetic field is characterized by the electric strength ( E) and magnetic ( N) fields.

Maximum permissible values E And N in this range is determined by the permissible energy load and exposure time. The energy load is equal to the product of the square of the field strength and the time of its exposure. The energy load created by the electric field is equal to EN E= = E 2 T, (V/m 2), magnetic - EN n =N 2. T, (A/m 2) h.

Calculation of maximum permissible values E And N in the frequency range 60 kHz - 300 MHz are produced according to the formulas

Where E pd And N pd- maximum permissible values ​​of electric (V/m) and magnetic (A/m) field strengths; T- exposure time, h; and - maximum permissible values ​​of energy load during the working day, (V/m) 2 /h and (A/m) 2 /h.

Maximum values , , are presented in Table 2.4.

Table 2.4

Simultaneous exposure to electric and magnetic fields in the frequency range from 0.06 to 3 MHz is considered acceptable if the following conditions are met:

Where EN E And EN N- energy loads characterizing the effects of electric and magnetic fields.

In the frequency range 300 MHz - 300 GHz, the intensity of the electromagnetic field is characterized by the surface energy flux density (SED), the energy load is equal to:

EN PPE = PPE. T

The maximum permissible values ​​of the PES of electromagnetic fields in the frequency range 300 MHz - 300 GHz are determined by the formula:

Where PPE PD- maximum permissible value of energy flux density, W/m (mW/cm, μW/cm); - maximum permissible value of energy load equal to 2 W h/m (200 μW h/m); TO- biological effectiveness attenuation coefficient equal to: I - for all cases of irradiation, excluding irradiation from rotating and scanning antennas; 10 - for cases of exposure from rotating and scanning antennas; T- time spent in the irradiation zone per work shift, hours.

Sanitary rules and norms SanPiN 2.2.4/2.1.8.055-96 establish maximum limits for exposure of people to electromagnetic radiation in the frequency range 30 kHz - 300 GHz, requirements for RF EMR sources, for the placement of these sources, measures to protect workers from exposure to RF EMR.

According to these rules and regulations, the assessment of the impact of RF EMR on people is carried out according to the following parameters:

By energy exposure, determined by the intensity of RF EMR and the time of its exposure to a person;

Based on RF EMR intensity values.

Energy exposure (EE) assessment is used for persons whose work or training requires them to stay in areas influenced by RF EMR sources, provided that these persons undergo medical examinations in the prescribed manner. Assessment based on RF EMR intensity values ​​is used for persons whose work or training is not related to the need to stay in areas influenced by RF EMR sources, for persons under 18 years of age, for pregnant women, for persons located in residential areas.

In the frequency range 30 kHz - 300 MHz, the intensity of RF EMR is estimated by the electric field strength values E(V/m) and magnetic field strength N(A/m). In the frequency range 300 MHz - 300 GHz, the intensity of RF EMR is estimated by the energy flux density PPE(W/m2; μW/cm2).

The energy exposure created by the electric field is equal to EE E = = E 2 T(V/m 2) h, and the one created by the magnetic field is equal to EE N = N 2 T(A/m 2) h.

Maximum permissible values ​​of RF EMR intensity ( E PDU, N PDU, PPE PDU) depending on the exposure time during the working day and the permissible exposure time depending on the intensity of RF EMR are determined by the formulas:

The regulatory document regulating the protection of the population from the effects of electromagnetic radiation is “Sanitary standards and rules for the protection of the population from the effects of the electric field created by overhead power lines of alternating current of industrial frequency” No. 2971-34. This document establishes the following values ​​of the maximum permissible level of electric field strength, kV/m: inside residential buildings - 0.5; in residential areas - 1; in populated areas, outside residential areas - 10; in uninhabited areas - 15; in hard-to-reach areas - 20.

SanPin 2.2.2.542-96 regulates the permissible values ​​of parameters of non-ionizing electromagnetic radiation when working with video display terminals (VDT), personal electronic computers (PC), which include:

Electromagnetic field strength according to the electrical component at a distance of 50 cm from the surface of the video monitor, V/m;

Electromagnetic field strength along the magnetic component at a distance of 50 cm from the surface of the video monitor, A/m;

Electrostatic field strength, kV/m;

Surface electrostatic potential, V;

Magnetic flux density, nT.

In addition, the above-mentioned regulatory document defines the requirements for the microclimate, the content of air ions, harmful chemicals in indoor air, noise, vibration, and the organization of work and rest regimes when working with VDTs and PCs.

The work and rest schedule is established depending on the type and category of work activity. Types of work activities are divided into three groups:

group A - work on reading information from the screen of a VDT or PC;

group B - work on entering information;

Group B - creative work in dialogue mode with a computer.

