HomeMy WebLinkAboutMCUP 09-16; AT&T NS0022-01 FOUR SEASONS; RADIO FREQUENCY POWER DENSITY SPECIFICATIONS; 2009-04-09Darrell W. Daugherty
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JERROLD T. BUSHBERG Ph.D., DABMP, DABSNM t; ,:,-,, p r "' . ..,.,,.
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7784 Oak Bay Circle Sacramento, CA 95831 p LJf!:,J !;J frj ;-· oi~~ .!,V
(800) 760-8414-jbushberg@hampc.eom 0 • ,.__ .-!
April 9, 2009
Escondido, California 92029-1362
Introduction
At yourrequest, I have reviewed the technical specifications and calculated the maximum radio frequency, (RF),
power density from the proposed AT&T wireless telecommunications site, (referenced as NS-0022-01 ), to be
located at the Four Seasons Resort 7045-B Osprey Terrace, Carlsbad, California as depicted in attachment one.
This proposed AT&T telecommunication site will utilize directional transmit panel antennae configured in three
(3) sectors. The antennae are planned to be mounted behind RF transparent panel inside a proposed chimney
extension and new chimney structure with their center at least 25 feet above grade directed at 100 (sector A),
190 ( sector B) and 290 ( sector C) degrees true north. The antennas specified are Powerwave fuc. model# 77 52
for all sectors. Technical specifications of these antennae are provided in attachment two. The sectorized
antennas are designed to transmit with an effective radiated power (ERP) of up to 244 watts per sector within
a bandwidth between approximately 824 and 896 MHz (Cellular frequencies) and with an ERP ofup to 488
watts per sector within a bandwidth between approximately 1,850 and 1,990 MHz (PCS frequencies).
Site measurements were made to include all existing ambient sources of RF exposures including the
contribution from other existing wireless facilities. This infonnation was used together with a worst case
calculation of the RF exposure from the proposed wireless facility to determine compliance with Federal
Communications Commission (FCC) requirements for RF public exposure safety. The maximum cumulative
RF exposure from the proposed facility and all existing RF sources in the area are provided in this report.
RF Exposure Measurement Methods & Results
The measurements at the subject property and the surrounding area were made in the morning on March 18,
2009 utilizing a NARDA Industries model 8718B broadband exposure meter with an associated frequency
shaped B8742D probe. All measurements were made in accordance with the manufacturer's recommendations
as provided in their user's guide for this instrument. This included a RF response check to assure that the meter
and probe were responding appropriately to a RF energy source. This response check was performed
i1mnediately before and after the site measurements. In addition, all environmental operating conditions, as
specified by the manufacturer for this instrument, were satisfied. The probe and meter were calibrated by the
manufacturer with standards traceable to the U.S. National Institute of Standards and Technology (NIST) on
August23, 2007. In accordance with the manufacturer's recommendations, the next calibration will be due prior
to August 23, 2009.
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The Narda meter/probe combination senses fields within the frequency range from 300 kHz to 3 GHz and
indicates exposure as a percentage of the FCC public exposure standard. The dynamic range of the instrument
is between O. 6 and 600% of the FCC public exposure standard. For PCS frequencies, this response range equates
to a power density range between 6 µW/cm2 and 6 mW/cm2. The data supplied by the manufacturer sets the
frequency response of the probe as± 1 dB and calibration accuracy and isotropicity as± 0.5 dB and± 1 dB
respectively. The probe is isotropic, meaning that it can directly measure the strength of complicated fields
independent of the orientation, polarization, or arrival angle.
Measurements were made from ground level to head height (approx. 6 feet) above the ground. The probe was
swept over approximately±3 feet to avoid destructive interference thus assuring the highest power density was
being measured at a given location. A continuous observation of the exposure allowed the location of the
maximum power densities to be determined. During the survey the meter displayed RF exposure levels between
0.1545 and 0.5122% of the FCC public exposure safety standard. Thus the maximum environmental RF
exposure measurement result, at all locations, was less than 0.6% of the FCC public exposure safety standards
for continuous exposure.
In so far as it was not possible to determine if all antennae at the site were transmitting at maximum power
during the measurements, a conservative multiple of five (5) was applied to all reading in order to assure that
maximum potential exposures would not exceed the values provided in this report. Even with the conservative
multiple of five applied to the measured value (i.e., 0.6%) the exposures would still be below the public MPE
(i.e., 3.0%).
Calculation Methodology, Results & Recommendations
Calculations were made in accordance with the recommendations contained in the Federal Communications
Commission, Office of Engineering and Technology Bulletin 65 ( edition 97-01, page 24, equation 10) entitled
"Evaluating Compliance with FCC-Guidelines for Human Exposure to Radio frequency Electromagnetic Fields."
