How the electromagnetic field affects human health. How to protect yourself from this field. What are the sources of the electromagnetic field. You will find the answer to this by reading this book.
HOW ELECTROMAGNETIC FIELD INFLUENCES HUMAN HEALTH .
Electrosmog is environmental pollution caused by electromagnetic fields of various origins. A person encounters this phenomenon every day - in an apartment, on the street, in transport, in an office, in a country house - i.e. wherever you are. This is the price of modern life. Electrosmog is one of the strongest biologically active factors that can affect a living organism. With the development of technology, it becomes more dangerous than radiation. Electrosmog, unlike pollution from industrial waste, is invisible, but it interacts with the human electromagnetic field and partially suppresses it. As a result of this interaction, a person’s own field is distorted, immunity is reduced, information and cellular exchange are disrupted, which can lead to various diseases.
An electromagnetic wave, like a lace, consists of two cleverly intertwined inseparable “strings” - electric and magnetic. Taking turns, supporting and “encouraging” each other, they do one common thing - create an electromagnetic field. Until relatively recently, it was believed that only the electrical component is capable of causing mischief, encroaching on our health, while the magnetic component in the habitats of ordinary mortals does not pose any threat to their life and health. The electrical “harm” was studied from all sides and driven into a “cage” of strict sanitary standards, recklessly deciding that they were protected from the omnipresent influence of the electromagnetic field. But at the end of the 80s, Americans, Swedes, Finns and Danes, independently of each other, became interested in the health of their fellow citizens living next to power lines. Then it turned out that the second participant - magnetic - was not as simple as it seemed. Cancer rates are high in areas where she is especially zealous. Leukemia is especially common in children. These data refer to the case of not short-term, but rather long-term irradiation.
To experience everything that the electromagnetic field is capable of, you don’t have to sit astride an electric generator or live under power line masts. The consumer electronics with which our apartments are crammed to capacity are quite sufficient. Everything that you plug into a power outlet inevitably rewards you with an electromagnetic field in addition to heat, light or music. It can be small, for example, from an iron. Or a large one - from a microwave oven. One such device, manufactured with high quality, is not dangerous - the impact of the electromagnetic field extends no further than 1.5-2 meters. But when a TV mounted on a refrigerator is adjacent to an electric stove equipped with an extractor hood, and a microwave is flashing its light bulbs next to it, the small kitchen turns out to be oversaturated with electromagnetic fields. Like cards in solitaire, they overlap each other, leaving the owners no chance to find a “quiet corner.”
Only an absolutely healthy person can afford to plunge into such an electromagnetic “bath” several times a day. For a pregnant woman, child or old man, it would be better to turn on the same stove and retreat immediately.
Biological effect of EMF.
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. Electromagnetic fields can be especially dangerous for children, pregnant women (fetuses), 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. 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.
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.
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 when exposed to 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 was noted in the ovaries than in the testes. 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.
As mentioned above, since the beginning of the 60s, extensive research has been carried out in the USSR to study the health of people who have contact with EMFs 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 primarily by changes in the functional state of the nervous and cardiovascular systems.
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. Phase changes in the composition of peripheral blood are also noted with the subsequent development of moderate leukopenia. 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 anxiety. 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 prolonged repeated exposure to maximum permissible EM radiation can lead to mental disorders.
HOW TO PROTECT YOUR BODY FROM ELECTROMAGNETIC FIELD .
The protection of humans from the adverse biological effects of EMFs is based on the following main areas: organizational measures, engineering and technical measures, therapeutic and preventive measures
To organizational events protection against EMF includes: 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 current maximum permissible standards 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.
Engineering and technical protective measures are based on the use of the phenomenon of EMF shielding 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. 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.
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.
In some cases, the walls of buildings 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 the film is applied to both glass surfaces, the attenuation reaches 10,000 times.
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 local objects by radio waves.
How to protect yourself from the influence of the electromagnetic field em.
Today in the world there are many sources of electromagnetic radiation of varying power. There are no unambiguous measures to protect or limit their influence; you can only limit yourself from exposure. Let's consider the main sources, general and specific measures of protection against the harmful effects of EMF.
In cities there is a fairly high level of radiation from electric transport. Special standards and GOSTs have been developed to reduce the harmful effects of radiation on the population. Basically, they all come down to “protection by distance,” that is, the organization of a sanitary zone near sources of EMF, which can be tram and trolleybus lines, and metro or electric train lines.
The same protection measures must be observed near power lines. Depending on the power of the power line, the width of the sanitary zone increases.
The most powerful EMF is created by television and radio broadcasting stations. Sometimes they are located directly in a residential area. In such cases, it is necessary to use all methods of protection. Here, the main principle of ensuring safety is compliance with the maximum permissible levels of the electromagnetic field established by Sanitary Standards and Rules.
MAIN SOURCES OF ELECTROMAGNETIC FIELD :
Electrical wiring inside buildings
Household electrical appliances
Office equipment
Industrial electrical equipment
Power lines
Electric transport
TV stations
Broadcasting stations
Satellite connection
cellular
Radar stations
Radiation intensity is measured in T (Tesla) - a unit of measurement of magnetic induction in the International System of Units. The safe level of radiation for human health is 0.2 μTL.
The most common sources of electromagnetic radiation are:
Wiring . This integral part of the life support of the population makes the greatest contribution to the electromagnetic environment of residential premises. Electrical wiring includes both cable lines supplying electricity to and inside all apartments, as well as distribution boards and transformers. In rooms adjacent to these sources, the level of the magnetic field is usually increased, and the level of the electric field is not high and does not exceed permissible values.
