The main sources of the electromagnetic field

Among the main sources of EMF can be listed:

Electric transport (trams, trolleybuses, trains, …);

Power lines (city lighting, high voltage, …);

Wiring (inside buildings, telecommunications, …);

Household electrical appliances;

TV and radio stations (transmitting antennas);

Satellite and cellular communications (transmitting antennas);

Personal computers.

Electric transport. Electric transport - electric trains, trolleybuses, trams, etc. – is a relatively powerful source of magnetic field in the frequency range 0 ÷ 1000 Hz. Maximum values ​​of flux density of magnetic induction V in commuter trains they reach 75 µT with an average value of 20 µT. Mean V in transport with a DC electric drive, it was fixed at the level of 29 μT.

Power lines(power line). The wires of a working power transmission line create an electrical and magnetic field industrial frequency. The distance over which these fields propagate from the wires of the line reaches tens of meters. The range of propagation of the electric field depends on the voltage class of the transmission line (the number indicating the voltage class is in the name of the transmission line - for example, a 220 kV transmission line), the higher the voltage, the larger the zone advanced level electric field, while the dimensions of the zone do not change during the operation of the power transmission line. The range of propagation of the magnetic field depends on the magnitude of the flowing current or on the load of the line. Since the load of the power transmission line can change several times both during the day and with the change of the seasons of the year, the size of the zone of an increased level of the magnetic field also changes.

Biological action. Electric and magnetic fields are very strong factors influencing the state of all biological objects that fall into the zone of their influence. For example, in the area of ​​action of the electric field of power lines, insects show changes in behavior: thus, increased aggressiveness, anxiety, decreased efficiency and productivity, and a tendency to lose queens are recorded in bees; in beetles, mosquitoes, butterflies and other flying insects, a change in behavioral responses is observed, including a change in the direction of movement to the side with a lower field level. Anomalies of development are common in plants - the shapes and sizes of flowers, leaves, stems change, 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.

V last years among the long-term consequences are often called oncological diseases.

Sanitary standards, despite the fact that the magnetic field around the world is now considered the most dangerous to health, the maximum permissible value of the magnetic field for the population is not standardized. Most of the power lines were built without taking into account this danger. Based on mass epidemiological surveys of the population living in conditions of exposure to magnetic fields of power lines as a safe or “normal” level for conditions of prolonged exposure that does not lead to oncological diseases, independently of each other by Swedish and American specialists the value of the flux density of magnetic induction is 0.2 ÷ 0.3 μT. The basic principle of protecting public health from the electromagnetic field of power lines is to establish sanitary protection zones for power lines and reduce the electric field strength in residential buildings and in places where people can stay for a long time by using protective screens, the boundaries of sanitary protection zones for power lines of which are on existing lines determined by the criterion of electric field strength - 1 kV / m (tables 1.2 ÷ 1.4).

Table 1.2. Borders of sanitary protection zones for power lines

Table 1.4. Maximum permissible levels of exposure to the electric field of power lines

Continuation of table 1.4

The placement of high-voltage lines (VL) of ultra-high voltages (750 and 1150 kV) is subject to additional requirements for the conditions of exposure to an electric field on the population. So, the nearest distance from the axis of the designed 750 and 1150 kV overhead lines to the boundaries of settlements 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 the local power company, but you can try visually, although it is difficult for a non-specialist: 330 kV - two wires, 500 kV - three wires, 750 kV - four 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.

Maximum Permissible Levels (MPL). Within the sanitary protection zone of the overhead line, it is prohibited:

Locate residential and public buildings and structures;

Arrange areas for parking and stopping all types of transport;

Locate car maintenance enterprises and warehouses for oil and oil products;

Perform operations with fuel, repair machines and mechanisms.

Territories of sanitary protection zones are allowed to be used as agricultural land, but it is recommended to grow crops on them that do not require manual labor. In the event that in some areas the electric field strength outside the sanitary protection zone turns out to be higher than the maximum allowable 0.5 kV / m inside the building and above 1 kV / m on the territory of the residential development zone (in places where people can stay), they must steps 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 at least at two points. In buildings with metal roof it is enough to ground the roof at least at two points. In household plots or other places where people stay, 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 two meters high.

Wiring. The greatest contribution to the electromagnetic environment of residential premises in the industrial frequency range of 50 Hz is made by the electrical equipment of the building, namely cable lines, supplying electricity to all apartments and other consumers of the building's life support system, as well as switchboards and transformers. In rooms adjacent to these sources, the level of the power frequency magnetic field caused by the flowing electric current is usually increased. At the same time, the level of the electric field of industrial frequency is not high and does not exceed the MPC for the population of 500 V/m.

