|
through space, there is a byproduct known as radio
<br /> frequency radiation. Electromagnetic radiation is broken
<br /> into two groups: ionizing and non-ionizing radiation.
<br /> Radio frequency radiation is non-ionizing, which means it
<br /> does not possess enough energy to create ions. Ionizing
<br /> radiation, on the other hand, is capable of altering the
<br /> chemical structure of organic matter. Cellular communi-
<br /> cations devices and facilities generate non-ionizing
<br /> radiation. However, there is evidence ora very rare
<br /> phenomenon that occurs when complex organic mol-
<br /> ecules with short linear groups of atoms extending off the
<br /> main molecular body encounter strong, non-ionizing
<br /> energy at very high power densities. This rare encounter
<br /> can cause a frequency resonance to occur. The vibration
<br /> caused by this resonance can result in molecular alter-
<br /> ation. How this specifically translates into a human health
<br /> hazard is the subject of much debate among EMF
<br /> researchers. Until further clarity can be provided, the
<br /> scientific community advocates that proximity to higher
<br /> non-ionizing radiation sources be controlled where
<br /> possible. This approach is known as prudent avoidance.
<br /> EMFs and the health concerns associated with them
<br /> remain the most elusive aspects of cellular facility siting.
<br /> The federal government has adopted no formal standards
<br /> for what is or is not safe.
<br />
<br /> Both private and public organizations and government
<br /> agencies have proposed guidelines that limit exposure to
<br /> nonionizing radiation. These standards can be divided into
<br /> broad categories: emission standards, which set the limits on
<br /> the incidental (nonpurposeful) radiation emanating from a
<br /> device; and exposure standards, which set limits on the
<br /> radiation power density to which a person may be exposed.
<br /> Emission standards limit unwanted leakage from devices such
<br /> as microwave ovens that should contain the radiation inside
<br /> the device or that have shielding to protect operators and
<br /> others from exposure during normal operation. Exposure
<br /> standards limit exposure of persons to radiation present in
<br /> the environment, for example from a radio transmitter.
<br /> From Michael G. Yost, Nonlonizing Radiation Q_uestions
<br /> andAnswers (San Francisco Press, inc., 1988).
<br />
<br /> In the meantime, communities nationwide continue to rely
<br />on standards set by the American National Standards Institute,
<br />as reported in "IEEE Standard for Safety Levels with Respect to
<br />Human Exposure to Radio Frequency Electromagnetic Fields, 3
<br />!d--Iz to 300 GHz" (c.95.1-1992). Most responses to this
<br />question referred to these standards. This document is a revision
<br />ofANSI's 1982 standards in which they state that "devices
<br />operating on less than seven watts of power at frequencies less
<br />than 1,000 MHz will not cause immediate thermal effects."
<br />Cellular mobile phones operate berween 0.6 and three watts of
<br />power at frequencies between 800 and 900 MHz. PCS mobile
<br />communicators are anticipated to operate on no more than one
<br />watt of power at frequencies between 1,850 and 2,200 MHz.
<br />Both fall well below the seven-watt threshold.
<br /> Cellular sites, including monopoles, roof-mounted antenna
<br />sites, and building-mounted antenna sites, emit a maximum of
<br />3,000 watts of effective radiated power or ERP (the power
<br />supplied to an antenna multiplied by the relative gain of the
<br />antenna in a given direction). In comparison, radio broadcasting
<br />towers emit roughly 100,000 watts ERP, and television
<br />broadcasting towers emit approximately five million warts ERP.
<br />The radiation emitted from these broadcasting sources decreases
<br />according to the inverse square principle, which states that the
<br />
<br /> further the distance from the source, the less potent the
<br /> radiation. Transmission quality also operates on this principle.
<br /> For more information on cellular communications
<br /> technology and the subject of electromagnetic fields and
<br /> communication towers, we highly recommend Wireless
<br /> Communications Facilities Issues Paper (San Diego Association of
<br /> Governments, 1995).
<br /> What were some other conditions for approval?
<br />This section represents an assortment of unique conditions for
<br />approval that we did not anticipate in our survey design.
<br />Common among them was the exclusive acceptance of
<br />monopole towers or transmitting antennas that would be
<br />mounted on pre-existing buildings or structures such as water
<br />towers. Still other communities listed the exclusive acceptance
<br />of guy-wired lattice towers. As mentioned earlier, some
<br />communities required FAA approval when towers were to be
<br />located near airports or flight paths, in which case strobed
<br />lighting was required. One community specifically prohibited
<br />any signage or advertising on the site. Some communities also
<br />required the use ora specific color of paint on the tower, such as
<br />light gray or light blue. A variety of special conditions were
<br />applied to towers locating in residential areas. A public notice
<br />and hearing were often required. One community allowed
<br />towers in residential districts only if they were somehow
<br />disguised as part of an existing building. Another required proof
<br />that the owner had adequate insurance coverage for any
<br />potential damage caused by or to the tower. Yet another
<br />required that the applicant show a local demand for the
<br />technology to justify its necessity. The most unusual
<br />requirement was for an estimate of the number of vehicle trips
<br />per day for the proposed site. This may have been the by-
<br />product of a broader transportation impact analysis requirement
<br />for all uses proposed within a given commercial district.
<br />What types of approval procedures were used?
<br />This was not a question on the survey, but the responses
<br />revealed that most communities allowed towers with a
<br />conditional use permit. The second most common approval was
<br />via special use permit. Finally, a much smaller group of
<br />communities stated that towers were allowed by right in some
<br />districts but not in others (most notably, residential). For those
<br />communities that required approvals by more than their
<br />planning commission or zoning board of appeals, the most
<br />frequently mentioned entities were design review boards,
<br />historic preservation boards, the FAA, and the FCC. Though
<br />not reported by these respondents, we subsequently have heard
<br />of community deferral to the decision of a state-level utilities
<br />commission or board. Communities should verify whether this
<br />form of approval exists in their state.
<br />Third Party Wireless Go-Betweens
<br />Many third-party entities have stepped in to help facilitate the
<br />cellular revolution. Municipal planners and officials often need
<br />technical education, legal advice, and negotiating tips while
<br />cellular carriers often need help scouting and acquiring sites for
<br />their transmission devices. Some communities, in conjunction
<br />with the carriers who have approached them, have hired
<br />consultants to fulfill these needs. Some of these firms are
<br />subsidiaries of the telecommunications companies, and others
<br />are independent organizations that more or less serve the
<br />cellular communications industry. FoxPire Community
<br />Planning & Development in Denver and Unisite in Dallas are
<br />two such organizations. They bring a wealth of cellular
<br />technology experience and land-use expertise to the table.
<br />
<br />
<br />
|