Categories of work with VDTs and PCs (I, II, III) are established for groups A and B based on the total number of read or entered characters per work shift, for group B - based on the total time of direct work with VDTs or PCs.

Noise regulation when working with VDTs and PCs is provided in octave frequency bands with geometric mean values ​​of 31.5; 63; 125; 250; 500; 1000; 2000; 4000; 8000.

Permissible values ​​of vibration velocity and vibration acceleration in m/s, m/s 2 and dB are established for geometric mean frequencies of bands 1.6; 2.0; 2.5; 3.15; 4.0; 5.0; 6.3; 8.0; 10.0; 12.5; 16.0; 20.0; 25.0; 31.5; 40.0; 50.0; 63.0; 80.0, as well as in one-third octave frequency bands.

SanPin 2.2.2.542-96 also takes into account ergonomic requirements, such as the height of the table above the floor, the main dimensions of the chair for students.

Protection against electromagnetic fields. All protective measures can be divided into three groups:

Organizational;

Engineering and technical;

Therapeutic and prophylactic.

Organizational measures include the optimal relative position of irradiating objects and service personnel, the development of a work and rest regime in order to reduce to a minimum the time people are exposed to radiation.

The basis of engineering measures is shielding. Screens can be made flat and closed, in the form of shells. The main characteristic of screens is shielding efficiency, i.e. degree of attenuation of the electromagnetic field. It depends on the magnetic permeability of the material, its thickness, resistivity, and the frequency of the electromagnetic field.

Metals (steel, copper, aluminum) are usually used as materials for screens. Screens are made either solid or mesh. In addition to metals, rubber, wood fiber, foam rubber, and radioprotective glass with metal oxide film can be used.

Treatment and preventive measures include:

Preliminary and periodic medical examinations;

Half-holiday;

Additional holidays.

Protective clothing is made of metallized fabric in the form of overalls, gowns, aprons, jackets with hoods with built-in safety glasses.

As preventive measures when working with VDTs and PCs, the following should be provided:

Carrying out eye exercises every 20-25 minutes of work;

Carrying out cross-ventilation of premises during breaks;

Carrying out a physical training break during breaks;

Connecting a timer to VDTs and PCs or centrally turning off information on video monitor screens in order to ensure standardized operating time.

2.5.2. Laser radiation

Laser is an abbreviation consisting of the initial letters of the English phrase: Light Amplification by stimulated Emission of Radiation, which translated means amplification of light by creating stimulated radiation. Lasers are devices based on the principle of stimulated stimulated emission of atoms and molecules. The operation of the laser is based on the amplification of light radiation due to the energy accumulated by atoms and molecules of the laser medium during the pumping process. Pumping is the creation of an excess of atoms in an excited state. Pumping methods can be different: optical, electrical, electronic, chemical.

Laser systems have found wide application in all industries: in mechanical engineering for cutting, welding and strengthening of metals, in instrument making - for processing hard and superhard alloys, in radio electronics - for spot welding, for the production of printed circuits, micro-welding, in the textile industry - for cutting fabrics, in the watch industry - for sewing holes in stones, etc. The use of lasers in medicine is growing: in ophthalmic surgery and neurosurgery. The use of lasers in the field of communications, as light sources, and for monitoring chemical processes opens up great prospects.

General and hygienic characteristics of lasers. The main parameters characterizing laser radiation from a hygienic point of view are: wavelength - l, µm; energy illumination – W u, W/cm 2 ; pulse duration - t n,With; pulse repetition rate – f u, Hz; duration of exposure - t, With.

According to "GOST 12.1.040-83 Laser safety. General provisions" all lasers are divided into 4 classes according to the degree of danger of the generated radiation. Class 1 lasers - their output radiation does not pose a danger to the eyes and skin.

Class 2 lasers - the output radiation is dangerous to the eyes when irradiated with direct or specularly reflected radiation.

Class 3 lasers - their output radiation is dangerous when irradiating the eyes with direct, specularly reflected, and diffusely reflected radiation at a distance of 10 cm from a diffusely reflective surface and when irradiating the skin with direct and specularly reflected radiation.

Class 4 lasers - their output radiation is dangerous when irradiating the skin with diffusely reflected radiation at a distance of 10 cm from a diffusely reflecting surface.

Specularly reflected is laser radiation reflected at an angle equal to the angle of incidence. Diffusely reflected laser radiation is radiation reflected from a surface comparable to the wavelength in all possible directions within a hemisphere.

Depending on the radiation mode, there are two types of lasers: continuous and pulsed.

Based on the active element in which the pump energy is converted into radiation, lasers are distinguished into gas, liquid, semiconductor, and solid-state lasers. According to the method of heat removal, lasers can be naturally cooled, forced air or liquid cooled.

