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ELECTROMAGNETIC FREQUENCY RADIATION
RADAR 101
 AIR FORCE JSTARS





 Radiation Ovens

 RADAR Basics

 The New Killing Fields: Electromagnetic Weapons

 Cohen

 ABCNEWS.com : Zapping Teachers For Science


 





Ionizing and Non-ionizing Radiation

     Radiation can be broadly broken into two groupings: ionizing and non-ionizing. Ionizing
     means that there is enough energy in the radiation to alter the chemical structure of matter
     upon its absorption by knocking off electrically charged particles (ions). Non-ionizing
     means that there is not enough energy in the radiation to create ions. Instead, the energy
     is usually absorbed as heat. RFR is a form of non-ionizing radiation.

     Because of their extremely high frequencies and energies, X-rays and gamma rays are
     electromagnetic types of "ionizing" radiation, as are many types of high-energy,
     high-velocity sub- atomic particles that result from nuclear processes. When ionizing
     radiation interacts with living structures, it can cause severe damage. The chemical bonds
     of molecules struck by high energy particles can be broken, causing parts of the
     molecules to be split off, often as reactive charged particles (ions). These ions can
     promote additional chemical and physical reactions. If the absorbing molecules are DNA or
     other genetic materials, cellular metabolism can be interfered with and the cell's ability to
     reproduce itself can be destroyed or caused to malfunction (the latter sometimes leading
     to cancers). (Barrett, see references.)

     Electromagnetic waves of lower frequency levels and energies, such RFR and EMFs
     associated with radio systems, do not cause ionization and consequently are referred to
     as "non-ionizing" radiation. If absorbed at all, this type of energy is absorbed as heat.
     Unless generated at extremely high power densities and at just the right resonance
     frequencies so as to produce large amounts of heat resulting in actual burns, the frequency
     and resulting energy levels of non-ionizing radiation are almost always too low to affect
     biological materials. Non-ionizing radiation is not known to damage DNA as can ionizing
     radiation and generally has not been shown to cause irreversible changes that can
     accumulate over time (Yost, see references).

     There is one potential problem, however. Sometimes in a complex organic molecule short,
     linear groups of atoms extend off of a main chain or body of the complex. It has been
     shown that at the right frequencies, these extensions can be excited by strong,
     non-ionizing energy so as to cause frequency resonance to occur. The extension can then
     vibrate and on occasion break off, altering the structure of the molecule. This is the only
     other known interaction between non-ionizing radiation and biological structures. It is
     considered to be a rare phenomenon, as the frequency of the radiation must exactly match
     the natural resonance of the molecule and the power density must be very high. (Barrett,
     see references.)

     Why the Concern?

     Most scientists maintain that RFR and lower frequency EMFs such as those associated
     with wireless communications systems generally do not produce adverse health effects in
     humans because they are non-ionizing in nature and normal exposures are controlled so
     as not to result in thermal effects. Other researchers, however, note the possible molecular
     resonance problem described above and propose that continuous low-level exposures or
     exposures in combination with other chemicals may cause health problems that are not
     immediately evident. These researchers suggest that extra care should be taken until more
     is known.

     The media continue to report the work of these researchers and the public exhibits a sharp
     interest in the debate between the two sides. Some members of the public believe that
     even the remotest possibility of a health hazard constitutes grounds for forming public
     policy and regulations for facilities using radiofrequency radiation and generating
     electromagnetic fields. Consequently, there is often keen public interest in proposals for
     new wireless cell sites and facilities.

     ANSI, NCRP, and IRPA Radiation Protection Guidelines

     "Both private organizations and government agencies have proposed guidelines that limit
     exposure to nonionizing radiation. These standards can be divided into broad categories:
     emission standards, which set limits on the incidental (nonpurposeful) radiation emanating
     from a device; and exposure standards, which set limits on the radiation power density to
     which a person may be exposed. Emission standards limit unwanted leakage from devices
     such as microwave ovens that should contain the radiation inside the device or that have
     shielding to protect operators and others from exposure during normal operation. Exposure
     standards limit exposure of persons to radiation present in the environment, for example
     from a radio transmitter" (Yost, see references).

     There is no official, mandatory federal standard for radiation exposure protection in the
     United States. The official guideline for facilities regulated by the Federal Communications
     Commission (FCC) is currently the 1982 American National Standards Institute (ANSI)
     guideline. The 1982 ANSI guidelines recommend exposure limits covering RFR from 300
     kHz (kilohertz) to 100 GHz (gigahertz). The guidelines recognize that the human body
     absorbs radiofrequency energy at some frequencies more readily than at others. The most
     restrictive limits are in the frequency range of 30-300 MHz. However, the wireless
     communications systems discussed in this paper operate in the frequency range of 800 to
     2200 MHz -- frequencies outside of the most sensitive range.