Currently, many experts consider the maximum allowable value of magnetic induction equal to 0.2 ÷ 0.3 μT. At the same time, 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 measure of protection is preventive:

It is necessary to exclude a long stay (regularly for several hours a day) in places with an increased level of the magnetic field of industrial frequency;

The bed for night rest should be removed as far as possible from radiation sources, the distance to distribution cabinets, power cables should be 2.5 ÷ 3 meters;

If there are some unknown cables, distribution cabinets, transformer substations in the room or in the adjacent one, the removal should be as possible as possible, optimally - measure the EMF level before living in such a room;

If it is necessary to install electrically heated floors, choose systems with a reduced level of the magnetic field.

household electrical. All household appliances operating using electric current, are sources of EMF. The most powerful should be recognized as microwave ovens, convection ovens, refrigerators with a “frost-free” system, kitchen hoods, electric stoves, and televisions. The actual generated EMF, depending on the specific model and mode of operation, can vary greatly among equipment of the same type. The values ​​of the magnetic field 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 household appliances do not exceed several tens of V/m at a distance of 0.5 m, which is much less than the MPD of 500 V/m. (table 1.5 ÷ 1.6).

When staying in an apartment household appliances be guided by the following principles: place household appliances as far away from places of rest as possible, do not place household appliances nearby or stack them on top of each other.

A microwave oven (or microwave oven) in its work uses EMF, also called microwave radiation or microwave radiation, to heat food. The operating frequency of microwave radiation from microwave ovens is 2.45 GHz. It is this radiation that many people fear. However, modern microwaves equipped with sufficiently perfect protection, which does not allow EMF to break out of the working volume. However, one cannot say that the field does not penetrate outside the microwave at all. new oven.

Table 1.5. Power frequency magnetic field levels of household electrical appliances at a distance of 0.3 m

For various reasons, part of the EMF intended for the preparation of the product penetrates the outside, especially intensively, as a rule, in the region of the lower right corner of the door. To ensure safety when using ovens in the home, there are sanitary regulations that limit the amount of leakage of microwave radiation from a microwave oven. They are called "Maximum Permissible Levels of Energy Flux Density Generated by Microwave Ovens" and have the designation CH No. 2666-83. According to these sanitary standards, the EMF energy flux density should not exceed 10 μW / cm 2 at a distance of 50 cm from any point of the furnace body when one liter of water is heated. In practice, almost all new modern microwave ovens withstand this requirement by a large margin. However, when purchasing a new oven, make sure that the Certificate of Conformity shows that your oven complies with these health regulations. It must be remembered that over time the degree of protection may decrease, mainly due to the appearance of micro-slits in the door seal. This can occur both due to dirt ingress, and due to mechanical damage. The door and its seal therefore require careful handling and care.

The term of guaranteed durability of protection against EMF leaks during normal operation is several years.

After five to six years of operation, it is advisable to check the quality of protection, for which purpose, invite a specialist from a specially accredited EMF control laboratory. In addition to microwave radiation, the operation of a microwave oven is accompanied by an intense magnetic field created by a 50 Hz industrial frequency current 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.

Table 1.6. Maximum allowable levels of EMF for consumer products that are a source of EMF

A source	Range	Value of remote control	Measurement conditions
Induction furnaces	20 ÷ 22 kHz	500 V/m 4 A/m	Distance 0.3 m from the body
microwave oven	2.45 GHz	10 μW / cm 2	Distance 0.50 ± 0.05 m from any point, with a load of 1 liter of water
Video display terminal PC	5 Hz ÷ 2 kHz	E remote control = 25 V/m V PDU = 250 nT	Distance 0.5 m around PC monitor
2 ÷ 400 kHz	E PDU = 2.5 V/mV PDU = 25 nT
surface electrostatic potential	V= 500 V	Distance 0.1 m from the PC monitor screen
Other products	50 Hz	E= 500 V/m	Distance 0.5 m from the body of the product
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 \u003d 10 μW / cm 2

TV and radio stations. Transmitting radio centers (RTCs) are located in areas specially designated for them and can occupy rather large territories (up to 1000 ha). By their structure, they include one or more technical buildings, where radio transmitters and antenna fields are located, on which up to several dozen antenna-feeder systems (AFS) are located. The APS includes an antenna used to measure radio waves, and a feeder line that supplies high-frequency energy generated by the transmitter to it. The zone of possible adverse effect of EMF created by the PRC can be conditionally divided into two parts. The first part of the zone is the territory of the RRC itself, where all the services that ensure the operation of radio transmitters and AFS are located. This territory is protected and only persons professionally associated with the maintenance of transmitters, switches and AFS are allowed to enter it. The second part of the zone is the territories adjacent to the MRC, 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 PRC can be different, for example, in Moscow and the Moscow region, placement in the immediate vicinity or among residential buildings is typical. High levels of EMF are observed in the territories, and often outside the location of transmitting radio centers of low, medium and high frequencies (PRTS LF, MF and HF). A detailed analysis of the electromagnetic environment in the territories of the RRC 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 OCP. Widespread sources of EMF in populated areas are currently radio transmitting centers (RTTCs), emitting VHF and UHF ultrashort waves into the environment.

Comparative analysis of sanitary protection zones (SPZ) and zones of limited development in the area of ​​operation of such facilities showed that the highest levels of exposure to people and environment are observed in the area where the RTPC is located " old building” with an antenna support height of not more than 180 m. The greatest contribution to the total intensity of exposure is made by “corner” three- and six-story VHF FM broadcasting antennas.

