HomeMy WebLinkAboutT-MOBILE (CEDARWOOD PLAZA) WTF - PDP - 38-06A - REPORTS - ENVIRONMENTAL REPORTcause the the site to exceed FCC limits.2 Please refer. to T-Mobile's predictions. for the
company's estimateof worst -case power densities in public areas from this cell site:.
Access to penthouses, which are used solely for the T-Mobile sector antennas,-should.be
restricted to personnel who fall in the occupational exposure category.Because-the antennas
are at the highest point on the roof and face outward, the only way .to exceed"public exposure'
limits is for personnel to be inside the penthouse and standing in the narrow space between the.
transmit antenna and the stealth screen. To ensure compliance, either.T-Mobile.o'r Adams 12-
Five Star Schools should install one RF Notice sign at the open end of, each peiii iOUse. •Th•e
signs should be similar to the one shown in Figure 3. This sign is available;from Tessco,
(800) 472-7373, P/N 30661, $19.73 each.
Figure 3 - RF Notice Sign
'`Because the noise floor of the W&G ENIR-300 is 2.5% of the public limit and all measured levels Wpublic`areas-were below this
level. T-Mobile could.increase its average power by at least a factor of 40 before exceeding the FCC public limit. • Based on past a
experience and FCC measurements [6],. actual levels are almost certainly orders of magnitude below: the noise floor. of, the meter and. l
`.therefore a sienifirant cushion exists benvetn, the hi_hest practical pow•er,densities created bv.tMs cell site in'publte areas and'the FCC
pubhcexposure limit.
ARAPAHOE RIDGERADio FREQUENCY EXPOSURE SURVEY � � " . . • . ;
Rooftop (Not to Scale)
South Penthouse
Controlled
Environments
24
T-Mobile.Radio Cabinets
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% of Std:
No.
Location'
. Environment t
Site On '`7$ite-0ff
1
G mnasium-Center
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2
Cafeteria -Center -
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Music Room - Center
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Main Office - Center
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Lobb Outside Music Room
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Room B130 - Center -
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Room B106-Center
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Room B124 - Center
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Room B112--Center - -
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Room 8718 - Center
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11 Half Outside of Library
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12 Library- Center -
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13 Computer Room
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14 East Landin - Second Floor
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95 Room B216-Center
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.16 Room B218 - Center
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17 IRoomB214-Center
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18 IRoom B220 - Center
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19 IRoom B213 - Center
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20 lRoomB222-Center
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'1 21 lWest Landin - Second Floor
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22 IRoom A203 - Staff Loun e
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23 Microwave Oven in Staff Lounge 2" Power on High
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• 24 1 Rooftop - T-Mobile Radio Cabinets
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25 ISpot Meas. Cell Site Antenna - North Penthouse - -
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26 JlFrontolCell Site Antenna - North Penthouse
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27 Ispatial Averacle In Front of Antenna, From Roof
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28 1 Behind Sector Antennas - North Penthouse -
- C
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6.6
29 Ten Feel Behind Behind Sector Antennas - North Penthouse
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30 SDDt Meas. Cell Site Antenna - South Penthouse
ISpatial
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31 Front of Cell Site Antenna -South Penthouse
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" 32 Average In Front of Antenna From Roof - South Penthouse
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33 Behind Sector' Antennas - South Penthouse -
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.. 34 Ten Feet Behind Sector Antennas - South Penthouse
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.35' Adjacent to East Sector Antenna - Edge of S_ Penthouse
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-7.0 Engineer's Statement
Arapahoe Ridge Elementary School
Westminster, Colorado
This radio frequency survey covered electromagnetic radiation from 300 kHz -to 40.GBz
Fields from extremely low frequency (ELF) sources, such as those emitted by:60,B2 electrical `.
distribution lines, were not considered.
Measurements were conducted according to procedures described. in ANSI Standard C95:3-
2002 and the user's manual for the test instrument. All measurements were conducted with:
test equipment assumed to be calibrated and working "properly. . If new transmitters .are
installed at the site, power density levels may change. The reported,measurement,results are,
valid as of September 27, 2005.
Measurements show that the T-Mobile cell site at Arapahoe Ridge Elementary School complies.
with FCC guidelines for human exposure to radio frequency fields.
All representations contained herein are true to the best of my knowledge. .1 am a.' radio
engineer with over twenty years experience. I hold a Bachelor of Science degree in Electrical,
Engineering from Virginia Tech and a Master of Science degree m "Electncal .Engineering:
from Cornell University. I am a corporate officer and stockholder of Pericle Communtcgions,
Company and a Registered Professional Engineer in the, State of Colorado. '
Signed this l9th day of October„2005,. - {
1.
