Non-ionizing electromagnetic radiation monitoring in Greece

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16 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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Non-ionizing electromagnetic radiation
monitoring in Greece
Antonis Gotsis, Nikolaos Papanikolaou, Dimitris Komnakos, Agamenon Yalofas, and Dr.
Philip Constantinou
Mobile Radio-Communications Laboratory, School of Electrical and Computer
Engineering, National Technical University of Athens, Greece, 9 Heroon Polytechneiou
Street (tel: +30 210 772 3849; fax: +30 210 772 3848; e-mail:
{gotsis,npapan,dkomna,yalofas,fkonst}@mobile.ntua.gr)
The design, development and operation of a network for the monitoring of the non-
ionizing electromagnetic radiation in Greece is presented in this paper. Two
independent sub-networks, called “Hermes” and “pedion24” have been operating since
November 2002 in several areas, and more than 4,000,000 electric field strength
measurements have been conducted to date. The measurement results indicate that
the non-ionizing electromagnetic radiation levels are several times below the European
Commission Recommendation 1999/519/EC and the Hellenic Republic Law no.3431
reference levels.
1. Introduction
During the last decade, the installation and operation of several wireless networks,
such as the GSM, UMTS, TETRA and Wi-Fi systems has led to increasing public
concern about the exposure to electromagnetic (EM) radiation emitted by such
sources. In conjunction with traditional broadcasting systems (FM Radio and VHF-
UHF Television), RADAR systems etc. these concerns call for the continuous
information of the public regarding their exposure to EM radiation levels. On site,
“ad-hoc” measurements are the first step for estimating the exposure levels.
Nevertheless, ad-hoc measurements refer to a specific time period (usually 1-2
hours). On the other hand the notion of continuous measurement of EM radiation
levels on a 24-hour basis is more appealing to the concerned public. This is due to
the fact that the recorded values can be directly compared to the public exposure
safety values, called reference levels, which are set by the relevant organizations,
such as the EC [1] and local governmental authorities [2]. Therefore, a network for
the measurement and recording of non-ionizing Electromagnetic Radiation levels on
several sites and on a 24-hour basis is one of the best solutions for keeping the
public informed. Another important parameter of such a network is to present the
results of the measurements to the public via a user-friendly web site.
Monitoring networks are a valuable tool in attempting to deal with public concerns
about the potential health effects of non-ionizing electromagnetic radiation. As a
result, several monitoring systems are implemented all over Europe and Africa
(Italy, Spain, Portugal, United Kingdom, Malta, and Egypt) [3] - [6]. Moreover
network deployment entails a number of challenges, in terms of hardware
certification, network control and daily maintenance. With all the above
considerations in mind two Electromagnetic Radiation (EMR) monitoring networks
have been deployed in Greece. “Hermes” network [7] started its operation on
November 2002, while “pedion24” [8] (where “pedion” is the Greek word for field) on
November 2005. So far 46 continuous monitoring stations have been installed in
urban and rural areas of Greece and more than 4,000,000 measurements have
been conducted and stored. Moreover there is a plan for further expansion during
the next years. The paper is structured as follows: In Section II we present the
design aspects of such a monitoring network, regarding the hardware and the
software. Section III gives a brief description of the two monitoring networks
operating in Greece and Section IV presents overall measurement results
conducted by the two networks to date. In Section V we draw some conclusions
with relation to the measurement results and conclude our work.
2. System Architecture – Design Aspects
A typical system architecture of a centralized monitoring network is depicted in
Figure 1. The network consists of the remote measurement stations (RMSs) and
one or more control unit(s) (CU(s)). Each RMS communicates with the CU via a
public wireless network such as GSM, GPRS or UMTS. Such a wireless interface
allows the installation of a measurement station practically everywhere as long as
the area is covered by any cellular operator. The CU controls the remote units,
stores the measurement data and hosts the web site. Any interested party can
access the results through an Internet gateway. A detailed description of each part
of the system follows.

CU
RMS
RMS
RMS
Internet
GSM/GPRS/UMTS
Network
User PC
User PC
.
.
.
CU
.
.
.