Recommendations for protection. In this case, only preventive protective measures are used, such as: avoiding prolonged stay in places with high levels of industrial frequency magnetic fields;
proper arrangement of furniture for relaxation in a residential area, ensuring a distance of two to three meters to distribution boards and power cables;
when installing electrically heated floors, choose a system that provides a lower level of magnetic field;
If there are unknown cables or electrical cabinets or panels in the room, ensure that the living area is as far away from them as possible.
You should not place beds, chairs, or arrange rest areas near sockets and switches. It is not recommended to use switches that are capable of creating dim light, except in extreme positions (on/off). The principle of their operation is based on a change in the resistance level in the network, which leads to significant disturbances in the background of EM radiation. Avoid being near the head of the bed with passing electrical wires, especially their tangles. Avoid excessive tension or bending of wires. This reduces the cross-sectional area of the material, increases its resistance, and leads to disturbances in the EMF background.
It is necessary to carry out grounding to the grounding loop of the building (you cannot ground to a heating radiator, water pipes, or “zero” sockets). Try to minimize the number of electrical appliances that have power plugs in outlets, even when the appliance is turned off. This measure significantly reduces the density of electrosmog indoors.
Household electrical appliances. Naturally, all devices operating on electric current are sources of electromagnetic fields. The strongest sources of EMF are microwave and electric ovens, kitchen hoods, vacuum cleaners and refrigerators with a “no frost” system. The actual field they emit varies depending on specific models, but it should be noted that the higher the power of the device, the higher the magnetic field it creates. The value of the electric field is much less than the maximum permissible values.
Some TV models reach 2 µT; refrigerators with the “No frost” system exceed the value of 0.2 µT; an electric kettle produces radiation of 0.6 µT; the well-known microwave oven emits 8 µT; the electric stove reaches a value of 1-3 µT; and the most powerful home sources are a vacuum cleaner - 100 µT, an electric razor and a hair dryer can reach a value of 1500 µT. All these values, of course, depend on the specific model of equipment and the distance to it.
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. 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. Considering the specifics of the microwave oven, it is advisable to move away at a distance of at least 1.5 meters after turning it on - in this case, the electromagnetic field is guaranteed not to affect you at all.
Recommendations for protection. When purchasing household appliances, you must pay attention to the mark indicating the device’s compliance with the requirements of the “Interstate Sanitary Standards for Permissible Levels of Physical Factors when Using Consumer Goods in Domestic Conditions.”
use of devices with lower power;
the resting place must be sufficiently removed from household appliances that emit a sufficiently high level of magnetic field, such as “no frost” refrigerators, some types of electrically heated floors, televisions, heaters, power supplies and chargers;
placing electrical appliances at some distance from each other and removing them from the resting place.
Lamps at the head of beds should be connected to sockets located as far as possible from the beds, and the connection must be made with a solid wire. You should not buy any furniture with power supply units - beds with built-in lamps, desks and secretaries with lamps. TV can only be watched at a distance of at least 2 (preferably 3) screen diagonals. Never sit in front of a screen. It's better to sit a little to the side. It is good to place a saucer with table salt in front of the screen. It will absorb moisture from the air near the screen, resulting in the formation of a dry air layer, which will become a good protection against electrons. Just remember to change the salt every two to three days.
A lit candle also helps against harmful radiation, since an area with circulating air is formed above its flame, in which electrons quickly lose speed and energy.
Devices that operate for a long time (refrigerators, TV, microwave ovens, computer equipment, electric heaters, air conditioners, etc.) should be placed at a distance of at least 1.5 m from places of permanent residence or night rest.
Cellular communications . The issue of biological safety of cellular communications is quite relevant. Only one thing can be noted during the entire existence of cellular communications, not a single person has suffered obvious damage to health due to its use. Cellular communications are provided by radio transmitting base stations and mobile radiotelephones of user subscribers. Among the base station antennas installed in one place, there are both transmitting and receiving antennas, which are not sources of EMF. The influence of cell phones on human health has not been revealed, but that the body “responds” to the presence of cell phone radiation. Thus, we can only recommend that numerous cellular users follow some recommendations.
Recommendations for protection. Use a cell phone when necessary; do not talk continuously for more than three to four minutes; do not allow children to use cell phones; choose a phone with a lower maximum radiation power; use a hands-free kit in your car, placing its antenna in the geometric center of the roof.
It is worth paying special attention to the use of chargers for mobile phones - you must disconnect them from the network after use.
One more opinion . When cellular communication operates, its main components - the cell phone and the base station - create an electromagnetic field. Both the cell phone user and the person who does not use a cell phone but lives near cellular facilities are in this electromagnetic field. It cannot be said that the electromagnetic field of a cell phone “passes by” the human body. Anyone who says that is either deliberately misleading the audience or is an amateur. When talking on a cell phone, the electromagnetic field penetrates the human body and is absorbed, first of all, by the tissues of the head - the skin, ear, part of the brain, including the visual analyzer. All experts understand this; moreover, cell phone developers take into account the fact that some of the electromagnetic energy will “get stuck” in the head, and accordingly adjust the technical parameters of the antenna and radiotelephone transmitter. A lot of research is being carried out, but there is still no final verdict from scientists. There are many reasons for this - the complexity of the problem for researchers, the lobbying tasks of industry, the interests of governments of different countries and international organizations, etc. In general, there are enough reasons, but the consumer turns out to be extreme. According to the authoritative American magazine Microwave News, all of us - both cell phone owners and those living in areas covered by cellular networks - are participants in a unique mass experiment in history. The World Health Organization states that the effects of exposure to EMF from cellular communications, both on individuals and on the population as a whole, are not yet clear. Therefore, on the one hand, it is necessary to actively continue research, on the other hand, to adhere to the precautionary principle in ensuring safety. This principle states that if there is even a suspicion of adverse consequences, even if not yet conclusively proven, then every possible effort must be made to avoid these consequences.
