Scientific Study: RF Radiation Levels From Celluar Towers

This study presents data related to GSM (Global System for Mobile Communications) cellular phone radiation resulting from antenna sites and towers inside residential areas in Germany. A statistical evaluation of over 200 representative high frequency field measurements is presented for the years 2001 and 2002.

Measurements were conducted at different distances and directions using a frequency selective spectrum analysis to obtain only GSM power densities following the Swiss guideline for GSM cellular phone radiation measurements. Derived from this data, GSM cellular phone tower radiation is dominant in comparison to FM radio or TV emissions. The median power density was found to be in the range of 200 µW/m² with the maximum level exceeding 100,000 µW/m². A total of 25 percent of the power densities exceeds 1,000 µW/m², which has been suggested to be the average threshold value for non-thermal biological effects. Two of the most important factors are the distance and the direct line of sight to the antenna site. At the typical residential cell tower distance of about 250 m in cities, with direct line of sight, the observed levels are in the range of 200 µW/m².

The results show that, especially for future cellular UMTS (Universal Mobile Telecommunications System) applications, there are several options to minimize additional HF radiation exposures for the population and reduce the potential risk for harmful exposures.

Introduction

The GSM technology of wireless communication produces constant pulsed microwave radiation. The cellular base stations are transmitting continuously even when nobody is using the phone. We know from a variety of scientific studies, that significant biological effects result from the non-thermal effects of extremely periodic – pulsed – HF-radiation as are utilized in the most common modern digital cellular and cordless phone systems in Germany and round the world. Official international and national standards and safety guidelines (based on ICNIRP recommendations) are still only taking into account the risk of thermal effects of high energy HF-radiation.

Most of the official HF public exposure measurements are conducted to observe the percentage of the current standard with only broadband – not frequency selective – measurements. Only in very few cases one or more percent of the (thermal) guideline value is reached or exceeded close to antenna sites. Exposure recommendations based on non-thermal effects are by far lower by many magnitudes. Frequency selective measurements are necessary to observe the cellular base station downlink frequencies and differentiate from other radiation sources as FM radio or TV transmitters. Therefore, very limited information is available on the exposure to cellular base station radiation in residential areas at different distances and directions to antenna sites.

The objective of this field study was to collect measurement data, statistical evaluation, documentation and exposure assessment for cellular phone tower radiation in Germany. Measurements were conducted at different distances and directions, inside and outside of representative public and residential buildings. Frequency selective spectrum analysis was used to obtain GSM power densities following the current recommendations for GSM cellular phone radiation measurements.

Methods and Results

Power density measurements were performed with an Advantest R3131 spectrum analyzer (Rohde & Schwarz) and a calibrated periodic logarithmic log.per. antenna USLP 9143 (Schwarzbeck). The power density measurements were conducted under real-life conditions and only downlink frequencies of the GSM cellular base stations were measured. The antenna was directed in various orientations in order to receive local maximum power densities by peak hold measurements in respect to orientation, polarization, reflection, and interference. For each narrow band region of interest (GSM900, GSM1800) data collection was conducted for 3 x 1 min. scanning time. All measurements were conducted following VDB guideline (VDB 2002) and the Swiss BUWAL guideline (BUWAL 2002). The power density levels are given in µW/m² (microwatt per square meter). 1 µW/m² equals 0.1 nW/cm² (nanowatt per square centimeter). The limit of detection was 0.001 – 0.002 µW/m² (-70 dBm) per channel power density. The extended error is  ± 45 % (BUWAL 2002).

The measurements included a total of 272 locations (132 inside / 140 outside), power densities of all GSM downlink organization channels per location, summation to the maximum possible total power density, and documentation of the distance and the line of sight to the dominating antenna site. Distance profiles were taken for selected locations and different antenna heights and positions. In addition, data for FM radio, TV, DECT cordless phone and other significant HF sources were collected for comparison. Figure 1 shows a typical HF spectrum analysis overview of a location in close vicinity to an antenna site.

Figure 1: HF spectrum analysis – overview

Statistical Data and Percentiles

The percentiles for the observed power density values are presented in Table 1. Including all locations, the median distance was 150 meter (450 feet), which is in the range of typical residential distances to GSM base stations in larger cities. The 20^th percentile value is 10 µW/m² and can be considered as residential background GSM radiation level. The 50^th percentile value is found at 200 µW/m² (median). The 95^th percentile is observed at 6,300 µW/m² and can be considered as a significant exposure radiation level. The maximum value of 103,000 µW/m² was found in a residential building in the 4^th floor in line of sight and in the same height to the antenna site at a horizontal distance of 30 meter. In addition, data sets for line of sight, without line of sight, inside and outside locations were calculated separately. (see Table 1 and Figure 2 for further details)

Table 1: GSM cellular tower base station power density levels – percentiles

Figure 2: GSM cellular tower base station power density levels – percentiles

Figure 3: GSM cellular tower base station power density levels – line of sight and distance

Distance, Line of Sight and Exposure Parameters

The power density values are displayed in Figure 2 in respect to line of sight / without line of sight and the distance to the antenna site. It is obvious, that especially in proximity to the antenna site (< 250 m), the GSM radiation levels are scattering due to various influencing parameters and cannot be calculated easily by using antenna power and distance models only. Table 1 shows a significant systematic difference between the percentile data from line of sight and without line of sight measurements. Figure 2 displays the separated sets of data with trend lines decreasing exponentially to larger distances with lower exposures for without line of sight measurements in the range of 90% reduction (-10 dB). In general, the radiation exposure is predominantly determined by e.g. the following parameters:

