United States
Environmental Protection
Agency
Office Of Radiation
And Indoor Air
(6603J)
402-R-92-008
December 1992
EMF In Your Environment
Magnetic Field Measurements
Of Everyday Electrical Devices

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Mention of trade names, products, or services
does not convey, and should not be interpreted as
conveying, official EPA approval, endorsement,
or recommendation.
                                         Recyctod/R8cydabk>
                                         Printed on paper that contains
                                         at toast 50% recycled fflxir
            For sale by the U.S. Government Printing Office
  Superintendent of Documents, Mail Stop: SSOP, Washington, DC 20402-9328

                  ISBN 0-16-036282-2
   r
ISBN 0-16-036282-2
                                90000
                                              J

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 CONTENTS

 EMF In Your Environment
      What Are Electric and
         Magnetic Fields?	3
      The Electromagnetic
         Spectrum	   5
      60 Hertz Electric and
         Magnetic Fields	6
      Other Electromagnetic Frequencies	7
      Potential Health Concerns
         Associated With
         Electric and Magnetic Fields	7

Magnetic Field Measurements of
Everyday Electrical Devices	9
      Appliances and Magnetic
         Field Strength
      How Magnetic Field
         Measurements Were Taken	10

Tables	;	13.25

How Can I Use This Information _______ 26

Appendix A                !
      Technical Notes	28
      Data Sources	31

Appendix B
      Additional Reading and
         Information Sources 	    33

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 EMF IN YOUR ENVIRONMENT
      What are electric and magnetic fields
 (EMFs)? What common EMF sources do we
 encounter during a typical day? This publication
 compares the strength of 60 hertz magnetic fields
 produced by common electrical items and shows
 you how their strength diminishes as you move
 farther away from them.
     We still have a great deal to learn about
 electric and magnetic fields (EMFs). We really
 don't know if typical, everyday exposures to EMFs
 affect human health. Some studies indicate that
 they might - others suggest otherwise.  Most of
 the recent research on possible biological effects of
 60 hertz EMFs suggests that the magnetic, rather
 than the electric, fields are more likely to produce
 significant effects. Therefore, this publication
 focuses on them. The information presented here
 has to do with the strength of the magnetic field;
 however, we aren't certain that the strength of the
 field is the only important consideration. It may
 turn out that other factors are also important,
 such as how long the exposure lasts or whether
 particular characteristics of the field change
 rapidly.  Future research is likely to reveal that
 the information given in this publication is only
 part of the story - that is the chance we take in
 providing a public information document this early
 in the study of a complex environ-
 mental health issue.

 What Are Electric
 and Magnetic Fields ?
     Electric charges create
electric fields. Electric charges
which move (i.e., electric current)
create magnetic fields. An appli-
ance that is plugged in, and
therefore connected to a source of
electricity, has an electric field

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Electromagnetic Spectrum
           Gamma
            rays
X-rays
  4-
        t
     Ultraviolet
     radiation

    Visible light
        I
      Infrared
     radiation
  Microwaves
               UHF

               VHF
              Short
              wave
    Radio   Medium
    waves     wave
              Long
              wave
      t
 Extremely low
frequency (ELF)
        1
                      Frequency
                       (in hertz)
                           10 —
                           102—
                         101—

                         102L-
                           10—
                         105—
                           10—
                           10—
                           10—
                           m
                           I U
                           10'
                           10—
                          10—
                          10—
  -10—
-60 hertz -
 	10—
                                  Wavelength
                                  (in meters)
                                       10—
                                       10—
                                   — 10—
                                         ,-11
                                       10'
                                       10—
                                       10—
                                     10—
                                  — 10—

                                     1fV6	
                                      i u

                                  	10—
                                       10—
                                   — 10'3—
                                       1 Q-2 _
                 10 —

                  1  —

                 10 —

                 10—
                                       10—
                                       104
                                       105—
                                      10—
                                      10—
                                                          This illustrates
                                                          the point that
                                                          the higher the
                                                          frequency, the
                                                          shorter the
                                                          wavelength.  The
                                                          wavelengths are
                                                          infinitely long at
                                                          the bottom and
                                                          infinitessimally
                                                          short at the top
                                                          of the spectrum
                                                          so, obviously, the
                                                          drawing cannot
                                                          be done to scale.