5.0 Conclusions
To verify compliance of the T-Mobile cell site with Federal guidelines for human, exposure to
radio frequency energy, our firm. conducted a radio frequency. survey at Arapahoe.Ridge
Elernentary using a broadband exposure meter. This survey showed that power densities from
the T-Mobile base station are well within Federal limits. Inside the' -school and- on -school
grounds, levels from T-Mobile are less than 2.5% of the publiaexposure limit:'set.by,the
Federal Government. We conclude that the T-Mobile cell site on Arapahoe: R'idge.Elem_entary
School complies with Federal guidelines for human exposure to radio frequency energy
6.0 References
[1] ANSI C95.1-1999, "Safety levels with respect to human exposure toradio frequency,. '
electromagnetic fields, 3 kHz to 300 GHz."
j
i
[2] OET Bulletin No. 65, FCC, "Evaluating compliance with FCC guidelines for human
'.
exposure to radiofrequency electromagnetic fields," Edition 9.7-01, August .1997 -
i•
[31 ANSI C95.3-2002. "Recommended practice for the measurement .of: hazardous:
electromagnetic fields - RF and microwave."
[4] ANSI C95.2-1981,•"American National Standard radio frequency radiation hazard warning
i
' symbol."
[5] Code of Federal Regulation, Title 47, Parts 1.7307 - 1.1310' October 1, 2004
[6) FCC OET Bulletin 56, 4th Ed., Questions and Answers about Biolocrical Effects `and
Potential Hazards of Radiofrequency Electromagnetic Fields, August, 1999,..
' [7) Q. Balzano, O. Gray, and T. J. Manning, Jr.,'"ElectromaenetiEEnergy- Exposure, of
' Simulated Users of Portable Cellular Telephones," IEEE Transactions on'',Veh cirlar
Technology, pp. 390-403'', Aug 1995.'
[8] J.E. Moulder, et al.. ".Cell Phones and Cancer: What is the Evidence.for a,Connection?,`
1
Radiation Research, pp. 513-521, vol.151, 1999.
(9) Tide 42; Part 78. Code of Federal Regulations. Microwave Open Standards
i
..
k`.
..ARAPAHOE RIDGE RADIO FREOUENCY EXPOSURE SURVEY `
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4.0 Comparison with Other Sources
There is a common misconceptionthat power densities from cell sites are higher than.power' ..
densities from hand-held phones. This is rarely the case. Public exposure from cell phones,
although well within FCC limits, is usually higher than public exposure from' base station
antennas. A recent study by Balzano et al. [7) showed worst -case: specific absorption rate.,
(SAR) values between 40% and 100% of standard for the classic analog "flip phone" and
j
between 10% and 50% of standard for two types of digital phones.? 'According to the FCC, '
a typical power density measured at the base of PCS and cellular towers is l µW/cm2, or,0.]%
= of standard at PCS frequencies [6]. Cordless phones operate at power levels comparable. to „
.
cellular phones, so one would expect similar exposure levels from these devices [6] Another. .
common source of electromagnetic fields is a cell phone:used by.someone. nearby) Foi
example, a typical cell phone will create power densities at one meter .. inches)' of -A. J% of
the FCC limit.
The Food and Drug Administration allows leakage from microwave ovens to be:.as, high .as
5,000 µW/cm2 when measured 2.inches from the oven door [91.4 Levels at 20 inches from.
the oven will be "spread out" and much lower in intensity, perhaps as low,as;20,µW/cm? ,or
2% of the FCC standard. In Figure 4, we have graphed typical values of radio frequency
power densities for these everyday sources alongside a typical measured level frorh a cell site.
lou - -.
c
. .0 90
_
.
..
6050
.
5 0%
• ..
40
-
U ?0
t to
2.0% 1 .1:%.
FCC Standard Cell Phone Microwave Oven Cell Phone(] meter} Typical,Cell Site
Figure 4 - Comparison with Other Sources of Radio Frequenev,Enerp
3Specific Absorption Plate is the preferred measure or energy absorption for partial body exposure and t`usually re ortzd to t.nurof
F
, .•:, !.watts/ki_logram. ..
4Please note that although microwave oven leakage standards may appear to exceed FCC limb for,continuous.exposure.(1,000
- ..-µWkm2). the maximum permissible exposure is :t while body spatial average and localized leakage rom,a microswve o%en'ntall owed ,. .
levels %vill not cause whole body exposure in excess of the FCC standard.