When operating laser systems, the following harmful and dangerous factors may arise:

Laser radiation;

Increased voltage in laser power supplies;

Increased dust and gas contamination of the air in the working area;

Increased levels of ultraviolet radiation;

Increased light brightness;

Increased noise and vibration levels in the workplace;

Increased level of electromagnetic radiation;

Increased level of infrared radiation;

Increased equipment surface temperature;

Explosion hazard in laser pumping systems.

The effect of laser radiation on the human body. The biological effect of laser radiation depends on the radiation power, wavelength, pulse nature, repetition rate, duration of irradiation, size of the irradiated surface and on the anatomical and functional characteristics of the irradiated tissues.

Continuous laser radiation is characterized by a thermal mechanism of action, which results in protein coagulation (clotting) and, at high powers, evaporation of biological tissue.

When exposed to pulsed laser radiation with a pulse duration of less than 10 -2 s, the radiation energy is converted into the energy of mechanical vibrations, in particular, a shock wave.

Irradiation of the abdominal wall with such radiation can lead to damage to the liver, intestines and other abdominal organs, and irradiation of the head can lead to intracellular and intracerebral hemorrhages.

Laser radiation poses a great danger to the eyes and skin. The most vulnerable organ is the eyes. Although the sensitivity of eye tissue differs little from the sensitivity of other tissues, the focusing ability of the optical system of the eye sharply increases the energy density of laser radiation and therefore the eyes, especially the retina, are considered a critical organ in relation to laser radiation. The degree of absorption of laser energy depends on the pigmentation of the fundus of the eye: blue and green eyes are more affected, and brown eyes are less affected. When laser energy enters the eye, it is absorbed by the pigment layer and increases the temperature, causing a burn.

Laser radiation also causes skin damage from redness to superficial charring. The degree of impact is determined both by the laser radiation parameters, skin pigmentation, and the state of blood circulation. Pigmented skin absorbs significantly more laser rays than light skin.

In addition, under the influence of laser radiation, functional disorders in the activity of the central nervous system, cardiovascular system, decreased performance, fatigue, and impaired cerebral circulation are possible.

Hygienic regulation of laser radiation. Maximum permissible levels (MPL) of laser radiation are established in accordance with the requirements of "Sanitary norms and rules for the design and operation of lasers" No. 2392-81. The maximum permissibility of laser radiation for specific exposure conditions is calculated using appropriate formulas taking into account the wavelength l, duration of exposure t, energy exposure N, eye pupil diameter d 3, background illumination of the cornea, as well as a number of correction factors for the pulse repetition frequency, duration of exposure to a series of pulses.

The MPL values ​​calculated for various biological effects are compared with each other and the smallest MPL value is taken as the determining one.

When simultaneously exposed to laser radiation of different parameters, but having similar biological effects, the following condition must be met:

Where N (1,2...)- energy exposures created by various sources of laser radiation; N remote control- Energy exposure remote control for the corresponding radiation source.

Protection from laser radiation. When developing protective measures, they are guided by the hazard class of lasers. All protective measures can be divided into organizational, technical and treatment and prophylactic.

Lasers of hazard classes 3 and 4 should be used only in closed-type installations, in which the area of ​​interaction of laser radiation with the target and the laser beam along its entire length are isolated from workers. The premises where laser installations are operated must meet the requirements of sanitary standards. The walls of the premises should have a matte surface, ensuring maximum radiation scattering. To paint walls, it is recommended to use chalk-based adhesive paints.

Depending on the radiation wavelength, protection methods are chosen:

Reducing the time of contact with radiation;

Increasing the distance to the radiation source;

Attenuation of radiation using light filters.

Glass grades used in laser protection products are selected based on the type of laser and wavelength.

Introduction

It is known that radiation can be harmful to human health and that the nature of the observed effects depends on the type of radiation and the dose. The health effects of radiation depend on the wavelength. The consequences most often referred to when talking about the effects of radiation (radiation damage and various forms of cancer) are caused only by shorter wavelengths. These types of radiation are known as ionizing radiation. In contrast, longer wavelengths - from near ultraviolet (UV) to radio waves and beyond - are called non-ionizing radiation, and their effects on health are completely different. In the modern world, we are surrounded by a huge number of sources of electromagnetic fields and radiation. In hygienic practice, non-ionizing radiation also includes electric and magnetic fields. Radiation will be non-ionizing if it is not capable of breaking the chemical bonds of molecules, that is, it is not capable of forming positively and negatively charged ions.