There are classic methods of protection: time and distance. It remains extremely important to develop a regulatory framework that would take into account the prognosis of the development of pathology in the user in the long term. It is necessary to strictly limit the use of mobile communications by children and sharply change the focus of related advertising.
Personal computers . The influence of computers clearly affects human health, affecting both the general condition and vision and other organs. The main source of EMF in a personal computer is a cathode ray tube monitor. In comparison, all other PC devices produce minimal radiation, with the possible exception of the uninterruptible power supply. Modern technologies make it possible to abandon the use of cathode ray tube monitors and use liquid crystal monitors, which differ significantly for the better both in technical parameters and in terms of their impact on human health.
Power lines – taking into account the characteristics of this source, the distance to the power line and the time spent in the coverage area of the power line are of great importance.
Electric transport – in a tram the radiation intensity is in the range of 10-40 µT; in a trolleybus it is 20-80 µT; in the train – 20 µT; the highest value is given by the metro - on average 100 µT.
Electricity is all around us
Electromagnetic field (definition from TSB) is a special form of matter through which interaction between electrically charged particles occurs. Based on this definition, it is not clear what is primary - the existence of charged particles or the presence of a field. Perhaps only due to the presence of an electromagnetic field can particles receive a charge. Just like in the story with the chicken and the egg. The bottom line is that charged particles and the electromagnetic field are inseparable from each other and cannot exist without each other. Therefore, the definition does not give you and me the opportunity to understand the essence of the phenomenon of the electromagnetic field and the only thing that should be remembered is that it special form of matter! The electromagnetic field theory was developed by James Maxwell in 1865.
What is an electromagnetic field? One can imagine that we live in an electromagnetic Universe, which is entirely permeated by an electromagnetic field, and various particles and substances, depending on their structure and properties, under the influence of an electromagnetic field acquire a positive or negative charge, accumulate it, or remain electrically neutral. Accordingly, electromagnetic fields can be divided into two types: static, that is, emitted by charged bodies (particles) and integral to them, and dynamic, propagating in space, being separated from the source that emitted it. A dynamic electromagnetic field in physics is represented in the form of two mutually perpendicular waves: electric (E) and magnetic (H).
The fact that the electric field is generated by an alternating magnetic field, and the magnetic field by an alternating electric field, leads to the fact that electric and magnetic alternating fields do not exist separately from each other. The electromagnetic field of stationary or uniformly moving charged particles is directly related to the particles themselves. With the accelerated movement of these charged particles, the electromagnetic field “breaks away” from them and exists independently in the form of electromagnetic waves, without disappearing when the source is removed.
Sources of electromagnetic fields
Natural (natural) sources of electromagnetic fields
Natural (natural) sources of EMF are divided into the following groups:
Earth's magnetic field. The magnitude of the Earth's geomagnetic field varies across the earth's surface from 35 μT at the equator to 65 μT near the poles.
Earth's electric field directed normally to the earth's surface, which is negatively charged relative to the upper layers of the atmosphere. The electric field strength at the Earth's surface is 120...130 V/m and decreases approximately exponentially with height. Annual changes in EF are similar in nature throughout the Earth: maximum intensity is 150...250 V/m in January-February and minimum 100...120 V/m in June-July.
Atmospheric electricity- These are electrical phenomena in the earth's atmosphere. The air (link) always contains positive and negative electrical charges - ions that arise under the influence of radioactive substances, cosmic rays and ultraviolet radiation from the Sun. The globe is negatively charged; There is a large potential difference between it and the atmosphere. The electrostatic field strength increases sharply during thunderstorms. The frequency range of atmospheric discharges lies between 100 Hz and 30 MHz.
Extraterrestrial sources include radiation outside the Earth's atmosphere.
Biological electromagnetic background. Biological objects, like other physical bodies, at temperatures above absolute zero emit EMF in the range of 10 kHz - 100 GHz. This is explained by the chaotic movement of charges - ions, in the human body. The power density of such radiation in humans is 10 mW/cm2, which for an adult gives a total power of 100 W. The human body also emits EMF at 300 GHz with a power density of about 0.003 W/m2.
Anthropogenic sources of electromagnetic fields
Anthropogenic sources are divided into 2 groups:
Sources of low-frequency radiation (0 - 3 kHz)
This group includes all systems for the production, transmission and distribution of electricity (power lines, transformer substations, power plants, various cable systems), home and office electrical and electronic equipment, including PC monitors, electric vehicles, railway transport and its infrastructure, as well as metro, trolleybus and tram transport.
Already today, the electromagnetic field on 18-32% of urban areas is formed as a result of automobile traffic. Electromagnetic waves generated by vehicle traffic interfere with television and radio reception and can also have harmful effects on the human body.
Sources of high-frequency radiation (from 3 kHz to 300 GHz)
This group includes functional transmitters - sources of electromagnetic fields for the purpose of transmitting or receiving information. These are commercial transmitters (radio, television), radiotelephones (car, radiotelephones, CB radio, amateur radio transmitters, industrial radiotelephones), directional radio communications (satellite radio communications, ground relay stations), navigation (air traffic, shipping, radio point), locators (air communication, shipping, transport locators, air transport control). This also includes various technological equipment using microwave radiation, alternating (50 Hz - 1 MHz) and pulsed fields, household equipment (microwave ovens), means of visually displaying information on cathode ray tubes (PC monitors, TVs, etc.) . Ultra-high frequency currents are used for scientific research in medicine. The electromagnetic fields that arise when using such currents pose a certain occupational hazard, so it is necessary to take measures to protect against their effects on the body.