• 
  

  Distance to the antenna site

  
  


• 
  

  Line of sight to the antenna site

  
  

• 
  

  Type of the antennas, e.g. omni directional or directional antennas

  
  


• 
  

  Number, power, and orientation of the antennas

  
  


• 
  

  Capacity of the antenna site (number of channels / frequencies)

  
  


• 
  

  Vertical distance between location and antenna site

  
  


• 
  

  Type of building construction / type of window glass

  
  


• 
  

  Total reflection of the environment

  
  

Distance and Phone Tower Positions

The distance profiles were taken for selected locations and different antenna heights and positions. For high antenna positions (e.g. 50 – 90 m, pole mount position) the maximum power at ground level is reached in about 300 meter and is rather moderate. For low antenna positions (15 – 20 m, typical roof top position) the maximum power at ground level is relatively high and is reached in about 50 meter. Figure 4 shows the average (mean) density values found in distance ranges. We observed no straightforward exponential decrease by distance only. The slight increase in the distance range of 150 – 200 meter (1,480 µW/m²) can be explained by the influence of high antenna positions with maximum values shifted to larger distances.

Figure 4: GSM power density levels and distance ranges

Below and Close to Roof Top Positions

Directly below roof top positions (e.g. schools, preschools, homes) significant exposures in the range of a few 1,000 µW/m² were observed due to secondary side lobes and reflections. During our data collection, the highest exposure values in the range of 10,000 – 100,000 µW/m² were observed very close to low antenna / roof top positions at inside and outside locations in line of sight and distance < 100 meter.

DECT, TV and FM Radio

The data for FM radio, TV, DECT cordless phone and other significant HF sources show that the GSM cellular phone tower radiation is the dominating HF source in residential areas. DECT signals were detected in 60 inside locations. The maximum DECT power density levels were 0.01 µW/m² (20^th percentile), 1 µW/m²

(50^th percentile) and 1,680 µW/m² (95^th percentile). High exposure levels > 1,000 µW/m² were only detected when the DECT cordless base station was located in the same room or very close to the testing site.

Summary

The results of this study show that the GSM cellular phone tower radiation is the dominating HF source in residential areas in Germany. The median power density is found in the range of 200 µW/m² (50. percentile) with the maximum value exceeding 100,000 µW/m². No location reached or exceeded the official standard values for the USA or Germany.

For comparison, thermal (official threshold), other non-thermal (recommendations), and cellular tower exposure reference values are listed in the table 2 below.

Table 2: Comparison of Standard Threshold Values and Recommendations

	Total	With line of sight	Without line of sight	Outside	Inside
Number of measurements (n)	272	177	95	140	132
Distance in meter (median)	150	100	250	200	100
Power density in µW/m2
Mean	1,800	2,650	130	1,150	2,450
20th percentile	10	70	2	20	10
50th percentile (median)	200	430	20	200	170
70th percentile	640	1,700	70	580	640
90th percentile	3,400	5,200	280	3,260	3,770
95th percentile	6,300	8,500	610	6,490	5,330
99th percentile	23,000	25,000	1,340	12,350	32,000
Maximum	103,000	103,000	2,200	14,400	103,000

Therefore, in respect to recent studies and review of articles regarding non-thermal biological effect of e.g. digital pulsed GSM radiation, the stoa study concluded with a considerable concern revealing a need clear need for radio frequency safety. For example, 25 % of the locations the long term exposure levels are very high above 1,000 µW/m², which has been suggested to be the average threshold value for non-thermal biological effects. These levels are reached especially in proximity of the antenna sites, directly below antenna sites and in line of sight in a distance of < 250 m. Two of the most important limiting factors are the distance and the direct line-of-sight to the antenna site. But, in proximity to the antenna site, the GSM radiation levels are scattered due to various influencing parameters and cannot be calculated easily by using antenna power and distance models only. In general, exposures for without line of sight locations are about 90% (-10 dB) lower than those for line of sight.

In comparison to recommendations for exposure assessment (OEKOTEST 2001), the statistical data evaluation is the following (see figure 2):

• 
  

  20 % of data in the range of low exposure below 10 µW/m² (20^th percentile, background level)

  
  


• 
  

  25 % of data in the range of medium exposure between 10 – 100 µW/m²

  
  


• 
  

  55 % of data in the range of high exposure above 100 µW/m²
  

  
  

Very few measurement data are in the range of extreme exposure 10,000 µW/m²to 100,000 µW/m².

Conclusions

As long as the only basis for official standards for high frequency radiation are thermal effects and heating of the body tissue (ICNIRP, ANSI, IEEE, NCRP, FCC, SSK, WHO) there is no need for the industry to invest into less emitting and saver products. More and more scientists state that the view of energy absorption only is insufficient to describe the possible rf radiation effects on human health. Potential biological effects need to be considered due to

1. 
   

   Non-thermal or low intensity levels of HF radiation,

   
   


2. 
   

   Chronic versus acute exposure and,

   
   


3. 
   

   Pulsed HF radiation, which is reported to be more bioactive than constant wave RF radiation.

