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Environmental management in cellular and

PCS phones: A Saudi Telecom-Assir study

M. Bayoumi* & S.T. Jerman^^Arab Academy for Science and TechnologyD̂irector General of the Assir region ofArabi Saudi Telecom

Abstract

Saudi Telecom is concerned with the relationship between human health andcellular and PCS phones and their base stations. From the point of view ofenvironmental management principals, it was necessary to review this subjectand evaluate the potential impact on human health. It was also necessary todefine regional and international criteria to ensure that phones and base stationswill meet the safety standards.

The above mentioned review and criteria are involved in the actual study.The technical specifications of the 55 base station towers covering the Assirregion in the Arabic Saudi Telecom were also given. The study shows that theRF exposure around the tower for the type of antenna and towers used is withinthe safety limits determined by the Institute of Electrical and Electronics,American National Standards Institute (ANSI / IEEE) and the National Councilof Radiation Protection and Measurement (NCRP).

The Assir-Telecom company have created a code of practice for working inthe controlled spaces which have RF radiation limits above the maximumpermissible determined for public.

1 Radiation

Human beings are surrounded by both natural and artificial radiation. Forexample, the sun is the most well known producer of natural radiation. Itswavelength ranges from long wave infra red to ultraviolet. In general, radiation isdefined as a sort of energy contained in high-speed particles and electromagneticwaves. If the radiation has enough energy during its interaction with thesurrounding atoms; enough to remove tightly bound electrons from their orbits

Management Information Systems, C.A. Brebbia & P. Pascolo (Editors) © 2000 WIT Press, www.witpress.com, ISBN 1-85312-815-5

24 Management Information Systems

causing an atom to become charged or ionized. This type of radiation is calledionized radiation [1]. If the radiation does not have enough energy to removebound electron from their orbits around atoms, this type of radiation is callednon-ionizing radiation.

1.1 Ionizing radiation

According to the above-mentioned definition of ionizing radiation, several typescan be identified [2]); X-ray, alpha particles, beta particles, y-rays, Neutrons andcosmic radiation. Ionizing radiations are measured in Gray (Gy) and Sievert(Sv): The quantity of radiation or the doze received by a person is measured interms of the energy absorbed in the body tissue and expressed in grays. TheSievert is related to the biological effect caused by radiation. One sievertradiation produces a constant biological effect regardless of the type of radiation.The normal background radiation from natural sources is 2 m Sv/year.

1.2 Non-ionizing radiation

Some known sources of non-ionizing radiation are ultraviolet, visible light,microwaves, television electromagnetic radiation, AM and FM radiation andpower lines electromagnetic fields [2]. In this part we review some non-ionizingradiation sources, applications and discussing their biological effects.

LasersLaser equipment is widely used. The lasers used for surveying and leveling aredetailed in certain publications, e.g. [3]. Helium and neon gas laser devices areused for these applications, as the light travels in a straight line over longdistances. For accurate leveling for a large area, a motor driven prism reflectormay be used to rotate the laser beam [4].

Biological damage may be caused to the absorbing tissues due to laserheating: The human eye may focus on the beam causing thermal burning toretina. The Australian standards 2211-1981 [5], related to laser safety, classifythe laser devices into four categories or classes. This classification includes thebeam energy and other technical specifications. Although the class of the deviceis determined by the standard 2211-1981, another Australian Standard, 2397-1980, is used as a guide to the safe use of lasers in the construction industry [6].

MicrowavesMicrowaves, as visible light [6], are non-ionizing radiation and both are a part ofthe electromagnetic radiation at extremely high frequency radio waves.Microwaves are used in many applications such as radar, satellitecommunication and much domestic equipment such as microwaves ovens. Inovens the microwaves generated by a magnetron vibrate the water molecules inthe food to a frequency of around 2450 MHz. The friction between the vibratedmolecules produces the required heat.


Management Information Systems 25

The microwaves generated cease to exist once the supplied electrical poweris turned off. The microwaves are contained inside the designed equipment of theoven itself. In such ovens a safety interlock switch stops the generation of wavesonce the door is opened. Studies have been carried out to reduce door leakage[7]. Some countries like Australia produced standards for testing and approval ofsuch equipment [8]. The detectors used in testing have standards [9], and thepacemakers must not be susceptible to microwave radiation, any leakage must bewithin the limits of the standards.

