EMFs in the Home
Electromagnetic Fields
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 United States recommends a policy of “prudent
avoidance” with respect to EMF. Prudent avoidance means to measure
fields, determine the sources, and act to reduce exposure.
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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.
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.
- 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.
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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 United States. Half of the houses studied had
magnetic field measurements of 0.6 mG or less, when the average of
measurements from all the rooms in the house was calculated (the all-room
mean magnetic field). The all-room mean magnetic field for all houses
studied was 0.9 mG. The measurements were made away from electrical
appliances and reflect primarily the fields from household wiring and
outside power lines.
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.
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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The graph shows magnetic fields produced by electric blankets, including conventional 110-V electric blankets as well as the PTC (positive temperature coefficient) low-magnetic-field blankets. The fields were measured at a distance of about 2 inches from the blanket’s surface, roughly the distance from the blanket to the user’s internal organs. Because of the wiring, magnetic field strengths vary from point to point on the blanket. The graph reflects this and gives both the peak and the average measurement. |
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Sources of Magnetic Fields (mG)*
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Sources of Magnetic Fields (mG)*
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