006898
     WORK STAUONMA&miC FIELD SURVEY RESULTS
          IN WE MEKALFE FEDERAL BUILDING

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INDEX



A.    Background



B.    Survey Methodology



C.    Averages for Specific Areas




D.    Region I Survey Results



E.    Summary



F.    Appendices

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A..    BACKGROUND

On November 23, 1993, the Radiation Section  (renamed the Radiation and Indoor
Air Section) submitted a proposal to survey oscillating magnetic field
intensities on USEPA-occupied floors in the Metcalfe Federal Building.  The
proposal was submitted at the request of the Regional Health and Safety
Committee.  The Regional Health and Safety Committee requested that the Air
Toxics and Radiation Branch, Radiation Section, conduct a survey of the
electric and magnetic field levels to which workers in the Metcalfe Building
are exposed.

Magnetic field strength is measured in gauss or milligauss.  A milligauss  (mG)
is I/1000th of a gauss.  Background magnetic field measurements taken outside
of the Metcalfe Building range from 0.7 mG to 1.0 mG.  Away from all
appliances, a typical American home has background magnetic field levels
ranging from 0.5 mG to 4 mG.  The actual strength of the field at any 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.

No clear cause-and-effect relationship exists between magnetic fields and
adverse health effects.  Consequently, no national standards exist for
exposure to magnetic fields in the United States.  Also, it is not understood
whether proximity to or duration within a magnetic field may contribute to
adverse health effects.

Despite the lack of evidence regarding the relationship between magnetic
fields and disease, organizations such as the World Health Organization,
International Non-Ionizing Radiation Committee (WHO/INIRC) has proposed a
5,000 mG magnetic field intensity exposure limit.  The American Conference of
Governmental Industrial Hygienists (ACGIH) has recommended a 600,000 mG
occupational limit.

Jack Barnette, Radiation and Indoor Air Section Chief, believes that the
exposure limits set by WHO/INIRC and ACGIH are problematic.  "In light of what
we now know about biological effects from exposure to EMF and the public's
perception of potential risks, it would be imprudent to expose people to such
intense magnetic fields."

B..    SURVEY METHODOLOGY

In February, 1994, magnetic field measurements began to be taken on floors
occupied solely by USEPA employees in the Metcalfe Building.  Following
protocols used by USEPA Headquarters, Region 1, the National Air and Radiation
Environmental Laboratory (NAREL), and the State of California, and employing
recently calibrated instruments from NAREL, the Radiation Section began a
stratified random sample.  Both 5 percent of non-enclosed work stations and
5 percent of enclosed work stations were tested. Furthermore, copy rooms,
kitchenettes, and unique areas such as the main computer room and the library
were measured.  Sampling ended in March, 1994, and the data was compiled.

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c.
AVERAGES FOR SPECIFIC AREAS
The following table provides a summary of the magnetic field survey.  A room
description and the average of all the measurements for that room are given.
All average measurements have been rounded to the nearest hundredth of a
milligauss.
Room Description
Conference Rooms
Supervisor Offices
Offices (enclosed)
Work stations
File/Docket Rooms
Copy Rooms
Kitchenettes
Average Measurement (in mG)
0.36
2.30
1.67
1.37
0.66
4.38
2.62*
                 This figure does not include the 73.14 mG measurement

Of all the rooms sampled, the highest magnetic field measurements were found
in kitchenettes.  This is not surprising, given the large number of appliances
that operate in these areas.  The highest individual room measurement, 73.14
mG, was taken in the kitchenette on the eighth floor.  Because measurement
protocols were not followed when this measurement was taken, a comparatively
higher measurement was recorded.  To have a more accurate magnetic field
profile of this room, remeasurement following the appropriate protocols should
be performed.

Individual room measurements are provided in Appendix 1.  Measurements taken
in unique areas, such as the library and computer room, are also provided in
Appendix 1.
JL.
REGION 1 SURVEY RESULTS
Magnetic field measurements taken in the Metcalfe Building may be meaningfully
contrasted with magnetic field research performed by other Regional offices.
In March, 1993, Region 1 published "Extremely Low Frequency  [ELF] Magnetic
Fields in Offices', and Their Mitigation," in which 5 mG is cited as a "useful
tentative yardstick" for setting an occupational exposure standard in an
office (see Appendix 2).  An overall range of 0.1 to 50 mG for occupational
exposure in a large office facility is cited as acceptable.  All average room
measurements fall well within an acceptable overall range of 0.1 mG to 50 mG.

Region 1 also performed a magnetic field survey of USEPA facilities at Canal
Street and One Congress Street in February, 1993 (see Appendix 3).  All the
offices tested in that survey registered values which fell in the range of 5
mG to 50 mG.  Most of the work stations (95%) in both facilities registered

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values which fell within the range of 5 mG to 50 mG.  As stated earlier, the
average magnetic field intensity for work stations in the Metcalfe Building
measured 1.37 mG, while Supervisor offices measured 2.30 mG, and other
enclosed offices measured 1.67 mG.  These figures, when compared to those in
Region 1, indicate generally weak magnetic field strengths in the Metcalfe
Building.                                                         ^

E..    SUMMARY

This magnetic field survey provides an excellent profile of the magnetic field
environment in the USEPA-occupied portions of the Metcalfe Building.  The
research protocols followed and the use of recently-calibrated NAREL
instruments ensure that the magnetic field profile presented here is accurate.
Based on this profile, magnetic field strengths in the USEPA-occupied portions
of the Metcalfe building appear to be on the lower end of the scale for a
typical office building.

Currently, research is unclear regarding the possible health effects of
exposure to magnetic fields in our everyday environment.  USEPA has set no
standards for exposure to magnetic fields.

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APPENDIX 1
 BYFLOOR

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                                           Off1 BACXCaROQH) ABBtBBHBtT SURVEY
     FLOCR NUMBER
4
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                      NAME
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    Gi libra ted on October 1,  1993.