So, non-ionizing radiation includes: electromagnetic radiation (EMR) of the radio frequency range, constant and alternating magnetic fields (PMF and PeMF), industrial frequency electromagnetic fields (EMF), electrostatic fields (ESF), laser radiation (LR).

Often the effect of non-ionizing radiation is accompanied by other industrial factors that contribute to the development of the disease (noise, high temperature, chemicals, emotional and mental stress, light flashes, visual strain). Since the main carrier of non-ionizing radiation is EMR, most of the abstract is devoted to this type of radiation.

Consequences of radiation on human health

In the vast majority of cases, exposure occurs to fields of relatively low levels; the consequences listed below apply to such cases.

Numerous studies in the field of biological effects of EMF will allow us to determine the most sensitive systems of the human body: nervous, immune, endocrine and reproductive. These body systems are critical. The reactions of these systems must be taken into account when assessing the risk of EMF exposure to the population.

The biological effect of EMF under conditions of long-term exposure accumulates over many years, resulting in the development of long-term consequences, including degenerative processes of the central nervous system, blood cancer (leukemia), brain tumors, and hormonal diseases. EMFs can be especially dangerous for children, pregnant women, people with diseases of the central nervous, hormonal, cardiovascular systems, allergy sufferers, and people with weakened immune systems.

Effect on the nervous system

A large number of studies carried out in Russia, and the monographic generalizations made, give grounds to classify the nervous system as one of the most sensitive systems in the human body to the effects of EMFs. At the level of the nerve cell, structural formations for the transmission of nerve impulses (synapse), at the level of isolated nerve structures, significant deviations occur when exposed to low-intensity EMF. Higher nervous activity and memory change in people who have contact with EMF. These individuals may be prone to developing stress reactions. Certain brain structures have increased sensitivity to EMF. The nervous system of the embryo exhibits particularly high sensitivity to EMF.

Effect on the immune system

Currently, sufficient data have been accumulated indicating the negative impact of EMF on the immunological reactivity of the body. The results of research by Russian scientists give reason to believe that when exposed to EMF, the processes of immunogenesis are disrupted, more often in the direction of their inhibition. It has also been established that in animals irradiated with EMF, the nature of the infectious process changes - the course of the infectious process is aggravated. The influence of high-intensity EMF on the body’s immune system is manifested in a suppressive effect on the T-system of cellular immunity. EMFs can contribute to nonspecific inhibition of immunogenesis, increased formation of antibodies to fetal tissues and stimulation of an autoimmune reaction in the body of a pregnant female.

Effect on the endocrine system and neurohumoral response

In the works of Russian scientists back in the 60s, in the interpretation of the mechanism of functional disorders under the influence of EMF, the leading place was given to changes in the pituitary-adrenal system. Studies have shown that under the influence of EMF, as a rule, stimulation of the pituitary-adrenaline system occurred, which was accompanied by an increase in the content of adrenaline in the blood and activation of blood coagulation processes. It was recognized that one of the systems that is early and naturally involved in the body's response to the influence of various environmental factors is the hypothalamic-pituitary-adrenal cortex system. The research results confirmed this position.

Effect on sexual function

Sexual dysfunction is usually associated with changes in its regulation by the nervous and neuroendocrine systems. Repeated exposure to EMF causes a decrease in the activity of the pituitary gland

Any environmental factor that affects the female body during pregnancy and affects embryonic development is considered teratogenic. Many scientists attribute EMF to this group of factors. It is generally accepted that EMFs can, for example, cause deformities by acting at different stages of pregnancy. Although there are periods of maximum sensitivity to EMF. The most vulnerable periods are usually the early stages of embryo development, corresponding to the periods of implantation and early organogenesis.

An opinion was expressed about the possibility of a specific effect of EMF on the sexual function of women and on the embryo. A higher sensitivity to the effects of EMF of the ovaries than the testes was noted.

It has been established that the sensitivity of the embryo to EMF is much higher than the sensitivity of the maternal body, and intrauterine damage to the fetus by EMF can occur at any stage of its development. The results of epidemiological studies will allow us to conclude that the presence of contact of women with electromagnetic radiation can lead to premature birth, affect the development of the fetus and, finally, increase the risk of developing congenital deformities.

Other medical and biological effects

Since the beginning of the 60s, extensive research has been carried out in the USSR to study the health of people exposed to electromagnetic fields at work. The results of clinical studies have shown that prolonged contact with EMF in the microwave range can lead to the development of diseases, the clinical picture of which is determined, first of all, by changes in the functional state of the nervous and cardiovascular systems. It was proposed to identify an independent disease - radio wave disease. This disease, according to the authors, can have three syndromes as the severity of the disease increases:

asthenic syndrome;

astheno-vegetative syndrome;

hypothalamic syndrome.