_
. �. ARAPAHOE RIDGE RADIO FREQUENCY EXPOSURE SURVEY.. - - /..'
power densities are very low in .public areas, a significant increase in power level, will.still. notl
cause the the site to exceed FCC limits.2 Please refer to T-Mobile's predictions for the
company's estimate of worst -case power densities in public areas from: this. cell, site.
Access to penthouses, which are used solely for the T-Mobile sector', antennas, should be
restricted to personnel who fall in the occupational exposure category. Because the antennas
are at the highest point on the roof and face outward, the only way to exceed public exposure
limits is for personnel to be inside the penthouse and standing in the narrow space, between the
transmit antenna and the stealth screen.. To ensure compliance, either T-Mobile•or Adams' 12
Five Star Schools should install one RF Notice sign at the open end of.each penthouse. The.
signs should be similar to the one shown in Figure 3. This sign is availa'06.1rom Tessco,
(800) 472-7373, P/N 30661, $19.73 each.
New .
------------
r
Radio frequency fields beyond::
this point may exceed the FCC J
general public exposure limit., 1,
Obey all posted signs and site guidelines
forworking.in radio frequency
environments. 3
In mcadmcewth Federal Comrrurnicanons ConrNssbn rules a1 raic
lrsauency emissions 47 CFR 1.1307ini
Figure 3 - RF Notice Sian
Because the noise floor ol'the W&G EMR-300 is 2.5% of the public limit and all measured IeTclb rmpublic areas•sgere belov,. dii,- • -
level. T-\lobile could increase its acelage power by at least a factor of 40 before exceeding the FCC pukI limit., Based on,pasl
'experience and FCC measurement's 16]. actual levels are almost certainly orders of maerikude below the noise floor of,.the meter•ancr
thereforea,signincantcushion exists between the hirzhest practical power densities created by this cell sue;in;public areas and the�FCC,
public exposure, limit. ; ..
s.
- ARLPAHOE RIDGE RADIO FREQUENCY EXPOSURE SURVEY ' _ 6
.. • Fr
3.0 Measurements
Radio frequency power densities were measured at the school on September 27, 2005 starting
at 11:00 p.m. and and continuing until'1:00 a.m. on the 28th,. Measurements were conducted in ;
accordance with the guidelines published in ANSI C95.3-2002 [3] and FCC Bulletin OET-65
[2]. The exposure survey was accomplished with the test equipment listed in•Table ]
i
Instrument I S/N I `',Calibration
Wandel & Goltermann (W&G) EMR-300 8-0053 4/200§.
Wandel 8 Goltermann Type 25:1 Probe, 300 kHz- 40 GHz B-0053 . 4/2005`.
The FCC standard isa whole body average exposure standard, so the measurements must:;be
taken over a volume comparable to that occupied by a standing adult: The W&G.probe'an,d
meter record power density as percent of the FCC controlled environment standard -The
W&G meter also performs an automatic average as the user sweeps the volume of interest.
Measurements were taken at least 20 cm from the ground or other reflecting objects in'
accordance with ANSI C95.3-2002.[3].. Magnetic field probes tend to exhibit false readings
above 300 MHz. Because the source operated at 1900 MHz, we did not use a magnetic fiel"d: '
probe, only an electric field probe.
Like all radio frequency exposure instruments, the W&G is designed to measure strong signals
and cannot measure weak signals accurately. The noise floor for the W&G is"2.5% of the
j
'-public.ezposure-standard. Although the meter Wiilt-displ readings below this Jeva,such
readings are not reliable.
Present during the survey were Jay M. )acobsmeyer, P.E. (Pericle Comrnunica ions) ,Brian:"
Lamer (Adorns 12) and Greg Hronich (Adorns 12). We measured 46 locations at the school;
including the school _roof, grounds, and classrooms.
. The highest reading was. recorded directly in front of the sou th west. sector T Mobilei'transmit
antenna. This reading was 38.1% of the occupational limit (up to 1.00% is allowed), ;All other,
readings on the roof, other than directly in front of a transmit antenna, were below ,the nose -
floor of the meter (i.e., less than 2.5% of the FCC public exposure standard)'. .
'We also took measurements on the school grounds and in several classrooms ' :All,of-these
I
readings were below the noise floor.of the meter. Please see the appendix.of thi.s!report for a
' complete list of all measurements collected.
e.
T-Mobile may add other radio carriers to the site and the duty cycle of each carnzr.may;bz
higher during busy hours than it was during the measurement period. Because:the measured
v
--'ARAPAHOE RIDGE RADIO FREQUENCY EXPOSURE'SURVEY-
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0.