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                                              EMF BACKGROUND ASSESSMENT SURVEY
       FLOCR NUMBER    *3~
   WORKSPATTON
NAME
CUBE
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DAtt
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IN

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                                           EMF BACHSRCXBD ASSESSMENT SURVEY
    FLOCP NUMBER
WORKSTATION
NAME
  CUBE
  TYPE
DATE
TIME
MEASURER
INI    AVE
1
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  MHUGAUSS
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                                            Off BACKGROUND ASSESSMENT UUKVEV
     FLOOR NUMBER
 WORKSTATION
  NAME
  CUBE
  1YPE
DATE
                                                      TIME
                                             MEASURER
Ittl    AVE
MEASUREMEfflS IN
  NHUGMUBS
                     ytyiiy V-\IL
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    FLOCR NUMBER
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                                                              ci-
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WOPKCTATTON f
NAME
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TYPE
DATE
TlMfi
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                                            EMF BACKGROUND ASSESSMENT BORVE?
      FLOOR NUMBER
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-------
    FLOCR NUMBER
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                                            EMF BACKOtOtlND ASSfeBSMBfr 8URVE*
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                                         EMF BAdttiRCRJND ASSESSMENT SURVEY
     FLOOR NUMBEK
 WORK.^J'ATTON #
NAME
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                                          DATE
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       NUMBER
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                                            EMF BACKGROUND ASSESSMENT SURVEY
      FLOCR NUMBER    /^
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TYPE
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                                           IMF HACRBROdrib ASSfi&SMEMT BUKVEt
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DATE
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                                            EMF BACKGROUND ASSESSMENT SURVEY
           NUMBER
  WORKSTFATTON #
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DATE
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                                         EMF BACKGROUND ASSESSMENT SURVEY
     FLOCR NUMBER
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                                       EMF BACR3WOND ASSESSMENT SURVEY
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                                        EMF BACKQWOND ASSESSMENT SURVEY
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       APPENDIX 2
MAGNETIC FIELDS IN OFFICES,
  AND THEIR MnKAJION"

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   •HOTT.
                     UNITED STATES  ENVIRONMENTAL PROTECTION AGENCY
                                                3EGICN :

                l.F. KENNEDY FEDERAL BUILDING.  BOSTON. MASSACHUSETTS  02203-221 i
                              Extremely Low Frequency [ELF]
                   Magnetic  Fields in Offices, and Their Mitigation
                                       N. A. Beddows CM. CSP
                    Abstract

        60  Hz,   magnetic  fields  exist  in  the
occupiabie space of offices, generally at one-naif to
five milliCauss levels. In a relatively small number of
cases, magnetic  flux density is higher, by two or
three orders of  magnitude.  This is  attributable
invariably to closeness to fixed electrical equipment.
but only, within the facility.  Elevated magnetic fields
are often  discovered by a malfunction of  a PC
monitor which is  correctable by relocation.
        Personal exposures and area  flux  density
can  be   measured.   Two   standards-setting
organizations have established  daily occupational
limits for exposure. The World Health Organization
(WHO) daily,  occupational limitation is 0.5 milHTesta
(5.000  milHGausst. This  is based on potential
induction of a current density level (~  10 mA. m*)
which is comparable to the levels occurring normally
in the body. The WHO limitation is lit three orders of
magnitude greater  than the magnetic  flux  density
which exists  in most occupiabie spaces. (HI seldom
if ever encountered in offices, and (Hit is far greater
than  the  minimal  level which  affects computer
monitors (10 milHGausst.
        A  tentative 'yardstick' for magnetic flux
density in offices  is five milliCauss. No deterioration
of acceptable work space  quality,  and minimizing
potential  exposures is  appropriate and  prudent
policy.       „     .      •
        Bevtttd field strengths in  offices may be
reducible,  economically, by a judicious use of low
carbon  steef end/or 48%  or 80% nickel content
alloys. A   magnetic shield must  have very low
reluctance  and  remain  unsaturated.  When  wall
shielding is required.  80% nickel  content alloy is
especially useful because of its high permeability.
        Shield   design   involves   attaining   low
magnetic   reluctance  while  averting magnetic
saturation,  and   excessive  incremental structural
loading, thermal overloading, disruption  to business,
and costs.
        Success in shield engineering is meeting the
 customer's expectation. In many mitigation projects.
 this translates to a twenty to thirty decibel average
 attenuation in flux density in occupiabie spaces.
        Feasibility  of successfully,  economically
 engineering a solution to an intrusive magnetic field
 problem can  be evaluated. Mitigation projects are
 described.  To  assure  project reliability and cost-
 containment,  the services  of a shielding specialist
 who can demonstrate  capability and experience is
 desirable,  and may be necessary.
.••   This material summarizes certain personal recent
inquiries  and findings on the practical aspects of
magnetic fields in offices, consequences of their
presence, and mitigation possibilities. It is intended
to be useful  in a  practical  sense to office  and
facilities managers, and employees who are looking
for basic information on the captioned subject,  and
as relevant safety engineering material.
     •"   Disclaimer: The information presented is
believed, out is not claimed, to be accurate. No claim
is made or implied for any agency,  official or
committeeandorseaent, concurrence, perspective or
approval.  No  endorsement  or warrantee  of  any
product, process or service is made or implied.  This
material is the sole work product and responsibility
of the author.

                                   N.A.8. 3/25/93
                                        HUNTED ON MCYCJ.EO

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Introduction

       Magnetic  fields are  non-ionizing.
Unlike X-rays and other types of ionizing
radiation,  including  sunlight,  they  do not
cause  actual breakage  of  molecule bonds.
However,  they  can  induce  low  density
electrical currents into  the head and trunk.
Magnetic  fields  are  not  perceived  by
humans,  and   they  can  penetrate  non-
ferromagnetic   materials,  unlike   electric
fields which cause hairs on the body to stand
up, and which are stopped by  all materials.'0
       Extremely  low  frequency  (ELF)
magnetic  fields  occur  in   every   office
environment. Their frequencies are predomi-
nantly 60 Hz, with higher harmonics to 300
Hz.  Other,  lower frequencies  (e.g., 5 Hz)
occur. These fields are created by alternat-
ing current in single-phase  or three-phase
electrical conductors.m The  60  Hz flux
density  average  levels  in  the occupiable
spaces of most offices are about one-half to
five milliGausst, but the average  magnetic
flux density levels  may  be  elevated  in  a
relatively small number of cases. And, of
course, some variation can exist within each
setting.  The  existence  of ELF  magnetic
fields  in offices  is now well-known.  First
evidence of their presence is  likely to be
computer screen flickering which stops when
the monitor is  placed outside of the fields.
An ambient magnetic flux density of about
ten milliGauss  will cause a monitor to jitter
or  lose  image, or  color  integrity.  PC
computers  themselves  create   external
magnetic fields.  Their  contribution to the
average  flux density in  an office is minor.