     ANSI has adopted C95.1-1992, a revision of the 1982 standard, and the FCC has proposed
     its adoption. The new standard "contains a number of significant differences from
     guidelines and recommendations issued by ANSI in 1982. In many respects, the 1992
     guidelines are more restrictive in the amount of environmental RF exposure permitted, and
     they also extend the frequency range under consideration to cover frequencies from 3 kHz
     to 300 GHz. The new 1992 guidelines specify two sets of exposure recommendations, one
     for 'controlled environments' (usually involving workers) and another for 'uncontrolled
     environments' (usually involving the general public). (FCC 93-142).

     For controlled environments, the 1992 ANSI/IEEE standards recommend maximum power
     density levels calculated by dividing frequency by 300 (f/300). For example, for a cellular
     frequency of 888 MHz, the standard would be calculated by dividing 888 by 300, yielding
     an exposure level of 2.96 mW/cm2 (milliwatts per square centimeter). For uncontrolled
     environments, the revised standards recommend maximum power density levels calculated
     by dividing frequency by 1500 (f/1500). As a result, for the same cellular frequency of 888
     MHz, the exposure standard for the uncontrolled environment would be 0.592 mW/cm2
     (888/1500). Thus, for both controlled and uncontrolled environments, the ANSI/IEEE
     exposure standards for wireless communications are dependent upon the technologies
     frequencies.

     In addition to the ANSI standard, there are two other widely discussed public exposure
     standards: that of the National Council on Radiation Protection (NCRP) and that of the
     International Radiation Protection Association (IRPA). Because the NCRP standards cover
     the 1500 MHz to 1011 MHz frequency range and the IRPA standards cover the 2,000 MHz
     to 1011 MHz frequency range, these two exposure standards apply only to the upper
     portions of the PCS frequency range. They do not apply to the cellular or ESMR
     technologies, whose frequency ranges lie between 800 and 900 MHz.

     The NCRP is a non-profit corporation chartered by the United States Congress to, among
     other things, develop information and recommendations concerning radiation protection.
     The guidelines issued by the NCRP specify a level of 1 mW/cm2 (milliwatt per square
     centimeter) for the exposure of the general public in the frequency range listed above.

     The IRPA is a non-governmental international organization representing most of the
     national radiation protection societies in the world. These recommendations form part of
     the World Health Organization (WHO) United Nations Environmental Programme (UNEP).
     IRPA guidelines for public exposure also recommend 1 mW/cm2 for the frequency range
     listed above. It should be noted that both the NCRP and IRPA exposure standards are
     more restrictive than the revised ANSI standards for PCS frequencies above 1500 MHz in
     uncontrolled environments and for all PCS frequencies in controlled environments.

     Some states, including Massachusetts, New Jersey, Oregon, and Washington, as well as
     some local jurisdictions have adopted their own radiation guidelines.

     Radiation Levels

     The levels of RFR to which the public is routinely exposed are far below the levels
     necessary to pose a health risk. A 1989 report by the Office of Engineering and
     Technology stated that the U.S. Environmental Protection Agency estimates that in seven
     metropolitan areas studied across the United States, 98 to 99 percent of the population is
     exposed to less than 0.001 mW/cm2 of radiation. The standards listed above are
     considerably more restrictive than the exposure levels that the majority of the public
     experiences.

     Additionally, the 1982 ANSI guidelines for radiation exposure indicate that devices
     operating on less than seven watts of power at frequencies less than 1,000 MHz will not
     cause immediate thermal effects. Cellular mobile phones operate between 0.6 and three
     watts of power at frequencies between 800 and 900 MHz, ESMR mobile communicators
     operate between 0.5 and 1.5 watts of power in the 800 MHz frequency band, and PCS
     mobile communicators are anticipated to operate on no more than 1 watt of power at
     frequencies between 1,850 and 2,200 MHz, all falling well below the seven watt threshold.

     Typical cell sites, including monopoles, roof-mounted antenna sites, and building-mounted
     antenna sites, emit a maximum of 3,000 watts of effective radiated power (ERP) (the power
     supplied to an antenna multiplied by the relative gain of the antenna in a given direction). In
     comparison, radio broadcasting towers emit roughly 100,000 watts ERP, and television
     broadcasting towers emit approximately 5,000,000 watts ERP. The radiation emitted from
     these broadcasting sources decreases according to the inverse square principle. As a
     result, exposure to radiation decreases as distance from broadcasting sources increases.