1.2.1 Radiation from Video Display Terminals (VDTs)VDTs are used to interact with computers. Most VDTs are based on Cathode-Ray Tube (CRT) [10]. This type is designed to emit visible radiation. The CRTis an evacuated tube which has an electron source at one end and a phosphorus-coated screen at the other end. The interaction of electrons with phosphor causesthe emission of visible radiation and a small amount of ultraviolet radiation fromthe screen. Also low energy X-rays, which are absorbed by the glass, and someinfra red radiation is found. Radio frequency radiation is emitted by thedeflection coil moving the beam by the CRT or the beam high voltagetransformer. An extremely low frequency electromagnetic field (EMF) wasdetected. The RF emissions and the low frequency EMF occur in all directionsfrom the VDT.

Some health effects were documented, such as eye problems and skindisorders. Eye problems were observed in operators having close-visual tasks.Skin disorders are due to the build-up of electrostatic charges on the operator'sbody. The Australian Radiation Laboratory has measured microwave, radiofrequency, ultraviolet and X-rays emissions from different models of VDTs [11].The levels of emission were computed by the limits of exposure given by theInternational Radiation Protection Association and were found to be withinnormal limits.

1.2.2 Marine radar microwavesSome small marine vessels are equipped with radar, with power up to 10 kW[12]. This type of radar emits short pulses of microwave radiation, which may bereflected by objects. This reflection is displayed on the radar screen. Themicrowave radiation from this radar may therefore reach a crew or people aroundthe vessel. This type of radiation is not hazardous unless its intensity is highenough to cause sufficient heating in living tissues due to the absorption ofmicrowaves and its conversion to heat energy. The Australian Standard 2772-1985 specifies a maximum safety limit for microwave exposure [13]. Thisstandard states that persons must not be exposed to a level higher than anaverage 0.2 mW/cnr, with the peak level not exceeding 1 W/crn̂ . Measurement[14] showed that at 1 meter from the antenna, the peak level is about 0.5 W/cnfwhile the average intensity is between 0.5 and 0.8 mW/cnf. At several metersfrom the antenna the intensity drops to below 0.2 mW/cm".



1.2.3 Mobile phone Radio Frequency radiationWhen a call is made from a mobile phone, RF signals are transmitted between itsantenna and the nearest antenna base station [15]. This type of phone emitssignals in a frequency ranging from 800 to 2200 megahertz (MHz). These wavesor signals are received by a rod like antenna. Two types of antenna are knownand can be distinguished far from the base station; whip and sector antenna. Thewhip antenna is known as a low gain antenna and the sector as a high gainantenna [16]. They can be mounted on a tower or on a building roof, see figure 1.

2 Environmental management in the RF phones issue

The present concern that people have about RF exposure implies the applicationof the environmental management principles to this issue: Starting with a reviewof the problem, evaluating its state of knowledge, and applying the transparencyprinciple to reach real, and correct, public awareness and ending by finding thelimits between the clear and ambiguous elements in the issue under examination.

The actual study is applied to the Assir-region in Saudi Arabia. The mobilephone system uses 55 towers serving 28253 users in a region of a populationabout 200489 citizens.

The actual study can be used to raise public awareness of the RF phonesissue. In the next sections, RF used in mobiles is determined in theelectromagnetic radiation spectrum. Also, the safe limits of exposure aroundtowers and at roofs are given, accompanied by its scientific credibility basis.

Some of the mathematical methods used in the environmental exposureevaluation are reviewed, especially the Near and Far Field RF modeling.

2.1 The mobile RF and the electromagnetic radiation spectrum

In the previous sections, the radiation was classified into ionizing and non-ionizing radiation, according to its energy, and the possibility that energy affectsthe human cell or the chemical bonds for elements inside it. It is important tonote that sometimes the classification is based on the frequency. It is the samesince there is a direct relation between the energy and the frequency through aconstant called Planck's constant. The frequency is the rate at which anelectromagnetic field changes its direction.

From the electromagnetic spectrum shown in figure 2, this spectrum can beclassified into non-ionizing and includes the non-thermal, the thermal and opticalfrequencies extending up to 10^ Hz. Radio waves, microwaves, infrared andultraviolet waves are also referred to as non-ionizing. The ionizing frequenciesinclude the very high frequency X-rays and those of radiation mentioned in theprevious part as a, p, y and neutron radiation.

The electric power in Saudi Arabia has 50 Hz frequency. The AM and FMradio frequencies are around 1 MHz and 100 MHz respectively. Microwaveovens have a frequency of 2450 MHz, while X-rays have frequencies up to 1million MHz. Mobile phones operate at frequencies ranging from 800 to 2200MHz according to the phone type system.