t  MilliGauss is used in field  surveying; and
microTesIa, in  Industrial hygiene and health
physics, for exposure. Some interchanging of
flux density terms is necessary in this paper to
maintain  the broad perspective.
       Personal   exposures    from   PC
 computers,  even ones with high resolution
 monitors, are rrujiimal, about  one-tenth to
 one-half of a microTesIa, at about (i) 24
 inches from the  screen and  (ii)  36 inches
 from the side or back of any  nearby unit.
       Average magnetic flux density levels
 several orders of magnitude greater than the
 upper limit of the general  office range  may
 be encountered in a relatively small  number
 of offices. Elevated average flux density is
 attributable   invariably  to  proximity  to
 unshielded  bus  bars, distribution centers,
 open cabling in trays, or cabling in  walls.
       Exposure  to  magnetic   fields  in
 offices  may become a concern in some
 situations.   The  public   is  aware  that
 associations  between  various cancers  and
 leukemia and electromagnetic  fields have
 been  claimed   in   some   epidemiologic
 studies.m   And,   public   exposures  and
 possible  biological   effects  have  been
 featured recently in the press and televisionr
 Explaining, magnetic  fields and discussing
 the associations of potential exposures  and
 diseases is difficult. The popular media have
 heightened public awareness  of issues  sur-
 rounding magnetic field exposures, however,
 some underlying factual aspects have gone
 unrealized.  Some studies  which suggest a
cancer  association   with   electromagnetic
exposures   were   based   on   indirect
assessments  of exposure, such as the wiring
codes employed  in home construction in
geographic  areas near power lines,  rather
than actual  measurement of  magnetic  flux
density.  Some   studies   which   suggest
associations  between  health and  magnetic
 fields indite  exposures which are less than
the theoretical threshold level for creation of
an electrical current density in the head or
 trunk which is comparable in magnitude to
current density levels which occur in normal
body processes. And,  some studies indicate

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that there  is  no significant  linkage  at che
surrogate exposure levels reported in studies
whach  suggest   some  association.  Other
studies  indicate  that weaker  magnetic field
flux densities are associated with an adverse
response, while stronger ones are not;<4) and,
data in  some studies would even support a
hypothesis  of potential, beneficial effect. At
this time, it is evident that there is extreme
uncertainty in effect-exposure-response mat-
ters concerning weak magnetic fluxes.
       In  considering  the epidemiological
reports   on   extremely   low   frequency
magnetic fields, it may be helpful to know
the   position'51   of  the  World   Health
Organization,   International   Non-Ionizing
Radiation Committee (WHO/INIRC) of the
International   Radiation    Protection
Association, The WHO/INIRC states:
       " Although these epidemiological data
can not be dismissed, there must be additional
studies before  they can  serve as a basis for
health hazard assessment. Furthermore, scant
laboratory  evidence  exists to  support  the
hypothesis that there is an association between
50/60 Hz fields and increased cancer risk.'

      The preceding WHO/INIRC position
is echoed by other authorities, including the
National  Radiological  Protection  Board
(NRPB), and the Committee on Interagency
Radiation Research and  Policy Coordination
(OSTP). These  organizations  and others,
however, support a major research initiative.
And, on  this  point,  to  quote  the  EPA
Scientific Advisory Board:
       'Restjtrch   is  needed.  The
Subcommittee  therefore recommends  that
scientific information  sufficient to  support
credible formal risk assessment of exposure to
electric and magnetic fields be developed..... *

      EPA is pursuing research  on ELF
and higher  frequency band, electromagnetic
fields; with cancer,  bio-mechanisms and
exposure assessment being high priorities.
  Flux Density Levels & Factors

       Strong magnetic fields do not exist in
 occupiable  spaces in a typical large office
 facility.  The average,  60 Hz magnetic field
 flux density in such spaces in most offices in
 a typical large facility, is less  than five
 milliGauss,  and the  corresponding  range is
 typically  about  an   order  of magnitude.
 However, a small percentage of offices ui
 such  a facility  may have  (i)  higher than
 average flux densities and (ii) area magnetic
 hot-spots due to the influence of external but
 close, fixed power distribution centers, bus
 bars, open  cabling  in trays,  sub-stations,
 elevator  machinery rooms,  electrical cables
 in walls or main-frame computer equipment.
 The  materials  used  in  construction, and
 room orientation also can influence the level
 of effect from electrical apparatus.
       Magnetic field flux density at a point
 is weakened greatly  by separation  of  the
 point from  the  source.  Attenuation  is  an"
 inverse  function  of  the  square  of  the
 distance.(4) In most office layouts, separation
 of occupied  space from fixed high-power
 electrical    services    or    equipment   is
 substantial.  Some offices will be close  to,
 and affected  by, such electrical services  or
 equipment.
       With    some   affected   offices,
 rearrangement of desks, computers or seats
 will reduce potential exposures or eliminate
 video  monitor problems.   Some  affected
offices, however,  will need to be physically
 shielded  to  adequately attenuate  magnetic
 fields created by external electrical  apparatus
and cabling, if they can not be relocated.

Survey Meters &r Monitoring

       Most  office facilities have  electrical
apparatus which generate two or three 60 Hz
 harmonics, as well as lower frequencies.