The main technogenic sources are:
A peculiarity of exposure in urban conditions is the impact on the population of both the total electromagnetic background (integral parameter) and strong EMF from individual sources (differential parameter).
1. What is EMF, its types and classification
2. Main sources of EMF
2.1 Electric transport
2.2 Power lines
2.3 Electrical wiring
2.4 Household electrical appliances
2.5 TV and radio stations
2.6 Satellite communications
2.7 Cellular
2.8 Radars
2.9 Personal computers
3. How does EMF affect health?
4. How to protect yourself from EMF
What is EMF, its types and classification
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.
By definition, an electromagnetic field is a special form of matter through which interaction occurs between electrically charged particles. 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 away” from 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, symbol - l (lambda). A source that generates radiation, and essentially creates electromagnetic oscillations, is characterized by frequency, designated f.
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 3l. 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 there is a connection 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 Russia, at frequencies above 300 MHz, the electromagnetic energy flux density (PEF), or the Poynting vector, is usually measured. 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.
International classification of electromagnetic waves by frequency
| Frequency range name | Range limits | Name of wave range | Range limits |
| Extreme low, ELF | 3 - 30 Hz | Decamegameter | 100 - 10 mm |
| Ultra-low, SLF | 30 – 300 Hz | Megameter | 10 - 1 mm |
| Infra-low, INF | 0.3 - 3 kHz | Hectokilometer | 1000 - 100 km |
| Very low, VLF | 3 - 30 kHz | Myriameter | 100 - 10 km |
| Low frequencies, LF | 30 - 300 kHz | Kilometer | 10 - 1 km |
| Mids, mids | 0.3 - 3 MHz | Hectometric | 1 - 0.1 km |
| Treble, 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 |
| Hyperhigh, HHF | 300 – 3000 GHz | decimmillimeter | 1 - 0.1 mm |
2. Main sources of EMF
Among the main sources of EMR are:- Electric transport (trams, trolleybuses, trains,...)
- Power lines (city lighting, high voltage,...)
- Electrical wiring (inside buildings, telecommunications,…)
- Household electrical appliances
- TV and radio stations (broadcasting antennas)
- Satellite and cellular communications (broadcast antennas)
- Radars
- Personal computers
2.1 Electric transport
Electric vehicles - electric trains (including subway trains), trolleybuses, trams, etc. - are a relatively powerful source of magnetic field in the frequency range from 0 to 1000 Hz. According to (Stenzel et al., 1996), the maximum values of the magnetic induction flux density B in commuter trains reach 75 μT with an average value of 20 μT. The average value of V for vehicles with a DC electric drive was recorded at 29 µT. A typical result of long-term measurements of the levels of the magnetic field generated by railway transport at a distance of 12 m from the track is shown in the figure.
2.2 Power lines
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.
Biological action
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.
Sanitary standards
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 Norms 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.
Principles for ensuring public safety
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
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.
How to determine the voltage class of power lines? It is best to contact your local energy company, but you can try visually, although this is difficult for a non-specialist:
330 kV - 2 wires, 500 kV - 3 wires, 750 kV - 4 wires. Below 330 kV, one wire per phase, can only be determined approximately by the number of insulators in the garland: 220 kV 10 -15 pcs., 110 kV 6-8 pcs., 35 kV 3-5 pcs., 10 kV and below - 1 pc. .
Permissible levels of exposure to the electric field of power lines
| 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 of 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, even if 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.
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.
2.3 Electrical wiring
The greatest contribution to the electromagnetic environment of residential premises in the industrial frequency range of 50 Hz comes from the electrical equipment of the building, namely the cable lines supplying electricity to all apartments and other consumers of the building’s life support system, as well as distribution boards and transformers. In rooms adjacent to these sources, the level of the industrial frequency magnetic field, caused by the flowing electric current, is usually increased. The level of the electric field at industrial frequency is usually not high and does not exceed the maximum permissible limit for the population of 500 V/m.
The figure shows the distribution of the magnetic field of industrial frequency in a residential area. The source of the field is a power distribution point located in an adjacent non-residential building. At present, the results of the studies performed cannot clearly justify the limit values or other mandatory restrictions for long-term exposure of the population to low-frequency magnetic fields at low levels.
Researchers from Carnegie University in Pittsburgh (USA) have formulated an approach to the problem of the magnetic field which they call “prudent prevention”. They believe that while our knowledge regarding the relationship between health and the consequences of radiation exposure remains incomplete, but there are strong suspicions about the health consequences, it is necessary to take steps to ensure safety that do not incur heavy costs or other inconveniences.
A similar approach was used, for example, in the initial stage of work on the problem of the biological effects of ionizing radiation: suspicion of risks of damage to health, based on solid scientific grounds, should in itself constitute sufficient grounds for taking protective measures.
Currently, many experts consider the maximum permissible value of magnetic induction to be 0.2 - 0.3 µT. It is believed that the development of diseases - primarily leukemia - is very likely with prolonged exposure of a person to fields of higher levels (several hours a day, especially at night, for a period of more than a year).
The main protective measure is precautionary.
- it is necessary to avoid prolonged stay (regularly for several hours a day) in places with an increased level of industrial frequency magnetic field;
- the bed for night rest should be kept as far as possible from sources of prolonged exposure; the distance to distribution cabinets and power cables should be 2.5 - 3 meters;
- if there are any unknown cables, distribution cabinets, transformer substations in or adjacent to the room, removal should be as much as possible; optimally, measure the level of electromagnetic fields before living in such a room;
- If it is necessary to install electrically heated floors, choose systems with a reduced level of magnetic field.
2.4 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.