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even when the appliance is turned off.  To produce
a magnetic field, however, the appliance must be
not only plugged in, but also operating, so that the
current is flowing.
     The electric current we use in our everyday
life produces certain kinds of electric and magnetic
fields.  There are many other kinds of electric and
magnetic fields as well, found throughout nature.
The term "electromagnetic" field implies that the
electric and magnetic fields are interrelated.
     These fields can be characterized by either
their wavelength or their frequency, which are
related. The amount of energy an electric or
magnetic field can carry depends on the frequency
and wavelength of the field. The wavelength
describes how far it is between one peak on the
wave and the next peak. The frequency, measured
in hertz, describes how many wave peaks pass by
in one second of time.
The Electromagnetic Spectrum

      If you take all the different kinds of electro-
magnetic fields we know about and place them on
a chart, from the lowest frequency (i.e., lowest
energy) to the highest, you have a chart of the
electromagnetic spectrum. (See chart on the
previous page.) The low end of the spectrum
includes electric and magnetic fields produced by
everyday electrical appliances. At the top of the
spectrum are X-rays and gamma rays.
     When you hear about "EMFs" in the news
media, the term usually refers to electric and
magnetic fields at the extremely low frequency (or
ELF) end of the spectrum, such as those associ-
ated with our use of electric power. The term
"EMF" can be used in a much broader sense as
well, encompassing electromagnetic fields across
the spectrum.  When we use "EMF" in this bro-
chure we mean extremely low frequency (ELF)
electric and magnetic fields. We should note that
in the ELF range, electric and magnetic fields are

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               not coupled or interrelated in the same way that
               they are at higher frequencies, so it is actually
               more accurate to refer to them as "electric and
               magnetic fields" rather than as "electromagnetic
               fields." In the popular press, however, you will see
               both terms used, abbreviated as "EMF."
Electric fields from most appliances primarily create charges or
current on or near the surface of the body and not in the internal
organs.  Magnetic fields, however, pass through the  body and
actually induce electric currents within the body.  We don't know
exactly what effect, if any, this has on the different internal organs,
but many studies are now underway to try to find out.
              60 Hertz Electric And Magnetic Fields

                    It is relatively easy to shield people from
              exposure to electric fields using commonly avail-
              able materials. Magnetic fields, however, can pass
              through anything. Even though both are present
              around appliances and power lines, more recent
              interest and research have focused on potential
              health and biological effects of magnetic fields of
              various strengths.
                   This publication presents  information re-
              garding magnetic fields associated with 60 hertz
              alternating current (AC) electric power - that is,
              the kind of electric power we use in North America
              which flows back and forth or alternates at a rate
              of 60 times per second (60 hertz).  We will not
              focus here on equipment that is powered by "direct
              current" (DC) such as battery-operated appli-
              ances.  The magnetic fields created by
              direct current are primarily static;
              that is, they do not vary with time
              as do AC fields. Direct current
              (DC) magnetic fields have not
              raised as many questions
              about potential health

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concerns as have the time-varying fields created
by alternating ffurrent (AG). We should point out,
however, that some DC-powered equipment can
produce alternating magnetic fields, but these are
usually not 60 hertz fields.
Other Electromagnetic Frequencies

     Although the information presented here has
to do with the low frequency magnetic fields
associated with 60 hertz electrical current, we
should note that some appliances, such as micro-
wave ovens, baby monitors, and video display
terminals, use 60 hertz electrical energy to create
other electromagnetic frequencies.
     The measurements we give for microwave
ovens, for example, describe the magnetic field
that results from the 60 hertz electrical current
used to operate the oven. We are not describing
the magnetic field associated with the approxi-
mately three billion hertz microwaves inside the
oven which heat the food and from which people
are protected when the door is secured properly.
     Oddly enough, we can be easily shielded from
the higher frequency microwaves' magnetic fields,
but not from the 60 hertz magnetic fields. This is
because even though the microwave's frequency
is higher, its length is much, much shorter (about
1 cm) than the wavelength of a, 60 hertz field
(about 5000 kilometers). The shorter wave can be
blocked by materials such as thin metal sheets,
whereas the much longer wave cannot.
Potential Health Concerns Associated
With Electric and Magnetic Fields

      Electric and magnetic fields from 60 hertz
electric power (as well as microwaves and radio
waves) are sometimes called non-ionizing radia-
tion. The term "radiation" simply means energy
                                                                 7