DV radio stations(frequencies 30 ÷ 300 kHz). In this range, the wavelength is 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, electric field can be higher than 630 V / m, and magnetic - higher than 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 transmitter with a power of 50 kW) .

HF radio stations(frequencies 3 ÷ 30 MHz). HF radio transmitters usually have lower power. However, they are more often located in cities, they can even be placed on the roofs of residential buildings at a height of 10 ÷ 100 m. A transmitter with a power of 100 kW 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 are usually located in cities. Transmitting antennas are usually located at a height above 110 m. From the point of view of assessing the impact on health, field levels at a distance of 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. The problem of assessing the EMF level of television transmitters is relevant in connection with a sharp increase in the number of television channels and transmitting stations.

The basic principle of ensuring safety is compliance with the maximum permissible levels of the electromagnetic field established by the Sanitary Norms and Rules. Each radio transmitting facility has a Sanitary Passport, which defines the boundaries of the sanitary protection zone. Only if this document is available, the territorial bodies of the State Sanitary and Epidemiological Supervision allow the operation of radio transmitting objects. Periodically, they monitor the electromagnetic environment for its compliance with the established remote control.

Satellite connection. Satellite communication systems consist of a transceiver station on Earth and a satellite in orbit. The radiation pattern of the antenna of satellite communication stations has a pronounced narrowly directed main beam - the main lobe. The power flux density (PFE) in the main lobe of the radiation pattern can reach several hundred W/m 2 near the antenna, also creating significant field levels at a great distance.

For example, a station with a power of 225 kW, operating at a frequency of 2.38 GHz, creates a PES of 2.8 W/m 2 at a distance of 100 km. However, the scattering of energy from the main beam is very small and occurs most in the area where the antenna is located.

Cellular. Cellular radiotelephony is today one of the most intensively developing telecommunication systems. The main elements of the system cellular communication 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 a cellular radio communication system is the very efficient use of the radio frequency spectrum allocated for the operation of the system (repeated use of the same frequencies, the use of different access methods), which makes it possible to provide telephone communications to a significant number of subscribers. The system uses the principle of dividing a certain territory into zones, or "cells", usually with a radius of 0.5 ÷ 10 km. Base stations (BS) communicate with mobile radiotelephones located in their coverage area and operate in the mode of receiving and transmitting a signal. Depending on the standard (table 17), BS emit electromagnetic energy in the frequency range 463 ÷ 1880 MHz. BS antennas are installed at a height of 15 ÷ 100 m from the ground 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 transceiving) and receiving antennas, which are not sources of EMF. Based on the technological requirements for building a cellular communication system, the antenna pattern in the vertical plane is calculated 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 the adjacent buildings, which is necessary condition for the normal functioning of the system.

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 BS load is almost zero , i.e. Stations are mostly "silent".

Table 1.7. Brief specifications of cellular radio system standards

Name of the standard	BS operating frequency range, MHz	MRI operating frequency range, MHz	Maximum radiated power of the BS, W	Maximum radiated power
MRI Radius "honeycomb" NMT-450. analog	463 ÷ 467.5	453 ÷ 457.5		1W; 1 ÷ 40 m
AMPS. analog	869 to 894	824 to 849		0.6 W; 2 ÷ 20 km
D-AMPS (IS-136). Digital	869 to 894	824 to 849		0.2W; 0.5 ÷ 20 km
CDMA. Digital	869 to 894	824 to 849		0.6 W; 2 ÷ 40 km
GSM-900. Digital	925 ÷ 965	890 ÷ 915		0.25 W; 0.5 ÷ 35 km
GSM-1800 (DCS). Digital	1805 ÷ 1880	1710 ÷ 1785		0.125 W; 0.5 ÷ 35 km

Mobile radiotelephone(MRI) is a small 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 site, the lower the MRI radiation power. The maximum power is in the range of 0.125 ÷ 1 W, but in a real situation it usually does not exceed 0.05 ÷ 0.2 W. The question of the effect of MRI radiation on the user's body is still open. Numerous studies conducted by scientists from different countries on biological objects (including volunteers) have led to ambiguous, sometimes contradictory, results. The fact that the human body "responds" to the presence of cell phone radiation remains undeniable.

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, first of all, by his head. What happens in the human body, how dangerous is this effect for health? There is still no single answer to this question. However, the experiment of scientists showed that the human brain not only senses the radiation of a cell phone, but also distinguishes between cellular communication standards.

