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HomeMy WebLinkAbout01-09 Non-Ionizing Radiation Hazard Assessmentof CO MS EA R CN P. Coy NON -IONIZING RADIATION HAZARD ASSESSMENT BY CALCULATION AND ANALYSIS Proposed 120' Height Telecommunications Tower Located on Route 11, Martinsburg Pike Winchester, Virginia Prepared For AT&T Corporation December 2008 19700 Janelia Farm Boulevard. - Ashburn, Virginia 20147, USA - 703.726.5500 - Fax 703.726.5597 TABLE OF CONTENTS SECTION 1 introduction and Background 1.1 Introduction 1.2 Background SECTION 2 Methodology and Results SECTION 3 Conclusions SECTION 1 INTRODUCTION AND BACKGROUND 1.1 Introduction The purpose of this report is to document the results of radio frequency (RF) power density calculations performed on behalf of the AT&T Corporation by Comsearch. The calculations were performed to define the RF radiation conditions at a proposed 120' height telecommunications tower to be located at an existing AT&T facility on Route 11, Martinsburg Pike, in Winchester, Virginia. The purpose of this study is to provide the analysis required by the local Zoning Ordinances to obtain a Conditional Use Permit for the proposed telecommunication tower. The calculated power density levels presented in this report have been compiled for the purpose of evaluating the proposed site's compliance with the most recent human exposure guidelines for radio frequency radiation as adopted by the Federal Communications Commission (FCC). The guidelines referenced by the FCC are intended to apply to both occupational (workers at the site) exposures as well as general public exposures to radio frequency radiation. Therefore, the data presented in this report can be used to determine potential non -ionizing radiation hazards, which may affect persons working at or living near this facility. 1.2 Background The possible adverse effects from exposure to nor. -ionizing (radio frequency) radiation has become a growing concern in recent years. In light of this concern, research by several organizations has shown that exposure to high levels of RF radiation can be harmful. This research has concluded that the ability of RF energy to heat biological tissues rapidly is one concern deserving attention. It has been shown that the extent of the biological heating is dependent upon several factors including the following: A) Specific radiated frequency B) Size, shape, and orientation of the exposed object C) Duration of exposure to RF radiation D) Surrounding environmental conditions E) Efficiency of heat dissipation These factors along with other health considerations concerning human exposure to RF radiation prompted the Federal Communications Commission (FCC) to consider its responsibility in developing policies controlling RF radiation emissions from FCC licensed and regulated facilities. Following several public notices and inquiries to other government agencies, the Commission determined that a FCC regulated facility should be required to comply with established guidelines concerning the potential biological effects and hazards of RF radiation. Therefore, the FCC issued a report in March of 1985 that in effect amended the Commission's rules and provided for an environmental analysis in regard to human exposure to RF radiation. The exposure guidelines for the FCC radiation policy were placed in effect on January 1, 1986. On August 1, 1996, the Federal Communications Commission issued a Report and Order (FCC 96-326) amending the Commission's rules to adopt new guidelines for evaluating the environmental effects of radio frequency (RF) radiation from FCC -regulated transmitters. And, these guidelines were restated in their Notice of Proposed Rule Making (NPRM) NO. 03 —137 released four years ago and which is now in effect. In R&O (FCC 96-326), the FCC identified two reports developed by different agencies: the first from the American National Standards Institute (ANSI) which adopted guidelines from the Institute of Electrical and Electronic Engineers, Inc. (IEEE) to formulate ANSI/IEEE (C95.1-1992), and the second from the National Council on Radiation Protection and Measurements (NCRP) which formulated NCRP Report No. 86 (1986). The FCC has adopted limits for maximum permissible exposure generally based on the exposure guidelines set forth in NCRP Report No. 86 (1986). In the frequency range from 100 MHz to 1500 MHz, exposure limits for field strength and power density are also generally based on those contained in the ANSI/IEEE report (C95.1-1992). These guidelines were chosen because they are scientifically based, widely accepted, and applicable to the general population as well as to workers. The currently adopted FCC standard establishes exposure limits for controlled as well as uncontrolled environments. Controlled environments are locations where there is exposure that may be incurred by persons who are aware of the potential for exposure as a circumstance of employment or by other cognizant persons. Uncontrolled environments are locations where there is the exposure of individuals who have no knowledge or control over their exposure. Compliance to the FCC's RF radiation policy is generally through a process of self -certification. There will be 2 transmitting stations on the proposed tower on the property. The power density calculations performed in this report take into account and aggregates all of transmitting antennas in determining the power density levels. The FCC MPE limit for uncontrolled areas for transmitting systems varies from 0.2 to 1 mW/cm2 for the frequency range of operation of the transmitting antennas. These limits are outlined in Table 1 and graphically represented in Figure 1 of this report. For additional information, please see FCC Office of Engineering and Technology (OET) Bulletin #65 (Edition 97-01) at: www.fcc.gov/oet/rfsafety, which provides full details regarding FCC guidelines for human exposure to radio frequency electromagnetic fields. Table 1 Limits for Maximum Permissible Exposure (MPE) (A) Limits for Occupational/Controlled Exposure Frequency Electric Field Magnetic Field Power Averaging Range Strength (E) Strength (H) Density Time (MHz) (V/m) (A/m) (S) JE 12, IH 12 or S mW/cm2 minutes 0.3-3.0 614 1.63 (100y 6 3.0-30 1842/f 4.89/f (900/f')- 6 30-300 61.4 0.163 1.0 6 300-1500 -- -- f/300 6 1500-100,0 -- -- 5 6 00 (B) Limits for General Population/Uncontrolled Exposure Frequency Electric Field Magnetic Field Power Averaging Range Strength (E) Strength (H) Density Time (MHz) (V/m) (A/m) (S) JE 12, IH 12 or S mW/cm2 minutes 0.3-1.34 614 1.63 (100)- 30 1.34-30 824/f 2.19/f 180/ * 30 30-300 27.5 0.073 0.2 30 300-1500 -- -- f/1500 30 1500-100,0 -- -- 1.0 30 00 f = frequency in MHz power density *Plane -wave equivalent NOTE 1: Occupational/controlled limits apply in situations in which persons are exposed as a consequence of their employment provided those persons are fully aware of the potential for exposure 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 provided he or she is made aware of the potential for exposure. NOTE 2: General population/uncontrolled exposures apply in situations in which the 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 cannot exercise control over their exposure. FCC Limits for Maximum Permissible Exposure (MPE) Plane -Wave Equivalent Power Density �,Oa0 Occupational/ Controlled Exposure N - - - General Population/ Uncontrolled.Exposure 100 4 4 ..`', 10 \ � 5 � � 4 A � G� 1 O r a k r 0.2 Q n3 t 3 3b :00 f 3, 000 30,000 � 300, 070 134 Frequency (MHz) 1 -M 100,000 Figure 1 FCC Limits for Maximum Permissible Exposure (MPE) SECTION 2 METHODOLOGY AND RESULTS The methods used for the calculations and analysis in this radiation safety effort are those described in the FCC Office of Science and Technology (OET) Bulletin No. 65, "Evaluating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields, Revision 97-01," August 1997. The FCC adopted limits for the maximum permissible exposure for areas occupied by personnel in their R&O (FCC 96-326) released 1 August 1996. To carry out the calculations, the parameters for the transmitting systems were taken from the FCC license applications and as recorded in the FCC and Comsearch databases. There is 1 communication tower located on proposed site. Table 2 contains the data for the transmitting systems on the tower. For this project the transmit power, antenna characteristics, antenna center -line, and system frequency of operation are listed in the data tables as these parameters are used in the calculations. Table 2 Tower 1 Transmit Systems Frequency of Operation 5925 — 6425 MHz and 10700 — 11700 MHz Transmit Power 1 Watt Antenna Type Parabolic Antenna Dimension 1.83 meters Antenna Gain off Axis (in direction of the ground) 1032-25*10ge > 1 Height of Antennas Above Ground 23.77 meters Using the data in Tables 2 and the following formulas, the power density was calculated at the ground location directly under the proposed antennas. Wd(n) =0. 1 *Pt *G(0)n/(4fI)*Rn2 And, Pd = EWd(n) Where, 1%Vd(n) = Radiated power density at the calculation point (point of interest) from each transmitting microwave station (There are two and they are co -located, milliWat+/cM2 Pd = Summation of the power densities from the transmitting microwave stations at the calculation point (point of interest), milliWatt/cm2 Pt = Transmit power of each microwave station system, 1 Watt Gn(0) = Gain of the microwave station antenna in the direction of the calculation point at the base of the tower (point of interest) = 1032-25.1090 1 Rn = Distance to the calculation point (point of interest) from each of the microwave station antennas, 21.77 meters (Height of a person's head 2 meters above ground) Closest point maximum level will occur at head height. 0.1 = Factor that converts Watts/meter2 to milliWatts/cm2 n = Point of interest (1 - 2) Based on the above identified parameters, the resulting radiated power density levels are: Wd = 1.68x10-6 milliWatts/cm2 Pd(2) = 3.36 x10-6 milliWatts/cm2 SECTION 3 CONCLUSIONS Based on the calculations performed above the radiated power density levels are far below the standard and will not exceed the FCC MPE Limit safety criteria for either controlled or uncontrolled areas at the base of the proposed 120' height antenna. Therefore, no harmful radiation hazard will exist to either workers or the general public as a result of the proposed system.