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                       transmitted by waves.  "Ionizing" radiation has
                       enough energy to strip electrons from atoms. (X-
                       rays are a form of ionizing radiation.) Extremely
                       low frequency EMF cannot do this. Higher
                       frequency non-ionizing radiation, such as micro-
                       waves, can heat up biological tissue by vibrating
                       molecules.  The lower frequency 60 hertz EMFs
                       cannot. Because of their relatively lower energy,
                       60 hertz EMFs were not, until recently, thought to
                       be connected with any potential health problems.
     There are no national standards in the United States for exposure to
     60 hertz electromagnetic fields. Several states have formally adopted
     standards to limit the permissible magnetic field strength along rights
     of way of electric transmission lines.  Federal legislation has been
     enacted to establish and support national EMF research and public
     information programs, but no exposure standards have been pro-
     posed.
                           Some recent scientific studies have suggested
                      a link — a statistical association — between expo-
                      sure to 60 hertz EMFs and specific types of cancer,
                      primarily leukemia and brain cancer. Other
                      studies have found no such association (see Appen-
                      dix B). In a sense, this can be compared to circum-
                      stantial evidence in a court of law. Laboratory
                      studies have shown electromagnetic fields to affect
                      cells in various ways, but whether these effects are
                      important in terms of human health  is still not
                      clear. Almost everyone involved in EMF research
                      agrees that much more needs to be learned before
                      conclusions can be reached about the relative
                      safety or harm of 60 hertz EMF exposure.
                           Some people doubt that the EMFs generated
                      by 60 hertz electrical appliances and internal
                      household wiring have any significant effect on
                      human health, because they know that the earth's
                      magnetic field, to which we are all constantly
                      exposed, is stronger (sometimes over  100 times
                      stronger) than the magnetic fields produced by
8

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 many of the appliances listed in this publication.
 However, the earth's magnetic field is primarily a
 DC field rather than a time-varying field. Our
 bodies seem to react differently to these
 different types of fields so comparing
 them can be misleading.
      At this point, we are not at all
 sure that exposure to EMFs such as
 we find in our everyday environment
 has an adverse effect on our health.
 However, we cannot say with certainty
 that such exposure is safe for us, either.
 More research is needed — and is underway.
 Meanwhile, many people have expressed an
 interest in having information about everyday
 sources of EMF exposure. This booklet is in
 response to that interest.
                                                 ©
 MAGNETIC FIELD MEASUREMENTS
 OF EVERYDAY ELECTRICAL DEVICES

      This publication gives information about the
 strength of the magnetic fields generated by
 everyday 60 hertz electrically powered equipment.
 It shows how the magnetic field strength dimin-
 ishes with increased distance  from the object.

 Appliances and
 Magnetic Field Strengths

      Magnetic fields from individual appliances
 can vary considerably, depending on the way they
 were designed and manufactured.  One brand of
toaster, for example, may generate a much stron-
ger magnetic field than another. The strength of
the magnetic field is measured in units of gauss
(G) or milligauss (mG). A milligauss is l/1000th
of a gauss. (The international standard unit is
microtesla which is the same as 10 milligauss.)
     It is important to keep in mind that a typical

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                     American home has a background magnetic field
                     level (away from any appliances) ranging from 0.5
                     mG to 4 mG. The actual strength of the field at a
                     given place in a room depends upon the number
                     and kinds of sources, how far away they are, and
                     how many are operating at one time. Walls
                     generally do not block magnetic fields. An electri-
                     cal appliance located near a wall extends its
                     magnetic field into the room on the other side of
                     the wall as well.
                     How Magnetic Field
                     Measurements Were Taken

                       The data in the tables (beginning on page 13)
                     came from three different organizations: the
                     Electric Power Research Institute (EPRI), the
                     Illinois Institute of Technology Research Institute
                     (IITRI), and the U.S. Environmental Protection
                     Agency (EPA). What we present here will give you
                     an idea of the relative strength of magnetic fields
                     produced by electrical items you are likely to use
                     in your home or at work.
                          The strength of the magnetic fields has been
                     measured at 6 inches from the item, and then at
                     distances of 1, 2, and 4 feet. These distances do
10

-------
not, in every case, correspond to the distance you
would typically be from the appliance when you
use it, but we kept the measurements consistent
so that the magnetic field strength could be com-
pared from appliance to appliance. It should also
be mentioned that different body parts will be
exposed to different magnetic field levels from the
same appliance, depending on how far that part of
the body is from the appliance when it is in use.
An electric shaver when used, for example, may be
three inches from the brain and two feet from the
liver. Notice in the chart below how the strength
of the magnetic field diminishes dramatically just
a foot or two away from the appliance.

   o
   LJJ

   O
   2
   UJ
   o
   UJ
   cc
       200
   E   160
120-
          0.00
             0.50
1.00
1.50
2.00
                 DISTANCE FROM APPLIANCE (fe'et)
                                                                 11