2.2 Safety standards and RF safety limits

The scientific credibility of the RF safety standards is based on a number ofstudies [17-24]. Common agreement between these studies can be grouped intothree important aspects. The first states that the extensive radio waves studiesreveal that radio waves, even for those frequencies not used in mobiles, cancause related heat damage at high rates of exposure. This damage is common inall applications such as radar, ovens, etc. In mobile application, public exposurecannot exceed the safety limits, as antenna power intensity is designed to befixed at a certain power. The second indicates that the biological effects of radiowaves depend on the absorption rate of energy. The third shows that mobilephones are an application like any other well established application; it onlyneeds a scientific public awareness.

Regarding the safety standards, for many countries there are national andinternational standards of public exposure to RF. The most widely usedstandards are developed by International Commission on Non-Ionizing RadiationProtection (ICNIRP) 17], the Institute of Electrical and Electronics Engineers[18] (IEEE) and the National Council on Radiation Protection and Measurements(NCRP) [20]. These societies, which are international or governmental societieswith great scientific credibility, gave radio frequency standards expressed in"plane wave power density" and measured in mW/cnf. The definition of "planewave" will be detailed below. These societies give exposure standards of 1.2mW/cnf for the general public (IEEE) and 0.57 mW/cnf (NCRP). It must benoted that all measurements take into consideration a safety factor superimposedon the lower limit of exposure causing damages. For this reason the techniciansworking in this field may be exposed to higher rates knowing, of course, the realexposure limits.

Knowing the standards for safety exposure limits, it was important to testthese values around the tower or the roof. Two studies [25] were effectuated foran antenna mounted at 40 ft which is similar in height to the Assir-Telecomtowers. The studies showed that the ground level power density at its highervalue was 0.005 mW/cnr, which is much lower than the standard. Power densityinside a building will be lower by a factor of 3 to 20 than outside.

2.3 RF modeling

As mentioned in the previous section, the radio frequency exposure standards areexpressed in "plane wave power density". This expression comes from the factthat the field radiates from an antenna like a ripple on the water [26] after apebble is thrown.

Before detailing the antenna models, it must be noted that the expressionplane wave means that it is far from the source or a far field case. This explainsthat the safety standards are measured and applied at far field conditions.



Cylindrical modelFor a rod-like antenna in a vertical position, the power density can be calculatedusing a circular radiation pattern and the height of the antenna. At a distance Xcm from the antenna and for a total antenna power P in mW, the power density D(mW/cnf) can be calculated, forming a cylinder around the antenna of height h(cm), by the formula

D = (m W/cnf)

2%Xh

From this formula, the shorter the antenna, the higher the field intensity forthe same antenna power. Also at the closer distance, the higher the fieldintensity.

Spherical modelIn far field situations, the antenna is considered as the point source. The powerdensity can be calculated by the formula

PGD = (m W/cnr)

where G is the gain ratio of antenna.

RF environmental energy managementAs mentioned before, there is no problem with exposure, except at the roof areawhere an array of antenna is located. Below the roof the intensity is reduced by afactor from 3- 20 times that in an open air.

This means that the exposure for the public is within the safe limits. Only theroof, at which antenna is located, must be inspected and modeled to determinethe intensity map at the roof level to prevent RF levels exceeding the safeprocedures for working and maintenance in the roof area. The above equationsare used in the modeling.

It will be interesting to compare the theoretical models for calculating thenear field and the far fields power densities around the antenna. The RF emissionfrom 1000 W power gain is represented in figure 3, the top view of powerdensity close to the antenna. The curve represents the power densities calculatedfrom the equations are a power given. This means that these equations can beused later to predict the power densities around the antenna of the Assir towersin order to put an environmental energy management plan for technicalassistance and maintenance for antenna and its supporting constructions in abuilding roof level and near an antenna tower into action.



3 Assir mobile phones network

The phone system is composed of 55 towers. Most of them are on separatetowers except those located at the Assir hospital, the Abha prison, theintermediate school, the old water station, the PTT Compound and theIntercontinental Hotel.

3.1 The system and network

The technical information for GSM used in Assir region is given in the followingtable:

AntennaeTypes ofantennaeDirection ofcoverageNo. of antennae

Antennaefunction

Duplex

1 way

1 antennae

Receive & transmit

Omni

Multi way

Receive & transmit

Sectorize

1 way

3antennae2 receive& 1transmit

FrequenciesType of linkFrequency

Up link890-9 15 MHz

Down link935-960 MHz

3.2 Electromagnetic energy management and awareness

In the previous section, it has been mentioned that the higher levels of RFenergies exist in the near field around the antenna sites. For this reason theadministration or the sites manager must prepare the necessary routine andemergency procedures to be applied in these sites existing in the near field area.The site plan must raise the worker's awareness of RF radiation and equipmentissues including antenna, antenna selection, antenna sites, building sites, towers,different RF levels and corresponding zones, documentation, operationguidelines, warning tags and caution signs etc.