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Monitoring^ magnetic flux density levels in
offices  is performed  using  a  survey meter
which can measure down to about one-tenth
of a  milliGauss  [0.01  microTesla]  on the
maximum-sensitivity   scale.   The   meter
should  have an  accuracy  of ±5%  at the
calibration  frequency.  It   needs  to be
accurate   over   the   frequency   range
encountered.  Readout  is  "milliGauss" or
"microTesia."  Apart  from  area  survey
meters (which can also be used to determine
time weighted average exposures), magnetic
field dosimeters are available for monitoring
personal exposures. They can be  linked to
data loggers to  facilitate large scale  data
collection and analysis.
       A magnetic flux density meter uses
either a single-axis probe or a  three-axis
probe. The single axis probe is sensitive to
a field only in one direction.  This feature,
however, is invaluable in determining  field
magnitude and direction, which is needed in
shield  design  work.   When a  single-axis
meter  is  used  as an  area  or  personal
dosimeter, the operator turns the probe in all
directions, takes spot measurements in three
perpendicular axes, computes the  square
root of  the sum of the squares of the three
perpendicular plane readings,  and reports
the  computed  (rms)  mean  as   the  flux
density. Taking readings in the three  axes is
necessary because of the vector nature of
magnetic   fields.  The  computation  is
conservative when the field is elliptically
polarized (as with a three-phase generator).
The  three-axis probe simultaneously  senses
magnetic  fields   in   three  perpendicular
directions.   The  meter   automatically
integrates the three, directional flux densities
and displays a single (rms) value.
       Survey meters and dosimeters must
be  calibrated  before  use,  and  at  least
quarterly. The calibration  source must be
traceable to  a national  primary  standard.
 Guidelines for calibration are provided in
 MEL-STD 4566A, and  in an  ANSI/IEEE'"
 standard.  Portable calibrators  are available.
 Users  must follow the recommendations of
 both  the  calibrator  manufacturer and  the
 meter  manufacturer.
       A  large  number of  measurements
 need to be made over the day, when work
 places or personal  exposures  are  to be
 characterized. This is necessary to factor in
 power usage, which may or may not change
 over time  and cause a change in the ambient
 magnetic  field strength. Evaluating a work
 space requires measuring  the  mean (three-
 axes) flux density in  at  least five locations,
 including  the room center, any  walls near
 seating, and  the wall centers  and top and
 bottom comers.  Evaluating  a  personal
 exposure  involves  determining  the  time
 weighted average, mean  flux density at waist
 height.
       When spot measurements are  made
 in occupied spaces for any purpose, upon art
 employee's, request, it would be  reasonable
 to (i) explain what is being  measured, and
 (ii) make  the results  available. Transmittal
of data might best be made by  letter, with a
clear explanation of the  situation. This will
avoid misunderstanding or misinterpretation.

 Guidelines & Limitations

       A  knowledge  of  guidelines  and
 limitations for occupational exposure and the
 rationale   for setting   the  limitations  is
invaluable  when  potential   occupational
exposure  to  magnetic  Melds  becomes  an
issue. Two organizations  provide relevant
occupational guidelines and limitations:

 *   The   World  Health  Organization,
 International   Radiation   Protection
 Association,   International   Non-Ionizing
 Radiation  Committee (WHO/INIRC).

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 >   The American Conference  of Govern-
 mental  Industrial Hygiemsts.'9' ACGEH.

       The 1989 WHO/INIRC occupational
 Limitation is die  more stringent of the two
 limitations.
       The basic criterion  of the  WHO
 limitation is a biological one.  This criterion
 is  that of maintaining flux density below the
 level  which can induce an electrical current
 density  in the body of about 10 mA m'2.
       The criterion limitation carries  no
 implication whatsoever that  the referenced
 biological change progresses to any adverse
 health effect.
       The  WHO,   International   Non-
 Ionizing Radiation Committee, in  referring
 to  the  daily  magnetic  field occupational
 limitation, -states:
       "The magnetic flux density,  B,  ...  is
 accepted as the most relevant quantity for
 expressing  magnetic fields associated with
 biological effects."
            to  be   conservative,   current
 densities induced by external... magnetic fields
 should not significantly exceed 10 mA m*."
       "[The limits recommended] correspond
 to  induced current  densities  that are  at or
 slightly above those normally occurring in the
 body (up to  JO mA m'). "
       "[A reduction factor of ten is applied to
 the  WHO/INIRC  occupational,  whota-body
exposure  limitation   IS  milliTesia)   which
corresponds to an induced current density of
 JO mA m'l because of the sparseness of data
on long-term exposures ...."
       "[The xtO  factor-modified]  magnetic
 flux density for continuous exposure in the
occupational environment is limited toO.SmT.'

       The ACGIH Committee, in  referring
 to  its occupadonal standards, states in the
preamble to all of the standards:
       "[A  limitation to which] it is believed
 that  nearly  all  workers may be repeatedly
exposed day after day without adverse health
effects.'

       The 1993 ACGIH occupational limit
 is 60 milliTesia, it is unchanged from  1992.
        OSHA':m has no applicable standard,
 and its [§5(a)l] General Duty clause is  not
 applicable because no recognizable, serious
 hazard exists.  Electromagneuc exposure is
 not on the 1993 OSHA Regulatory Agenda.

 A Yardstick for Decision-Making.
 Minimizing Potential Exposures

       Offices in  proximity  to  large, fixed
 electrical equipment can be expected to have
 stronger field strengths than offices which
 are remote  from such  equipment. If higher
 than average magnetic fields being  present
 in an office becomes an issue,  some sort of
 yardstick will  be needed  for  making  a
 decision.  If one accepts  the WHO/INIRC
 daily   occupational   limitation   as   a
 conservative  guideline  (many industrial
 hygienists do), and, that the magnetic field
 flux density in a typical large office facility
 is two or three  milliGauss,  which is three
 orders  of  magnitude  lower  than  the
 WHO/INIRC  limitation,  then  one  might
 agree  that a useful tentative yardstick  for
 decision-making is five milliGauss, or one-
 half of a microTesla, in exposure terms. [At
 this flux density, one would not expect any
 interference with computer monitors].
       Apart  from  having  an  acceptable
 yardstick  for use  in decision-making, one
 might  also want to employ certain criteria
 for prudent avoidance,  even though no basis
exists to believe that there  is any degree  of
 hazard with office-level exposure. One may
elect to adopt measures to avoid exposures,
even if doing so  may or may not reduce any
potential, albeit  unknown, risk.  A criterion
 for this  philosophy could be  one of "no
significant deterioration." Another criterion
could  be a goal of reducing  flux density
when this is practicable and economical.