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                            TABLES

      In the following tables, you will see three numbers listed for each
 appliance at each distance. First is the lowest measurement we have,
 followed by the median, and then the highest measurement taken. For
 some appliance categories, hundreds of individual items were measured.
 In other cases, the data gathering was less extensive. The median
 measurement is simply the middle number in a series of measurements.
      The appliances are organized according to where you might en-
 counter them during the day (in the kitchen, the office, the bedroom,
 etc).  The magnetic field strength is measured in milligauss  (mG).
      For a detailed description of the methodology used by each of the
 three groups that conducted these measurements, please refer to Ap-
 pendix A. Also in Appendix A .is a reference chart showing the source of
 the data.
^ 	 •*«• "•--*»- ;
*» ^•^IsEiMJiljSSlWjJUHCillU^Gft^fe
P™^SPftwll^MHm!BaiJl .''±f f ' „
Distance from Source
6"

1'
2'
4'
HAIR DRYERS
Lowest
Median
Highest
1
300
700
_
1
70
_
-
10
.
_
1
ELECTRIC SHAVERS
Lowest ;
Median
Highest
4
100
600
_
20
100
_
_
10
_
_
1
                       Magnetic field measurements in units of milligauss (mG)
The dash (-) in the above table means that the magnetic field measurement at this
distance from the operating appliance could not be distinguished from background
measurements taken before the appliance had been turned on.
                                                                  13

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Distance from Source
6"
1'
2'
4'
BLENDERS
Lowest
Median
Highest
30
70
100
5
10
20
_
2
3
_
.
-
CAN OPENERS
Lowest
Median
Highest
500
600
1500
40
150
300
3
20
30
..
2
4
COFFEE MAKERS
Lowest
Median
Highest
4
7
10
..
-
1
_
.
-
_
_
-
CROCK POTS
Lowest
Median
Highest
3
6
9
_
1
1
_
-
-
_
-
-
DISHWASHERS
Lowest
Median
Highest
10
20
100
6
10
30
2
4
7
_
-
1
FOOD PROCESSORS
Lowest
Median
Highest
20
30
130
5
6
20
.
2
3
_
.
-
   Magnetic field measurements in units of milligauss (mG)
   The dash (-) in the above table means that the magnetic field measurement at this
   distance from the operating appliance could not be distinguished from background
   measurements taken before the appliance had been turned on.
14

-------
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Distance from Source
6"
1'
2'
4'
GARBAGE DISPOSALS
Lowest
Median
Highest
60
80
100
8
10
20
1
2
3
_
.

MICROWAVE OVENS
Lowest
Median
Highest
100
200
300
1
40
200
1
10
30
„.
2
20
MIXERS
Lowest
Median
Highest
30
100
600
5
10
100
—
1
10
„
.
-
ELECTRIC OVENS
Lowest
Median
Highest
4
9
20 .
1
4
5
_
.
1
_
.
-
ELECTRIC RANGES
Lowest
Median
Highest
20
30
200
_
8
30
_
2
9
_
_
6
REFRIGERATORS
Lowest
Median
Highest
_
2
40
.
2
20
_
1
10
_
_
10
TOASTERS
Lowest
Median
Highest :
5
10
20
_
3
7
_
_
-
_
.
-
Magnetic field measurements in units of milligauss (mG)
                                                 15

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"- "• - " ^'WW^AM^^
Distance from Source
6"
1'
2'
4'
CEILING FANS
Lowest
Median
Highest

3
50
6
1
WINDOW AIR CONDITIONERS
Lowest
Median
Highest

3
20
1
6
4
TUNERS/TAPE PLAYERS
Lowest
Median
Highest
1
3
1
-
-
COLOR TVs
Lowest
Median
Highest

7
20
2
8
4
BLACK AND WHITE TVs
Lowest
Median
Highest

1
3
10
2
1
   Magnetic field measurements in units of milligauss (mG)
  The dash (-) in the above table means that the magnetic field measurement at this distance
  from the operating appliance could not be distinguished from background measurements
  taken before the appliance had been turned on.
16