Antenna sitesThere are two common sites used for antenna installation; the building and thetowers.

The most suitable building is the highest, and the antennas are mounted onthe roof at a certain height from the roof ground. The antenna is mounted on atubular structure and separated by at least 3 ft distance. It must be note that whilethe RF field from one antenna may be below the maximum permissible energylevel, several antennas located near each other may give levels exceeding the



occupation or the controlled maximum permissible energy level. Roof-View andTower-Calc [27] made a software modeling program for antenna sites. Zone oneincludes the lowest EME levels in the site, which is below 20% of theoccupational maximum permissible level. Zone two is any area in the near field.Figure 4 shows RF fields with five antenna transmitting. It can be seen that thecombined field produces levels over the MPE and the near field area requiresexposure controlling.

Towers are usually used as antennas supporting structures in isolated areas.The height of the tower depends on the required coverage. It was found that thecellular configuration gives less EME exposure to workers on the tower than thetwo-way tower configuration. The site manager must be aware that, in two-waytowers, a worker may be climbing the faces of several antennas at variouslocations with different powers up to 200 Watts.

Without going into technical detail, the EME level depends on the number ofantennas located at the tower. Figure 5 shows the EME mapping of a towercarrying 5 antennas. It can be seen that the EME levels for 5 activated antennasexceed the limits. The workers must be acquainted with this EME mapping. Thisgives an example of the necessity to an EME management to secure the safety ofthe workers: This responsibility lies with the site manager.

3.3 EME management factors

Some important factors for the site manager to consider are:1 - The type of antenna supporting construction, building or tower.2- The uptime period for the same antennas.3- The training of workers.The ideal objective of the site manager is to find the best environment for the

workers, with the lowest exposure conditions possible.As discussed in the previous section the site manager must have an EME

mapping for the site. This enables the worker to go through the working areaknowing all exposure conditions.

Also it was found that transmitters activities vary during the day and night.This variation may reach 30% and tests and measurements could produce anuptime period. So the site manager must locate the uptime periods since it affectsthe EME exposure levels on a site.

The training of a worker on-site is a must. No worker should pass into thecontrolled access of the antenna site unless he has received specific technicaltraining and EME awareness information. The site manager must issue"guidelines" for working in a radio frequency environment.

3.4 Guidelines of the Assir Telecom company for working in a radiofrequency environment

After surveying all the previous information and seeking advice from experts inthis field, the Assir Telecommunication administration created guidelinesdivided into three sections:-



Section A: GeneralSection B: Normal Working Practice•to ^Section C: Emergency and Accidental Working Practice.

GeneralThis section includes the site information, the appointed workers and therequired protection equipment.

The site manager must map the working spaces and transfer this knowledgeto appointed worker and must determine the site signs containing all theguidelines related to the site. The regions with RF levels above the MPE forpublic must have a special sign.

The site manager must create guidelines for the appointed workers includingthe necessity of ensuring that the working area carries the correct signs accordingto the RF mapping delivered by the site manager and that the transmitters are notoperating without shields.

The site manager must determine the correct RF monitors to be used by theworkers at the site. The correct functioning of these monitors is directly relatedto worker safety. In addition, the site manager must detenuine the properprotective clothing used in the controlled area.

Normal working practicesThis section includes all details beginning with approaching the site to workinginside and to leaving the site. Examples of these details are: "Before going intothe site to work with antenna, the worker must notify the manager and disablethe transmitters." The worker must be aware that human error may occur; theworker must verify that all requirements set out for him are obeyed. The workeralso must obey all signs in the controlled area.

Emergency and accidental working practiceThe site manager creates a working practice code for any emergency. This isimportant since working in restricted sites may include trouble-shooting of someworking radio transmitters. The site manager is responsible for choosing themost suitable worker for this task. The transmitters are usually supplied withshields to prevent strong RF radiation from reaching the workers. The code mustcontain regulations for occasions when the shield is removed to ensure that it isreturned to its place before starting the transmitter. The Assir Working Practicecode includes a special section for emergency and accidental cases.

4 Conclusions

In this study the Assir Telecommunication Management (ATM) reviews ionizingand non-ionizing radiation. This was carried out from the point of view ofcomparing the known used non-ionizing radiation to show where ATM can placethe RF radiation used in mobile phones. The literature showed that the RFradiation levels in worldwide systems, including mobile phones, are lower thanthe maximum permissible limit determined by the Institute of Electrical and



Electronics Engineers (IEEE), the American National Standards Institute (ANSI)and the American Federal Commission (FCC).