J
environment) limit. The FCC exposure standards are plotted as functions,of•.frequency to
Figure 2.
The human body does not react to power densities instantaneously and :_short-term exposure to _
levels exceeding FCC power density limits does not necessarily. exceed. the FCC exposure
limits. The FCC limits are for whole -body exposure averaged over.a period of.6 minutes for
controlled environments and 30 minutes for uncontrolled environments. [11, [2],..[5]. For
example, if a radio technician working at an FM broadcast site is exposed to &power density of
0.5 mil]iwatts/cm2 for a period of 4 minutes and then enters a field of 1.5 milliwaits/cm?. for a'
period of 2 minutes, the average exposure in the six minute period is 0.83 milltwatislcm? `1
which is below the FCC limit for controlled environments.
1.000
Occupational, 6 minute averaging„
--o-- Generalpopulation,30min'
ueaver6ging'
^ 100
10
i
0 }
0. 1 t0 100 1.000 Io,Ooo .boo OOo .' ?'
Frequency, HIH [t
Figure 2 - FCC Exposure Standards
(Plane wave equivalent E-field power.density values).
Note from Figure 2 that in the PCS radio. band, where T-Mobile operates, the .occupational
exposure limit is 5,000 µW/cm2 and the public exposure.limit is 1,000 µW/cm2
Althou-h other Federal agencies, publish RF exposure standards (in'cludln'g' OSHA). the
governing standard for communications sites is the FCC standard. The FCC has prepaied':an. .
easy -to -read publication explaining its RF exposure police [6]. This publicahom,is a�arlable'
. from the FCC web site at Wlrw..fc•c•.g0v.
The next section describes the method of measurement and the measuiemenvresults
q.
,4RAFAHOE RIDGE RADIO FREQUENCY EXPOSURE SURVEY'4•
To conduct this survey, we used a Wandel & Goltermann (W4G)':,EMR7300 broadband.
exposure meter with a Type 25J shaped probe. The W&G meter employs a broadband sensor'
and an isotropic antenna and is the correct instrument to verify compliance with exposure
limits set by the Federal Government.
The remainder of this report is organized as follows: Section 2:0. describes the
Government standards for exposure to radio frequency energy. Section 3.0 is.a summary`,of'
the measurements taken at Arapahoe Ridge Elementary School and�Section 4;0 compares.
measured power densities to those from other common sources of radio frequency energy:
Section 5.0 concludes the report with a summary of the findings.
2.6 RF Exposure Standards
,r
The possible health effects -associated with, exposure to radio frequency energy;,have�lieen.
studied for more than half a century. The only established adverse effect is heating of'tiody
tissue. To protect the public from harmful exposure, the FCC requires that: its licensees
comply with its published radio frequency exposure standards, found' in"Parts 1.1307.through
1.1310 of Title 47
.voluntary standardsopubli published by he American �National Standards Institute 1ANSIband the.
�] P
(., ) he'
National Council on Radiation Protection and Measurement (NCRP).' FCC; limits are.,
conservative and include a safety factor of 10 for occupational exposure and•a safety factor of .
50 for public exposure. F•
FCC rules apply different standards for occupational, or controlled environments ,and general i
population, or, tin con trolled environments. The definitions of controlled and°.uncon trolled t
environments are as follows (5]: ,
Controlled Environment'- "Occupational/controlled limits apply in situations in wh'ich'persons areexposed.as
a consequence of their employmenrprovided those persons are fully aware of the potential tor.ezposure and
can exercise control over their exposure. Limits for occupational/controlled exposure also apply in situations
when an individual is transient through a location where occupational/controlled limits; apply proytded heor,
she is made aware of the potential for exposure."
Uncontrolled Environment - "General population/uncontrolled exposures apply in=situations wwhich.[he
general public may be exposed, or in which persons that are exposed as a consequence of their. -employment
may not be fully aware of the potential for exposure or can not exercise control over [heir:.exposure.":
For controlled environments, the FCC sets a standard of 1 milli"att/cm2.in the VHF band (39-
300 'MHz).! In the lower UHF band (300 MHz - 1.5 GHz), the FCC limit is iJunegon, of '
" fregttency.and is given by the expression f/300 milliwtiltsYcm'-, vdheretfas"the frcq,uency,in
MHz. In the broadcast radio bands (FNI and TV) and wireless communications bands, the`:
general population limit is exactly a factor of five below the occupational (controlled:
:! t milliwatt per square centimeter (mNN`/cm'-) = 1,000 microwaus per square centimeter (p%cm').
