A basic guide to EMFs
[Guide to EMFs]
EMFs (Electromagnetic fields) are a highly complex subject which can be
difficult to understand, especially given the level of jargon used. We hope to
explain some of the basics here, including references to further information
What are EMFs?
An EMF (which stands for "Electromagnetic Field") is a field of energy
created by electrically charged objects. An electromagnetic field has two
"components", a magnetic component and an electric component. The electric field
is produced by stationary charges, and the magnetic field by moving charges
(currents). Electromagnetic fields are also often referred to as "Electromagnetic
Radiation" (EMR). You can't see, feel or hear electromagnetic fields, apart from
visible light, which is a part of the electromagnetic spectrum.
What is the electromagnetic spectrum?
The electromagnetic spectrum refers to the range of different types of
These are usually sorted by the frequency. The frequency which the field oscillates
at defines the type of EMR.
Here are some of the technologies that use or give off EMFs:
- Mains electricity
- Mobile Phones
- Microwave ovens
- Visible light
For visual explanation, NASA have a simple but useful diagram, and there is a far more detailed diagram available from thinkgeek (purchase required).
Pulsing / Continuous signals
We believe that one of the main reasons that EMFs (particularly microwave
frequencies) are potentially bioactive is due to the nature of the signal
For a more in-depth analysis, please read our article "To pulse or not to pulse".
Where do EMFs come from?
We have evolved with the natural levels of EMFs produced by both the sun and
world around us. Background levels of EMFs vary hugely depending on which part
of the spectrum being looked for - natural light is an obvious example. The
earth's magnetic fields are static fields, unlike man-made alternating current
(AC), which has no natural counterpart. Microwave frequency exposure is a
relatively new phenomenon: 100 years ago the background radiation was millions
of times lower than it is now, and it is as recent as the mobile phone boom
(~1990's) that the modern, digitally pulsed signals have become ubiquitous in
the Western world.
Power frequency (50Hz in the UK) is given off by any appliance or
transmission of AC (alternating current) electrity. Electrical wiring creates
electric and magnetic powerfrequency fields throughout houses and other wired
buildings, but these levels are usually very low unless there is a wiring fault.
Many standard household goods will leak power-frequency EMFs due to poor
Are EMFs dangerous?
Absolute proof of whether something is safe or unsafe is not possible to
establish. Most areas of science can only deal in probabilities, and that
becomes clearer as more scientific studies investigating health effects are
produced. Unfortunately the studies are not always well done, and the flaws in
any given study (showing an effect or otherwise) are often not reported.
Childhood leukaemia has been internationally accepted as linked to
powerfrequency exposure magnetic fields, with a wealth of literature finding
increases in risk to this and other illnesses. There is more disagreement about
ill health effects from radiofrequency radiation, which is newer for most of the
population, though a well-established 'microwave sickness' has been described.
Precautionary levels which will protect us from illness have not been agreed on,
as some countries wish the levels to be lower than others.
It is well documented and generally accepted that over-exposure to
ultraviolet rays can cause burning and skin cancer. As a result fortunes are
spent on protective sun cream and information services as to prudent avoidance
of such exposures.
Microwave Frequency Electromagnetic Radiation (300 MHz to 30 GHz)
The "Radiofrequency EMFs and health risks" article in the Powerwatch
article library has a detailed and
up-to-date overview of the existing science on microwave frequency EMFs and
their effects on health.
Microwave ovens work on another well documented and understood
principle. Molecules in the food are vibrated by high levels of microwave
frequency Electromagnetic energy, causing it to heat up and subsequently cook.
If you stood in front of an operational microwave with no door your insides
would slowly be cooked. Because of this, microwave ovens are stringently
designed against leaks, and opening the door operates a safety mechanism which
disables the oven, thus removing the risk to the operator.
There are internationally accepted guidelines by the International Commission
for Non-Ionising Radiation Protection (ICNIRP) that have been designed to limit
both residential and occupational exposure to levels that are safely below those
that can heat up tissue. Currently these guidelines are between 28 and 61 volts
per metre (V/m) depending on frequency.
However, recently there has been a number of studies showing very specific
biological effects far lower than these levels (see our Studies list), and as yet there is no international guidance that has taken
any of these studies into effect. This, coupled with misleading statements
designed to imply that there is currently no published evidence showing a link
from organisations such as WHO, are the primary reasons why this topic remains
in such hotly-disputed contention.
In contrast to the exposure guidelines leves set by ICNIRP, health effects
are being reported as low as 0.06 V/m.
Typical sources of exposure from microwave frequency EMFs are:
- Mobile Phones
- Mobile Phone Masts
- Digital Cordless Phones
- WiFi and WiMax
- TETRA (police communication system)
Power Frequency Electromagnetic Radiation (50 Hz (UK) and 60 Hz (USA))
Powerfrequency electromagnetic fields are generated by any appliance running
off AC (alternating current) power - anything plugged into a main power socket
will generate them to some degree. ICNIRP have set guidelines for residential
and occupational exposure to powerfrequency magnetic fields, based primarily on
electric shock responses and induced currents, currently set at 100 microtesla
(µT) - equivalent to 1 Gauss.
At the moment, health effects primarily associated with powerfrequency EMFs
are due to the magnetic component - these include, but are not limited to,
Childhood Leukaemia, Adult Leukaemia, Amyotrophic Lateral Sclerosis,
Miscarriage, and Clinical Depression. The evidence on these is mixed, but the
link with Childhood Leukaemia is now considered to be pretty solid, with a
doubling in risk at magnetic fields above 0.4 µT (again far below the
guidelines set by ICNIRP).
There is a fairly brief overview of health risks and evidence in the health concerns section of the electric power transmission article on
Wikipedia. This research and considerably more is covered in greater depth in
the "Power Frequency EMFs and health risks" article in the Powerwatch article library.
Typical sources of exposure from power frequency EMFs are:
- Electrical Substations
- House Wiring
- Many standard electrical appliances