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HBBBBPIll^^

••^BfflHHfflHHIBBHK^^^fej'i? "~,.~-~ ~-=~,,: ._;. ",:.:.' •;=., ----- .^~-:~~
Distance from Source
6"
1 J a j€j ^ jjfcSj^^^^i^^^^^^jfe^^^^
r
2'
4'
ELECTRIC CLOTHES DRYERS
Lowest
Median
Highest
2
3
10
_
2
3
_
-
-
_
-
-
WASHING MACHINES
Lowest
Median
Highest
4
20
100
1
7
30
.
1
6
- _
.
-
IRONS
Lowest
Median
Highest
6
8
20
1
1
3
_
-
.
.
.
-
PORTABLE HEATERS
Lowest
Median
Highest
5
100
150
1
20
40
_
4
8
_
_
1
VACUUM CLEANERS
Lowest
Median
Highest
100
300
700
20
60
200
4
10
50
_
1
10
Magnetic field measurements in units of milligauss (mG)

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Distance from Source
6"
1'
2'
4'
DIGITAL CLOCKS
Lowest
Median
Highest



_
1
.8
w
-
2
_
-
1
ANALOG (CONVENTIONAL CLOCK-FACE) CLOCKS
Lowest
Median
Highest



1
15
30
_
2
5
_
_
3
BABY MONITORS
Lowest
Median
Highest
4
6
15
.
1
2
„
_
-
_ >
_
-
   Magnetic field measurements in units of milligauss (mG)
        The clocks described in the above table are electrically powered
   using alternating current (AC), as are all the appliances described in
   these tables.  The measurements for baby monitors were taken for the
   unit nearest the child.
   The dash (-) in the above table means that the magnetic field measurement at this distance
   from the operating appliance could not be distinguished from background measurements
   taken before the appliance had been turned on.
18

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o
£

45

40

35

30

25

20

15

10

 5

 0
                Measurements taken 5 cm. from the blanket surface
                       39.4
                                                *   '  5 cm peak
                                                Y//A  5 cm average
                           21.8
                      Conventional
                                     PTC
                                 Low-Magnetic-
                                     Field
  Information courtesy of the Center for Devices and Radiological Health, U.S. Food
  and Drug Administration
       The above graph presents information regarding magnetic fields
  produced by electric blankets, including conventional 110 volt electric
  blankets as well as the newer model PTC (Positive Temperature
  Coefficient) Low Magnetic Field blankets.  The fields were measured
  at a distance of five centimeters (a little less than 2 inches) from the
  surface of the blanket, roughly approximating the distance from the
  blanket to the users' internal organs. Because of the way blankets
  are wired, magnetic field strengths vary from point to point on the
  blanket. The graph reflects this and gives  you both the peak as well
  as the average measurement.

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Distance from Source
6"
1'
2'
4'
AIR CLEANERS
Lowest
Median
Highest
110
180
250
20
35
50
3
5
8
—
1
2
COPY MACHINES
Lowest
Median
Highest
4
90
200
2
20
40
1
7
13
_
1
4
FAX MACHINES
Lowest
Median
Highest
4
6
9
«.
-
2
_
.
-
.
_
-
FLUORESCENT LIGHTS
Lowest
Median
Highest
20
40
100
_
6
30
_
2
8
_
_
4
ELECTRIC PENCIL SHARPENERS
Lowest
Median
Highest
20
200
300
8
70
90
5
20
30
_
2
30
VIDEO DISPLAY TERMINALS
(PCs WITH COLOR MONITORS) (See note on following page)
Lowest
Median
Highest
7
14
20
2
5
6
1
2
3
_
_
-
   Magnetic field measurements in units of milligauss (mG)
   The dash (-) in the above table means that the magnetic field measurement at this distance
   from the operating appliance could not be distinguished from background measurements
   taken before the appliance had been turned on.
20

-------
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! iS«Ssssi;f|tv3ffll;SKC^S;i^Sy/yQ RKS H O P\SO U R G KS'is^smSSttSSSaSiisSSK
••MMBHMM«KSi^^^;^^--"^ -.-•-- -•-• :v^~ -:«— c^s^-ii
Distance from Source
6"
1'
2'
4'
BATTERY CHARGERS
Lowest
Median
Highest
3
30
50
2
3
4
-
-
DRILLS
Lowest :
Median
Highest
100
150
200
20
30
40
3
4
6
-
POWER SAWS
Lowest
Median
Highest
50
200
1000
9
40
300
1
5
40
4
ELECTRIC SCREWDRIVERS (while charging)
Lowest
Median ;
Highest
-
-
-

                     Magnetic field measurements in units of milligauss (mG)
 Although the U.S.  has set no standards for magnetic fields from video
 display terminals (VDTs), the Swedish government has. Its standard
. of 2.5 milligauss (mG) at a distance of 50 centimeters (about 1 '8") from
 the VDT has  become a de facto standard in  the  VDT  industry
 worldwide.