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       The relation of the WHO/INIRC and
ACGEH  guideline-limitations  and  typical
levels of magnetic flux density in offices is
illustrated in the following text box.
          1992  -  1993  ACGIH
          OCCUPATIONAL  LIMIT •
          60 MidiTesla.
DAILY.
    ££  2 ORDERS OF MAGNITUDE
           LOWER            *
                              r
         1989  [&.  1993]  WHO  /  INIRC
         DAILY, OCCUPATIONAL LIMIT -
         0.5 MilliTesla. [5.000 MilliGaussl

         3 ORDERS OF MAGNITUDE
           LOWER,  AGAIN     *
         PC Video Problems
         [at 10-t- MilliGauss]
         MOST OFFICES at 5 MilliGatm or
         Less. [0.5 MicroTesJa or Less!
       Reducing  office  magnetic   field
strengths might require physically shielding
a work space from intrusive magnetic Melds
emanating  from  adjacent  electrical power
apparatus,  equipment or cables. Reducing.
personal exposures  might be achieved  by
rearranging, desks'and seats, or relocating an
employee.  [Relocation  might  be offered as
an  accommodation  for  an  employee].
Regardless of whether an engineering or an
administrative effort is made, an assessment
of the area "will be needed. This will involve
representative monitoring of office spaces.
       Characterizing an office  facility and
assessing   potential   exposures  in  offices
require  a  large data  base  of magnetic flux
 density  and duration  of  exposure.  Data
 ought  to be resolved in terms of office-flux
 density  distributions.   Setting  an   overall
 range for this purpose is arbitrary, but it can
 be  done sensibly.  A  range  of 0.1  to 50
 milliGauss  is  believed to  be  appropriate,
 because: (i) the upper limit is rwo orders of
 magnitude below the WHO limitation, and is
 only rarely exceeded in offices; and (ii) 0.1
 milliGauss is the  lowest flux  density which
 one can measure ordinarily.
       Depending  on  observations,  the
 quality of the available information, and the
 reference point (yardstick) used,  one can
 decide whether or not to  mitigate  a flux
 density problem in a particular work space.
 In this matter, one might bear in mind that:

 •     Optimal work  space quality may be
 equated to magnetic field flux density, but it
 is most definitely related to good  lighting,
 uniform acceptable temperatures, low noise^
 level, and a high rate of fresh air supply;
 compromise is needed, invariably.

 «     Employees having  to  work with
continually malfunctioning video monitors is
 unacceptable, might be construed to be an
ergonomic hazard, and ought  not to be pan
of a space-quality compromise.

 •     Work places which are perceived to
be of less-than-optimal quality might better
 be used  for minimal-occupancy activities:
 record-keeping, and equipment storage.

 •     There  is  no  requirement  on  an
employer to make an extraordinary effort to
 measure  or attenuate magnetic  fields in
offices when there is no likelihood of a
 recognizable serious health hazard existing.
 Initiating such an effort, however, may be
 necessary  to   maintain good employee
 relations and productivity.

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Economically Feasible Engineering.

       When considering the desirability of
reducing  potential  personal  exposure  or
eliminating   electronic   interference,
associated  with  an intrusive magnetic field
caused by an external electrical current, the
manager needs answers to two questions:

o  What is involved in,  and what  is the
economic feasibility of, attenuating magnetic
fluxes in an affected work space?

o  What has been successful  in efforts to
attenuate  intrusive  magnetic  fields  using
economically feasible and practical methods?

       Project performance data is propriety
information to the designers and installers of
magnetic shields. One respected source for
shield design and manufacture conditionally
agreed  to   provide  the writer  with  pre-
treatment and post-treatment, average flux
density   data   and   information   on
methodology  and  material  selection,  for
several  remedial projects.  These particular
projects were described as 'conventional and
generally   economical."   The  prescribed
conditions   were:  (i)  data were  to  be
described in  terms of  "attained minimal
decibel  attenuation" [rather like  acoustical
engineering]  and,  (ii)  only  a  general
description   would  be   made  of   the
construction materials  and arrangements
used. These restrictions,  however, do  not
prevent one from assessing the feasibility of
employing  economical   engineering   to
attenuate fields  to  eliminate an equipment
interference problem or an exposure issue.
And,  they do not stop one from providing a
sense of the engineering effort that can be
involved in  their mitigation.   Feasibility
information, and summaries  of reported
projects are provided in the following parts.
 1.     Feasibility-Related Information,

 •     Intrusive  magnetic  fields  can  be
 attenuated to  non-problematic average flux
 density levels  by implementing a program of
 surveillance, shield design and installation.

 •     Success, in context with economical,
 conventional  shielding   for  offices  and
 laboratories, means attaining the goal set by
 the customer.  Depending on the  average
 value of  flux  density  initially existing, an
 attenuation of  average flux density of twenty
 to thirty decibels or greater may be attained
 without having  to  resort to extraordinary
 (high cost) shielding engineering. In general,
 the lower the value of the starting point flux
 density, the lower will be the decibel level
 of attained attenuation.

 •     Conventional   magnetic   shielding
 design  and   installation  has   had  many
 customers with office type  problems. The-
 record of numerous projects is evidence for
 the economic feasibility of shielding offices.

 •     Methodology    for   assessing
 economical    engineering   feasibility   is
 illustrated in the following example:

       A large, premium office space is being
 affected by intrusive magnetic fields believed to
 be  caused by apparatus  in  an  accessible
 electrical,  vault  situated  in  a   basement
immediately  below the affected space.  One
 employee, using an inexpensive  hobby-type
 Gaussmeter,  has  found  about  50  to  60
milliCauss in the occupiable spaces, and higher
levels on some  walls. The management wants
 to  make  the  occupiable  space  the same,
magnetically, as the other (unaffected) offices,
but, it 7i  'nor~ going   to  pay  for  any
 extraordinary engineering work. * The Building
Manager  has asked  'Would using physical
 shielding   be  feasible?   What   would  be
involved?'