Power frequency magnetic field levels of household electrical appliances at a distance of 0.3 m.
Maximum permissible electromagnetic field levels for consumer products that are sources of EMF
| Source | Range | Remote control value | Note |
| Induction furnaces | 20 - 22 kHz | 500 V/m 4 A/m |
Measurement conditions: distance 0.3 m from the body |
| Microwave ovens | 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 |
| PC video display terminal | 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/mV pdu = 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.
- 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 an apartment, be guided by the following principles: place household electrical appliances as far as possible from rest areas, do not place household electrical appliances close together and do not stack them on top of each other.
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.
Considering the specifics of the microwave oven, it is advisable to move away at a distance of at least 1.5 meters after turning it on - in this case, the electromagnetic field is guaranteed not to affect you at all.
2.5 TV and radio stations
A significant number of transmitting radio centers of various affiliations are currently located on the territory of Russia. Transmitting radio centers (RTC) are located in specially designated areas and can occupy fairly large areas (up to 1000 hectares). In their structure, they include one or more technical buildings where radio transmitters are located, and antenna fields on which up to several dozen antenna-feeder systems (AFS) are located. The AFS includes an antenna used to measure radio waves and a feed line that supplies high-frequency energy generated by the transmitter to it.
The zone of possible adverse effects of EMFs created by the PRC can be divided into two parts.
The first part of the zone is the PRC territory itself, where all the services that ensure the operation of radio transmitters and AFS are located. This territory is guarded and only persons professionally associated with the maintenance of transmitters, switches and AFS are allowed into it. The second part of the zone is the territories adjacent to the PRC, access to which is not limited and where various residential buildings can be located, in this case there is a threat of exposure to the population located in this part of the zone.
The location of the RRC can be different, for example, in Moscow and the Moscow region it is typically located in close proximity or among residential buildings.
High levels of EMF are observed in areas, and often outside the location of transmitting radio centers of low, medium and high frequencies (PRC LF, MF and HF). A detailed analysis of the electromagnetic situation in the territories of the PRC indicates its extreme complexity associated with the individual nature of the intensity and distribution of EMF for each radio center. In this regard, special studies of this kind are carried out for each individual PRC.
Widespread sources of EMF in populated areas are currently radio engineering transmitting centers (RTTCs), emitting ultrashort VHF and UHF waves into the environment.
A comparative analysis of sanitary protection zones (SPZ) and restricted development zones in the coverage area of such facilities showed that the highest levels of exposure to people and the environment are observed in the area where the “old-built” RTPC is located with an antenna support height of no more than 180 m. The largest contribution to the total The intensity of the impact is contributed by the “corner” three- and six-story VHF FM broadcasting antennas.
DV radio stations(frequencies 30 - 300 kHz). In this range, the wavelengths are relatively long (for example, 2000 m for a frequency of 150 kHz). At a distance of one wavelength or less from the antenna, the field can be quite large, for example, at a distance of 30 m from the antenna of a 500 kW transmitter operating at a frequency of 145 kHz, the electric field can be above 630 V/m and the magnetic field above 1. 2 A/m.
CB radio stations(frequencies 300 kHz - 3 MHz). Data for radio stations of this type say that the electric field strength at a distance of 200 m can reach 10 V/m, at a distance of 100 m - 25 V/m, at a distance of 30 m - 275 V/m (data are given for a 50 kW transmitter) .
HF radio stations(frequencies 3 - 30 MHz). HF radio transmitters usually have lower power. However, they are more often located in cities, and can even be placed on the roofs of residential buildings at a height of 10-100 m. A 100 kW transmitter at a distance of 100 m can create an electric field strength of 44 V/m and a magnetic field of 0.12 F/m.
TV transmitters. Television transmitters are usually located in cities. Transmitting antennas are usually located at altitudes above 110 m. From the point of view of assessing the impact on health, field levels at distances from several tens of meters to several kilometers are of interest. Typical electric field strengths can reach 15 V/m at a distance of 1 km from a 1 MW transmitter. In Russia, at present, the problem of assessing the level of EMF of television transmitters is especially relevant due to the sharp increase in the number of television channels and transmitting stations.
The main principle of ensuring safety is compliance with the maximum permissible levels of the electromagnetic field established by Sanitary norms and rules. Each radio transmitting facility has a Sanitary Passport, which defines the boundaries of the sanitary protection zone. Only with this document do the territorial bodies of the State Sanitary and Epidemiological Supervision permit the operation of radio transmitting facilities. They periodically monitor the electromagnetic environment to ensure it complies with the established remote controls.
2.6 Satellite communications
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.
2.7 Cellular
Cellular radiotelephony is one of the most rapidly developing telecommunication systems today. Currently, around the world there are more than 85 million subscribers using the services of this type of mobile (mobile) communications (in Russia - more than 600 thousand). It is expected that by 2001 their number will increase to 200–210 million (in Russia - about 1 million).
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
Base stations maintain communication with mobile radiotelephones located in their coverage area and operate in signal reception and transmission modes. Depending on the standard, BS emit electromagnetic energy in the frequency range from 463 to 1880 MHz. BS antennas are installed at a height of 15–100 meters from the surface of the earth on existing buildings (public, service, industrial and residential buildings, chimneys of industrial enterprises, etc.) or on specially constructed masts. Among the BS antennas installed in one place, there are both transmitting (or transceiver) and receiving antennas, which are not sources of EMF.
Based on the technological requirements for building a cellular communication system, the antenna radiation pattern in the vertical plane is designed in such a way that the main radiation energy (more than 90%) is concentrated in a rather narrow “beam”. It is always directed away from the structures on which the BS antennas are located, and above adjacent buildings, which is a necessary condition for the normal functioning of the system.