ARAPAHOE RIDGE RADIO FREQUENCY EXPOSURE SURVEY - 3-•
Multiple Access (TDMA). One of the eight time slots in one radio carrier, per sector.is,used'
for the control channel. The control channel transmits continuously. Other time slots transmit
only during an active call. At Arapahoe Ridge, T-Mobile employs three sectors with t�vo
antennas per sector. One sector is located in the north penthouse, over the north building
,
entrance. The other two sectors are located in the south penthouse above the main entrance to
the school. The antennas are at the highest point on the roof and are roughly 30 feet above the '
' ground.
One might ask why.power densities from base station antennas are so low when base stations .
operate at higher power levels than cellular phones. While abase station aught operate at20
j
Watts and a cell phone might operate at 100 milliwatts, the public is not close to the base' '
,station antenna. Signals attenuate through free space at a rate of 6 dB: (factor of four) per
octave and even greater attenuation occurs when obstructions are between the�b'ase station
antenna and the observer. The base station antenna also focuses most of its energy toward the
horizon. A typical base station antenna elevation pattern is shown in Figure.1,. Note that the
,
amount of energy directed downward is more than,30 dB (factor of ones thousand),lower.than
the. energy directed toward the horizon.
0
�.
= Main'beam'
30
-40 - —_
-50
c-60
-70 — _... --- — ------ —
I
-80
(Directly below antenna
l; -
-90
30 -25 -20 -15 -10 -S 0
'
Relative power, dB
Figure 1 - Antenna Pattern for Typical PCS Base Station:Antenna
- ._. _..._ (EMS WirelessRR90-14-04DP).
' The combination of physical separation and antenna pattern typically result in.yery loci°power
Li
,, , .
densities from cell site base station antennas. .
-a
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- -ARAPAHOE RIDGE RADIO FREQUENCY EXPOSURE SORVEY - - _ : 2
Radio Frequency Exposure Survey
T-Mobile Cell Site
Arapahoe Ridge Elementary School
Summary
Pericle Communications Company was retained by Adams 12 Five Star;Schools zo conduct a
radio frequency exposure survey at Arapahoe Ridge Elementary School, l3095.Pecos Street,
Westminster, CO 80030. T-Mobile operates a newly -constructed cell site from the:rooftop of
Arapahoe Ridge Elementary and the school district requested an independent venfcatton,tfiat
the site complies with Federal guidelines for human exposure to radio frequency energy. The
applicable guidelines for radio frequency exposure are found in the Code of Federal,-
Regulations (CFR), Title 47, Parts 1.1307-1.1310. The enforcement agency is the Federal
Communications Commission (FCC). We conducted the survey, on September 27,. 2005.'
Forty-six locations were measured on the roof, school grounds, and inside classrooms. All
measurements were well within FCC exposure limits. We can conclude that the T.7M9Mj1e cell'
site located on Arapahoe Ridge Elementary School complies with Federal guidelines for radio `
frequency exposure.
1.0 Introduction
It is natural for parents, teachers and staff to be concerned about exposure from. the: T Mobile -
cell site at Arapahoe Ridge Elementary School. Public exposure_ from cell. sites js actually
s
ggite t6w, but this'factts not always obvious: The purpose'of this study, was ;to measure actual
power densities at the school and to compare these levels to Federal exposure limits
The termradio frequency radiation is often used to describe the fields, emitted ;by radio•
antennas, but we must distinguish between the non -ionizing radiation from'
radio waves and
the ionizing radiation. from much -higher frequency sources.such as X-rays.' It Js physically i
impossible for radio frequency sources to cause ionization in the human body... Consequently, }
there is no similarity between the biological effects of ionizing radiation .(X-rays) and non-
ionizing radiation (radio waves). '
We must also distinguish radio frequency fields from extremely low,frequency, (ELF) fields
such as those associated with 60 Hz power lines. ELF fields do not readily radiate. from their
source and are an entirely different phenomenon.
In the Denver metropolitan area, T-Mobile operates its base stations (cell'sites) from 1,950 to:
:`1965MHz. At the time of this writing, T-Mobile employs an airlinl standard called GSM.
,GSM channels are 200 kHz wide and GSM radios typically operate at'a maximum po�s,er level• .
,,
of. 20 Watts Up to eight subscribers can share each radio carrier, using` Time Dttitsion;
�ARAPAHOE RIDGE RADIO FREQUENCY. EXPOSURE SURVEY
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No Text