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        The level to be attained is the "good"
office  average level,  say,  an  average of two
milliGauss. Let us accept that  the meter which
the employee  used was  fairly accurate.  The
preliminary challenge is to assess the feasibility
of attenuating flux density from an average of
sixty (Hmj to an average of two (H,) milliGauss,
using   conventional,   economical   shielding
engineering (which  may yield 20 decibels  
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                                         -- 9
  •    Efficient  shielding  is  a matter  of   '    2. Reported Successful Projects.
balancing  permeability  against  saturation,    !
while maintaining material workability, and
project simplicity and economy.
 •     Multiple  layers  of  material  or a
 laminated arrangement may have to be used
 in  some  cases  for  efficiency.   Laminar
 structures offer the great benefit of effective
 attenuation by  air spacing.

  •    It is generally preferable to shield the
 source,  when  possible,  consistent  with
 maintaining adequate  heat dissipation and
 required   equipment   operational
 temperatures. The benefits are (i) generally,
 minimal   surface   area  treated,  and  (ii)
 minimal  disruption  of work place activities.

 •     Shielding  at the  receptor  site may
 involve affixing one-quarter or even one-half
 inch thick, low carbon steel plates to floors,
 and  a  laminate   of  low  carbon   steel,
 plywood, and a 80% nickel content alloy to
 walls.  Placing a one-quarter inch thick steel
 plate  on a floor  creates  an incremental
 uniform  loading  of about ten pounds per
 square   foot.   Generally,  this   level  of
 incremental floor loading is not a problem.
 Shielding  arrangements  of  these types,
 reportedly,  are  quite  usual as   required
 treatment for affected work spaces.
       In some circumstances, an alternative
(or  a  compttmtnttfy action)  to  physical
shielding might b* a preferred solution. Such an
alternative might include • but is limited to •
eliminating open bus ban and replacing them
with shielded cables,  twisting  three-phase
conductors ~to achieve EMF-cancellation, re-
routing cabling to achieve maximum distance
from the affected receptor site, and terminating
conduits in heavy steel enclosures to further
confine magnetic fields.
        Reportedly   successful  cases,   for
 which certain  proprietary information and
 attenuation  data have  been  provided, are
 described in the following sections.
 •     A large room with interference of
 computer  operations  and  video  screen
 problems,  caused  by  external  magnetic
 fields, was treated successfully by covering
 certain  wall  sections, which had  magnetic
 hot-spots, with 60 mil  thick,  80% nickel
 content alloy sheeting; and the floor,  with
 one-quarter  inch  thick, low  carbon  steel
 plates. Reported average attenuation: 30 dB.

 •     A room  with  sensitive  electronic
 analytical  equipment   was  affected   by
 magnetic fields created by a power control
 center  in   a  vault  below   the  room.
 Elimination of interference, with an average
 ambient  flux density less  than ten milli-..
 Gauss,   was   attained.  Reportedly,   this
 involved using  1/4" 1010 steel plates for the
 floor, and 60 mil, 80% nickel content alloy
 sheets for the wall,   magnetic  hot spots.
 Average flux density attenuation: 30 dB.

 •     A hospital room  affected by 60 Hz
 magnetic   Melds   from   adjacent   power
distribution   equipment,  reportedly,  was
effectively  treated using only  low carbon
 steel plates placed on  the floor and on some
wall areas. Average attenuation: 25 dB.

 •     Designed, fabricated-to-order, nickel
alloy   (high   magnetic   permeability)
enclosures  are reported  to be  effective in
shielding video monitors from  screen jitter
and image distortion caused by ambient 60
Hz  magnetic  Melds  created   externally.
Reported average attenuation: 40+ dB.

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                                               10
Concluding Remarks

        It  may  be  worth  summarizing  a
personally  associated, failed  project:  Low
carbon steel plates were fixed to the ceiling
of  a  power distribution  equipment vault
located almost directly beneath offices which
were having problems with  video monitors.
The average flux  density in the vault space
exceeded  40   Gauss. The average  flux
density   in   the  affected  room,   before
treatment, was about fifty milliGauss. The
average   flux   density   after   treatment
exceeded  ten   milliGauss.   The  monitor
problems  remained.  Treatment  was  not  a
success.  Now,  it is obvious  that,  as  a
minimum,  comprehensive  area shielding,
and significantly greater shielding efficiency,
Ln the vault space  itself, was needed.
       This experience prompts me to make
two,  closing  comments   on  the point of
looking for engineering solutions:

1.     Knowing what works and what does
not, and knowing  what is cost-effective and
what is not are invaluable for cost avoidance
and project reliability. This knowledge must
come from first-hand  experience. Trying to
remedy  a  major  magnetic field problem
without  prior experience could  result in
repeated, failed attempts and excessive cost.

2.     Shield design is the  province of the
expert. Design,  and  probably installation
also, might better be left  to a company
which specializes  in this work.
                   * *  *
 References & End-Notes

 1.2.S.   For  a  good  explanation  of  the creation  of
 magnetic fields and electric field*, and their properties, sea
 Engineering  Electromagnetics,  William  H.  Hayr. . Jr.
 McGraw-Hill Book Company. Also. EPA Publication AQ2-R-
 92-009:  'Questions and Answers About Electric and
 Magnetic Field*'
 3,4.     Feychting. M. Anders. A.: Magnetic fields ana
 cancer in people neer Swedish high voltage power lines.
 IMM-rapport 8/92. Stockholm Insotet for milijomedicin.
 Karolinaka institet. Stockholm. Sweden.
 5.      For a thorough review of (he WHO.IRPA/INIRC
 Guidelines and Limitations, see Health Physics  Vol. 53,
 No.1  (January) pp. 113-122. 199O.
 7.      Monitoring for exposure assessment is  different
 than area/home surveillance. Spot measurements are taken
 over the day, at waist height, to establish a time weighted
 average for the daily exposure. A minimum of 16 readings.
 spaced evenly through the day,  per personal exposure is
 recommended.
 8.      IEEE Standard 0644.1979. Institute of Electrical
 and Electronic Engineer*, New York, NY.
 9.      Technical Information  Office:  650O Glenway
 Avenue, building D-7. Cincinnab. OH 45211-4438.
 10.     The   Occupational  Hearth  and  Safety
 Administration. OSHA set* occupational standard*. The
 General Duty clause may apply when no specific standard
 is relevant and a senous recognizable hazard exists.
            . Acknowledgment

        The test data and work contributions of
my colleagues L. Darveau and J. Cherniack are
acknowledged with pleasure. My thanks to W.
Chenoweth,  W. Ho/brook  and  R.  Hinten for
their reviews and  comments.  Special thanks
go  to  L   Maltin.  Amuneal  Manufacturing
Corporation, Philadelphia,  PA  13124,  for
sharing  with   me proprietary  attenuation
information  from  some  of  his  mitigation
projects, as well  as information on material
properties and proven uses.
         The author would welcome additional
information on the matters mentioned here •
especially  information  on  mitigation efforts
which have proven to be either successful or
unsuccessful.  Norman  Beddows,  Region  1
Safety,   Health and  Environmental  Program
Manager.   United   States   Environmental
Protection   Agency,  J.F.  Kennedy  Federal
Building, Boston, Massachusetts 02203-2211.
(617) 565-3388.

