The popularity of cell phones and wireless communication devices has resulted in a proliferation
of cell towers across the American landscape. Opposition to the placement of these towers has sometimes
developed among segments of the population, usually based upon aesthetics, concern over the electromagnetic
radiation, or both.
EMF Services can conduct testing and site assessments for individuals, schools, businesses, or municipalities who wish to
become aware of the RF levels at a location near cell phone or broadcast towers. The report that we provide
will permit comparison of measured levels with FCC Maximum Permissible Exposures (MPEs), precautionary
guidelines, and routine background levels for comparable environments. If new antennas or towers are
planned for your location, our site survey can be used to establish a baseline RF level for later comparison
(before and after testing). Follow-up readings are provided at substantially reduced cost compared to the initial survey.
The purpose of this testing is to empower you to make responsible, fact-based decisions about the RF environment
surrounding your community, facility, or home. If exposure reduction measures are desired, we can provide
recommendations. All services are delivered by personnel with several years of experience in planning and
directing the installation of radio communication facilities, using equipment with current factory calibration
certificates. The greatest advantage of our surveys over that of other providers is the
ability to address the issue of low-level, long-term, non-thermal exposures, and to articulate the scientific
rationale for a precautionary exposure guideline.
Sample RF Survey Report - Excerpts
Some International Precautionary Exposure Guidelines
RF Units Conversion Table
EMF Services no longer performs standard RF compliance surveys. We provide only enhanced testing services that involve more detailed
data collection, and a more extensive and broader coverage report, than a conventional compliance survey. Our surveys
incorporate procedures and equipment to separately measure cellular power density, in addition to the composite power density
(the combination of all RF signals present).
The purpose of our testing services is not to provide a basis for contesting the siting of cell
phone towers or to seek their removal once sited. This position is not the result of an alliance between
EMF Services and the cellular service providers. They are not our clients. Rather, it represents
an effort to avoid leading you down the path toward a disappointing result. The RF levels near a cell
tower will not approach Maximum Permissible Exposures at ground level where people are present. Therefore,
from a legal perspective, grounds for such an action do not exist. Further, a court of law is not the best
venue for a challenge to the science on which existing standards are based. The likely result is disappointment
and a wasted financial expenditure. The best reason for testing and measurement services is to understand the field
levels that exist, and what can be done to reduce them.
Standards vs. Guidelines - The Rationale for Testing
Regulations adopted by the Federal Communications Commission (FCC) in 1996, and fully
implemented in 2000, limit human exposure to electromagnetic radiation from cell phone,
broadcast, and other radio communication systems. Both U.S. and international standards
governing exposure to radio frequency (RF) fields have long existed, and the FCC regulations
were adapted from a pre-existing standard. They establish Maximum Permissible Exposures,
or MPEs, for the full range of frequencies encountered near transmitting equipment,
towers, and antennas. These are the formal exposure standards in the U.S., and have full regulatory force.
For cellular antennas on towers, the level of RF energy that one would realistically be exposed to is
usually less than 1% of the MPE. For broadcast towers and building mounted cellular antennas, much higher
exposures are possible, although the MPEs are still unlikely to be exceeded in areas accessible to
the public. So why are people concerned about cell towers, or RF exposure in general? Is some
caution warranted? Three reasons for this concern are recognized:
- Some people don't trust the cell phone companies or the government to act with the public's
best interest in mind.
- Many people equate the potential adverse health effects of cell phone use, which has received
a lot of media coverage, with the presence of cell towers. (In reality, the energy that one is
exposed to while holding a cell phone to the head is far greater than one is exposed to in the vicinity
of a cell tower.)
- The existing exposure limitations are based primarily on the avoidance of energy deposition in
the body sufficient to cause heating of tissue. More recent research data indicates that
some types of radio frequency fields influence cellular function through mechanisms that do not
involve heating. Therefore, the existing limitations may be based upon incomplete and outdated
science, and thus not fully protective.
To address the issues raised by recent health effects research (#3 above), it is necessary to look beyond the current
exposure limits. Through a review of research on exposure to radio frequency radiation, it
is possible to identify a range of numbers below which no adverse effects have been noted (or which have been
reported only in limited or questionable studies), and above which potentially adverse effects have
been seen. This range of numbers can form the basis for a "precautionary guideline." The science from
which it is derived is not, at this time, sufficient in strength or consistency to permit the revision of
existing standards. However, reference to such a precautionary guideline will permit those individuals
who seek a level of protection beyond that conferred by existing standards to do so in a rational manner
while research proceeds on this important public health issue.
Technical Challenges
Measurement of the emissions from cell phone towers presents particular technical challenges
beyond those encountered for broadcast antenna sites. To understand these challenges,
a few brief comments about radio frequency measurement are required.
Protocols for the measurement of RF energy for the purpose of human exposure assessment
recommend the use of an "isotropic broadband probe" whenever possible. This type of sensor
responds equally to energy arriving from any direction, and over a broad frequency range, as does
the human body. Unfortunately, some of the instruments used by companies which perform
RF compliance surveys are unable to accurately measure the low field strengths or power densities
present at some cell sites. An alternate approach is required.
A related problem involves the concurrent presence of other signals besides those from the cell
phone system. The "broadband" characteristic of the isotropic broadband probe means that it will measure
any signals across a wide range of frequencies. The reading produced by the
instrument will be the combination of all signals present. In a large number of cases, the other signals
present near a cell tower will be as strong as the cellular signals that one is trying to measure. In fact,
an FM radio broadcast station a half mile away, and out of sight, can be the strongest signal present near
a cell tower. Realistically, this composite measurement of all signals may be the most relevant exposure
metric, but an interpretation of the significance of a reading sometimes requires that one know the frequency
of the signal that produced it. For instance, is it FM, TV, cellular, or something else? Again,
an alternate testing approach is required.
A third challenge results from the fact that field strength or power density levels at a cell tower site are not
always constant, as they usually are at a broadcast antenna site. People use their cell phones much more at
some times of the day, and on some days of the week, than at others. The cellular service
providers maintain additional capacity in the form of multiple channels which will become active as
needed to meet demand. Each active channel adds to the measured power density at the cell site. The
variable and cyclic nature of power density levels at the site must be taken into account when performing
an assessment. When necessary, we can employ data logging to produce a graphic representation of field strength
over time. This technique will capture the field strength transitions that occur with varying
levels of cellular usage on the system, and produce a more meaningful assessment than spot readings with
a simple handheld meter.
RF measurement surveys conducted by EMF Services employ procedures and equipment to address
each of the challenges noted above. We use a high sensitivity isotropic broadband probe for measurement
of the composite power density. A spectrum analyzer is used for identification of RF sources, and for
assessment of the relative magnitude of signals in different frequency ranges. The use of this instrument
with a calibrated antenna will allow "narrow band measurement" of the strength of an individual signal, or a
sensitive and precise "channel power measurement" across a selected frequency range. Our comprehensive analytical
report summarizes the above data, and includes spectrum analyzer plots of the RF activity at each site location, as shown below.
