General Directorate of Environment & Wildlife Protection, Public Commission for the Protection of Marine Resources, Environment & Wildlife, Kingdom of Bahrain
FIELD STUDIES OF RF & EMF IN BAHRAIN
Mirza Salman Khalaf
Head of Pollution Control Section
1. Introduction
The Kingdom of Bahrain with a population of over 700,000 and land area of 712 sq. km. consist of 33 islands. The land limitation is responsible for having a population density of around 900 persons per sq. km., which is the highest compared to other gulf countries. The high population density, limited land resources, fast urbanization and industrial development are creating a host of public health and environmental related problems.
The Kingdom of Bahrain like other developing countries is also making use of modern and up-to-date technologies and are using tools, equipments, and machinery for individual, domestic, medical, commercial and industrial purposes which radiate Radio Frequencies (RF) and Electro Magnetic Radiation (EMF), which is considered as a source of hazard to the public health and the environment. The main sources of RF and EMF include television, radio, computers, mobile and cellular phone, microwave ovens and equipment used in medicine at universities and in industries.
In response to the public concern regarding EMF exposure and its adverse impacts on human health, the Public Commission carried out field studies and investigation during the last decade and has issued Health & Safety Guidelines to protect the public and workers from the Non Ionizing Radiation (NIR) exposure. The paper briefly describes the outcome of the studies and results conducted in the country.
2. Background
a. People in the Kingdom of Bahrain like in many other countries are very concerned that exposure to RF & EMFs could lead to adverse health effects including damage to nervous and reproduction systems and may lead to cancer. The health hazardous associated with living, working and playing near by the sources of RF & EMF were assessed by the Public Commission to address these main public concerns as the exact damage and impacts have not been identified through any study conducted. Furthermore, there is a misconception amongst people that the adverse impacts due to RF & EMF are not widely publicized by the Government agencies, which is mainly due to the lack of awareness and education on the subject. In this respect following two aspects are of main concern, which seems to be contradictory to each other:
i) After several detailed investigations and technical studies, many international organizations such as WHO and ICNIRP have concluded that there is no evidence that RF & EMFs can cause health effects such as cancer or any carcinogenic diseases.
ii) Many studies and reports are available on the Internet carried out by individuals and groups worldwide, which concluded that there are possible health effects due to RF & EMFs.
3. SURVEYS AND FIELD STUDIES
To date three comprehensive surveys and studies have been carried out by the Pollution Control Section, Public Commission for the Protection of Marine Resources, Environment & Wildlife along with the international and national experts in the years 1995, 1999 and 2001. The studies have elaborated on the hazardousness associated with the RF & EMF, investigating the protection procedures standard, prevention policies and exposure limits as well as adverse impact on the people located near to the facilities.
During the surveys, significant sources of NIR (RF&EMF) have been evaluated including telecommunication, meteorological and electricity generating and transmitting stations, navigational aid facilities, air traffic control, broadcasting and medical facilities, overhead transmission lines etc. The detail of the three surveys carried out is briefly mentioned as under.
3.1 THE FIRST RF & EMF STUDY
The first study was carried out along with an expert from WHO, Dr. John Leonowich and Mirza Khalaf from Public Commission during the period from 17-28 November 1995.
3.1.1 Purpose of the study
The purpose of the study was to:
- Define the extent of the hazardousness associated with the use of NIR in Bahrain.
- Develop a programmatic document with appropriate protection standards covering the complete spectrum of NIR from low frequency fields.
- Provide Basic training to the occupational health specialist in the analysis of RF&EMF hazardousness.
iv. Recommend appropriate instrumentations to measure the RF&EMF.
3.1.2 RF & EMF Sources
During the study and investigations, site visits were made to all the significant sources of RF & EMF including telecommunication stations, electricity main stations, air traffic control facilities and broadcasting facilities.
3.1.3 Equipment
The equipment used during the survey was a NARDA Model 8718 electromagnetic monitor with both electric and magnetic probes.
3.1.4 Results
The survey results showed that only in the diathermy physiotherapy unit in Salmaniya Medical Complex (Operation on 27 mHz) is exposed to electric field strengths which are more than 30 times the safety limits standards allowed by the ANSI/IEEE C951-1993. The other values noted were insignificant and much lower than the international standards.
3.2 SECOND RF & EMF STUDY
The second study was carried by the second Author during the period from 4-28 December 1999.