     Ongoing and Future Research

     Although many studies have been conducted examining the effects of RFR and EMFs on
     animals and humans, scientists have been unable to reach consensus on the results for
     various reasons, including: difficulty in interpreting the extrapolation of studies performed
     on animals and cells to humans; difficulty in explaining the effects of natural influences,
     such as the earth's magnetic field; difficulty in controlling crucial variables in the study,
     such as the amount of energy absorbed by test organisms; difficulty in replicating and
     generalizing results obtained at specific power levels, frequencies, and modulation
     patterns, to other situations; difficulty in distinguishing between slight normal human
     changes and subject variations; and difficulty in agreeing on the results and methodologies
     of epidemiological studies.

     While some studies suggest that long-term exposure to some forms of RFR may cause
     adverse health effects in humans, many other studies do not. According to a report
     published in 1994 by the United States General Accounting Office, both the Food and Drug
     Administration (FDA) and the Environmental Protection Agency (EPA) agree that the
     information from the most current studies is insufficient to determine whether the risks are
     substantive, if present at all.

     In fact, some cities, such as the City of San Diego, have addressed this issue by
     distinguishing between actual and perceived health hazards when performing CEQA
     (California Environmental Quality Act) review. The city recognizes that the public's fear of
     the unknown sometimes causes "perceived health hazards." Since studies have been
     found inconclusive in relation to the thresholds established by the ANSI standards, the city
     does not identify EMF impacts on human health as significant. Nonetheless, the policy of
     the Environmental Analysis Section (EAS) of the Development and Environmental Planning
     (DEP) section of the Development Services Department (DSD) is to disclose the presence
     of EMF sources, and advise "prudent avoidance," where possible. An example of prudent
     avoidance would be to place power lines or other sources of radiation in places of
     low-intensity human uses, such as parking lots. Concurrently, the City of Poway has
     suggested that required buffer distances would be helpful in separating such facilities from
     areas where people tend to cluster, such as schools, residences, parks, and day care
     centers.

     RFR Research Related to Wireless Communications

     In 1991, the California Public Utilities Commission (CPUC) opened Investigation 91-01-012
     to consider whether the CPUC should adopt a role to mitigate potential health effects, if
     any, of EMFs created by electric utility power lines and cellular facilities. Consensus was
     reached that EMF issues involving electric utilities and cellular utilities should be
     addressed separately. A cellular steering committee composed of five individuals was
     established with one individual representing each of the following agencies: the CPUC's
     Commission Advisory and Compliance Division (CACD), the Division of Ratepayer
     Advocates (DRA), the California Department of Health Services (DHS), the Cellular Carriers
     Association of California (CCAC), and the "Citizens Concerned About Telecommunications
     EMF." In July 1993, the steering committee held an informational workshop addressing
     three issues: levels of cellular utilities' EMF and RFR impacts, issues for further
     consideration, and interim safety measures.

     In December 1994, the CACD released a summary of the workshop. The report concluded
     that although little is known about potential health hazards related to EMF and RFR
     exposure levels, cellular power densities have been found to be consistently below present
     exposure standards. In the absence of scientific evidence linking cellular exposure levels to
     human health risks, the steering committee decided not to adopt a specific numeric set of
     EMF and RFR exposure standards associated with cellular facilities. However, recognizing
     that future scientific research may provide more definitive information, the CACD adopted
     the responsibility to serve as a clearinghouse of EMF and RFR research and to hold
     periodic workshops informing interested parties of new findings.

     On November 8, 1995, the CPUC released Decision 95-11-017. The decision (1) adopts the
     CACD's workshop report (except for a proposed interim measure requiring cellular utilities
     to consider alternative cell site locations and restrict access to their cell sites through
     warning signs or physical barriers); (2) approves the designation of the CACD to hold
     workshops as additional health information becomes available and requires that the
     workshop results be reported to the CPUC through the resolution process; and (3) closes
     Investigation 91-01-012.

     In November of 1994, the United States General Accounting Office published a report addressing
     the status of scientific knowledge on the effects of RFR caused by cellular telephones. The report
     found that no long-term studies on low levels of radiation from cellular phones have been
     completed, and that the research conducted on other sources of low-level RFR are inconclusive.
     The report further determined that both epidemiological and laboratory studies are needed to
     ascertain whether portable cellular phones produce adverse health effects. Two such studies are
     under way:

     1. In 1991, Motorola, Inc., contracted with a prominent U.S. research company to study the
     effects of analog and digital signals from cellular telephones on animals and cells. Results are
     expected to be released in late 1995 or early 1996.