Brief technical characteristics of cellular radio communication system standards operating in Russia
Name of the standard Operating frequency range of BS Operating frequency range of MRI Maximum radiated power of BS Maximum radiated power of MRI Cell radius
NMT-450 Analog 463 – 467.5 MHz 453 – 457.5 MHz 100 W 1 W 1 – 40 km
AMPS Analog 869 – 894 MHz 824 – 849 MHz 100 W 0.6 W 2 – 20 km
D-AMPS (IS-136) Digital 869 – 894 MHz 824 – 849 MHz 50 W 0.2 W 0.5 – 20 km
CDMADigital 869 – 894 MHz 824 – 849 MHz 100 W 0.6 W 2 – 40 km
GSM-900Digital 925 – 965 MHz 890 – 915 MHz 40 W 0.25 W 0.5 – 35 km
GSM-1800 (DCS) Digital 1805 – 1880 MHz 1710 – 1785 MHz 20 W 0.125 W 0.5 – 35 km
BS are a type of transmitting radio engineering objects, the radiation power of which (load) is not constant 24 hours a day. The load is determined by the presence of cell phone owners in the service area of a particular base station and their desire to use the phone for a conversation, which, in turn, fundamentally depends on the time of day, location of the BS, day of the week, etc. At night, the load of the BS is almost zero , i.e. the stations are mostly “silent”.
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.
Research into the possible influence of the biological effect of the electromagnetic field of elements of cellular communication systems is of great interest to the public. Publications in the media fairly accurately reflect current trends in these studies. GSM mobile phones: Swiss tests have shown that the radiation absorbed by the human head is within the limits permitted by European standards. Specialists from the Center for Electromagnetic Safety conducted medical and biological experiments to study the influence of electromagnetic radiation from mobile phones of existing and future cellular communication standards on the physiological and hormonal state of a person.
When a mobile phone is operating, electromagnetic radiation is perceived not only by the base station receiver, but also by the user’s body, and primarily by his head. What happens in the human body, and how dangerous is this effect to health? There is still no clear answer to this question. However, an experiment by Russian scientists showed that the human brain not only senses cell phone radiation, but also distinguishes between cellular communication standards.
The head of the research project, Doctor of Medical Sciences Yuri Grigoriev, believes that cell phones of the NMT-450 and GSM-900 standards caused reliable and noteworthy changes in the bioelectrical activity of the brain. However, a single 30-minute exposure to the electromagnetic field of a mobile phone does not have clinically significant consequences for the human body. The lack of reliable measurements in the electroencephalogram in the case of using a GSM-1800 standard telephone can characterize it as the most “friendly” for the user of the three communication systems used in the experiment.
2.8 Radars
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. Thus, 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.
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.
2.9 Personal computers
The main source of adverse effects on the health of a computer user is the means of visual display of information on a cathode ray tube. The main factors of its adverse effects are listed below.
Ergonomic parameters of the monitor screen
- reduced image contrast in conditions of intense external illumination
- specular reflections from the front surface of monitor screens
- flickering of the image on the monitor screen
- 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 main components of a personal computer (PC) are: a system unit (processor) and various input/output devices: keyboard, disk drives, printer, scanner, etc. Each personal computer includes a means of visual display of information called differently - monitor, display. As a rule, it is based on a device based on a cathode ray tube. PCs are often equipped with surge protectors (for example, "Pilot" type), uninterruptible power supplies and other auxiliary electrical equipment. All these elements during PC operation form a complex electromagnetic environment at the user’s workplace (see Table 1).
PC as a source of EMF
Source Frequency range(first harmonic)
Monitor network transformer power supply 50 Hz
static voltage converter in switching power supply 20 - 100 kHz
frame scanning and synchronization unit 48 - 160 Hz
line scanning and synchronization unit 15 110 kHz
monitor anode accelerating voltage (only for CRT monitors) 0 Hz (electrostatic)
System unit (processor) 50 Hz - 1000 MHz
Information input/output devices 0 Hz, 50 Hz
Uninterruptible power supplies 50 Hz, 20 - 100 kHz
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.
Maximum EMF values recorded at the workplace
Field type, frequency range, field strength unit Field strength value along the screen axis around the monitor
Electric field, 100 kHz - 300 MHz, V/m 17.0 24.0
Electric field, 0.02-2 kHz, V/m 150.0 155.0
Electric field, 2-400 kHz V/m 14.0 16.0
Magnetic field, 100 kHz - 300 MHz, mA/m nhp nhp
Magnetic field, 0.02-2 kHz, mA/m 550.0 600.0
Magnetic field, 2-400 kHz, mA/m 35.0 35.0
Electrostatic field, kV/m 22.0 -
Range of electromagnetic field values measured at PC user workplaces
Name of measured parameters Frequency range 5 Hz - 2 kHz Frequency range 2 - 400 kHz
Alternating electric field strength, (V/m) 1.0 - 35.0 0.1 - 1.1
Alternating magnetic field induction, (nT) 6.0 - 770.0 1.0 - 32.0
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.
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.
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.
Influence of air ion composition. The areas that perceive air ions in the human body are the respiratory tract and skin. There is no consensus regarding the mechanism of influence of air ions on human health.