Figure 1: System Architecture

2.1 Remote Measurement Stations


The Measuring Equipment must be a fully autonomous unit which is able to: (a)
operate continuously (on a 24-hour basis), (b) perform Electromagnetic Radiation
measurements in the frequency range of interest covering the main sources that
contribute to the total electromagnetic pollution, (c) store the measurements in its
internal memory and transmit them to the Control Unit via a wireless interface for
further elaboration, (d) supplied either by the main power supply or a solar panel
(preferable), (e) be fully remotely controlled, which means that after its installation
no human presence is needed on site and (f) detect abnormal operation of any kind
(self diagnostics such as power loss and overheating problems) and report it to the
CUs. In order to fulfill these requirements, a remote monitoring station would consist
of a broadband isotropic and triaxial electric field sensor, a module containing the
necessary electronics, a GSM/GPRS/UMTS modem, as well as temperature and
humidity sensors. A major problem encountered in this system is the periodic
calibration of the monitoring stations. Regarding the measurement quantities, either
broadband or narrow-band measurements can be conducted. Broadband
Measuring Stations record the Electric Field Strength and/or the Power Flux Density
for a given frequency range. A range of 100 KHz - 3 GHz is usually enough in order
to take into account the vast majority of the sources. Other possible ranges are for
example 880 - 960 MHz (the GSM900 band), 1880 - 2100 MHz (GSM-1800 plus
UMTS band), etc. In [9] - [11] the interested reader can find a plethora of
commercially available monitoring units. Recently, selective monitoring systems
became commercially available [12]. The referred stations are fully autonomous and
can be remotely controlled via the GSM/GPRS protocol.
2.2 Control Unit(s)


The Control Unit is a Server computer equipped with a wireless modem and the
necessary software applications for (a) controlling the remote monitoring stations
and configuring the operational parameters, (b) downloading the measurement data
via the wireless interface, (c) storing the data in its hard disk and (d) processing the
measurement results and publishing them to the corresponding web site. Usually
the RMS manufacturer provides a software application for the control of the units
and the data collection. Through this application the system administrator is able to
change the measurement and communication parameters. The data is collected
and exported in formatted text files (csv files). The measurement data is stored in a
database therefore a full historical record for every measurement site is kept on the
CU. An administrative tool (desktop- or web-based) is developed in order to perform
the above operations. Finally a Web Server running on the CU hosts the web site. A
more detailed description of the hardware and software architecture can be found in
[13] – [16].
3. Operating Networks in Greece
Two EMR monitoring networks have been deployed in Greece. These networks
share a common scientific goal, that is, to conduct accurate, long-term, continuous
measurements of the non-ionizing electromagnetic radiation in our country and to
determine and understand trends and variability of the field values.
3.1 “Hermes” Monitoring Network

In November 2002, Mobile Radio-Communications Laboratory (MRCL) of the
National Technical University of Athens, commenced the operation of the first EMR
monitoring network in Greece, named “Hermes”. The formation of this network was
motivated by the lack of previous systematic measurement and recording of EM
field strength levels over the country and aimed at providing valid, up-to-date
information to citizens about the results of these measurements, namely, the level
of exposure to non-ionizing EM radiation. The system at its present state (January
2007) comprises 37 remote monitoring stations spread all over Greece and two
control units located in two University laboratories (National Technical University of
Athens – NTUA and Aristotle University of Thessaloniki – AUTH). MRCL controls
stations located on the southern part of Greece, while the AUTH Laboratory the
northern part. The stations are located at schools, universities, public authorities’
buildings and private flats. From now on, we will only refer to the stations that are
under the control of the Mobile Radio-Communications Laboratory (21 active and 4
inactive stations). The measurement results are open to the public through a
devoted web site. The web site contains both static and dynamic pages and aims at
presenting the measurement results for all the monitored sites. It also provides
thorough information concerning the non-ionizing electromagnetic radiation
exposure issue. Through the web site the visitor may view graphs of the measured
values for custom date/time interval selection. Furthermore, a comparison of the
measured values with the Greek legislation reference levels is presented. A
feedback form is also available to the public in order for them to express questions
or comments to the system administrators. Although the electric field strength is
recorded by the RMSs, Power Flux Density values are presented on the web site.
3.2 “pedion24” Monitoring Network

In November 2005 Mobile Radio-Communications Laboratory started the operation
of a second monitoring network, named “pedion24” network. The design and
operating principles of this network are similar to those of “Hermes”. “pedion24”
network at its present state (January 2007) consists of 21 remote monitoring
stations. Locations of monitoring stations are carefully chosen to cover places of
special interest such as schools, hospitals, nurseries, areas with high population
density and also private flats in Attica and five other prefectures of Greece. The
network is continuously expanded throughout Greece.
Detailed description of the networks and the results can be found in [7] and [8].
4. Overall results from the continuous monitoring stations
Broadband measurements for the band 100 kHz – 3GHz
Until December 2006 4,175,000 6-minutes average values of the Electric Field Strength
measured on 46 different sites have been accumulated in the databases of the two
measurement networks. The number of the recorded values, the mean value (
E
) and
the standard deviation per site ( σ) of the measured values for both networks are shown
in Table 1.

