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Electromagnetic
Fields
Electromagnetic fields (EMF) are
invisible forces created by power charges that surround any electrical device.
There are two components of an electromagnetic field:
- Electrical Field
- This is created by a device
that is plugged into a working outlet and results from the strength of the
electrical charge. The strength of the electrical field is due to the amount
of voltage. An electrical field is easily weakened by barriers between you
and the device producing the electrical field. Electric fields are measured
in volts or kilovolts per meter (V/m or kV/m)
and it may be possible to feel an electric field over 20kV/m as a tingling
sensation.
- Magnetic Field
- When we actually turn on an
electrical device, we then produce a magnetic field from the current being
generated. The strength of the magnetic field is proportional to the amount
current, measured in amperes, flowing through, or to the device. The
magnetic field is not easily shielded or weakened and you can not feel its
presence. Magnetic fields are measured in Teslas
(10,000Gauss), Gauss and milliGauss (1/1000 of a Gauss),
to determine its level. Magnetic fields have two frequency ranges which are
the most common around our homes.
Extremely Low Frequencies (ELF) - These radiate from
60 Hz current found in power lines and current to our electrical devices and
appliances.
Very Low Frequency (VLF) - These magnetic fields are found
emanating from our television sets and equipment with cathode ray
tubes (CRT) such as computer monitors.
All electrical devices and
electric transmission lines produce EMF's. Alternating current (AC)
may produce small flows of current in the human body. Direct
current (DC) produced by the earth and battery operated devices are not
likely to create currents in people.
The strength of EMF's and their
size is related to the amount of current that is flowing and the distance from
the flowing current. Therefore a reduction in the amount of current and/or
an increase in the distance from the electrical current will weaken the strength
of the EMF.
There have been numerous studies
which debate the effects and health hazards of EMF's on humans. Some of these
studies indicate EMF's may contribute to brain tumors, birth defects,
miscarriages, leukemia, and immune system disorders. In 1990 the EPA reviewed
numerous studies and has acknowledged that low level EMF's may increase our risk
of cancer. The U.S. Department of Energy however, has taken the view that no
adverse health effects are directly linked to exposure to EMF's. It is generally
agreed that more research is needed to understand the risks associated with
electromagnetic fields and determine the safe exposure levels and the cellular
mechanisms that may be causing detrimental health effects from EMF's.
A general consensus based on
studies, regarding a level of exposure to EMF that may begin to create
detrimental health effects is 2-3 mG (milliGauss). Try to avoid
areas that have levels above 1 mG. The International Radiation Protection
Association has established guidelines of 5 kV/m for continuous
exposure to electric fields and 2 milliGauss (mG) for magnetic
fields. It is important to use an EMF
Detection Meter to find areas with elevated electromagnetic fields that
need to be avoided and to determine safe distances from electrical devices and
appliances.
Since there is considerable
evidence that electromagnetic fields can pose a health hazard, it is advisable
to take a preventative stance to reduce our exposure and decrease the levels of
EMF's in our immediate vicinity. We should look carefully at areas
in and around our homes that may be "hot spots" for
EMF'S.
- Power Lines,
Substations, Local Transformers - Power transmission lines carry
very high voltages and emit electrical and magnetic fields. These voltages
from primary transmission lines can reach over 700,000 volts. The
extremely low frequency (ELF) magnetic field measured below one of these primary
lines can reach a few hundred mG. Substations reduce the electrical voltage
from the primary lines (usually 115,00 to 230,000 volts) to the local lines
(4,000 to 13,800 volts) and give off high magnetic fields. Your
neighborhood transformer reduces this voltage (4,000 to 13,800 volts) to a
level to be used by your home (120/240 volts). Generally an ELF under
an overhead transformer at street level is comparable to the measurement
under a power line and are not considered a significant concern.
Transformers mounted on the ground have elevated levels of ELF's at close
proximity (within a few feet). Burying your electrical supply lines does not
negate the levels of EMF's because magnetic fields are not blocked by solid
barriers.
-
- Home Environment - Wiring
in the home can effect your levels of EMF exposure, proper grounding and
routing of your wiring inside and to your home will help control
electromagnetic fields. A competent, knowledgeable licensed electrician can
help you determine problem areas or design a low EMF wiring system for your
home. Computer displays, televisions, electric blankets, electric clocks,
microwave ovens, fluorescent lights, telephones, electric razors, hair
dryers and all other appliances requiring electricity for operation will
produce electromagnetic fields.
Some
Precautions you can take to minimize your exposure to electromagnetic fields:
- Try to distance
yourself as much as possible from sources of EMF's. An
electromagnetic fields strength will decrease rapidly with an
increase in distance from the source. We can reduce the amount
of exposure and strength of electromagnetic fields if we follow some
guidelines when using and being close to electrical equipment and
appliances.
- Determine safe
distances from electrical devices (appliances, computer monitors,
TV's, electric clocks, microwave ovens, etc.) when in operation
(magnetic fields) and when just plugged in (electrical fields). Try
to avoid consistent close exposure to power lines, transformers and
microwave towers.
- Don't use electric
blankets as these create magnetic fields that penetrate the body and
are a source of long term exposure. Some new electric blankets
have been designed to produce little or no magnetic fields but may
still produce electric fields. Analog electric clocks produce high
magnetic fields and shouldn't be near your head while sleeping.
- Locate your electric
meters and subpanels at locations where you spend little time such
as on the exterior garage wall or basement wall where activity is
minimal around and above it. Locate your wiring runs in walls,
ceilings and floors away from areas of expected high activity and
use romex wire. Utilize a capable electrician to properly ground all
wiring, especially using a grounding rod into the earth at the
electrical meter. An underground service should be located in
an area of little activity.
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