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              APPENLOX3
REGION 1 MAGNETIC FIELD SURVEY ASSESSMENT

-------
 -          UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
 f                                  B€C10NI
                       MDlflAt
To:            P. Meaney, Acting Deputy Regional Administrator.

Through:       S. Perkins, Deputy Assistant Regional Administrator.

From:         N.A. Beddows, CIH, CSP   /i*/>— •& . H/.
               Regional Health and Safety  Manager.    "/"' *

Subject:        Extremely Low Frequency (ELF) Magnetic Fields in Regional Off.
               Information For Use in Addressing Possible Employees' Concerns
A. Consideration of the Pfeseppp of A, Hazard

  At the outset, I  want to assure  you and our  employees that  there are no t$n
recognizable health hazards related to  ELF magnetic fields in any office or work :
in either of the Canal Street or the  Congress Street EPA Facilittes.

  With respect to ihis assurance, I should explain that occupational exposures to extre
low frequency (ELF; 60 hertz) magnetic fields occur in every office environment.
thcal power sources, power distribution centers, elevator electrical machinery, com
centers, lighting and personal computers generate electromagnetic non-ionizing radia
However, the m»fn«ie component of every electromagnetic Meld from such sour:
weakened dramatically by separation by distance. Such separation by distance ex:
ail of the office layouts employed in the two Boston offices of Region 1 .

  J. Cherniack, L.  Darveau. R. Hintan and myself were involved in one or more a:
of monitoring (1) magnetic flux densities in offices and researching relevant guide:
Seveni hundred spot measurements of magnetic  flux densities in our offices have
measured in the last few weeks by J. Cherniack and L. Darveau, using  a Holac;
3627 Electromagnetic Field Survey Meter. I  believe that the extent and quality <•,
monitoring used, most of which I either witnessed or identified as required, adeqi
characterizes the referenced facilities.

  In the offices in  the EPA facilities at Canal  Street and One Congress Street, pot
office ELF  magnetic (B flux density) exposures  span two orders of magnitude. T
evident from the flux density data  that J. Cherniack and Linda Darveau have me:
and reported.  However, the highest flux density reported for any work station m an
of a station is two  orders of magnitude less  than the  World Health Organ::
International Radiation Protection  Association's  (WHO/IRPA) Occupational Lien.
 for continuous occupancy exposure to ELF magnetic fields (discussed later;.
                                «•«••» «0 OH

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 What we have as'.erminea is sufficient to allow me to feel comfortable in cec:ar;nz
there  are no known, recognizable  hazards  associated with ELF  magnetic  fields  ir.
referenced offices. In saying tnis.  I realize that data gaps and unansweraoie  sues1.
abound on many aspects of this topic.
3. Background Information

  As you know, exposure to ELF electromagnetic fields is an emerging public ccr
because cancers have been associated with exposure :n some epidemiologic studies
more significantly,  perhaps, the topic has featured recently in the press, teievisio.-
in a few wcll-puolicizcd  litigated eases.

  Explaining ELF magnetic fields in offices and the significance of measured expc
to employees is difficult in most situations, and it is especially difficult when  fac:
emotion generated out )f articles, whether sensational or evenly balanced.

  While  the media have heightened  public  -.wareness  of issues  surrounding
electromagnetic exposures, some underlying factual aspects, which are too Uiff.c
address in a few sound  bites, go unrealized. To the point, some studies  which
suggested a caneer association with certain ELF electromagnetic exposures were
on indirect assessments  of exposure - the types of wiring  codes employed  in
construction in geographic areas near power lines,  et cetera  • rather than actua.
measurements  of magnetic flux densities in homes.  Some  studies  which sugg
association are at odds  with  the theoretical basis for establishing the  magmtuc;
magnetic  field density  which  could  induce  a current  density  in  skin  and
comparable to  those current density levels which occur normally in the body. And
studies made by competent authorities indicate that there is no significant linkage sf.
comparable to the surrogate exposure levels reported in studies which say the  op:

  It seems fair to say that no one is even sure  that  weak electromagnetic forces
 human health  and  that there  is even greater uncertainty in regard to exposure-
 question* with such fields.
 C.
   After reviewing the technical literature, there are two relevant occupational lirv
 to consider: the limitation  of  the  American Conference  of Governmental Iru
 Hygienists (ACGIH),  and the limitation of World Health  Organizationxlnterr
 Radiation Protection Association (WHOMRPA).  The WHOURPA limitation is th
 stringent of the two. OSHA has no applicable  standard, and its [5(a)l] Gencr:
 clause is neither relevant nor applicable.

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                                      -3-
 Dealing with the WHO/IRPA Occupational Limitation, the following points arc rraac

     »    The  criterion underlying  the  magnetic  flux  density-based limitation
         predicated on that flux density which may induce a current density  in hums
         tissue which is comparable to the levels of those which correspond  to norm
         physiological functioning [reportedly,  10 mA m2].

     *    The limitation includes a reduction factor of 5. This factor is used to acccu
         for the scarcity  of  relevant human  data. As  a  concluding remark,  tr
         WHOMRPA  limitation is provided with the  acknowledgment that enteric
         employed does not signify that a human health hazard occurs with the releva
         induced current density.