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                         ELfeCt RIC POWER WES
   Another obvious source of everyday exposure to 60 hertz EMFs is
   from electric power lines.
                                   Transmission
                                   69 kV to 765 kV
                                                      Substation
                                                      step-down
                                                      transformer
Generation
20 kV
Step-up
transformer
                                          Distribution
                                          primaries
                                          5-35 kV
                            Distribution
                            step-down
                            transformer
                          Circuit o
                          breakers
         End User
         115 230 Volts
                                                                Distribution
                                                                secondaries
                                                                115/230 Volts
   From Carnegie Mellon brochure: Electric and Magnetic Fields from 60 Hertz Electric
   Power, 1989.
      Substations:   Some  people are particularly concerned about  the
      magnetic fields generated by electric substations.  In fact, as with
      appliances, the  fields produced by  substation  equipment quickly
      diminish in strength a short distance away and do not extend beyond
      the substation boundaries. However, magnetic fields near substations
      can be stronger than those in other parts of the neighborhood because
      the power lines drop down closer to the ground as they go in and out
      of the substation, bringing their accompanying magnetic fields closer
      to people on the ground.
22

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     The next table (see page 24) gives typical magnetic field measure-
ments for several types of single circuit electric power lines at varying
distances from the lines, both at times of average electricity usage and
at peak usage times. A single circuit power line is actually a set of three
lines.  If you see more than three lines, it means that more than one
circuit runs along the same right-of-way (ROW), in which case higher
fields are possible. The first measurement on the table gives the maxi-
mum magnetic field strength measured within the power line ROW.
The next four measurements are at distances of 50', 100', 200', and 300'.
Power line ROW widths vary among utilities. All measurements were
taken at a height of one meter above the ground.
     The measurements shown here are from electric "transmission"
lines, which use very high voltages and go long distances. The electrical
lines you see in typical neighborhoods are "distribution" lines, which
usually carry less voltage than transmission lines.  Voltage is not,
however, the critical issue with regard to magnetic field strength.
Rather, magnetic field strength is directly proportional to current, which
can be high in distribution lines as well as in transmission lines. Resi-
dential exposures to distribution lines are usually under 5 mG, but have
been reported to be as high as 50 mG where the lines pass within a few
feet of living space in densely populated areas.
     It is interesting to note that the highest magnetic field strength
measurement we have directly on the right of way of 500 kV transmis-
sion lines during peak usage is lower than the median measurement we
have for magnetic field strength within 6 inches of many household
appliances, such as hair dryers and vacuum cleaners. However, the
duration of exposure to EMFs from power lines near a home is typically
much longer than the duration of exposure to EMFs from most appli-
ances.  Is this an important distinction? We just don't know yet.
                                                                 23

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Types of
Transmission
Lines
Maximum
on Right-
of-Way
Dis
50'
stance
100'
from li
200'
nes
300'
115 Kilovolts (kV)
Average usage
Peak usage
30
63
7
14
2
4
0.4
0.9
0.2
0.4
230 Kilovolts (kV)
Average usage
Peak usage
58
118
20
40
7
15
1.8
3.6
0.8
1.6
500 Kilovolts (kV)
Average usage
Peak usage
87
183
29
62
13
27
3.2
6.7
1.4
3.0
   Magnetic field measurements in units of milligauss (mG)

   Information courtesy of Bonneville Power Administration.
     Burying power lines underground often does reduce their magnetic
     fields. This is not because they are underground, however, since dirt
     does not act as a shield. Instead, the lower magnetic field is due to the
     way lines are arranged and encased when they are buried, which can
     have the effect of cancelling part of the field. Underground power lines,
     are still capable of exposing you to magnetic fields if you are very close
     to them.
24

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   Inside a car, the dominant sources of 60 hertz magnetic field exposure
 are those you pass by (or under) as you drive, such as power lines. Car
 batteries involve direct current (DC), rather than alternating current
 (AC). Car phones are also battery-powered and are therefore not
 sources of 60 hertz magnetic fields, although they do transmit and
 receive fields in the radio frequency range. Some car components, such
 as alternators, can create alternating fields, but not necessarily in the
 60 hertz frequency.
    Trains present a more complicated picture.  Some electrically
 powered trains operate on alternating current, such as the New York
 City subway and the Baltimore/Washington commuter train. Measure-
 ments taken on the Baltimore/Washington train in 1991* showed 25
 hertz magnetic field strengths as high as 500 mG in the passenger
 areas at seat height. Other trains, such as the Washington D.C. Metro
 and the San Francisco Bay Area Rapid Transit (BART), run on direct
 current, but even these trains are not free of AC fields. Areas of strong
 AC magnetic fields have been measured on the Washington D.C. Metro,
 close to the floor, presumably near equipment located underneath some
 train cars.  Train motors and other equipment create some very intense
 alternating fields at higher than 60 hertz frequencies. In addition to
 sources of magnetic field exposure from the train itself, train passengers
 are exposed to magnetic fields from sources the train passes on its
 route.
* 24-Hour Exposure Measurements to 60 Hertz Magnetic Fields: A Pilot Project,
presented by Lynne Gillette, U.S. EPA, at the Air and Waste Management Association
Annual Meeting, June 1992.
                                                                  25

