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Electromagnetic non-ionising radiation

Electromagnetic radiation (EMR) present in the environment may originate both from natural sources (the Earth’s magnetic field, cosmic radiation, lightnings), and artificial sources introduced into the environment, in a way that is: intentional (radio and television transmitters, mobile telephone transmitters, radar stations, etc.) or unintentional, as a side effect of the operation of various devices (transmission lines, transformer stations and all kinds of power consumers). The EMR artificially introduced into the environment is sometimes called electromagnetic smog. The scope of electromagnetic non-ionising radiation ranges from 0 Hz to 300 GHz and covers: static electric and magnetic field  (0 Hz), low-frequency fields (up to 300 Hz) and radio waves, including their sub-band, that is microwaves.

All organisms living on the Earth evolved in the magnetic field of natural origin and learned not only to tolerate the field, but also – in the case of many species – even to use in various life processes. The impact of the EMR on living organisms and on all objects located in the impact zone of consists in transmitting energy. The phenomenon takes different courses for fields of low and high frequency. Low frequency field causes the so-called non-thermal phenomena, whereas high frequency fields (over 100 kHz), transmitting their energy, cause increase in temperature of the object they affect (so-called thermal phenomenon). The impact of the ERM on plants and animals is different. Also the impact of the electrical and magnetic components is different, and changes both along with the frequency of radiation and the energy which the radiation carries.

In relation to the above, it is understandable that the fact of increasing the levels of electromagnetic fields as a result of human activity gives rise to concern. The increase causes the necessity to monitor the state of the environment.

 

In the light of the provisions of the Environmental Protection Law Act, “protection against electromagnetic fields consists in ensuring the best possible state of the environment through:
1. keeping the levels of electromagnetic fields below or at least at the limit values;
2. reduction of the levels of electromagnetic fields at least to the limit values, when they are not met.”
Article 121 of the Environmental Protection Law Act of 27 April 2001

 

Poland is one of few countries with a complete legal system for protection of the population against electromagnetic radiation. The limit values of non-ionising radiation determined for areas intended for residential development and places available for the public are, according to the regulations binding in Poland, much lower than those included in the Recommendation of the European Council, applied in the other EU Member States. The legal order binding from 2007 requires that monitoring measurements be carried out in central districts or housing estates of cities with population of over 50,000, in other cities and in rural areas.

Carried out in 2008 by voivodeship environmental protection inspectors, monitoring of electromagnetic fields in 547 measurement points indicate lack of exceedances of the limit values in the environment. The results of measurements show that the average values of intensities of electromagnetic fields are much lower than the national limit values.

Determination of long-term trends in the levels of electromagnetic fields is possible on the basis of examinations carried out in the previous years on commission from the Chief Inspector for Environmental Protection in selected Polish cities. Measurements were taken in the years: 1993, 2001-2003, 2005 and 2006 by various scientific and research institutes. For the Capital city of Warsaw, the location of measurement points has not changes in years, to observe trends in the levels of the EMR. It should be kept in mind that the examination of the levels of electromagnetic fields, although carried out by two different laboratories applying different methodologies, show convergence.

The obtained results of measurement carried out in 1993 and in the years 2001-2003 show no changes in the levels of electromagnetic fields in points located around the Palace of Culture and Science, where numerous radio and television transmitters are placed. In points distant from the Palace, there was recorded a growth of the levels of electromagnetic radiation by several or a dozen times in 2003 in relation to the results of measurements carried out in 1993 and 2001. Such a significant increase in the levels of the EMR has been caused by the development of cellular telephony in the mid-1990s. According to Regulation of the Minister of the Environment of 30 October 2003 on limit values of electromagnetic fields in the environment and the ways to comply with those levels, for the range of frequencies from 80 MHz to 1300 MHz, the legally defined permissible level of intensity of the electromagnetic field in the environment is 7 V/m. Currently mobile networks are operating in the range of frequencies from 450 MHz to 3600 MHz. The intensities of electromagnetic fields measured on the territory of Warsaw in the range of frequencies of 80 MHz-1300 MHz, fluctuate between 0.07% to 8.57% of limit values.

The results of measurements carried out in 2005 are consistent with the results of measurements performed in the years 2001–2003. The arithmetic mean value of the intensity of the electric field measured in 2005 for Warsaw is 0.65 V/m, whereas the arithmetic mean intensity of the electric field measured in 2001 in seven points located in the central districts of Warsaw also amounts to 0.65 V/m (for the range 10 MHz – 2000 MHz) .