3.2.1 Purpose of the Study
The purpose of the study was to provide appropriate data and information to assess the degree of power density and the effective radiated power from the main sources of radio frequency in the Kingdom of Bahrain.
3.2.2 Equipment
Direct Measurement Method was used to measure the power density of RF. The instrument used was Model RAHAM (481) with serial No. 13100.
3.2.3 RF & EMF Sources
The RF & EMF sources investigated are mentioned below:
i) Telecommunications
§ Earth Station (Buj-Jarjorr Station).
§ Al-Hamala Telecommunication Station
§ GSM Station
§ Other Telecommunication Station
ii) Radio & TV Stations
iii) Air Port – Transmitting & Receiving Stations
§ Air to ground communication
- High Frequency (HF).
- Very High Frequency (VHF)
§ Radar frequencies.
§ Navigational Aids .
§ Metrology.
§ Weather Radar
3.2.4 Results
The radio frequency sources and the range of measurements carried out are summarized as follows:
- Radio Station 801 kHz to 959 MHz
- T.V Station – 62MHz to 7 GHz.
- Airport Station – 75 MHz to 3050 MHz.
- GSM Towers – 945.200 MHz to 959.800 MHz
- Earth Station – 9525 MHz to 6425 MHz
- Al-Hamala Station – 3MHz to 30 MHz with max.22MHz.
The summary of results from Power Density from the RF sources are mentioned as follows:
- Radio Station Transmitting & Receiving Towers (short & medium wave and AM broadcasting)-0.2uw/cm2.
- T.V. Station (VHF, FM, Microwave, and other T.V. channels) – from 0.1uw/cm2 to 10uw/cm2.
- Air Port Radar's and other communication transmitting system – from 0.01uw/cm2 to 9.5uw/cm2.
- Al-Hamala Station (Transmitter Towers) from 0.01uw/cm2 to 4uw/cm2.
Earth Satellite Station from 0.3uw/cm2 to 0.4uw/cm2
- Salmaniya, Sanad and Jabal Al-Dakhan Stations from 0.0002 to 0.4uw/cm2.
The study confirmed that most of power transmitter antennas are located on high towers (30 - 40 meters). The air traffic tower, weather radar's and satellite dishes are built with narrow beam width in accessibility. Therefore, these sources are not hazardous or do not pose a hazard to individuals on the ground and will not be risky to the workers and to the
general public. These sources can however, pose a potential hazard only for workers who climb the radars and towers for maintenance purposes if they perform the tasks without any protection or without putting off the source.
From the overall results of these measurements and investigation, the basic conclusion drawn is that the measurement values and results in all sources and areas are insignificant and much lower than the international standard recommended levels.
Only two sources (Microwave sources in TV station – 10uw/cm2 and Cossor radar's at the air port near antenna joint-9.5uw/cm2) were identified within the National proposed standard (10uw/cm2). Although, the results were within International Standard, but the expose workers should be advice to reduce the time of exposure by reducing the their working schedule and using personal protection equipment.
3.3. Third RF& EMF STUDY
This study was carried by a German Company (Rohde & Schwarz Cologne) in co-operation with the Public Commission and Batelco. It was conducted during the period from 22-31 July 2001. The results obtained were sent to WHO and ICNIRP for assessment. The ICNIRP then recommended the appointment of Dr. Michael Bangay from the Australian Radiation Protection and Nuclear Safety Agency (ARP&NSA) to have carry out the evaluation of the survey.
3.3.1 The Purpose of the Survey
The purpose of the survey was to investigate any possible negative impacts on the people living nearby the RF&EMF sources.
3.3.2 Equipment
The equipment used for the measurements at Substations and Overhead-Power lines included the following:
1. / Magnetic (B-) Field Analyzer / EFA-300 / BN2245 / 5 Hz to 32 kHz2. / Electric (E-) Field Sensor for EFA / BN2245/90.31 / 5 Hz to 32 kHz
The equipment used for the measurements at Broadcast and TV- Transmitter stations and at Airport Facilities included the following:
1. / Spectrum Analyzer / FSBS / Rohde & Schwarz / 100 Hz to 5 GHz2. / Crossed Log.-Per.-Antenna / HL 024 A1 / Rohde & Schwarz / 1 GHz to 18 GHz
3. / Log.-Per.-Antenna / HL 223 / Rohde & Schwarz / 200 MHz to 1.3 GHz
4. / Biconical Antenna / HK 116 / Rohde & Schwarz / 20 MHz to 300 MHz
5. / Loop Antenna / HFH 2-Z2 / Rohde & Schwarz / 9 kHz to 30 MHz
6. / Spectrum Analyzer / HP8563E / Hewlett Packard / 300 MHz to 26.5 GHz
(Equipment No. 6 was only used for the measurement of the weather radar)
3.3.3 RF&EMF Sources
Following RF & EMF sources were assessed and analyzed.