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                     HOW CAN I USE THIS
                     INFORMATION?
                          Many people are surprised when they com-
                     pare magnetic field measurement data from
                     appliance to appliance and see that magnetic field
                     strength does not depend on how large, complex,
                     powerful or noisy the appliance is. In fact, the
                     magnetic fields near large appliances are often
                     weaker than those near smaller devices. There
                     are many reasons why this can happen, all of them
                     related to product design. The stronger
                     MAGNETIC  HELD CHARACTERISTICS
                                   STRE.N6TH
                                   DURATIOM
                                   CHANGES
                                   DISTANCES
                     magnetic fields from smaller appliances tend to
                     diminish in strength more quickly as distance
                     increases than do the fields from larger appli-
                     ances, however.
                          If you are trying to determine your potential
                     exposure to a magnetic field from a particular
                     appliance, it is important that you consider
                     how close you are to the appliance and how long
                     you use it. The electric alarm clock at the head of
                     your bed may expose you to a magnetic field of 15
                     mG for 7 or 8 hours each night. The electric can
                     opener in the kitchen is also capable of producing
                     a magnetic field of 15-20 mG at a distance of one
26

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 foot away, but your potential ^exposure to that field
 is for a much shorter duration.
     Does it matter how long we are exposed to a
 magnetic field? We don't know. Magnetic fields
 that are cycled on and off repeatedly, such as those
 from photocopiers, may have a different kind of
 effect on us than those from appliances that run
 constantly, such as alarm clocks.
     Obviously, many remaining questions about
 EMF need to be answered before we can say what
 is safe or unsafe. The government and the private
 sector are currently working together to sponsor
 research that attempts to answer some of these
 questions.
     This publication presents what we hope are
 some helpful pieces of the EMF puzzle - informa-
 tion about how magnetic field strengths of various
 everyday appliances compare with each other and
 how their strength diminishes the farther away
you are from the appliances. In many instances,
you can substantially reduce your exposure to
magnetic fields by simply putting more distance
between yourself and EMF sources.
                                                                27

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                     APPENDIX A

                     Technical Notes

                          The data in the tables came from three
                     different organizations:  the Electric Power Re-
                     search Institute (EPRI), J.R. Gauger of the Illinois
                     Institute of Technology Research Institute (IITRI),
                     and the U.S. Environmental Protection Agency
                     (EPA). Each set of data was collected  in a differ-
                     ent manner.

                     EPRI DATA
                          The EPRI data comes from the September
                     1992 Interim Report of EPRI's nationwide Survey
                     of Residential Magnetic Field Sources. (EPRI TR-
                     100194, Project 2942-06.) The survey  involved 707
                     homes. Data was collected with Star magnetic
                     field instruments at different distances from the
                     appliances' front surfaces, at a height  of 3 feet
                     from the ground. The Star magnetic field meter
                     measures only 60 hertz magnetic fields.  EPRI did
                     not measure magnetic field strengths  at a distance
                     of 6 inches from the appliance, as did IITRI and
                     EPA.  Therefore, the missing 6 inch measurements
                     for appliances covered in the EPRI survey was
                     provided either by ITTRI or by the EPA.  It is
                     important to note that although the tables in this
                     publication give measurements at distances of 6
                     inches, 1 foot, 2 feet, and 4 feet from the source,
                     the EPRI measurements were actually made at
                     slightly closer distances from the appliances:
                     approximately 10.5", 22.3", and 46". The number
                     of appliances of each type measured by EPRI
                     ranged from 60 to 400. EPRI researchers collected
                     information on manufacturer and model of the
                     appliances they measured, but they did not report
                     that information.
28

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HTRIDATA
     The IITRI data set is from a 1984 report by
J.R. Gauger of IITRI, prepared for the U.S. Naval
Electronic Systems Command, entitled "House-
hold Appliance Magnetic Field Survey" Technical
Report E06549-3, Contract No. N00039-84-C-0070.
IITRI used measurement equipment of their own
design.  They measured the maximum 60 hertz
magnetic field for appliances in the location in
which they were normally used, and turned off or
otherwise minimized all other EMF sources in the
vicinity of the appliance being measured. The
IITRI data set is based on a smaller sample of
appliances than EPRI used. About five appli-
ances of each type were measured.