Electric Field Strength (V/m)
Measurement Site Number of records
E

σ
PEDION24 STATION 1 43,064 1.32 0.06
PEDION24 STATION 2 72,663 1.14 0.15
PEDION24 STATION 3 56,919 3.36 0.42
PEDION24 STATION 4 55,442 1.95 0.15
PEDION24 STATION 5 50,535 1.11 0.20
PEDION24 STATION 6 50,726 2.96 0.39
PEDION24 STATION 7 29,447 1.14 0.05
PEDION24 STATION 8 23,979 1.53 0.05
PEDION24 STATION 9 10,765 1.58 0.06
PEDION24 STATION 10 24,613 2.51 0.15
PEDION24 STATION 11 51,361 2.44 0.28
PEDION24 STATION 12 33,136 3.89 0.22
PEDION24 STATION 13 666 2.98 0.10
PEDION24 STATION 14 51,570 0.20 0.11
PEDION24 STATION 15 43,825 0.25 0.11
PEDION24 STATION 16 16,716 1.33 0.60
PEDION24 STATION 17 7,635 0.90 0.06
PEDION24 STATION 18 7,006 0.48 0.02
PEDION24 STATION 19 6,918 1.15 0.08
PEDION24 STATION 20 8,561 1.08 0.06
PEDION24 STATION 21 7,429 1.33 0.09
HERMES STATION 1 77,603 1.57 0.12
HERMES STATION 2 77,609 1.86 0.14
HERMES STATION 3 72,726 2.57 0.17
HERMES STATION 4 322,957 1.71 0.27
HERMES STATION 5 309,926 1.19 0.44
HERMES STATION 6 225,626 2.68 0.36
HERMES STATION 7 265,420 0.83 0.32
HERMES STATION 8 263,785 1.57 0.17
HERMES STATION 9 252,850 1.28 0.25
HERMES STATION 10 175,015 2.39 0.29
HERMES STATION 11 177,787 2.25 0.37
HERMES STATION 12 93,824 2.25 0.12
HERMES STATION 13 13,130 3.29 0.31
HERMES STATION 14 18,173 2.52 0.07
HERMES STATION 15 3,088 1.48 0.24
HERMES STATION 16 1,894 3.93 0.35
HERMES STATION 17 255,593 0.55 0.50
HERMES STATION 18 268,537 1.62 0.38
HERMES STATION 19 90,105 0.03 0.14
HERMES STATION 20 214,864 0.15 0.37
HERMES STATION 21 105,070 1.63 0.92
HERMES STATION 22 103,795 1.97 1.05
HERMES STATION 23 71,320 0.05 0.25
HERMES STATION 24 26,595 1.02 0.34
HERMES STATION 25 34,894 0.55 0.22
Table 1: Overall Measurement Results for the period 11/2002 – 12/2006

A sample time graph of the 6-minutes average value of the electric field strength
dynamically created on the web site of “pedion24” project is shown in Figure 2. The
specific diagram depicts the electric field strength levels concerning one RMS for a time
period of one week. Two safety reference levels are also shown.The specific values
correspond to the strictest reference levels in the FM and GSM bands [2]. In Figure 3,
the electric field strength probability density function and a gaussian fitting curve are
illustrated.



Figure 2: A sample graph of the 6-min average recorded electric field strength versus time

0,00
0,02
0,04
0,06
0,08
0,10
0,12
Electric field histogram
Gaussian fitting
Probability Density
Electric Field Strength (V/m)

Figure 3: A mean field strength distribution and Gaussian Fitting PDF for all measurements.

Broadband Measurements per band (100 KHz – 900 MHz, 900 MHz – 3 GHz)
The measurement stations have the ability to measure the electric field strength for
two narrower bands, namely 100 KHz – 900 MHz and 900MHz – 3GHz. The
resulting histogram (pdf) is shown in Figure 4. Observing the specific diagram it can
be seen that for electric field values below 1.4V/m the probability density for 100kHz
– 900MHz band is greater than the probability density for 900MHz – 3GHz band. On
the contrary for electric field values above 1.4 V/m the greater probability density is
that for 900MHz - 3GHz band, which contains services like GSM 900 (downlink),
DCS 1800 and UMTS. This can be explained by the fact that the remote
measurement stations are installed in sites near GSM, DCS and UMTS base
stations.
Comparison of the results with the reference levels
A comparison of the mean measured Electric Field Strength per station with the
strictest reference level in the band 100 KHz – 3 GHz (which is 21.7 V/m [2]), is
presented in Figure 5. Actually, we depict the inverse of the ratio of the measured
value to the reference level, which expresses how many times below limits are the
measured field values. The accumulated measurement results are in average 46
times below the above reference value.
0
0,02
0,04
0,06
0,08
0,1
0,12
0,14
0,
2
-0
,
4
0,4
-
0,
6
0,
6
-0
,
8
0,
8
-1
1-
1
,2
1
,2
-
1,
4
1,4
-
1,
6
1
,6
-1
,
8
1
,8
-
2
2-
2
,2
2,2
-
2,
4
2,4-2,6
2
,6
-
2,
8
2,8
-
3
3-3,2
3,2
-
3,
4
3,
4
-3
,
6
3
,6
-
3,
8
3,8
-
4
4-4,2
4,2
-
4,
4
4
,4
-4
,
6
4,6
-
4,
8
Electric Field Strength (V/m)
Probability Density
100kHz-900MHz
900MHz-3GHz