Radar stations are equipped, as a rule, 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, however individual systems can operate at frequencies up to 100 GHz. The EM signal they create is fundamentally different from the radiation of other sources. This is due to the fact that the periodic movement of the antenna in space leads to spatial discontinuity in irradiation. The temporal discontinuity of irradiation is due to the cyclic operation of the radar for radiation. The operating time in various modes of operation of radio equipment can be calculated from several hours to a day. So for meteorological radars with a time interval of 30 minutes - radiation, 30 minutes - pause, the total operating time does not exceed 12 hours, while airport radar stations in most cases work around the clock. The width of the radiation pattern in the horizontal plane is usually several degrees, and the duration of irradiation during the survey period is tens of milliseconds. Metrological radars can create PES ~ 100 W/m 2 at a distance of 1 km for each irradiation cycle. Airport radars generate PES ~ 0.5 W/m 2 at a distance of 60 m. Marine radar equipment is installed on all ships, usually it has a transmitter power an order of magnitude lower than that of airfield radars, therefore, in normal mode, PES scanning generated at a distance several meters, does not exceed 10 W/m 2 . 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 EMP in the microwave range and creates large areas with a high energy flux density on the ground. The most unfavorable conditions are in residential areas of cities within which airports are located.

Personal computers. The main source of adverse effects on the health of a computer user is a 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;

Mirror reflections from the front surface of monitor screens;

Image flickering on the monitor screen.

Emissivity characteristics of the monitor:

The 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 of 1,050 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: 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 - a monitor, a 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, the Pilot type), uninterruptible power supplies and other auxiliary electrical equipment. All these elements during the operation of the PC form a complex electromagnetic environment at the user's workplace.

Table 1.8. Frequency range of PC elements

The electromagnetic field created by a personal computer has a complex spectral composition in the frequency range 0 ÷ 1000 MHz (table 1.9). The electromagnetic field has an electric ( E) and magnetic ( H) components, and their interrelation is quite complex, so the estimate E and H produced separately.

Table 1.9. Maximum EMF values ​​recorded at the workplace

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 computers and organization of work."

Means of protecting users from EMF. Basically, protective filters for monitor screens are offered from the means of protection. They are used to limit the impact on the user of harmful factors from the side of the monitor screen.

Technological progress also has a downside. The global use of various electrically powered equipment has caused pollution, which has been given the name - electromagnetic noise. In this article, we will consider the nature of this phenomenon, the degree of its impact on the human body and protective measures.

What is it and sources of radiation

Electromagnetic radiation is electromagnetic waves that occur when a magnetic or electric field is disturbed. Modern physics interprets this process within the framework of the theory of corpuscular-wave dualism. That is, the minimum portion of electromagnetic radiation is a quantum, but at the same time it has frequency-wave properties that determine its main characteristics.

The frequency spectrum of the electromagnetic field radiation makes it possible to classify it into the following types:

• radio frequency (these include radio waves);
• thermal (infrared);
• optical (that is, visible to the eye);
• radiation in the ultraviolet spectrum and hard (ionized).

A detailed illustration of the spectral range (electromagnetic emission scale) can be seen in the figure below.

Nature of radiation sources

Depending on the origin, sources of radiation of electromagnetic waves in world practice are usually classified into two types, namely:

• perturbations of the electromagnetic field of artificial origin;
• radiation from natural sources.

Radiations coming from the magnetic field around the Earth, electrical processes in the atmosphere of our planet, nuclear fusion in the depths of the sun - all of them are of natural origin.

As for artificial sources, they are a side effect caused by the operation of various electrical mechanisms and devices.

The radiation emanating from them can be low-level and high-level. The degree of intensity of the electromagnetic field radiation completely depends on the power levels of the sources.

Examples of high EMP sources include:

• Power lines are usually high-voltage;
• all types of electric transport, as well as the accompanying infrastructure;
• television and radio towers, as well as mobile and mobile communication stations;
• installations for converting the voltage of the electrical network (in particular, waves emanating from a transformer or distribution substation);
• elevators and other types of lifting equipment where an electromechanical power plant is used.

Typical sources emitting low-level radiation include the following electrical equipment:

• almost all devices with a CRT display (for example: a payment terminal or a computer);
• various types of household appliances, ranging from irons to climate systems;
• engineering systems that provide electricity to various objects (not only a power cable is meant, but related equipment, such as sockets and electricity meters).

Separately, it is worth highlighting the special equipment used in medicine, which emits hard radiation (X-ray machines, MRI, etc.).

Impact on a person

In the course of numerous studies, radiobiologists came to a disappointing conclusion - prolonged radiation of electromagnetic waves can cause an "explosion" of diseases, that is, it causes the rapid development of pathological processes in the human body. Moreover, many of them introduce violations at the genetic level.

Video: How electromagnetic radiation affects people.
https://www.youtube.com/watch?v=FYWgXyHW93Q

This is due to the fact that the electromagnetic field has a high level of biological activity, which negatively affects living organisms. The influence factor depends on the following components:

• the nature of the radiation produced;
• how long and with what intensity it continues.

The impact on human health of radiation, which has an electromagnetic nature, directly depends on the localization. It can be both local and general. In the latter case, large-scale irradiation occurs, for example, radiation produced by power lines.

Accordingly, local irradiation refers to the impact on certain parts of the body. Electromagnetic waves emanating from an electronic watch or a mobile phone are a vivid example of a local impact.