Effect on vision. The visual fatigue of the VDT user includes a whole range of symptoms: the appearance of a “veil” before the eyes, the eyes become tired, become painful, headaches appear, sleep is disturbed, and the psychophysical state of the body changes. It should be noted that vision complaints can be associated both with the above-mentioned VDT factors and with lighting conditions, the operator’s state of vision, etc. Long-term statistical load syndrome (LTSS). Display users develop muscle weakness and changes in the shape of the spine. In the USA, it is recognized that DSHF is the occupational disease with the highest rate of spread in 1990-1991. In a forced working position, with static muscle load, the muscles of the legs, shoulders, neck and arms remain in a state of contraction for a long time. Since the muscles do not relax, their blood supply deteriorates; Metabolism is disrupted, biodegradation products and, in particular, lactic acid accumulate. In 29 women with prolonged static load syndrome, a biopsy of muscle tissue was taken, in which a sharp deviation of biochemical parameters from the norm was discovered.
Stress. Display users are often under stress. According to the US National Institute for Occupational Safety and Health (1990), VDT users are more susceptible to developing stress conditions than other occupational groups, including air traffic controllers. At the same time, for most users, working on VDTs is accompanied by significant mental stress. It has been shown that sources of stress can be: type of activity, characteristic features of the computer, software used, work organization, social aspects. Working on a VDT has specific stress factors, such as the delay time of the computer’s response (reaction) when executing human commands, “learnability of control commands” (ease of memorization, similarity, ease of use, etc.), method of information visualization, etc. Being in a state of stress can lead to changes in a person's mood, increased aggressiveness, depression, and irritability. Cases of psychosomatic disorders, gastrointestinal dysfunction, sleep disturbances, changes in heart rate, and menstrual cycle have been recorded. A person's exposure to long-term stress factors can lead to the development of cardiovascular diseases.
Complaints from personal computer users and possible reasons for their origin.
Subjective complaints Possible causes
pain in the eyes visual ergonomic parameters of the monitor, lighting in the workplace and indoors
headache aeroion composition of air in the work area, operating mode
increased nervousness, electromagnetic field, color scheme of the room, operating mode
increased fatigue electromagnetic field, operating mode
memory disorder electromagnetic field, operating mode
sleep disturbance operating mode, electromagnetic field
hair loss electrostatic fields, operating mode
acne and skin redness, electrostatic field, aeroionic and dust composition of air in the work area
abdominal pain, improper sitting caused by improper workplace design
lower back pain, incorrect seating of the user caused by the design of the workplace, operating mode
pain in the wrists and fingers; incorrect configuration of the workplace, including the height of the table does not correspond to the height and height of the chair; uncomfortable keyboard; operating mode
The Swedish TCO92/95/98 and MPR II are widely known as technical safety standards for monitors. These documents define the requirements for a personal computer monitor based on parameters that can affect the user’s health. TCO 95 imposes the most stringent requirements on the monitor. It limits the parameters of the monitor’s radiation, power consumption, and visual parameters, so that it makes the monitor the most loyal to the user’s health. In terms of emission parameters, TCO 92 also corresponds to it. The standard was developed by the Swedish Trade Union Confederation.
The MPR II standard is less stringent, setting electromagnetic field limits approximately 2.5 times higher. Developed by the Radiation Protection Institute (Sweden) and a number of organizations, including the largest monitor manufacturers. In terms of electromagnetic fields, the MPR II standard corresponds to the Russian sanitary standards SanPiN 2.2.2.542-96 “Hygienic requirements for video display terminals, personal electronic computers and organization of work.” Means to protect users from EMF
The main types of protective equipment offered are protective filters for monitor screens. They are used to limit the user's exposure to harmful factors from the monitor screen, improve the ergonomic parameters of the monitor screen and reduce the monitor radiation towards the user.
3. How does EMF affect health?
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).
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. 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. In accordance with 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 primarily 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 prolonged repeated exposure to maximum permissible EM radiation (especially in the decimeter wavelength range) can lead to mental disorders.
4. How to protect yourself from EMF
Organizational measures for protection from EMF Organizational measures for protection from 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 zones 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. 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. 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.
Common terms and abbreviations
A/m ampere per meter – unit of measurement of magnetic field strength
BS Base station of a cellular radio communication system
V/m volt per meter – unit of measurement of electric field strength
VDT video display terminal
TPL temporary permissible level
WHO World Health Organization
W/m2 watt per square meter - a unit of energy flux density
GOST State Standard
Hz hertz – unit of measurement of frequency
power transmission line
MHz megahertz – a unit multiple of Hz, equal to 1000000 Hz
MHF microwaves
µT microtesla – a unit multiple of T, equal to 0.000001 T
MP magnetic field
MP IF power frequency magnetic field
NEMI non-ionizing electromagnetic radiation
PDU maximum permissible level
PC personal computer
PMF alternating magnetic field
PPE energy flux density
PRTO transmitting radio engineering object
IF industrial frequency, in Russia it is 50 Hz
PC personal electronic computer
Radar radar station
RTPC radio technical transmitting center
Tesla tesla – unit of measurement of magnetic induction, flux density of magnetic induction
EMF electromagnetic field
EP electric field
The abstract is based on materials from the Center for Electromagnetic Safety
In the process of evolution and life activity, a person is influenced by the natural electromagnetic background, the characteristics of which are used as a source of information that ensures continuous interaction with changing environmental conditions.
However, due to scientific and technological progress, the electromagnetic background of the Earth has now not only increased, but also undergone qualitative changes. Electromagnetic radiation has appeared at wavelengths that are of artificial origin as a result of man-made activities (for example, the millimeter wavelength range, etc.).
The spectral intensity of some man-made sources of electromagnetic field (EMF) may differ significantly from the evolutionarily developed natural electromagnetic background to which humans and other living organisms of the biosphere are accustomed.
Sources of electromagnetic fields
The main sources of EMF of anthropogenic origin include television and radar stations, powerful radio engineering facilities, industrial technological equipment, high-voltage power lines of industrial frequency, thermal shops, plasma, laser and X-ray installations, atomic and nuclear reactors, etc. It should be noted that there are man-made sources of electromagnetic and other physical fields for special purposes, used in electronic countermeasures and placed on stationary and mobile objects on land, water, under water, and in the air.