   
   

The human body reacts more complexly than acknowledged in the thermal model and is sensitive to extreme periodic stimuli. The biological system takes the “energy” as well as the “information” which is brought by the continuous pulsed modulation pattern. Much experimental evidence of non-thermal influences of microwave radiation on living systems have been published in the scientific literature during the last 30 years – relating both to in vitro and in vivo studies – and were reviewed just recently by the STOA commission for the European Parliament (STOA 2001). From the use of microwave wireless technologies e.g. the following non-thermal biological effects have been reported:

• 
  

  Changes in the electrical activity in the human brain (von Klitzing 1995)

  
  


• 
  

  Increase in DNA single and double strand breaks from RF exposure to 2.45 GHz (Lai & Singh 1996)

  
  


• 
  

  Increased lymphoma rates (2 fold) in transgenic mice exposed twice a day exposed to 30 minutes of cell phone (GSM) signals over 18 month (Repacholi 1997)

  
  


• 
  

  Increased permeability of the blood-brain barrier in rats (Persson 1997)

  
  


• 
  

  Production of heat shock proteins and cancer risk (French 2001)

  
  


• 
  

  Higher risk of uveal melanoma (Stang 2001)

  
  

Other reported effects include e.g. (STOA 2001):

• 
  

  Observation of an increase in resting blood pressure during exposure,

  
  


• 
  

  Increased permeability of the erythrocyte membrane,

  
  


• 
  

  Effects on brain electrochemistry (calcium efflux),

  
  


• 
  

  Increase of chromosome aberrations and micronuclei in human blood lymphocytes,

  
  


• 
  

  Synergistic effects with cancer promoting drugs and certain psychoactive drugs,

  
  


• 
  

  Depression of chicken immune systems,

  
  


• 
  

  Increase in chick embryo mortality,

  
  


• 
  

  Effects on brain dopamine/opiate electrochemistry,

  
  


• 
  

  Increases in DNA single and double strand breaks in rat brain,

  
  


• 
  

  Stressful effects in healthy and tumor bearing mice,

  
  


• 
  

  Neurogenetic effects and micronuclei formation in peritoneal macrophage.

  
  

In this review study, a threshold of 1,000 µW/m² was pointed out for non-thermal biological effects. For locations with any long-term exposure, a further safety factor of 10 was recommended for pulsed cellular phone radiation sources as cellular phone base stations. In this case, the power densities should not exceed 100 µW/m². Although, the power density of the radiation used in these experiments is typically found in the head area when using a cellular phone, the information content of the radiation emitted by the latter is the same; accordingly, these results are not irrelevant to the consideration of potential adverse health effects associated with chronic exposure to cellular or cordless base-station radiation.

From the scientific point of view, adverse human heath effects of non-thermal radiation levels cannot be exactly quantified, verified, or excluded at this time. Only limited toxicological information is available in respect to the widespread use and the economical impact of the cellular phone systems in industrial nations. On one side, there is always a demand for scientific proof for human adverse health effects and dose response when establishing official economically reasonable guideline exposure threshold values. On the other side, insufficient limit of detection, insufficient dosimetry and exposure control, and industry friendly research bias the risk assessment for long-term adverse health effects, especially in the field of the cellular phone industry. That makes it clear – that by definition – official guideline standard values can only limit the consequences of adverse health effects in the frame of the economical impact.

Recommendations

We recommend to follow the principle of prevention. This includes implementation of residential exposure minimization and prevention procedures in the frame of the technical feasibility as long as the non-thermal effects are not considered in any official standard and guideline. These will include especially sensitive locations as preschools, schools, hospitals, and residential areas. So far, no other technical aspects than interferences, system coverage and system performance are taken into account.

By official definition, the cellular phone system covers an area when the signal strength of about 0.001 µW/m² is reached. We expect that with little effort, cities, communities, and the providers will be able to significantly reduce the long term rf radiation exposures to cellular phone towers in residential areas.

Read Additional EMF RF Articles:

• RF Radiation Study: How To Measure RF Exposure


• Is An iPad Radiation Shield For RF Shielding Effective?


• Cell Tower Shielding In San Diego

If you have concerns about your home, building, school, or any other structure that is close to cell tower, call the experts at EMFRF Solutions to have your location tests and advice on how to properly shield from the radio waves. Call 760-942-9400 Today!

HF-Radiation Levels of GSM Cellular Phone Towers in Residential Areas

Thomas Haumann¹, Uwe Münzenberg², Wolfgang Maes³
AND Peter Sierck⁴

¹Umweltanalytik und Baubiologie, Meisenburgstrasse 25, D-45133 Essen, Germany

²AnBUS e.V., Mathildenstrasse 48, D-90762 Fürth, Germany

³Baubiologie Maes, Schorlemerstr. 87, D-41464 Neuss, Germany

⁴Environmental Testing & Technology, Inc., 1106 Second Street, Encinitas CA 92024, USA

References

BUWAL 2002 Schweizer Messvorschrift für GSM-Sender 2002, BUWAL – Bundesamt für Umwelt, Wald und Landschaft. (www.buwal.ch)

Ecolog 2000 Hennies K., Neitzke H.-P. & Voigt H., Mobilfunk und Gesundheit – Bewertung des wissenschaftlichen Erkenntnisstandes unter dem Gesichtspunkt des vorsorgenden Gesundheitsschutzes. Im Auftrag der T-Mobil. Hannover, April 2000 (ECOLOG-Institut für sozial-ökologische Forschung und Bildung, Nieschlagstr. 26, D-30449 Hannover, Germany)

French 2001 French P. W., Penny R., Laurence J. A. & McKenzie D. R. , Mobile phones, heat shock proteins and cancer. Differentiation 2001, 67 (4-5), pp. 93-97.

