Thanks for your question. First, let me request that if any of the
following is unclear or if you require any further research please
dont hesitate to ask me for a clarification.
You requested information regarding whether EMF absorption devices
work, how they work, if there is any scientific evidence supporting
the notion that they do work and whether there are any vendors who
can substantiate their claims with good science.
The whole arena of EMF protection smacks something of the medicine man
of bygone days. A quick search elicits hundreds of vendors offering
everything from amulets to bracelets to sophisticated devices. The
big question, however, remains does EMF cause any harm, and are such
devices even needed?
There is a significant amount of research being conducted in this area
ever since the government decided to take it seriously and budget for
it in 1992
In 1992, the U.S. Congress authorized the Electric and Magnetic
Fields Research and Public
Information Dissemination Program (EMF-RAPID Program) in the Energy
According to this report,
The scientific evidence suggesting that ELF-EMF exposures pose any
health risk is weak.
The strongest evidence for health effects comes from associations
observed in human
populations with two forms of cancer: childhood leukemia and chronic
leukemia in occupationally exposed adults.
The human data are
in the "right" species, are tied to "real life" exposures and show
some consistency that is
difficult to ignore. This assessment is tempered by the observation
that given the weak
magnitude of these increased risks, some other factor or common source
of error could
explain these findings. However, no consistent explanation other than
exposure to ELF-EMF
has been identified.
In general, however -
Wherever electricity is generated, transmitted or used, electric
fields and magnetic fields are created. These fields are a direct
consequence of the presence and/or motion of electric charges. It is
impossible to generate and use electrical energy without creating
these fields; hence they are an inevitable consequence of our reliance
on this form
Therefore, I guess its better to play it safe and employ such
absorption and protection devices if at all possible and practical.
How powerful is the magnetic field created by a video display monitor?
The NIEHS (National Institute of Environmental Health Science)
provides a wealth of statistics concerning the magnetic fields emitted
by a variety of devices in the home or office. For a video display
monitor, the data is as follows
VIDEO DISPLAY TERMINALS(PCs with color monitors)
Lowest 7 2 1
Median 14 5 2
Highest 20 6 3
The first number in each row is the strength of the magnetic field in
mG (milliGauss) at a distance of 6; the second is measured at a
distance of 1 and the third at 2. You can view comparables at
And you can read a tutorial on EMF basics at
Unless you are sitting very close to your monitor (I am over 2 away
from mine most of the time), even if your monitors emit the highest
levels of radiation, it is comparable to that which an average cashier
would encounter, as an example.
The NIEHS addresses the problem of personal computers directly
Personal computers themselves produce very little EMF. However, the
video display terminal (VDT) or monitor provides some magnetic field
exposure unless it is of the new flat-panel design. Conventional VDTs
containing cathode ray tubes use magnetic fields to produce the image
on the screen, and some emission of those magnetic fields is
unavoidable. Unlike most other appliances that produce predominantly
60-Hz magnetic fields, VDTs emit magnetic fields in both the extremely
low frequency (ELF) and very low frequency (VLF) frequency ranges.
Many newer VDTs have been designed to minimize magnetic field
emissions, and those identified as "TCO'99 compliant" meet a standard
for low emissions.
And, as relates to monitors directly,
The U.S. government has set no standards for magnetic fields from
computer monitors or video display terminals (VDTs). The Swedish
Confederation of Professional Employees (TCO) established in 1992 a
standard recommending strict limits on the EMF emissions of computer
monitors. The VDTs should produce magnetic fields of no more than 2 mG
at a distance of 30 cm (about 1 ft) from the front surface of the
monitor and 50 cm (about 1 ft 8 in) from the sides and back of the
monitor. The TCO'92 standard has become a de facto standard in the VDT
industry worldwide. A 1999 standard, promulgated by the Swedish TCO
(known as the TCO'99 standard), provides for international and
environmental labeling of personal computers. Many computer monitors
marketed in the U.S. are certified as compliant with TCO'99 and are
thereby assured to produce low magnetic fields.