     2. In 1993, due to public anxiety that portable cellular phones cause adverse health effects, the
     Cellular Telephone Industry Association (CTIA) allocated $15 to $25 million to study the safety of
     cellular phones for three to five years, including the effects of analog and digital radiation at
     cellular and PCS frequencies. The CTIA and other industry representatives established a Science
     Advisory Group on Cellular Telephone Safety to perform this research through epidemiological
     studies, cell cultures, animal testing, and genetic research. The research will be submitted to a
     scientific peer review coordinated through the Harvard University Center for Risk Analysis. This
     research will be open for federal participation in order to provide further objectivity.

     The federal government also is undertaking research that focuses specifically on cellular
     telephone safety issues. The National Cancer Institute has begun an epidemiological study of
     people with brain cancer to ascertain whether there is a statistical relationship between cancer
     and the use of cellular telephones. It is anticipated that this study will be completed between
     1998 and 1999.

     The research conducted up to the present is considered inconclusive, but important questions
     have been raised about the possible relationship between health complications and the exposure
     to radiofrequency radiation and electromagnetic fields. The studies cited above, in combination
     with other human and laboratory studies, could provide the kind of comprehensive research
     needed to determine the safety of wireless communications devices.

     RFR and EMF Information Sources

     In January of 1995, the Department of Energy released a booklet entitled Questions and
     Answers about EMFs, published by the department's Research and Public Information
     Dissemination (RAPID) program. The RAPID program was established in 1992 as a five
     year, $65,000,000 program to study if exposure to EMFs causes adverse health effects. To
     order free copies, call 1 (800) 363-2383, or call Alicia Hillery for bulk orders at (202)
     512-1708.

     For additional information on EMFs, Planning Advisory Service Report #435,
     Electromagnetic Fields and Land-Use Controls, by David Bergman, Louis Slesin, and
     Matthew Connelly (Chicago: American Planning Association, 1991) can be ordered through
     the American Planning Association's Planners Bookstore, 122 S. Michigan Ave., Suite
     1600, Chicago, IL 60603; (312) 431-9100. Additionally, the ANSI Standards, also known as
     IEEE Standard for Safety Levels with Respect to Human Exposure to Radio Frequency
     Electromagnetic Fields, 3 kHz to 300 GHz, 1992 (ANSI/IEEE c.95.1-1992), and
     Recommended Practice for the Measurement of Potentially Hazardous Electromagnetic
     Fields - RF and Microwave (ANSI/IEEE C95.3-1992) are available through the American
     National Standards Institute, 11 W. 42nd St., New York, NY 10036; (212) 642-4900.
 

     ABBREVIATIONS OF TERMS

          A/m                     Amperes per meter
          ANSI                    American National Standards Institute
          BTA                     Basic Trading Area
          CCAC                    Cellular Carriers Association of California
          CDMA                    Code Division Multiple Access
          CDPD                    Cellular Digital Packet Data
          CEQA                    California Environmental Quality Act
          CFR                     Code of Federal Regulations
          CGSA                    Cellular Geographical Service Area
          CPUC                    California Public Utilities Commission
          CTIA                    Cellular Telecommunications Industry Association
          DEP                     Development and Environmental Planning
          DHS                     Department of Health Sciences
          DRA                     Division of Ratepayer Advocates
          DSD                     Development Services Department
          EAS                     Environmental Analysis Section
          EIR                     Environmental Impacts Report
          ELF                     Extremely Low Frequency
          EMF                     Electromagnetic Field
          EPA                     Environmental Protection Agency
          ESMR                    Enhanced Specialized Mobile Radio
          FCC                     Federal Communications Commission
          FDA                     Food and Drug Administration
          GHz                     Gigahertz
          G.O.159 (A)             General Order 159 (A)
          IEEE                    Institute of Electrical and Electronic Engineers
          kHz                     Kilohertz
          LCP                     Local Coastal Plan
          MHz                     Megahertz
          MSO                     Main Switching Office
          MTA                     Metropolitan Trading Area
          mW/cm2          Milliwatt per square centimeter
          PCS                     Personal Communications Services
          RFR                     Radio Frequency Radiation
          RSA                     Rural Statistical Area
          SMR                     Specialized Mobile Radio
          SMSA                    Standard Metropolitan Statistical Area
          TDMA                    Time Division Multiple Access
          V/m                     Volts per meter
          WTB                     Wireless Telecommunications Bureau
 
 
 

     GLOSSARY

     Analog Technology (see Digital Technology)
     Analog technology replicates and amplifies voice messages as they are carried from the
     transmitting antenna to the receiving antenna. Traditionally, cellular phone systems have
     used analog transmission signals.