In the working area where levels exceed the maximum permissible for thepublic, the ATM created guidelines for working in radio frequencyenvironments. Those with technical and managerial experience developed thiscode into three sections. This code of practice would help to prevent accidents inrestricted areas. The detailed regulation of the code of practice would improveworker training and understanding of the RF radiation. Consequently thisimproves the working conditions of the telecommunications section.

References

[1] Radiation related terms- Dept. Nuclear Engineering- Oregon StateUniversity- \v\vw.ne.orst.edu/rhp//terms.html

[2] Non-Ionizing Radiation— www..health.gov.au/arl/hm nir.html[3] Charschan, S.S. (ed.)., Lasers in industry. New York: Van Nostrand, 1972.[4] Harry, I.E., Industrial lasers and their applications. New York: Mcgraw-

Hill, 1974.[5] Standards Association of Australia. Laser Safety. North Sydney, 1981.

A.S.2211.[6] Standards Association of Australia. Guide to the safe use of lasers in the

construction industry, 1980. A.S.2397.[7] National Health and Medical Research Council, Seventy-third Session,

Canberra, October 1971.[8] Standards Association or Australia. Australian Standard 3301-1980.

"Approval and Test Specification for Particular Requirements forMicrowave Ovens"

[9] Standard Association of Australia. Australian Standard 2889-1987."Microwave Oven Leakage Detectors for Household Use".

[10] Radiation Emissions from Video Display Terminals- vvww.healtlmov.au/arl/is_vdtrd.html

[11] Video Display Terminals- Health Concerns and Radiation Emissions.[12] Marine Radars Mounted on Small Craft-

www.heaJth.uov.au/arl/is marin.html[13] Australian Standard 2772 (1985)- "Maximum exposure levels-

Radiofrequency radiation 300 kHz to 300 GHz." Standards Association ofAustralia, North Sydney, NSW.

[14] D W Peak, D L Conover, W A Herman, R E Shuping- "Measurement ofpower density from marine radar." US Dept of Health, Education andWelfare publication (FDA) 76-8004, 1975.

[15] Mobile Telephone Communication Antennas: Are They a Health Hazard?-www.healtlygov.au/arl/is anten.html

[16] Cellular Phone Antennas and Human Health- www.mcu.edu/gcrc/cop/cell-phone-health-FAQ/toc.htrnl



[17] International Commission on Non-Ionizing Radiation Protection: Healthissues related to the use of hand-held radiotelephones and basetransmitters. Health Physics 70:587-593, 1996.

[18] IEEE Standards Coordinating Committee 28 on Non-Ionizing RadiationHazards: Standard for safety levels with respect to human exposure toradio frequency electromagnetic fields, 3 kHz to 300 GHz (ANSI / IEEEc95.1- 1991), The Institute of Electrical and Electronics Engineers, NewYork, 1992.

[19] International Commission on Non-Ionizing Radiation Protection:Guidelines for limiting exposure to time-varying electric, magnetic andelectromagnetic fields. Health Physics 74:494-522, 1998.

[20] National Council on Radiation Protection and Measurements: Biologicaleffects and exposure criteria for radiofrequency electromagnetic fields.NCRP Report No. 86, 1986.

[21] National Radiation Protection Board: Restrictions on human exposure tostatic and time varying electromagnetic fields and radiation. Doc NRPB4:1-69,1993.

[22] CG Likkle et al: Alteration of life span of mice chronically exposed to2.45 GHz CW microwaves. Bioelectomag 15:177-181,1994.

[23] MA Stuchly: Biological concerns in wireless communications. Crit RevBiomed Eng 26: 289-292,1991.

[24] J Juutilainen and R de Seze: Biological effects of amplitude-modulatedradiofrequency radiation. Scand J Work Environ Health 24:245-254,1998.

[25] RC Petersen et al: Radiofrequency electromagnetic fields associated withcellular-radio cell-site antennas. Bioelectromag 13:527-542,1992.

[26] Specifically, the ICNIRP standard is 0.40 mW/cm-sq for cellular phonefrequencies and 1.00 mW/cm-sq for PCS phone frequencies.

[27] Roof-Wiew and Tower-Calc - www.vegasnet/ stp/eme.htmI



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RF Emissions from a 1000W(ERP) Low-Gain Antenna(Top Yi«w of the Power Oensty Close to the Antenna)

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Figure 3 : Top view of the power density

Five Transmitting Antanoas Four Transmrtting Antennas

Figure 4 : (1 to 5) Activated antennae

Figure 5 : 1 and 5 Activated antennae


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