Several assumptions were made in order to provide the most conservative or "worse case" projections of power
densities. Calculations were made assuming that all channels were operating simultaneously at their maximum
design effective radiated power. Attenuation (weakening) of the signal that would result from surrounding
foliage or buildings was ignored. Buildings can reduce the signal strength by a factor of 10 (i.e., 10 dB) or more
depending upon the construction material. The ground or other surfaces were considered to be perfect reflectors
(which they are not) and the RF energy was assumed to overlap and interact constructively at all locations
(which they would not) thereby resulting in the calculation of the maximum potential exposure. In fact, the
accumulations of all these very conservative assumptions will significantly overestimate the actual exposures
that would typically be expected from such a facility. However, this method is a prudent approach that errs on
the side of safety.
The maximum public RF exposure from this AT&T facility was calculated to be less than 0.85 % of the FCC
public safety standard. This total exposure is comprised of 2.4 µ W/cm2 ( i.e., ~0.44 % of the public safety
standard at cellular frequencies) and less than 4.1 µW/cm2 ( i.e., ~0.41 % of the public safety standard at PCS
frequencies). Exposure details are shown in appendices A-1 and A-2. A sign conforming to with ANSI C95.2
color, symbol and content, and other markings as appropriate, should be placed close to the antennas with
appropriate contact infonnation in order to alert maintenance or other workers approaching the antenna to the
presence of RF transmissions and to take precautions to avoid exposures in excess of FCC limits.
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RF Safety Standards
The two most widely recognized standards for protection against RF field exposure are those published by the
American National Standards Institute (ANSI) C95. l and the National Council on Radiation Protection and
measurement (NCRP) report #86.
The NCRP is a private, congressionally chartered institution with the charge to provide expert analysis of a
variety of issues ( especially health and safety recommendations) on radiations of all fonns. The scientific
analyses of the NCRP are held in high esteem in the scientific and regulatory community both nationally and
internationally. In fact, the vast majority of the radiological health regulations currently in existence can trace
their origin, in some way, to the recommendations of the NCRP.
All RF exposure standards are frequency-specific, in recognition of the differential absorption of RF energy as
a function of frequency. The most restrictive exposure levels in the standards are associated with those
frequencies that are most readily absorbed in humans. Maximum absorption occurs at approximately 80 MHz
in adults. The NCRP maximum allowable continuous occupational exposure at this frequency is 1,000
µ W / cm2. This compares to 2,933 µ W / cm2 at cellular frequencies and 5,000 µ W / cm2 at microwave frequencies
that are absorbed much less efficiently than exposures in the VHF TV band.
The traditional NCRP philosophy of providing a higher standard of protection for members of the general
population compared to occupationally exposed individuals, prompted a two-tiered safety standard by which
levels of allowable exposure were substantially reduced for "uncontrolled " (e.g., public) and continuous
exposures. This measure was taken to account for the fact that workers in an industrial environment are
typically exposed no more than eight hours a day while members of the general population in proximity to a
source of RF radiation may be exposed continuously. This additional protection factor also provides a greater
margin of safety for children, the infirmed, aged, or others who might be more sensitive to RF exposure. After
several years of evaluating the national and international scientific and biomedical literature, the members of
the NCRP scientific committee selected 931 publications in the peer-reviewed scientific literature on which to
base their recommendations. The current NCRP recommendations limit continuous public exposure at cellular
frequencies (e.g.,~ 820MHz) to 550 µW/cm2 and to 1,000 µW/cm2 at microwave frequencies (~1,900 MHz).
The 1992 ANSI standard was developed by Scientific Coordinating Committee 28 (SCC 28) under the auspices
of the Institute of Electrical and Electronic Engineers (IEEE). This standard, entitled "IEEE Standards for
Safety Levels with Respect to Human Exposure to Radio Frequency Electromagnetic Fields, 3 kHz to 300 GHz"
(IEEE C95.l-1991), was issued in April 1992 and subsequently adopted by ANSI. A revision of this standard
(C95.1-2005) was completed in October 2005 by SCC 39-the IEEE International Committee on
Electromagnetic Safety. Their recommendations are similar to the NCRP recommendation for the maximum
permissible exposure (MPE) to the public at cellular and PCS frequencies (410 µW/cm2 and 950 µW/cm2 for
continuous exposure at 820 MHz and 1,900 MHz respectively) and incorporates the convention of providing
for a greater margin of safety for public as compared with occupational exposure. Higher whole body exposures
are allowed for brief periods provided that no 30 minute time-weighted average exposure exceeds these
aforementioned limits.