Lai & Singh 1996 Lai H. and Singh N.P. Single and double-strand DNA breaks after acute exposure to radiofrequency radiation. Int. J. Radiation Biol. 1996; 69: 13-521. See also: Singh N.P. and Lai H. Use of the microgel electrophoresis assay to study DNA strand breaks after microwave exposure. Proc. Asia Pacific Microwave Conf. (Editor: R.S. Gupta) 1996, Vol. 1 (B1-4), pp.51-55.

MAES 2000 Maes W., Stress durch Strom und Strahlung, 4^th ed. 2000, Verlag Institut für Baubiologie und Oekologie IBN, Neubeuern, Germany.

OekoTest 2001 Test “Mobilfunk-Sendeanlagen”, Öko-Test 4/2001 Germany, April 2001, pp. 32 – 40. (www.oekotest.de)

PERSSON 1997 Persson B.R.R. et al., Blood-brain barrier permeability in rats exposed to electromagnetic fields used in wireless communication, Wireless Networks 1997; 3: pp. 455-461.

Repacholi 1997 Repacholi M.H. et al. Lymphomas in E µ-Pim 1 transgenic mice exposed to pulsed 900 MHz electromagnetic fields. Radiation Res. 1997; Vol 147, pp. 631-640.

Resolution 2000 Salzburg Resolution on Mobile Telecommunication Base Stations – International Conference on Cell Tower Siting, Linking Science & Public Health, Salzburg, Austria, June 7-8, 2000. (www.land-sbg.gv.at/celltower)

SBM 2000 Baubiologie Maes and IBN, Standard der Baubiologischen Messtechnik SBM 2000, Richtwerte für Schlafbereiche, in “Stress durch Strom und Strahlung”, Maes W., 4^th ed. 2000, pp. 542 – 545, Verlag Institut für Baubiologie und Oekologie IBN, Neubeuern, Germany. (www.maes.de)

Stang 2001 Stang A., Anastassiou G., Ahrens W., Bromen K., Bornfeld N., and Jöckel K.H., “The possible role of radio-frequency radiation in the development of uveal melanoma” in: Epidemiology 2001, Vol, 12, pp. 7-12.

STOA 2001 THE PHYSIOLOGICAL AND ENVIRONMENTAL EFFECTS OF NON-IONISING ELECTROMAGNETIC RADIATION, STOA – Scientific and Technological Options Assessment, Options Brief and Executive Summary, PE Nr. 297.574 March 2001, (www.europarl.eu.int/stoa/publi/pdf/00-07-03_en.pdf)

VDB 2002 VDB-Richtlinie, Teil II A 3, draft 2002, Verband Deutscher Baubiologen e.V. (www.baubiologie.net)

von Klitzing 1995 von Klitzing L. “Low-Frequency pulsed electromagnetic fields influence EEG of man.” Physica Medica, Vol. 11, No. 2, 77-80, April-June 1995, see also von Klitzing, L. in “Elektrosmog – Wohngifte – Pilze, Baubiologie – praktische Hilfe für jedermann”, Maes W., 1st Ed.1999, Haug-Verlag, Heidelberg, Germany.

Read the full story at: http://www.emfrf.com/rf-radiation-levels-from-celluar-towers/

Comparison of Standard Threshold Values and Recommendations (electromagnetic fields, non ionizing radiation)	Total Power Density
Standards, GSM1800/GSM1900/UMTS/DECT (e.g.)
FCC/ANSI – USA	10,000,000 µW/m2
Germany, England, Finland and Japan	10,000,000 µW/m2
Belgium	1,200,000 µW/m2
Switzerland and Italy	90,000 µW/m2
Recommendations / References (e.g.)
Ecolog Study, Germany (Ecolog 2000)	10,000 µW/m2
Cellular tower radiation – significant exposure level, 95th percentile (this study)	6,300 µW/m2
Salzburg, Austria (Resolution 2000)	1,000 µW/m2
Cellular tower radiation – median level, 50th percentile (this study)	200 µW/m2
High exposure, Oeko-Test (OekoTest 2001)	100 µW/m2
EU Parliament (STOA 2001)	100 µW/m2
Cellular tower radiation – background level, 20th percentile (this study)	10 µW/m2
Low exposure, Oeko-Test (Oeko Test 2001)	10 µW/m2
Nighttime exposure, Baubiology Standard (SBM 2000)	0.1 µW/m2
Successful communication with GSM mobile phone, system coverage requirements	0.001 µW/m2
Natural cosmic microwave radiation (Maes 2000)	0.000001 µW/m2

What is EMF (Electromagnetic Fields) 101 – By EMF & RF Solutions

This report is an overview on what is EMF (electromagnetic fields), what are the sources, how do we test for EMF, what do the measured values mean and what are the recommendations from governmental agencies.

Introduction

Without electricity, our world would stop. Electricity has great benefits and makes our lives so much more convenient. The electrical power system produces the lighting, heating, cooling and power we all need for our appliances and electronic devices. Electrical power distribution systems use alternating currents (AC) to provide electricity to residential, commercial and institutional buildings. The current is generated in power stations, transformed to specific voltages, transported via transmission and distribution lines and building wiring to the user. Step down transformers provide the required voltage and bring the three phase electricity to one phase currents which our internal wiring systems can utilize.

Power Frequency

Frequency is the number of occurrences of a repeating event per unit time. For example, if our heart rate is 80 beats per minute, the frequency is 80 per minute. In electromagnetics, we use the unit of hertz (Hz).

One (1) hertz is one repetition of the sinusoidal wave per second. The frequency (f) is the frequency in hertz (Hz), meaning the number of cycles per second. One hertz simply means “one cycle per second”. 100Hz means “one hundred cycles per second”. The power line frequency is the frequency of the oscillations of alternating current (AC) in an electric power grid transmitted from a power plant to the end-user.