Also see WHO fact sheet on EMF related to video displays
The following page contains EMF exposure standards while there is no
federal standard as yet, several states have set levels that can be
used as proxies
How can one protect themselves from EMF?
Basically, the NIEHS suggests the following pointers for individuals
concerned about EMF exposure
1) Find major sources of EMF to which you are exposed and move away
from them or limit your exposure to them; note that exposure decreases
exponentially as you move away from a device, so that at arms length
exposure is typically already minimal
2) Purchase equipment designed to have low EMF emissions
3) Check for incorrect wiring, which is a common cause of
4) More expensive options include burying or compacting power lines
There is no information on EMF protection devices on the NIEHS site
not a good sign
The NIOSH recommends the following
The National Institute for Occupational Safety and Health (NIOSH) and
other government agencies do not consider EMFs a proven health hazard.
Because some studies have associated high magnetic field exposures
with increased cancer risks, the government will continue studying
EMFs. While research continues, concerned workers and employers might
consider the following simple, inexpensive measures for reducing EMF
+ Inform workers and employers about possible hazards of magnetic
+ Increase the worker's distance from the EMF source. Since magnetic
fields often drop off dramatically within about 3 feet of the source,
workers can stand back from electrical equipment, and workstations can
be moved out of the 3-ft range of stronger EMF sources.
+ Use low-EMF designs wherever possible (for the layout of office
power supplies, for example).
+ Reduce EMF exposure times. No action should be taken to reduce EMF
exposure if it increases the risk of a known safety or health hazard
such as electrocution
Great article on EMF sources and how to avoid them
And the WHO offers its own cautionary policies
Yet, the question remains what about those devices???
An article by Don Maisch claims the following
Though there is a wide range of devices being advertised that make
all kinds of unsubstantiated claims, they all have several features in
a) They neither attempt to reduce nor remove electromagnetic fields:
Using a suitable meter to measure either 50-60 Hz, radiofrequency or
microwave fields, no reduction will be found with, or without, the
b) they do not have any working limits: A blanket claim is usually
given with no restrictions as to what is the maximum level of EMF/EMR
exposure that the device can provide protection against.
c) the science that they quote is very speculative and arbitrarily
applied to some simple device without any scientifically acceptable
evidence of the truth of the claims.
The complete article is at
And the WHO (World Health Organization), backed by a battery of
Fear of adverse health effects from EMF emitted by VDUs has led to a
proliferation of products supposedly offering protection from any
adverse effects of these fields and radiation. These include special
aprons, screen shields or "radiation absorbing" devices for use with
VDUs. These items have no protective effect whatsoever on VDU
emissions. Even those that do reduce emissions are of no practical
value, since the EMF fields and radiation are only a very small
fraction of exposure limits permitted in national and international
standards. Except for screens that reduce glare (causing eyestrain),
protective devices are not recommended by WHO. Use of protective
devices to reduce EMF emissions is also not recommended by the ILO.
The WHO has published an excellent (and very pretty
) handbook on EMF
I think we can therefore come to some serious conclusions regarding
1) They dont work
2) There is, therefore, no way to explain how they do work, and
3) There is no scientific evidence proving that they do work
For some excellent correspondence on the subject, please see
Apparently, theres a discussion group on Yahoo that you could
subscribe to in order to be apprised of any developments heres one
link to a Maisch note in said group, from which you will be able to
navigate to the subscription page
Since there are a variety of devices on the market that can measure
EMF and such inspections are now routinely done for homebuyers for
around $150 it is a simple matter to test such devices. If they
were effective and they are not you can be sure that scientific
evidence would have flooded the pages of the World Wide Web long ago
I hope this response adequately addresses your request. Please let me
know if you are in need of additional information concerning this
NIEHS REPORT on Health Effects from Exposure to Power-Line Frequency
Electric and Magnetic Fields
(other references in text above)
Electric and Magnetic Fields Research and Public Information and
World Health Organization (WHO) International EMF Project
"emf protective devices"
"emf protection" .edu "emf absorption"
"emf protection" .edu