- Electricity substations (32) and overhead power lines (6)
- Air traffic control and navigational aid facilities (13)
- Broadcasting and T.V stations (9)
- Telecommunication stations (40 GSM base stations).
3.3.4 Measurement
a. Power Frequency Fields
Measurements of electric and magnetic fields at frequencies from 0 Hz to 2000 Hz was obtained in the vicinity of power generation and distribution facilities. The only signals above background were at the frequency of electric power, 50 Hz.
b. RF EME Fields
For active transmitters, the electric field strength was measured with a spectrum analyzer and an antenna appropriate for the particular frequencies being generated by each transmitter. At each site, the five highest electric field strengths were recorded from an antenna. The total output at each site was assessed by including the contributions from each of these five field strengths.
The measured electric field strength values were reported in the engineering units of decibel microvolts per meter (dB u V/m). These values maybe converted to units of V/m using the relations
E[V/m]= / Log-1 / E[dBuV/m]-12010 / 20
3.3.5 Results
The results of the study are briefly mentioned as follows:
1. ELF (Extremely Low Level Frequency) field levels recorded at locations near 220kv electrical sub-stations: Out of 6 sub-stations evaluated, the highest magnetic field strength recorded was at the Medinat Hamad site. The limit as set out by ICNIRP is at least 3 times greater than this level.
2. ELF magnetic field levels recorded at locations near 66kv electrical sub-stations: Out of the 23 sub-stations evaluated, the highest magnetic field strength recorded was found at the college site. The limit specified by ICNIRP is at least 16 times greater than this level.
3. ELF levels recorded at locations underneath power lines from Isa Town North to the Refinery: Out of the three locations evaluated, the highest electric field strength recorded was found at the University of Bahrain site. The limit specified by ICNIRP is at least 5.9 times greater than this level.
4. ELF levels recorded at locations underneath power lines from Sitra Power Station to the refinery: Out of the three locations evaluated, the highest electric field strength recorded was found at the Sitra High Way M.M. Kooheji site. The limit specified by ICNIRP is at least 10 times greater than this level.
5. Equivalent RF EME (electromagnetic energy power flux density) field strength: Out of the 41 locations evaluated, the highest level recorded was at Bukawara site in East Riffa. The limit specified by ICNIRP is at least 550 times greater than this level.
RF levels at locations around the Airport: The highest levels recorded were found to be at Gallali Village, next to Building No: 509 Road 5339 Block No: 253. The limit specified by ICNIRP is at least 1400 times greater than this level.
6. Output from Radio and TV transmission towers: The measurement of RF was taken at three locations. The highest level was being found at Isa Town, Road No: 915, Block No: 809 (Opposite Ministry of Education). The Limit specified by ICNIRP is at least 470 times greater than this level.
In conclusion, the magnetic fields measured near the sub-stations in close proximity to the residences were found to be insignificant and not off environmental and public health concern. Furthermore, there exist insufficient evidences to warrant relocation of the existing substations or undertaking any further and expensive field mitigations. However, it is suggested that future electrical power infrastructure (sub-station/transmission lines) should be located away from the residences as a response to the "passive regulatory action".
The study also showed that mobile base stations and broadcasting towers produce weak RF & EME. The highest reported level of base station for RF & EMF measurement in Bahrain was at Bukawara where the cumulative level was 550 times less than the ICNIRP limit. The highest broadcast RF & EME level was measured at Isa Town Road 915, Block 809 (opposite Ministry of Education) but was 474 times less than the ICNIRP limit.
The results clearly demonstrate that the RF & EMF values from GSM base-station, airport facilities and broadcast radio and television transmitters were at least several orders of magnitude below the limits set by ICNIRP.
4. Health Impacts
To date, the only health effect that has been proven to exist as a result of exposure to RF & EMF relates to the heating of human body parts, which is known as thermal effect. The ICNIRP limits have been set to avoid adverse heating effects caused by exposure to RF & EMF. There are unlikely to be any significant long-term or short-term impacts on the health on individuals with respect to the public exposed to the RF EMF fields.