In 2006, there were performed measurements of the levels of electromagnetic fields with a probe measuring the intensity of an electric field in the range of frequencies from 100 kHz to 3 GHz and calculated results of measurements of the intensity of electric field performed in 2001 in the range from 100 kHz to 2 GHz. The value of the mean of the maximum values of intensity of the electric field measured in particular 17 measurement points carried out in 2006 is 0.87 V/m, whereas the mean value of the resultant values of the  electric fields intensities measured in the same points performed in 2001 is 0.84 V/m. The above data indicate that the average level of the intensity of electromagnetic field on the area of Warsaw did not change significantly between 2001 and 2006. The value of those levels was also confirmed by measurements carried out in 2008 by the Mazovian Voivodeship Inspector for Environmental Protection.

Electromagnetic field is a phenomenon that is quite complex in terms of the sources. The main sources of electromagnetic radiation include terrestrial radio and television transmitters, base transceiver stations, radiolocation devices, power stations and lines. However, it must be born in mind that there exist, in the near surrounding of people, beside  the sources of electromagnetic fields mentioned above, a huge number of various kinds of devices powered with electricity, this producing electromagnetic fields around them, with a quite wide spectrum of frequencies.

Mobile telephony is the most developing area of human activity which uses devices emitting electromagnetic field. The GSM system covers practically the whole country with its scope. Three providers have their own transmitters, and a fourth one started building its own in 2008. The number of transceiver stations of the two GSM systems: 900 and 1800 is continuously increasing. Since 2008, the network of the so-called third generation telephony, called the UMTS, has been developed, which shall eventually replace the two GSM systems, but will function along them for some time. Antennae enabling wireless access to broadband Internet, as well as antennae forming the so-called picocells, covering single streets or even buildings, are more and more frequently installed in urban areas. Such antennae are also installed more and more frequently inside buildings (office buildings) and large shopping centres (Fig. 5.5.1.).

 

Pobierz dane wykresu w formacie CSV

Fig. 5.5.1.Number of transceiver stations of mobile telephony in Poland (source: CSO)


The above data indicate a constant growth in the number of one of the major sources of electromagnetic radiation, that is the mobile telephony transceiver stations, which, as a consequence, is reflected in the growth of EMR emissions to the environment.

Radio and television transmitters are the second important group of devices emitting electromagnetic radiation. The transmitters belong to high power sources, calculated in kilowatts, or even megawatts. At present, there are taking place quite important changes in the ways of emission of radio and television channels. Long, medium and short wavelengths are being abandoned. The GE06 Agreement, which was concluded in Geneva in 2006 during the IUT  Regional Radiocommunication Conference, assumes that final switch-off of analogue  broadcasting should take place until 17 June 2015. It means a complete turn to broadcasting channels in digital domain. According to the draft “Plan of digital TV implementation in Poland” the deadline of  analogue broadcasting switch-off is 31 July 2013. The fact entails the necessity to turn off some terrestrial transmitters, and, as a consequence, lowering the emission of electromagnetic radiation to the environment. At the same time, more and more of various kinds of services and corporations use their own, internal means of wireless communication. In the coming years, considering plans of formation of new production powers in electroenergetics, an increase in the number of high voltage transmission lines is expected, especially in the north of Poland, where the ability of energy transmission is limited. The construction of such transmission lines will be facilitated by the act on transmission corridors the assumption of which has been prepared by the Ministry of Economy.

 

 


The past monitoring measurements did not reveal exceedances of the levels of electromagnetic fields in the environment. During the last 17 years, there was recorded a growth in the levels of electromagnetic fields in the environment, caused by the development of cellular telephony to a high extent. The greatest increase in the intensity of the high frequency electromagnetic filed was recorded in the central districts or housing estates of large cities. It is expected that there will take place a development of terrestrial systems of digital techniques of broadcasting radio and television channels in the next few years, which might result in reduction in the power of radio and television transmitters, thus a drop in the intensities of electromagnetic fields around such structures. At the same time, there is taking place a quick development of wireless Internet access networks, as well as development of third generation mobile telephony, leading to increased density of mobile telephony base transceiver stations. The development of the above-mentioned sources may result in a slight growth in mean levels of electromagnetic fields, particularly in highly urbanised areas. Therefore, it may be concluded that one should not expect a radical increase in the levels of intensity of the EMR in the environment in the coming years, despite the growing number of radiation sources in the form of mobile telephony base transceiver stations.


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