In our power system, the electrical current changes its polarity from positive to negative and back to positive sixty times per second or 60 Hertz. In most parts of the world the power frequency is 50 Hz, although in the Americas it is typically 60Hz. The electrical system in airplanes uses a 400Hz frequency.

Electric and Magnetic Fields

Conductors are wires which transport the electrical current. Electrical power systems generate magnetic and electric fields extending from the conductors. Magnetic fields are produced by the current flow in a conductor. Electric fields are produced by the voltage present on a conductor even without a current flow. The AC magnetic field is scientifically referred to as the magnetic flux density and is measured in units of milliGauss (mG) in the United States and in Tesla (T) in Europe. Electric fields are measured in units of Volts per meter (V/m).

Magnetic fields are relatively easily measured with direct reading instruments. Magnetic fields extend in a quasi concentric circular pattern from the conductor (wire). Electric fields are significantly more difficult to measure. The field emitted from the source wants to reach the ground. The person conducting the measurements becomes part of this pathway and alters the electric field lines and results.

Almost all of the research, health effects studies, power design guidelines and EMF reduction methods common in the U.S. only address the magnetic component. In Europe and in the computer chip manufacturing and assembly industries, electric fields are an important component of field management.

The terms “line” and “point” sources are used to define the sources for the magnetic fields. Line sources are transmission and distribution lines, electrical feeders and internal building wiring systems. Point sources are electrical transformers and motors. In a point source the conductors (wires) are wound up to create a coil.

The magnetic flux density is commonly referred to as magnetic field levels or EMF levels. We will use these terms interchangeably.

The magnetic flux density at any location is a result of the interaction of the following factors:

• 
  
  Distance to the field source (conductor)
• 
  
  Current flow “load on the line”
• 
  
  Distance between the conductors (lines, wires)

• 
  
  Conductor configuration
• 
  
  Point or line source
• 
  
  Presence of net current flow (stray currents)

All factors being equal, the higher the current flow, the higher the magnetic field. This is a linear correlation. The further one moves away from any source the lower the magnetic field.

The magnetic field level in the space between separated conductors is much higher than the field on either side of these conductors. When such conductors are relocated to be directly next to one another (as in a cable), the surrounding field drops dramatically because the opposite but equal fields nearly cancel each other. Opposite and equal fields cancel themselves out. The distance between the conductors in a circuit is usually unimportant in internal building wiring, but is very significant for power transmission and distributions lines due to the large distance between the conductors.

AC Magnetic Fields	AC Electric Fields
Measured in milliGauss (mG), nT, µT, A/m	V/m, kV/m
Magnetic fields are created by current flow.	Electric fields are created by the voltage present.
Magnetic fields penetrate buildings and bodies.	Electric fields are directed towards the ground.
Background in nature is zero (0) mG
H or B field	E -field

Measuring Magnetic Fields

The magnetic flux density (EMF levels) can be measured with direct reading instruments. A direct reading measurement at one point in time at one location is referred to as a spot measurement. Due to the inherent fluctuation in the power supply on transmission and distribution lines EMF levels will change over time. To assess these fluctuations, data logging devices are used to obtain long-term measurement data.

	Single Conductor	Fields decrease with the inverse of the distance
	Multiple Conductors	Fields decrease with the square of the distance
	Coils and Loops	Fields decrease with the cube of the distance

Furthermore, data logging can provide information on the maximum, minimum and average field strength present at a location. This may provide useful information when trouble shooting for sources of high magnetic field levels.

Coils are used to measure the magnetic flux density. The magnetic field induces a current flow in the coil which is measured and calibrated to express the magnetic field strength. Since magnetic fields are directional, the coil needs to be oriented in space so that the magnetic field lines flow through the center of the coil. An instrument with a single coil is referred to as a single axis meter. It needs to be oriented around the x, y and z axis in space to obtain the maximum field strength reading. This can be cumbersome and time consuming. Therefore, today’s professional instruments contain three coils to measure the three axes at the same time and provide a measurement result without having to rotate the instrument. Single axis measurements are the tool of choice when trying to determine the EMF source. A professional instrument with a 3 axis sensor array should also have linear frequency response. That means that the EMF testing instrument measures correctly at different frequencies, such as frequencies between 30 -2000 Hz. The following formula is used to ascertain the actual magnetic field level of the different coils (x, y, and z).

This calculation is performed electronically internal inside the instrument. Consumer instruments may not have a linear frequency response, resulting in erroneous results when other 60 Hz frequency fields are present.

Measurements should be conducted at the outside of the building or structure to obtain ambient back ground levels. We conduct measurements at all for corners of the property. Secondly, we circle the building identifying pot spots such as power feeds into the building, step down transformers and service drops (circuit breaker box). EMF levels inside at room or area are commonly recorded at its central location in the room. However, surveys should include a sweep through the room, its floor, ceilings and wall. This can identify underline wiring errors causing elevated magnetic fields.

Magnetic Field Monitoring Results in mG
Location	Minimum	Maximum	Average	95%	50%
John Doe Property	2.9	21.5	12.1	14.7	7.7

High field out light switch	Elevated field at ceiling light
Low field at computer

High field next to an air filtration device

Service drops will create high field on opposing wall

EMF REFERENCE EXPOSURE GUIDELINES

There are currently no Permissible Exposure Limits (PEL) for EMF levels published by the Occupational Safety and Health Administration (OSHA) or the EPA. Therefore, we are providing you with a chart of reference data of published studies, national and international suggested guidelines, recommendations by unions, working groups or governmental entities.