Figure 4: Field Strength Distribution Probability per band
1,00
10,00
100,00
1000,00
Measurement stations
Times below the reference levels

Figure 5: Comparison of monitored field strength to the reference levels
5. Discussion – Conclusions
Two automated nationwide monitoring networks of the electric field strength
covering the RF spectrum were presented. More than 4,000,000 E-field strength
values have been recorded in the databases of these projects during the last years.
The results of the measurements were drawn for the whole band (100 KHz - 3
GHz), as well as for the lower (100 KHz – 900 MHz) and the higher (900 MHz - 3
GHz) part of the band. Since the commencement of operation the measured EM
Radiation levels are significantly below the safety reference levels. Specifically, 90%
of the stations have been measuring electric field strength values below 3 V/m. The
variation of the electric field on each site is negligible for the majority of the stations,
while the measured E-field depends on the relative position between the site and
the antennas. The most important emission sources are FM, TV and mobile
telephony antennas, at least at urban and suburban areas. A thorough examination
of non-ionizing EMF radiation in dense urban and rural environments is of utmost
importance. We are currently planning the installation of more remote stations in
these kinds of environments. More emphasis will be given in the measurement and
evaluation of the exposure levels in the proximity of mobile telephony base stations
References
[1] European Commission (EC), “Council Recommendation 1999/519/EC of 12 July 1999 on the
limitation of exposure of the general public to electromagnetic fields (0 Hz to 300 GHz)”, Off. J. Eur.
Comm., L 199, 59, 30 July 1999.
[2] Hellenic Republic Law No. 3431, About Electronic Communications and other Provisions,
Government Gazette, FEK No. 13 A’/ 03.02.2006.
[3] “monIT Project”: Electromagnetic Radiation Monitoring in Mobile Communications
http://www.lx.it.pt/monit/

[4] “Cassiopea Project”: http://www.stroud.gov.uk/docs/cassiopea/cassiopea.asp

[5] “Progett Gardjola”: http://gardjola.eng.um.edu.mt/emr

[6] “Project Horus”: http://www.projecthorus.com/EMF/

[7] “Hermes” project: A Project for Systematic Measurements of the Electromagnetic Radiation,
http://www.hermes-program.gr

[8] ”pedion24” project : A Project for Continuous Measurements of the Electromagnetic Radiation,
http://www.pedion24.ntua.gr

[9] Narda Area Monitor System 2600, “Narda Safety Test Solutions”: http://www.narda-
sts.com/en/produkte/2600.htm

[10] PMM 8055S Electric and Magnetic Field Monitoring Station, “PMM Safety Products”,
http://www.pmm.it/main/safetyproducts.asp

[11] EE4070, EE4070S,MCE Monitoring System, “E.I.T. s.r.l”, http://www.eitsrl.it/iMCE.htm

[12] Antennessa EMF Measurement Systems : http://www.antennessa.com/emfmeasurementsystems.php

[13] A. Yalofas, A. Gotsis, C. Veranopoulos, P. Constantinou, G. Belesiotis, M. Petkaris, N. Babalis, “A
Fully Automated and Geographically Distributed Network for the Continuous Measurement of the RF
Radiation – “Hermes” Project”, TELSICS, IEEE 6th International Conference on Telecommunications
in Modern Satellite, Cable and Broadcasting Services, Niš, Yugoslavia, October 2003.
[14] A. Gotsis, A. Yalofas, C. Veranopoulos, P. Constantinou, “Design and Development of an Automated
Web Controlled Measurement Network for the RF Field Strength Monitoring”, IEEE Region 8
EUROCON, The International Conference on Computer as a Tool, Ljubljana, Slovenia, September
[15] A. Gotsis, A. Yalofas , P. Constantinou, A. Boursianis, T. Ganatsos, N. Tachas, T. Samaras, T.
Daskalou, M. Petkaris, “Installation and Operation of an EM Radiation Monitoring Network In Greece”,
3rd International Workshop on Biological Effects of Electromagnetic Fields, Kos, Greece, October
2004
[16] D. Komnakos, A. Gotsis et al, “Design, development and operation of an electromagnetic radiation
monitoring network in Greece: “Hermes” project.”, 4th International Workshop on Biological Effects of
Electromagnetic Fields, Crete, Greece, October 2006