     Antenna
     A device used in communications which transmits or receives radio signals.

     Band
     A clearly defined range of radiofrequencies dedicated to a particular purpose.

     California Public Utilities Commission (CPUC)
     Governmental agency which regulates the terms and conditions of public utilities in the
     State of California. Of the three wireless communications services discussed in the Issues
     Paper, the CPUC presently regulates only cellular service providers.

     Channel
     A segment of a frequency band. Also referred to simply as “frequency.”

     Co-location
     Locating wireless communications equipment from more than one provider on a single site.

     Common Carrier
     A public radio service in which a single licensee provides one-way or two-way service to
     multiple users.

     Communications Facility
     A land use facility supporting antennas and microwave dishes that sends and/or receives
     radiofrequency signals. Communications facilities include structures or towers, and
     accessory buildings.

     Digital Technology
     Digital technology converts voice and data messages into digits that represent sound
     intensities at specific points of time and data content. ESMR and PCS service providers
     employ digital technology, and cellular providers are rapidly converting to digital as well.

     Dish Antenna
     A dish-like antenna used to link communications sites together by wireless transmission
     of voice or data. Also called microwave antenna or microwave dish antenna.

     Effective Radiated Power (ERP)
     The power supplied to an antenna multiplied by the relative gain of the antenna in a given
     direction.

     Electromagnetic Field (EMF)
     The local electric and magnetic fields that envelop the surrounding space. The most
     ubiquitous source of EMFs is from the movement and consumption of electric power, such
     as with transmission lines, household appliances and lighting.

     Federal Communications Commission (FCC)
     The federal agency responsible for licensing and regulating wireless communications
     providers. The FCC has primary regulatory control over communications providers through
     its powers to control interstate commerce and to provide a comprehensive national system
     in accordance with the Federal Communications Act.

     Frequency
     The number of cycles made by electromagnetic radiation in one second, usually
     expressed in units of hertz (Hz).

     Hertz
     A unit for expressing frequency which is the number of times a wave-like radio signal
     changes from maximum positive to maximum negative charge per second. 1 Hz = 1 cycle
     per second. 1 kilohertz (kHz) = 1,000 Hz; 1 megahertz (MHz) = 1,000 kHz or 1,000,000
     Hz; 1 gigahertz (GHz) = 1,000 MHz or 1 million kHz or 1 billion Hz.

     Interference
     Disturbances to reception caused by radiofrequency waves or other electric fields.

     Microwave
     Electromagnetic radiation frequencies from 3 GHz to 300 GHz; highly directional when
     used for radiofrequency transmissions. Uses relatively low transmitter power levels when
     compared to other forms of transmission.

     Monopole
     A structure composed of a single spire used to support communications equipment.

     Non-ionizing Electromagnetic Radiation
     Electromagnetic waves of low frequency, long wavelength, and low photon energy unable to
     cause ionization (i.e., to remove an electron from an atom).

     Panel Antenna
     An antenna or array of antennas designed to concentrate a radio signal in a particular area.
     Panel antennae are typically flat, rectangular devices approximately six square feet in size.
     Also called directional antennae.

     Power Density
     The magnitude of the electromagnetic energy flux density at a point in space, in power per
     unit of area (measured in milliwatts per square centimeter or mW/cm2).

     Radio
     A generic term referring to communication of impulses, sounds, and pictures through
     space by means of electromagnetic waves.

     Radiofrequency Radiation (RFR)
     Electromagnetic radiation in the portion of the spectrum from 3 kHz (kilohertz) to 300 GHz
     (gigahertz).

     Stealth Facility
     Any communications facility which is designed to blend into the surrounding environment.
     Examples of stealth facilities may include architecturally screened roof-mounted antennas,
     building-mounted antennas painted to match the existing structure, antennas integrated
     into architectural elements, and antenna structures designed to look like light poles. Also
     called concealed antennas.

     Wavelength
     The distance between points of corresponding phases of a periodic wave of two constant
     cycles. Wavelength = wave velocity/frequency.

     Whip Antenna
     An antenna that transmits signals in 360 degrees. Whip antennae are typically cylindrical
     in shape and are less than 6 inches in diameter and measure up to 18 feet in height. Also
     called omnidirectional, stick, or pipe antennas.