Table 1: EMF Reference Data in milliGauss (mG)

Power Lines and EMF levels

Electrical transmission lines create magnetic fields due to current flow and electric fields due to the voltage present. Power lines usually create relatively high magnetic field levels. This is related to the fact that the conductors (wires) are separated by large distances and therefore largely eliminating the cancelation effect of opposite and equal forces. Furthermore, large current flow contributes to the large magnetic flux density.

The power distribution system is divided into transmission lines, sub-transmission lines and distribution lines. The voltages on these lines are different. This voltage is reduced by step down transformers in substations. The following are the most common voltages present on power lines:

Levels	Source
1000 mG	World Health Organization (WHO) and International Radiation Protection Agency (IRPA)
1000 mG	American Conference of Governmental Industrial Hygienists (ACGIH) for industrial workplaces
<4.0 mG	International Agency for Research on Cancer (IARC) 2001
<2.5 mG	MPR 2 Swedish governmental standard for acceptable magnetic field emission for computer operator
<2.0 mG	TCO – Swedish labor union standard for acceptable magnetic field emission for computer operator
<2.0 mG	BioInitiative Report – Commercial buildings – EMF Working Group (US)
1.25 mG	Average EMF levels in US schools (L. Zaffanella study, 1998)
1.25 mG	California Department of Education’s (CDE) design goal for new school construction not to exceed 1.2 milliGauss
<1.0 mG	National Institute of Building Sciences (NIBS) 2006 – Precautionary Principle
<1.0 mG	BioInitiative Report – Residential environments – EMF Working Group (US)
0.9 mG	Average background level in residential buildings in a nationwide residential measurement survey of 1000 US homes (Luciano Zaffanella, 1994). Includes homes next to power lines and with wiring problems.
0.1-0.5 mG	Common background levels in residential not close to power lines and without wiring problems causing high fields (ET&T data)

Utility transmission lines carry three (3) electrical conductors (wires) for each circuit. Therefore, it is referred to as a 3-phase circuit. The configuration of the individual conductors on the towers has a significant effect on the strength of the resulting magnetic field.

In the graphs, we compare the most common conductor arrangement with the low EMF conductor configuration. The three different phases are depicted by the colors of blue, yellow and red. The most common configuration is termed “Untransposed” and the low EMF configuration as “Transposed”.

The second graph shows to more rapid drop off in the magnetic field levels in the transposed configuration. An optimized wire configuration creates the lowest magnetic field levels.

Power Line Set Back Requirements

Since 2004, the California Department of Education (CDE) as part of the California Code of Regulations, Title 5, Section 14010(c) implemented setbacks requirements from power line easements for new school construction. The California Department of Education (CDE) had a design goal that AC magnetic field levels in new construction school environments are not to exceed 1.2 milliGauss (Zaffanella study 1998).

The following set backs are required:

• 
  
  100 feet for 50-133kV line (interpreted by CDE up to <200kV)
• 
  
  150 feet for 220-230 kV line
• 
  
  350 feet for 500-550 kV line

Exemptions are permissible if areas close to the power lines are used for parking areas and green belts.

Net Currents

At point sources, such as motors and transformers the EMF fields are very high its proximity. However, the field drops off very rapidly with distance, within 3 – 5 feet to back ground levels. In building wiring systems, the “hot and “neutral” conductor should be positioned right next to each other and have the same current load. Therefore, the magnetic field is relatively and drops off rapidly.

In a Net Current or stray current situation, the hot and natural conductors are physically separated or have different current load condition. This causes current to travel an alternative pathway on other conductive materials. The magnetic field significantly increases around a single conductor or wire with a net current. If current flows on the grounding system, water pipes, and metal structural components such as beams, studs, and drop ceiling rails or a net current is present, the magnetic field can extend far into a building space. Net currents in wiring systems are a significant cause of elevated magnetic fields and are affecting large areas in buildings.

EMF Health Effects Research

EMF issues have reached a high level of concern among the general public and workers. This needs to be addressed at the international level since the problem is truly global in nature. Research objectives are needed with a clear focus on improving our database of scientific information used for health risk assessments.

EMF Health Summary

• Scientific studies have been conducted for about 30 year.
• Adverse health effects are still controversial.
• Most commonly suggested health effects of EMF are:
  • Childhood leukemia
  • Lymphoma
  • Brain tumors
  • Breast cancer
• Most entities call for Prudent Avoidance

1979, serious research about electromagnetic fields (EMF) and potential adverse health effects started with the publication of a study by Mrs. Nancy Wertheimer and Mr. Ed Leeper. Their epidemiological study was conducted in the Denver area and reported a higher occurrence of childhood cancer in residences located near high voltage power lines and step down transformers. The study was based on visual observations and distances but without measurements for EMF levels. Positive health effects of electromagnetic field are well known in the medical field for bone healing.

In the 1980’s and 90’s, a flurry of studies followed without providing a clear and unequivocal answer. Sparked by increasing public concerns, devaluation of homes near power lines, and litigation cases, the EMF issue was temporarily put to rest by a public announcement by three Nobel Laureates stating that there are no possible causative mechanisms for these alleged adverse health effects.