Separately, it is necessary to note the thermal effect of high-frequency electromagnetic radiation on living matter. The field energy is converted into thermal energy(due to the vibration of molecules), this effect is based on the work of industrial microwave emitters used for heating various substances. In contrast to the benefits production processes, thermal effects on the human body can be detrimental. From the point of view of radiobiology, it is not recommended to be near "warm" electrical equipment.

It must be taken into account that in everyday life we ​​are regularly exposed to radiation, and this happens not only at work, but also at home or when moving around the city. Over time, the biological effect accumulates and intensifies. With the growth of electromagnetic noise, the number of characteristic diseases of the brain or nervous system. Note that radiobiology is a rather young science, therefore, the harm caused to living organisms from electromagnetic radiation has not been thoroughly studied.

The figure shows the level of electromagnetic waves produced by conventional household appliances.

Note that the field strength level decreases significantly with distance. That is, in order to reduce its effect, it is enough to move away from the source at a certain distance.

The formula for calculating the norm (rationing) of electromagnetic field radiation is indicated in the relevant GOSTs and SanPiNs.

Radiation protection

In production, absorbing (protective) screens are actively used as a means of protecting against radiation. Unfortunately, it is not possible to protect yourself from electromagnetic field radiation using such equipment at home, since it is not designed for this.

• in order to reduce the impact of electromagnetic field radiation to almost zero, you should move away from power lines, radio and television towers at a distance of at least 25 meters (you must take into account the power of the source);
• for a CRT monitor and a TV, this distance is much smaller - about 30 cm;
• electronic watches should not be placed close to the pillow, the optimal distance for them is more than 5 cm;
• as for radios and cell phones, bringing them closer than 2.5 centimeters is not recommended.

Note that many people know how dangerous it is to stand near high-voltage power lines, but at the same time, most people do not attach importance to ordinary household electrical appliances. Although it is enough to put the system unit on the floor or move it away, and you will protect yourself and your loved ones. We advise you to do this, and then measure the background from the computer using an electromagnetic field radiation detector in order to visually verify its reduction.

This advice also applies to the placement of the refrigerator, many put it near the kitchen table, practical but unsafe.

No table will be able to indicate the exact safe distance from a particular electrical equipment, since emissions may vary, both depending on the model of the device and the country of manufacture. At the moment there is no single international standard, so in different countries standards may differ significantly.

You can accurately determine the intensity of radiation using a special device - a fluxmeter. According to the standards adopted in Russia, the maximum allowable dose should not exceed 0.2 μT. We recommend measuring in the apartment using the above-mentioned device for measuring the degree of electromagnetic field radiation.

Fluxmeter - a device for measuring the degree of radiation of an electromagnetic field

Try to reduce the time when you are exposed to radiation, that is, do not stay close to working electrical appliances for a long time. For example, it is not at all necessary to constantly stand at the electric stove or microwave oven while cooking. Regarding electrical equipment, you can see that warm does not always mean safe.

Always turn off electrical appliances when not in use. People often leave it on various devices, not taking into account that at this time electromagnetic radiation is emitted from electrical engineering. Turn off your laptop, printer or other equipment, it is unnecessary to be exposed to radiation once again, remember about your safety.

The sources of electromagnetic fields (EMF) are extremely diverse - these are power transmission and distribution systems (power lines - power lines, transformer and distribution substations) and devices that consume electricity (electric motors, electric stoves, electric heaters, refrigerators, TVs, video display terminals, etc.).

Sources generating and transmitting electromagnetic energy include radio and television broadcasting stations, radar installations and radio communication systems, a wide variety of technological installations in industry, medical devices and equipment (devices for diathermy and inductothermy, UHF therapy, devices for microwave therapy and etc.).

The working contingent and the population may be exposed to isolated electric or magnetic components of the field, or a combination of both. Depending on the attitude of the exposed person to the source of exposure, it is customary to distinguish between several types of exposure - professional, non-professional, exposure in the home and exposure carried out for medical purposes. Occupational exposure is characterized by a variety of generation modes and options for exposure to electromagnetic fields (radiation in the near zone, in the induction zone, general and local, combined with the action of other adverse factors production environment). In terms of non-professional exposure, the most typical is general exposure, in most cases in the wave zone.

Electromagnetic fields generated by various sources can affect the entire body of a working person (general exposure) or a separate part of the body (local exposure). At the same time, exposure can be isolated (from one EMF source), combined (from two or more EMF sources of the same frequency range), mixed (from two or more EMF sources of different frequency ranges), and also combined (under conditions of simultaneous EMF exposure). and other adverse physical factors of the working environment) impact.

An electromagnetic wave is an oscillatory process associated with interrelated electric and magnetic fields that change in space and time.

The electromagnetic field is the area of ​​distribution of electromagnetic

Characteristics of electromagnetic waves. The electromagnetic field is characterized by the radiation frequency f, measured in hertz, or the wavelength X, measured in meters. An electromagnetic wave propagates in vacuum at the speed of light (3 108 m/s), and the relationship between the length and frequency of an electromagnetic wave is determined by the relationship

where c is the speed of light.