     »    The WHOMRPA established (ELF magnetic field density) threshold limit vaii
         for occupational daily exposure is 0. 5 miiliTeslat.

               r Tht wvr Tttlt it tfif tcttfttO tfittmetwiH unit for gttenWng I8f maqnttic ft.
              tfwwry, lti$ *rwoy»tf m tnt fatnttftc /ournttt tn4 ay jr«/w«rw-jtrr/*»ff tutnonm
              On» Tim fowtt  10.000 $«WM. it is em&Qyrt Herein to factHtanjefennca.
     >    The rationale stated  by (he WHOMRPA Committee for establishing it
          limitation has wide support among industrial hygienists and health physicist

     »    The value of the WHOMRPA-Hmitation is two orders  of magnitude less tn;
          the threshold limit value (60 milliTeslas)  for continuous, daily, whole-be
          exposure established by the American Conference of Governmental Industr
          Hygienists (ACGIH) in 1992.

 I believe that the WHO/IRPA Occupational Limitation is entirely relevant and applies
as an interim guideline for large office environments. Of course, nothing prevents
from  establishing a more stringent limit as an interim internal standard. Moreove
attaining a significantly more stringent limit  for  continuous occupational exposure
achievable without any effort by most office facilities.
D. AiMMTnent Raoonad Spot Mftaitirefncnti of Magnetic Plux_Degsiiy.

  An assessment of the reported magnetic flux density data on the 90 Canal Street offu:
all of which have the usual electrical services and electronic equipment, is provided
the following part.

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                                       -4-
          All the offices' magnetic flux density values fall in the range of 0.03
                not* tnat 'in ueev tlm/t of rfw« rtngt /» rwo ortf«/j a/ magnituae
                   liirttttaen for » attfy 9CGuo*tfar&
          Most [95%] of the work stations in both facilities have magnetic fields of £
          density values which fall in the range of 0. 1 • 0.5 mjcroTeala.
                nQto (hit tho vpptr limit of this rmgo it ihrt* oratn of mtamtua* 6t/ow
          WHO'JRPA
          15 offices have the higher measured values. However, all have magnetic :
          densities which fail within the range of 0.13 • 5.0 ousiaTesla.

                not* thtt f/w uffttf Unttt ol thto rtng* it two orders of mtan'tud* o«/ow
 Baaed on the matters reported and for the reasons stated above, I believe that there
no irnawn. reco|piMhi« ELF magnetic Meld related health hazards in us office or w
space in either of the Canal Street or the Congress Street EPA Facilities.
B.
  There are several related but separate matters that I believe should be addressed at
point. They are:

      »    What should  be the philosophy in regard  to providing quality S-h
           oceupiable work spaces?

      »    What should w« establish as a (Regional only)  interim internal sundarc
           establishing office facilities?

      »    What engineering and administrative opportunities are there for minim
           magnetic fluxes and exposures in the office work spaces?

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  On the  first noint (applicable philosophy).  [ believe that in establishing layouts 2
 providing ot'fice work spaces one should place employees in optimal quality spaces -.-
 rteed to keep in mind thai naturai lighting, even temperatures, low noise level, anti h:
 venulaiion rate are very major components of quality) to the best extent possible, and
 utilize lesser  quality spaces fur minimal-occupancy  activities:  record-keeping c:mc
 equipment storage, and the like. I am not aware of die existence of an employer-duty
 any possibly  relevant health standard  which  requires an  employer to engage in .
 extraordinary research on  attenuating  ambient magnetic  fields (i.e.,  fields  with r*
 densities less than 5  microTeslu) for the  purpose of minimizing potential exposures
 offices.  Of course, we might need to do this in iome cases.
            note. w« caw/0 mate « ortamtnary avitu*non of rnt feastoimv of wgt/mnng out <*
              (fusts in gfffett. This mtgm 6* tntnttf vt*»n tourlous nicrnmtgfiattc Was aoc.
      to 09 tfficttng comouttf vtdto unin in icmt offfct locinan* us eoeaars TO ot me cue in a
      loctnont tt 90 Can*
   On the ^cond poii^ (eatablish^nj a t^egjqn^| peetipmnt exnpsure standard^, we airs;
 far exceed {fct-work space quality which is afforded by application of the  WHOMR
 Umi^uon. We have employed a metallic shielding with  apparent marginal success
 minimize 'the weak but higher man avenge magnetic fields present in a small numbe:
_fvrtr*'Ay .gcT'cmtf  """+  «paff « (n&»*  the current situation,  I  believe  that  it
 Appropriate to base a Regional-only internal standard on the principle of "no sigmfic
 deterioration . *

   The  e«i«tln   ranaa of  otential magnerie flux danaitv exoures in our fucilitiea as •
   The interim Magnetic Field Flux Density , 8-hour, Daily, Occupant-Exposure Stan.
  which I am recommending for Region 1 , is:

       1.   An avenge value of 0.5 microTealm (5  milUGausses) evaluated as an
            weighted mean value. And,

       2.   An upper limit of 3 microTeaUs (SO milliGausses) for S-hour occupancy

   In my judgment, these values characterize our current occupied office facilities
  respect to ELF magnet flux density.

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                                         •6-
  Dn  the  ultimate  OQint ( engineering and admini
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               UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                                REGION 5
                        77 WEST JACKSON BOULEVARD
                           CHICAGO, IL 60604-3590
                           AU6 2 3 1994                  REPLY TO THE ATTENTION OF:
MEMORANDUM

SUBJECT:  Region  5  Electromagnetic Field (EMF) Survey
FROM:     David A.  Ullrich       ^
          Deputy  Regional  Administrator

TO:       Division  and  Office Directors


Attached are two  copies of the results of the Electromagnetic
Field  (EMF) Survey  which was  conducted in February 1994, by the
Air Toxics and Radiation Branch,  Radiation Section, of EPA-
occupied space in the Metcalfe Building.  The survey covered
approximately five  percent of the non-enclosed workstations,
enclosed offices, copy  rooms  and  kitchenettes on each floor, and
also included unique areas such as the main computer room and the
library.  This survey was  primarily designed to determine
background EMF levels in the  Region.

This EMF Survey provides an excellent profile of the magnetic
field environment in EPA-occupied portions of the Metcalfe
Building.  Based  on this profile,  magnetic field strengths appear
to be on the lower  end  of  the scale for a typical office
building.

A copy should be  maintained by your Administrative Officer and be
available to any  employee  interested in viewing this document.

Attachments
                                                           Printed on Recycled Paper

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