In 1990, the EPA produced a report entitled “Evaluation of the Potential Carcinogenicity of Electromagnetic Fields.” which was released only in draft form and was withdrawn under some controversy as it classified EMF exposure as a potential human carcinogen. Another report, requested by the White House Office of Science and Technology Policy, produced by the Committee on Interagency Radiation Research and Policy Coordination (CIRRPC) of Oak Ridge Associated Universities, reached the opposite conclusion. This report, released in 1992, found no convincing evidence of health hazards from electromagnetic fields.

In 1991, Congress asked the National Academy of Sciences to review the available literature and provide information on the possible biological effects of EMFs and to perform a risk assessment. In 1996, the National Academy of Sciences report was released. It concluded that the current body of scientific data is insufficient to show that exposure to electromagnetic fields constitute a health hazard, primarily because no mechanism of action has been identified. However, the report recognizes that a clear association exists between residences near certain types of power lines and the incidence of childhood leukemia, although fields from the lines cannot be proven as the cause.

In late 1992 a widely reported Swedish study (Feychting & Ahlbom) demonstrated a statistically significant association between EMF radiation exposure & certain types of cancers. The study found that “children exposed to average fields of 3 mG or more in their homes had close to four times the expected rate of leukemia.” This was the first study that showed correlation of a dose-response gradient with the number of cases of childhood leukemia increasing in the presence of presumed higher exposure categories.

In 1992, Congress, as a part of the Energy Policy Act of 1992, mandated a $65 million, five year study to determine if exposure to low level, low frequency electromagnetic fields is detrimental to health and if so, to provide an assessment of risk. This full funding was never forthcoming. The Department of Energy (DOE) and the National Institute of Environmental Health Sciences (NIEHS) were charged with directing this research. Most of the work is known as the Research and Public Information Dissemination (RAPID) Program.

In 1993, the California Public Utilities Commission (CPUC) Decision 93-11-013 created the California Electric and Magnetic Fields (EMF) Program to research and provide education and technical assistance on the possible health effects of exposure to electric and magnetic fields from power lines and other uses of electricity. This program was funded by money provided by the state’s investor-owned utilities, and is based in the California Department of Health Services (CDHS). A number of studies on health effect related to magnetic fields were conducted.

In 1996, the International EMF Project was established by the World Health Organization (WHO) to provide a forum for a coordinated international response to health concerns raised by exposure to electromagnetic fields (EMF).

In 1999, NIESH issued the final report on the EMF RAPID program.

In 2002, the International Agency for Research on Cancer (IARC) classifies ELF (extremely low frequency) magnetic fields as “possibly carcinogenic to humans”). EMFs were identified as a potential risk factor for breast cancer. Since 1987 evidence has been rapidly growing indicating an association between magnetic field exposure and breast cancer with a plausible mechanism via modulation of melatonin. An association between cancers and EMF exposure has been reported in over 110 epidemiological studies. However, follow-up studies were not able to replicate these results.

In 2007, The BioInitiative Report was published by the BioInitiative Working Group. This working group is comprised of international scientists, researchers and public health policy professionals. They conducted a comprehensive meta-analysis of existing research and found a significant number of studies have shown potential EMF associated health effects such as increased and altered cell proliferation, influences on hormones, heart, circulatory, and nervous systems. Reported symptoms range from irritability, insomnia, heart palpitations, and arrhythmia. This raises serious concerns about the safety of existing public regulations that limit how much EMF is allowable from power lines, cell phones, and many other sources of EMF exposure in daily life.

Quotes From Selected Studies

The quotes selected in the report are not representative of the entire findings of the studies. For more information on these studies, please follow the provided links.

World Health Organization (WHO)¹

“Reports were first published in 1979 that childhood cancer might be associated with exposures to residential ELF (extremely low frequency) fields. Numerous studies in many countries have been undertaken since then of possible increased cancer risks in children and adults from ELF magnetic field exposures. Special attention has focused on leukemia and on brain tumors, which early reports had suggested might be increased.

“ IARC has now concluded that ELF magnetic fields are possibly carcinogenic to humans, based on consistent statistical associations of high level residential magnetic fields with a doubling of risk of childhood leukemia. Children who are exposed to residential ELF magnetic fields less than 0.4 microTesla (4 mG) have no increased risk for leukemia. Because of insufficient data, static magnetic fields and static and extremely low frequency electric fields could not be classified as to carcinogenic risk to humans.”

http://www.iarc.fr/en/media-centre/pr/2001/pr136.html

CDHS – California Electric and Magnetic Fields Program²

”First, these studies do not show a clear pattern of health hazards. Some but not all animal and cell studies have shown biological changes linked with magnetic field exposure. However, it is not clear whether these biological changes would be the same in humans. Second, it is not clear which component (frequency, strength, harmonics, etc.) of magnetic field exposure might be hazardous.” “Concern about possible health hazards from electric power use is supported by results of some scientific studies, but the evidence they provide is still incomplete and inconclusive and even, in some cases, contradictory. A good deal of research is underway to help resolve these questions and uncertainties.”