The speed of wave propagation in air is close to the speed of their propagation in vacuum.

The electromagnetic field has energy, and the electromagnetic wave, propagating in space, carries this energy. The electromagnetic field has electric and magnetic components (Table No. 35).

The electric field strength E is a characteristic of the electrical component of the EMF, the unit of which is V/m.

The magnetic field strength H (A / m) is a characteristic of the magnetic component of the EMF.

The energy flux density (EFE) is the energy of an electromagnetic wave carried by an electromagnetic wave per unit time through a unit area. The PES unit is W/m.

Table No. 35. EMF intensity units in the International System of Units (SI) Range Value Name Unit designation Permanent magnetic field Magnetic induction Field strength Ampere per meter, A/m Tesla, T Constant electric (electrostatic) field Field strength Potential Electric charge Volt per meter, V/m Coulomb, C Amp per meter, A/m Electromagnetic field up to 300 MHz Magnetic field strength Electric field strength Ampere per meter, A/m Volt per meter, V/m Electromagnetic field up to 0.3-300 GHz Energy flux density Watt per square meter, W/m2

For separate ranges of electromagnetic radiation - EMP (light range, laser radiation) other characteristics are introduced.

Classification of electromagnetic fields. The frequency range and wavelength of the electromagnetic wave make it possible to classify the electromagnetic field into visible light (light waves), infrared (thermal) and ultraviolet radiation, the physical basis of which is electromagnetic waves. These types of short-wave radiation have a specific effect on a person.

The physical basis of ionizing radiation is also made up of electromagnetic waves of very high frequencies, which have a high energy sufficient to ionize the molecules of the substance in which the wave propagates (Table No. 36).

The radio frequency range of the electromagnetic spectrum is divided into four frequency ranges: low frequencies (LF) - less than 30 kHz, high frequencies (HF) - 30 kHz ... 30 MHz, ultra-high frequencies (UHF) - 30 ... 300 MHz, ultra-high frequencies ( microwave) - 300 MHz. 750 GHz.

A special kind of electromagnetic radiation (EMR) is laser radiation (LI) generated in the wavelength range of 0.1...1000 µm. A feature of LI is its monochromaticity (strictly one wavelength), coherence (all radiation sources emit waves in one phase), sharp beam directivity (small beam divergence).

Conventionally, non-ionizing radiation (fields) include electrostatic fields (ESF) and magnetic fields (MF).

An electrostatic field is a field of fixed electric charges that interacts between them.

Static electricity is a set of phenomena associated with the emergence, conservation and relaxation of a free electric charge on the surface or in the volume of dielectrics or on insulated conductors.

The magnetic field can be constant, pulsed, variable.

Depending on the sources of formation, electrostatic fields can exist in the form of an electrostatic field proper, which is formed in various types of power plants and during electrical processes. In industry, ESPs are widely used for electrogas cleaning, electrostatic separation of ores and materials, electrostatic application of paint and varnish and polymeric materials. manufacturing, testing,

transportation and storage of semiconductor devices and integrated circuits, grinding and polishing of cases of radio and television receivers,

technological processes associated with the use of dielectric

materials, as well as the premises of computer centers, where multiplying computer technology is concentrated, are characterized by the formation

electrostatic fields. Electrostatic charges and the electrostatic fields created by them can occur when dielectric liquids and some bulk materials move through pipelines, pour dielectric liquids, roll film or paper into a roll.

Table number 36. International classification electromagnetic waves № range Band name by frequency Metric subdivision of wavelengths Length Abbreviated letter designation 1 3-30Hz Decamegameter 100-10 mm Extremely low, ELF 2 30-300 Hz Megameter 10-1 mm Ultra low, VLF 3 0.3-3 kHz Hectokilometer 1000-100 km Infralow, ILF 4 3 to 30 kHz Myriameter 100-10 km Very low, VLF 5 30 to 300 kHz Kilometer 10-1 km Low frequencies, LF 6 300 to 3000 kHz Hectometric 1-0.1 km Medium, midrange 7 3 to 30 MHz Decameter 100-10 m High, Treble 8 30 to 300 MHz Meter 10-1 m Very high, VHF 9 300 to 3000 MHz decimeter 1-0.1 m Ultra high, UHF 10 3 to 30 GHz centimeter 10-1 cm Ultra high, microwave 11 30 to 300 GHz Millimeter 10-1 mm Extremely high, EHF 12 300 to 3000 GHz decimillimeter 1-0.1 mm Hyper-high, GHF

Electromagnets, solenoids, capacitor-type installations, cast and metal-ceramic magnets are accompanied by the appearance of magnetic fields.

Three zones are distinguished in electromagnetic fields, which are formed at different distances from the source of electromagnetic radiation.

Induction zone (near zone) - covers the gap from the radiation source to a distance equal to approximately U2n ~ U6. In this zone, the electromagnetic wave has not yet been formed, and therefore the electric and magnetic fields are not interconnected and act independently (the first zone).