On August 9, 1996, the Federal Communications Commission (FCC) established a RF exposure standard that
is a hybrid of the current ANSI and NCRP standards. The maximum pennissible exposure values used to assess
environmental exposures are those of the NCRP (i.e., maximum public continuous exposure at cellular and
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microwave frequencies of 550 µ W/cm2 and 1,000 µ W /cm2 respectively). The FCC issued these standards in
order to address its responsibilities under the National Environmental Policy Act (NEPA) to consider whether
its actions will "significantly affect the quality of the human environment." In as far as there was no other
standard issued by a federal agency such as the Environmental Protection Agency (EPA), the FCC utilized their
rulemaking procedure to consider which standards should be adopted. The FCC received thousands of pages
of comments over a three-year review period from a variety of sources including the public, academia, federal
health and safety agencies (e.g., EPA & FDA) and the telecommunications industry. The FCC gave special
consideration to the recommendations by the federal health agencies because of their special responsibility for
protecting the public health and safety. In fact, the maximum permissible exposure (MPE) values in the FCC
standard are those recommended by EPA and FDA. The FCC standard incorporates various elements of the
1992 ANSI and NCRP standards which were chosen because they are widely accepted and technically
supportable.
The FCC standards "Guidelines for Evaluating the Environmental Effects of Radiofrequency Radiation"
(Report and Order FCC 96-326) adopted the ANSI/IEEE definitions for controlled and uncontrolled
environments. In order to use the higher exposure levels associated with a controlled environment, RF
exposures must be occupationally related ( e.g., wireless company RF technicians) and they must be aware of
and have sufficient knowledge to control their exposure. All other environmental areas are considered
uncontrolled ( e.g., public) for which the stricter (i.e., lower) environmental exposure limits apply. All carriers
were required to be in compliance with the new FCC RF exposure standards for new telecommunications
facilities by October 15, 1997. These standards applied retroactively for existing telecommunications facilities
on September 1, 2000.
The task for the physical, biological, and medical scientists that evaluate health implications of the RF data
base has been to identify those RF field conditions that can produce harmful biological effects. No panel of
experts can guarantee safe levels of exposure because safety is a null concept, and negatives are not susceptible
to proof. What a dispassionate scientific assessment can offer is the presumption of safety when RF-field
conditions do not give rise to a demonstrable harmful effect.
Summary & Conclusions
This proposed wireless facility as specified above will be in full compliance with FCC RF public safety
standards. Wireless PCS and cellular transmitters, by design and operation, are low-power devices. Even under
maximal exposure conditions in which all the channels from all antennas are operating at full power, the
maximum cumulative exposure from the proposed AT&T facility together with the existing RF sources will
not result in exposures in excess of3.85% of the public safety standard at any publically accessible location.
This maximum exposure is more than 25 times lower than the FCC public exposure standards for these
frequencies. A chart of the electromagnetic spectrum and a comparison of RF power densities from various
common sources is presented in figures one and two respectively in order to place exposures from wireless
telecommunications systems in perspective. It is important to realize that the FCC maximum allowable
exposures are not set at a threshold between safety and known hazard but rather at 50 times below a level that
the majority of the scientific community believes may pose a health risk to human populations. Thus the
previously mentioned maximum exposure from the site represent a "safety margin" from this threshold of
potentially adverse health effects of more than 1,298 times.
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Given the low levels of radio frequency fields that would be generated from this facility, and given the evidence
on biological effects in a large data base, there is no scientific basis to conclude that harmful effects will attend
the utilization of the proposed wireless telecommunications facility. This conclusion is supported by a large
number of scientists that have participated in standard-setting activities in the United States who are
overwhelmingly agreed that RF radiation exposure below the FCC exposure limits has no demonstrably
harmful effects on humans.
These findings are based on my professional evaluation of the scientific issues related to the health and safety
of non-ionizing electromagnetic radiation and my analysis of the technical specification as provided by AT&T.
The opinions expressed herein are based on my professional judgement and are not intended to necessarily
represent the views of any other organization or institution. Please contact me if you require any additional
information.
Sincerely,
Jerrold T. Bushberg Ph.D., DABMP, DABSNM
Diplomate, American Board of Medical Physics (DAB MP)
Diplomate, American Board of Science in Nuclear Medicine (DABSNM)
Enclosures: Enclosures: Figures 1-2; Attachments 1, 2; Appendices A-l&A-2, and StatementofExperience
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MISSING THE FOLLOWING ENCLOSURES:
FIGURES 1-2
ATTACHMENTS 1, 2
APPENDICES A-1 & A-2
STATEMENT OF EXPERIENCE