Any technical device that uses or produces electrical energy is a source of EMFs emitted into external space. A peculiarity of exposure in urban conditions is the impact on the population of both the total electromagnetic background (integral parameter) and strong EMF from individual sources (differential parameter).
The main sources of electromagnetic fields (EMF) of radio frequencies are radio engineering facilities (RTO), television and radar stations (RLS), thermal shops and areas in areas adjacent to enterprises. Exposure to industrial frequency EMF is associated with high-voltage power lines (OHLs), sources of constant magnetic fields used in industrial enterprises. 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.
Spectrum of electromagnetic radiation from the technosphere
An electromagnetic field is a special form of matter through which interaction between electrically charged particles occurs. An electromagnetic field in a vacuum is characterized by the vectors of electric field strength E and magnetic field induction B, which determine the forces acting on stationary and moving charges. In the SI system of units, the dimension of electric field strength [E] = V/m - volt per meter and the dimension of magnetic field induction [V] = T - tesla. The sources of electromagnetic fields are charges and currents, i.e. moving charges. The SI unit of charge is called the coulomb (C), and the unit of current is the ampere (A).
The forces of interaction of the electric field with charges and currents are determined by the following formulas:
F e = qE; F m = , (5.9)
where F e is the force acting on the charge from the electric field, N; q is the amount of charge, C; F M - force acting on the current from the magnetic field, N; j is the current density vector, indicating the direction of the current and equal in absolute value to A/m 2 .
The straight brackets in the second formula (5.9) denote the vector product of vectors j and B and form a new vector, the modulus of which is equal to the product of the moduli of vectors j and B multiplied by the sine of the angle between them, and the direction is determined by the right “gimlet” rule, i.e. . when rotating vector j to vector B along the shortest distance, vector . (5.10)
The first term corresponds to the force exerted by an electric field of intensity E, and the second to the magnetic force in a field with induction B.
The electric force acts in the direction of the electric field strength, and the magnetic force is perpendicular to both the speed of the charge and the magnetic field induction vector, and its direction is determined by the right-hand screw rule.
EMFs from individual sources can be classified according to several criteria, the most common of which is frequency. Non-ionizing electromagnetic radiation occupies a fairly wide frequency range from the ultra-low frequency (ULF) range of 0...30 Hz to the ultraviolet (UV) region, i.e. up to frequencies 3 1015 Hz.
The spectrum of man-made electromagnetic radiation extends from ultra-long waves (several thousand meters or more) to short-wave γ-radiation (with a wavelength of less than 10-12 cm).
It is known that radio waves, light, infrared and ultraviolet radiation, x-rays and γ-radiation are all waves of the same electromagnetic nature, differing in wavelength (Table 5.4).
Subbands 1...4 refer to industrial frequencies, subbands 5...11 - to radio waves. The microwave range includes waves with frequencies of 3...30 GHz. However, historically, the microwave range is understood as wave oscillations with a length of 1 m to 1 mm.
Table 5.4. Electromagnetic wave scale
|
Wavelength λ |
Wave subbands |
Oscillation frequency v |
Range |
|
No. 1...4. Ultra long waves |
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No. 5. Kilometer waves (LF - low frequencies) |
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No. 6. Hectometric waves (MF - middle frequencies) |
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Radio waves |
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No. 8. Meter waves (VHF - very high frequencies) |
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No. 9. Decimeter waves (UHF - ultra high frequencies) |
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No. 10. Centimeter waves (microwave - ultra high frequencies) |
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|
No. 11. Millimeter waves (millimeter wave) |
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|
0.1 mm (100 µm) |
Submillimeter waves |
||
|
Infrared radiation (IR range) |
4.3 10 14 Hz |
Optic range |
|
|
Visible range |
7.5 10 14 Hz |
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|
Ultraviolet radiation (UV range) |
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|
X-ray range |
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γ-Radiation |
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|
Cosmic rays |
The optical range in radiophysics, optics, and quantum electronics refers to the range of wavelengths from approximately submillimeter to far ultraviolet radiation. The visible range includes vibrations of waves with lengths from 0.76 to 0.38 microns.
The visible range is a small part of the optical range. The boundaries of the transitions of UV radiation, X-ray, and γ-radiation are not exactly fixed, but approximately correspond to those indicated in the table. 5.4 values of λ and v. Gamma radiation, which has significant penetrating power, transforms into radiation of very high energies, called cosmic rays.
In table Table 5.5 shows some man-made sources of EMF operating in various ranges of the electromagnetic spectrum.
Table 5.5. Technogenic sources of EMF
|
Name |
Frequency range (wavelengths) |
|
Radio engineering objects |
30 kHz...30 MHz |
|
Radio transmitting stations |
30 kHz...300 MHz |
|
Radar and radio navigation stations |
Microwave range (300 MHz - 300 GHz) |
|
TV stations |
30 MHz...3 GHz |
|
Plasma installations |
Visible, IR, UV ranges |
|
Thermal installations |
Visible, IR range |
|
High voltage power lines |
Industrial frequencies, static electricity |
|
X-ray installations |
Hard UV, X-ray, visible light |
|
Optical range |
|
|
Microwave range |
|
|
Process installations |
HF, microwave, IR, UV, visible, X-ray ranges |
|
Nuclear reactors |
X-ray and γ-radiation, IR, visible, etc. |
|
Special-purpose EMF sources (ground, water, underwater, air) used in electronic countermeasures |
Radio waves, optical range, acoustic waves (combination of action) |