Interference zone (intermediate zone) - located at distances from approximately U2p to 2lX. In this zone, the formation of EMW occurs and the person is affected by electric and magnetic fields, as well as an energy effect (second zone).

Wave zone (far zone) - is located at distances over 2nX. In this zone, an electromagnetic wave is formed, electric and magnetic fields are interconnected. A person in this zone is affected by the energy of the wave (the third zone).

The action of the electromagnetic field on the body. The biological and pathophysiological effect of exposure to electromagnetic fields on the body depends on the frequency range, the intensity of the influencing factor, the duration of exposure, the nature of the radiation and the mode of exposure. The effect of EMF on the body depends on the patterns of radio wave propagation in material media, where the absorption of electromagnetic wave energy is determined by the frequency of electromagnetic oscillations, electrical and magnetic properties of the medium.

As is known, the leading indicator characterizing the electrical properties of body tissues is their dielectric and magnetic permeability. In turn, differences in the electrical properties of tissues (dielectric and magnetic permeability, resistivity) are associated with the content of free and bound water in them. All biological tissues, according to the dielectric constant, are divided into two groups: tissues with a high water content - over 80% (blood, muscles, skin, brain tissue, liver and spleen tissue) and tissues with a relatively low water content (fat, bone). The absorption coefficient in tissues with a high water content, at the same values ​​of the field strength, is 60 times higher than in tissues with a low water content. Therefore, the penetration depth of electromagnetic waves in tissues with a low water content is 10 times greater than in tissues with a high water content.

The thermal and athermal effects underlie the mechanisms of the biological action of electromagnetic waves. The thermal effect of EMF is characterized by selective heating of individual organs and tissues, an increase general temperature body. Intense EMF irradiation can cause destructive changes in tissues and organs, however, acute forms of damage are extremely rare and their occurrence is most often associated with emergency situations in violation of safety regulations.

Chronic forms of radio wave lesions, their symptoms and course do not have strictly specific manifestations. However, they are characterized by the development of asthenic conditions and vegetative disorders, mainly with

side of the cardiovascular system. Along with general asthenia, accompanied by weakness, increased fatigue, restless sleep, patients develop headache, dizziness, psycho-emotional lability, pain in the heart area, increased sweating, decreased appetite. Signs of acrocyanosis, regional hyperhidrosis, coldness of the hands and feet, tremor of the fingers, lability of the pulse and blood pressure with a tendency to bradycardia and hypotension develop; dysfunction in the pituitary-adrenal cortex system leads to changes in the secretion of thyroid and gonadal hormones.

One of the few specific lesions caused by exposure to electromagnetic radiation of the radio frequency range is the development of cataracts. In addition to cataracts, when exposed to electromagnetic waves of high frequencies, keratitis and damage to the corneal stroma can develop.

Infrared (thermal) radiation, light emission at high energies, as well as high-level ultraviolet radiation, with acute exposure, can lead to expansion of capillaries, burns of the skin and organs of vision. Chronic exposure is accompanied by a change in skin pigmentation, the development of chronic conjunctivitis and clouding of the lens of the eye. Ultraviolet radiation of low levels is useful and necessary for humans, as it helps to enhance metabolic processes in the body and the synthesis of a biologically active form of vitamin D.

The effect of exposure to laser radiation on a person depends on the intensity of the radiation, wavelength, nature of the radiation and exposure time. At the same time, local and general damage to certain tissues of the human body is distinguished. In this case, the target organ is the eye, which is easily damaged, the transparency of the cornea and lens is disturbed, and damage to the retina is possible. Laser study, especially in the infrared range, is able to penetrate tissues to a considerable depth, affecting internal organs. Prolonged exposure to laser radiation of even low intensity can lead to various functional disorders of the nervous, cardiovascular systems, endocrine glands, blood pressure, increased fatigue, and decreased performance.

Hygienic regulation of electromagnetic fields. According to the regulatory documents: SanPiN "Sanitary and epidemiological requirements for the operation of radio electronic equipment with the conditions for working with sources of electromagnetic radiation" No. 225 dated 10.04.2007 of the Ministry of Health of the Republic of Kazakhstan; SanPiN "Sanitary rules and norms for the protection of the population from the effects of electromagnetic fields created by radio engineering objects" No. 3.01.002-96 of the Ministry of Health of the Republic of Kazakhstan; MU

“Guidelines for the implementation of state sanitary supervision of objects with sources of electromagnetic fields (EMF) of the non-ionizing part of the spectrum” No. 1.02.018 / y-94 of the Ministry of Health of the Republic of Kazakhstan; MU "Methodological recommendations for laboratory monitoring of sources of electromagnetic fields of the non-ionizing part of the spectrum (EMF) in the implementation of state sanitary supervision" No. 1.02.019 / r-94 of the Ministry of Health of the Republic of Kazakhstan regulates the intensity of electromagnetic fields of radio frequencies at the workplaces of personnel,
carrying out work with sources of electromagnetic fields and the requirements for monitoring, as well as regulated exposure to an electric field, both in terms of intensity and duration of action.

