6.3. Electromagnetic contamination
The electromagnetic radiation of long-wave, middle-wave, short-wave and ultra-high diapason is widely used in wireless communication and also in high-frequency heating arrangement. Television uses ultra-short and decimeter waves, radar-location -centimeter. In electrical networks of high voltage (over 1000 V) the electromagnetic fields of audio frequencies (50 Hz) are used. The electromagnetic radiation of anthropogenous origin can be considered as one of the energy contaminators as they negatively influence on people organism, other living organisms and harmfully affect ecological system.
During exposure of the person the significant part of electromagnetic radiation is absorbed by the organism. Absorbed energy turns into thermal what induce intensive heating of tissue and liquid. The greatest danger it has for internal organs which have slight circulation of blood and other liquids and due to what heat hardly transfers from them. That can bring about irreversible consequences (modification of cell structure, tissue deaden, extravasation and other). Dangerous level of electromagnetic radiation intensity is set by the standard «ГОСТ 12.1.006-84». The electromagnetic fields influence on endocrine, nervous and cardiovascular systems, reproductive function, and morphological structure of blood and exchange of substances.
The anthropogenous sources of electromagnetic radiation are divided into three groups:
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Point (radio-station, television center);
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Joint (plants, radar-tracking stations);
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Linear (electricity transmission, contact networks of electrical transport).
The level of radiation intensity from these sources has sharply increased now because of growing of their amount and power; in some regions it exceeds average natural level «natural background» in hundred times.
One of the most powerful sources of electromagnetic radiation is also electricity transmission line. Measures on reducing influence of electromagnetic fields include construction along electricity transmission line special protection zone with the following breadth: for voltage of 1150 kV and higher, outside of localities it is 300 m to each side from line axis; for 500 kV -150 m outside of localities and 50 m - in boundaries of localities; for 22 kV - accordingly 10 and 7 m.
Except protection zones construction the special modes for agricultural and forestry works (short working day, minimum using of machines and mechanisms) are provided in zones of electromagnetic influence.
Main sources of high-frequency energy on people living medium are radio- and television centers and radar-tracking stations. Electromagnetic fields intensity measuring should be carried out periodically both on territory of radio-stations, and in living zones, which are close to transmitting antennas. When the limits of acceptable level are exceeded it is necessary to realize complex of protective measures: shielding of apartment houses, changing of antenna directivity, reducing of the transmitter power. If these measures are not sufficient there's a necessity to move radio-station out of the borders of the locality or to remote living buildings from a zone of electromagnetic fields influence. Together with the mentioned above measures the shielding of territories by buildings with large contents of ferro-concrete constructions (radiation intensity is reduced in 1,5 – 2 times); multi-row green planting (having breadth 15 – 20 m radiation intensity is reduced for 10 – 15%) are applied.