“Most but not all epidemiological studies show an association between leukemia (a type of cancer) and an “indirect” estimate of high magnetic field exposure such as living very near a type of powerline that could cause of high magnetic fields or working where there is high electrical exposure. These estimates may not really represent a person’s true exposure at the critical time period when they may have started developing an illness. Also, these studies show that some estimates of magnetic field exposure might be related to cancer, but this does not necessarily mean that magnetic fields cause cancer. Indirect ways of estimating exposure may unintentionally include other risk factors like chemicals used at work or living in a particular neighborhood.” http://www.ehib.org/emf/shortfactsheet.PDF

NIEHS – EMF RAPID Report³

“The scientific evidence suggesting ELF-EMF exposures pose any health risks is weak” “Although each of these studies has its limitations, the limitations are different across studies, as are the designs and exposure assessment methods. Taken together, the studies suggest an association between exposure to magnetic fields and brain cancer, although the results are somewhat inconsistent.” “Although each of these studies has its limitations, the limitations are different across studies, as are the designs and exposure assessment methods. Taken together, the studies of incidence suggest an association between exposure to magnetic fields and chronic lymphocytic leukemia (CLL). “ “The NIEHS concludes that ELF-EMF cannot be recognized as entirely safe because of weak scientific evidence may pose a leukemia hazard.” “The NIEHS suggests that the level and strength of evidence supporting ELF-EMF exposure as a human health hazard. Are insufficient to warrant aggressive regulatory actions; thus, we do not recommend actions such as stringent standards on electric appliances and national program to bury all transmission and distribution lines. Instead, the evidence suggests passive measures such as a continued emphasis on educating both the public and the regulated community on means aimed at reducing exposures.”

“NIEHS suggests that the power industry continue its current practice of siting power lines to reduce exposures and continue to explore ways to reduce the creation of magnetic fields around transmission and distribution lines without creating new hazards.” http://www.niehs.nih.gov/health/assets/docs_a_e/assessment_of_health_effects_from_exposure_to_powerline_frequency_electric_and_magnetic_fields.pdf

Bioinitiative Report⁴

“New regulatory limits for ELF are warranted. ELF limits should be set below those exposure levels that have been linked in childhood leukemia studies to increased risk of disease, plus an additional safety factor. It is no longer acceptable to build new power lines and electrical facilities that place people in ELF environments that have been determined to be risky (at levels generally at 2 mG and above).

“While new ELF limits are being developed and implemented, a reasonable approach would be a 1 mG planning limit for habitable space adjacent to all new or upgraded power lines and a 2 mG limit for all other new construction, It is also recommended for that a 1 mG limit be established for existing habitable space for children and/or women who are pregnant . This recommendation is based on the assumption that a higher burden of protection is required for children who cannot protect themselves, and who are at risk for childhood leukemia at rates that are traditionally high enough to trigger regulatory action. This situation in particular warrants extending the 1 mG limit to existing occupied space. “Establish” in this case probably means formal public advisories from relevant health agencies.”

“This report stands as a wake-up call that long-term exposure to some kinds of EMF may cause serious health effects. Good public health planning is needed now to prevent cancers and neurological diseases linked to exposure to power lines and other sources of EMF. We need to educate people and our decision-makers that, business as usual, is unacceptable” states public health expert and co-editor of the report, Dr. David Carpenter, Director, Institute for Health and the Environment at the University of Albany, New York.

http://www.emfrf.com/images/stories/pdfs/Bioinitative_Report.pdf

After many decades of scientific research, the controversy about potential health effect still exists. The Occupational Safety and Health Administration (OSHA) has not established permissible exposure limits (PEL) for work places. However, a number of scientific studies and professional organizations advocate the principle of prudent avoidance and some have recommended guideline values. See the next section Reference Data.

Examples of proposed exposure metrics include: the average field intensity over a period of time, time spent in the field over some threshold value, field variability, the presence of switching transients on the field waveform, time in the day-night cycle when exposure is received, and the strength and direction of the earth’s geomagnetic field in relation to the power frequency field. Until the mechanisms by which electromagnetic fields interact with biologic systems are better understood, these questions cannot be answered, and a fully valid risk assessment will not be possible.

Conversion Tables

The following are conversions for commonly used measurement units.

Transmission Lines	220kV and 500kV
Sub-Transmission Lines	66kV and 115kV
Distribution Lines	4kV, 12kV, 16kV and 33kV
Secondary Lines	120, 240, 208 and 480 Volt (Customer Service Voltages)

Magnetic Field	Electric Field
1 Milligauss [mG] = 100 Nanotesla [nT] 1 Milligauss [mG] = 0.1 Microtesla [µT] 1 mG = 0.0796 A/m 1 nT = 0.01 mG 1 µT = 10 mG 1 nT = 0.001 μT = 100,000 mT = 1,000,000 T 1 A/m = 1,257 μT 1 T (Tesla) = 10 000 G (Gauss) 1 G = 100 μT	1 kV/m = 1,000 V/m = 103 V/m

Conversion Factors for Various Magnetic Field Strength Units

Frequency	Power Density
1 kHz = 1,000 Hz = 103 Hz 1 MHz = 1,000 kHz = 1,000,000 Hz 1 GHz = 1,000 MHz = 1,000,000 kHz = 109 Hz	1 mW/cm2 = 10 W/m2 1 mW/cm2 = 0 dBm 1 μV/m = 0 dBμV/m 1 W/m2 = 19,42 V/m = 0,052 A/m [S = Z H²; S = E²/Z ; Z = 377 6 (in space and far field)

1 International Agency for Research on Cancer (IARC), Press Release No.136, 27 June 2001

2 California Department of Health Services, California Electric and Magnetic Fields Program, Short Fact Sheet on EMF, 1999

3 National Institute of Environmental Health Sciences, Report on Health Effects from Exposures to Power-Frequency Electric and Magnetic Fields, NIH Publication No. 99-4493, 1999

4 BioInitiative Report: A Rationale for a Biologically-based Public Exposure Standard for Electromagnetic Fields (ELF and RF), 2007

Report Prepared by:

Peter H. Sierck, Principal/Industrial Hygienist

EMF & RF Solutions

1106 Second Street, Suite 102 Encinitas, CA 92024

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