EPA DATA
     EPA staff conducted measurements of
commonly used electrical appliances for which
data had not already been collected. At least five
different types of a given appliance were mea-
sured.  The measurement protocol used by the
EPA in its data collection was the following:

     1)  Equipment consisted of a measuring tape
and an Emdex II magnetic field meter measuring
in the broadband magnetic field resultant mode
every 1.5 seconds.

    2)  Sources being measured were left in their
original positions in the environment.  Other
operating sources within 3 feet of the object source
were turned off when the measurements were
taken.

    3)  Measurement sites were at given dis-
tances from the center of the source surface closest
to the most likely source user position. The
measurement sites were on a line from the center
of this surface, in the direction of the user position
and parallel to the floor.
                                                                29

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                          4) For each of the measurement sites, before
                      turning on the source to be measured, an initial
                      measurement of the background EMF was taken.
                      This measurement was based on the average of
                      ten consecutive Emdex II readings, rounded to the
                      nearest tenth of a milligauss. With the source
                      operating at its maximum output, the measure-
                      ments were taken with the same averaging tech-
                      nique. Background measurements were taken
                      again after the source was turned off.

                          5) In cases where the source field changed
                      periodically (such as with some copy machines) the
                      measurements were taken during the period of
                      .operation when the field was strongest.
30

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 The following chart shows, for each appliance listed in the publica-
 tion, which organization provided the data.
j^^^^^^^^^^^^^^ijKifc^^SBjjitiN^^^i^ * — -
V K- _ .
__

EPRI
IITRI
-a ^ ^ -i »
-------
1 .' " V'"M/^

EPRI
IITRI
MM.
EPA
WORKSHOP
Battery Chargers
Drills
Power Saws
Screw Drivers





•
•

•


•
LIVING/FAMILY ROOM
Ceiling Fans
Window Air Conditioners
Stereo Tuners
Color Televisions
Black & White Televisions
•
•

•
•







•


OFFICE SOURCES
Air Cleaners
Copy Machines
Fax Machines
Fluorescent Lights
Electric Pencil Sharpeners
Video Display Terminals



•





*


•
•
•

•
•
BEDROOM
Digital Clocks
Analog Clocks
Baby Monitors
•
•






•
                                             * Indicates Source of 6" Measurements
32

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 APPENDIX B

 Additional Reading and Information Sources

 Public Information Brochures

 Electric and Magnetic Fields from 60 Hertz Electric Power: What do
 we know about possible health risks?, Department of Engineering and
 Public Policy, Carnegie Mellon University, Pittsburgh, PA 15213,
 1989. Available from Carnegie Mellon: (412)268-2670. ($3.00)

 Electric Magnetic Fields Brochures Series, Edison Electric Institute
 (EEI). A series of brochures targeted for various audiences (consum-
 ers, employees, realtors, teachers, physicians, etc.). Available from
 EEI:  (202)508-5424. ($1.25+)


 Research Reviews

 Biological Effects of Power Frequency Electric and Magnetic Fields-
 Background Paper, Office of Technology Assessment, May 1989.
 OTA-BP-E-53. Available from the U.S. Government Printing Office:
 (202) 783-3238.  GPO# 052-003-01152-2. ($4.70+)

 Electric and Biological Effects of Transmission Lines: A Review,
 Bonneville Power Administration, 1989. Available from BP: 1-800-
 622-4520.  Publication number:  DOE/BP-945. Free. 107 pages.


 Basic Science

Electric and Magnetic Field Fundamentals: An EMF Health Effects
Research Paper, Electric Power Research Institute (EPRI), January
 1991.  Available from EPRI:  (510)934-4212. Publication number:
EN-7066. ($5.00)

Basic Electromagnetic Theory, by Demetrius T. Paris and F. Kenneth
Kurd, McGraw Hill, 1969. Available in public libraries and book-
stores.

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    For more information contact:
  Office of Radiation and Indoor Air
     Radiation Studies Division
U.S. Environmental Protection Agency
              (6603J)
      Washington, D.C.  20460

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