The frequency range of radio frequencies of electromagnetic fields (60 kHz - 300 MHz) is estimated by the strength of the electric and magnetic components of the field; in the frequency range of 300 MHz - 300 GHz - the surface density of the radiation energy flux and the energy load (EN) created by it. The total energy flux passing through the unit of the irradiated surface during the action (T) and expressed as the product of the PES T is the energy load.

At the workplaces of personnel, the EMF intensity in the frequency range of 60 kHz - 300 MHz during the working day should not exceed the established maximum permissible levels (MPL):

In cases where the time of exposure to EMF on personnel does not exceed 50% of the working time, levels higher than those indicated, but not more than 2 times, are allowed.

Rationing and hygienic assessment of permanent magnetic fields (PMF) in industrial premises and workplaces (Table No. 37) is carried out differentiated, depending on the time of exposure to the worker during the work shift and taking into account the conditions of general or local exposure.

Table No. 37

The PMF hygienic standards (Table No. 38), developed by the International Committee on Non-Ionizing Radiation, which operates under the International Association for Radiation Protection, are also widely used.

Modern man lives surrounded by a huge number of objects that are sources of electromagnetic radiation. About what types of radiation are the most dangerous and how to protect yourself from dangerous exposure, says the Deputy Director General of NNPO named after. Frunze, a member of KRET, Ilya Averin.

Electromagnetic fields (EMF) are an integral part of the human environment in modern world. According to the degree of interaction with a person, they can be divided into fields of natural origin and artificial fields of anthropogenic origin, as a result of human activity.

Natural, as a rule, include the electric and magnetic fields of the Earth, cosmic sources of radio waves, atmospheric electricity: lightning discharges, charge fluctuations in the ionosphere. As a permanent environmental factor, these fields largely determine the evolutionary processes of the Earth's biosphere, including man. For example, the Schumann resonant frequencies - the phenomenon of the formation of standing electromagnetic waves of low and ultra-low frequencies between the Earth's surface and the ionosphere caused by lightning discharges - correlate with the rhythms of the human brain.

The level of EMF from artificial sources of radiation in places of their intensive use can significantly exceed the natural background radiation, more than 1000 times.

As a rule, in their daily activities, a person deals with radio frequency fields, which are part of the electromagnetic spectrum. As part of the study of the effects of EMF on humans, such fields lie in the frequency range from 300 Hz to 300 GHz.

Common sources of artificial RF fields include: monitors and video displays (3-30 kHz), radio communications and broadcasting (30 kHz-3 MHz), industrial induction heaters, RF heat sealers, medical diathermy equipment (30 kHz-30 MHz) , FM broadcast (30-300 MHz), TV broadcast, mobile phones, microwave ovens, medical diathermy equipment (0.3-3 GHz), radars, satellite links, microwave communications (3-30 GHz), and various microwave and EHF radio equipment (3-300 GHz) .

Radio frequency fields (RF) are non-ionizing radiation. Unlike ionizing radiation(X-rays and gamma rays), they are weak enough to break the bonds that hold molecules together in cells. However, RF fields can have different effects on biological systems such as cells, plants, animals and humans. The nature of this effect depends on the frequency and strength of the field.

The maximum permissible levels of EMF are determined based on the established values ​​of energy exposure and exposure time. For the population, as a rule, the values ​​of EMF levels are accepted as an acceptable level, which, with daily exposure to a given source, do not cause deviations in the state of health.

Modern man lives surrounded by a huge number of radiating objects, and each of us needs to know that any electromagnetic radiation is dangerous, regardless of its source, while the danger criterion is the excess of its level relative to the norms regulated by the sanitary and epidemiological legislation of the country.

This regulatory framework consists of 18 regulatory documents (GOST) and Sanitary Rules and Norms (SanPiN), which are mandatory for execution throughout Russia. In particular, to control the limit allowable norms EMI in Russia, there are more than 18 regulatory documents on regulation, measurement methods, sanitary norms and rules, as well as about 19 guidelines on the procedure for measuring electromagnetic fields, depending on the frequency range and type of emitting devices.

State standards are the most common documents and contain requirements, norms and rules aimed at ensuring safety, maintaining human health and performance in the process of work. Sanitary rules and norms govern in more detail the hygienic requirements for specific exposure situations and individual types of products. A number of SanPiN set standards for the impact of EMF on the population. Sanitary standards are usually accompanied guidelines on the methods of control of the electromagnetic environment and the implementation of protective measures.

At present, the regulatory framework of Russia and the EU countries tends to converge. At one time in the USSR, the regulation of remote control was more humane. So, for example, earlier in the microwave range, the permissible level for the population was normalized to no more than 1 μW / sq. cm, now the permissible level has increased to 10 μW / sq. see Rationing of electromagnetic radiation abroad is based on the damaging effect, taking into account the thermal dissipation of the energy of the electromagnetic field in the human body, forgetting, for example, about the specifics of powerful short-duration pulsed radiation with a large duty cycle, that is, with small average values. In domestic practice, there are quite a lot of works indicating the influence of electromagnetic fields of lower levels.