Electro-Magnetic Fields (EMF's)
Can the electric and magnetic fields (EMF) to which people are
routinely exposed cause health effects? What are sources of
EMFs, and when are EMFs dangerous?
EMF (or ElectroMagnetic Field) is a broad term which includes
electric fields generated by charged particles in motion, and
radiated fields such as TV, radio, hair dryer, and microwaves.
Electric fields are measured in units of volts per meter or V/m.
Magnetic fields are measured in milli-Gauss or mG. The field is
always strongest near the source and diminishes as you move away
from the source. These energies have the ability to influence
particles at great distances. For example, the radiation from a
radio tower influences the atoms within a distant radio antenna,
allowing it to pick up the signal. Despite the many wonderful
conveniences of electrical technology, the effects of EMF on
biological tissue remains the most controversial aspect of the
EMF issue, with virtually all scientists agreeing that more
research is necessary to determine safe or dangerous levels.
Research since the mid-1970s has provided extensive information
on biological responses to power-frequency electric and magnetic
fields. The Electric and Magnetic Fields (EMF) Research and
Public Information Dissemination (RAPID) Program was charged
with the goal of determining if electric and magnetic fields
associated with the generation, transmission, and use of
electrical energy pose a risk to human health. The fact that 20
years of research have not answered that question is clear
evidence that health effects of EMF are not obvious and that
risk relationships, if risk is identified, are not simple.
Because epidemiologic studies have raised concerns regarding the
connection between certain serious human health effects and
exposure to electric and magnetic fields, the program adopts the
hypothesis that exposure to electric or magnetic fields under
some conditions may lead to unacceptable risk to human health.
The focus of the program is not only to test, as far as possible
within the statutory time limits, that hypothesis for those
serious health effects already identified, but to identify as
far as possible the special conditions that lead to elevated
risk and to recommend measures to manage risk.
Electromagnetic hypersensitivity (ES) is a physiological
disorder characterized by symptoms directly brought on by
exposure to electromagnetic fields. It produces neurological and
allergic-type symptoms. Symptoms may include, but are not
limited to, headache, eye irritation, dizziness, nausea, skin
rash, facial swelling, weakness, fatigue, pain in joints and/or
muscles, buzzing/ringing in ears, skin numbness, abdominal
pressure and pain, breathing difficulty, and irregular
heartbeat. Those affected persons may experience an abrupt onset
of symptoms following exposure to a new EMF such as fields
associated with a new computer or with new fluorescent lights,
or a new home or work environment. Onset of ES has also reported
following chemical exposure. A concerted effort to provide
scientifically valid research on which to base decisions about
EMF exposures is under way, and results are expected in the next
several years. Meanwhile, some authorities recommend taking
simple precautionary steps, such as the following:
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Increase the distance between yourself and the EMF source – sit at arm’s length from your computer terminal.
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Avoid unnecessary proximity to high EMF sources – don’t let children play directly under power lines or on top of power transformers for underground lines.
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Reduce time spent in the field – turn off your computer monitor and other electrical appliances when you aren’t using them.
The Office of Technology Assessment of the Congress of the
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Detect EMFs in your home and work environment. It is good to know where the sources of EMF are in your everyday world and how strong these sources are. Is there wiring in the wall behind your bed that you don’t even know about? Is the vaporizer emitting strong fields in the baby’s room? How much EMF are you and your family getting from the power lines in the street? Even hair dryers emit EMFs. Home inspectors often have meters to measure EMFs, or they can be purchased and shared with friends.
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Diminish your exposure to the EMFs you find. Determine how far you must stay away from the EMF emitters in your home and work environment to achieve less than 2.5 mG of exposure—the microwave oven, the alarm clock, the computer, and so on. Rearrange your furniture (especially the beds, desks, and couches where you spend the most time) away from heaters, wiring, fluorescent lights, electric doorbells, and other EMF “hot spots.” Where practical, replace electric appliances with non-electric devices. Where practical, replace electric appliances with non-electric devices. Have an electrician correct faulty high EMF wiring and help you eliminate dangerous stray ground currents. Consult a qualified EMF engineer if necessary. Contact National Electromagnetic Field Testing Association at 1-847-475-3696 for consultants in your area.
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Shield yourself. Use shielding devices on your computer screen and cellular phone. Add shielding to your household wiring, circuit box, and transformers.
Electric fields in the home, on average, range from 0 to 10
volts per meter. They can be hundreds, thousands, or even
millions of times weaker than those encountered outdoors near
power lines. Electric fields directly beneath power lines may
vary from a few volts per meter for some overhead distribution
lines to several thousands of volts per meter for extra high
voltage power lines. Electric fields from power lines rapidly
become weaker with distance and can be greatly reduced by walls
and roofs of buildings.
Magnetic fields are not blocked by most materials. Magnetic
fields encountered in homes vary greatly. Magnetic fields
rapidly become weaker with distance from the source.
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The chart on the left
summarizes data from a study by the Electric Power Research
Institute (EPRI) in which spot measurements of magnetic fields
were made in the center of rooms in 992 homes throughout the
If you are comparing the information in this chart with
measurements in your own home, keep in mind that this chart
shows averages of measurements taken throughout the homes, not
the single highest measurement found in the home.
Magnetic fields close
to electrical appliances are often much stronger than those from
other sources, including magnetic fields directly under power
lines. Appliance fields decrease in strength with distance more
quickly than do power line fields.
The following table, based on data gathered in 1992, lists the
EMF levels generated by common electrical appliances. Magnetic
field strength (magnitude) does not depend on how large,
complex, powerful, or noisy the appliance is. Magnetic fields
near large appliances are often weaker than those near small
devices. Appliances in your home may have been redesigned since
the data in the table were collected, and the EMF they produce
may differ considerably from the levels shown here.
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Sources of Magnetic Fields (mG)* |
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Sources of Magnetic Fields (mG)* |
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