Is there scientific evidence of adverse health effects? Yes. There are serious health effects, including cancer and depression, associated with living in ELF magnetic fields above 2 mG: see www.powerwatch.org.uk/elf/powerlines.asp. Researchers also found a doubling of leukemia rates associated with exposure to ELF magnetic fields greater than 3 mG to 4 mG: http://www.ncbi.nlm.nih.gov/pubmed/10944614 , http://www.ncbi.nlm.nih.gov/pubmed/11055621.
What are mG and uT? These are units of magnetic field level or strength, measured using a gaussmeter: mG means “milligauss” and uT means “microtesla.” 1 mG = 0.1 uT so you can easily convert uT to mG, just multiply by 10.
How do I measure ELF Magnetic Fields in the home? A gaussmeter such as the Bell-4180 (photo at right) will measure these fields. It is very accurate and easy to use: just push the ON button, wait 10 seconds while it starts, and then read the magnetic field strength shown on the screen in mG (or in uT if you prefer). It is a triple-axis gaussmeter which is much easier to use than single axis gaussmeters. Our quick-start directions will have you measuring total magnetic field strength in less than a minute.
What is the ELF magnetic field level in a typical home? Most single-family homes measure 0.5 mG or less at most locations in the house away from appliances or wiring. Apartments and condos are usually a bit higher. Some locations in the house will read higher due to nearby appliances, or wires in the walls or floor.
Near to the “drop line” will show high fields; it is the thick cable bringing power from the street to the electric meter and it often passes along an exterior wall of the house. Magnetic fields go through practically all wall materials, so a bed could be getting high fields close to the drop line without seeing it since there is a wall in between. Beds or places where people spend a lot of time can be put where fields are lower.
Why are ELF magnetic fields much higher in some houses? The most common reason is improper wiring connections that were not wired according to the National Electrical Code (NEC). This problem is most common in old houses that have been re-wired, or if the electrician didn’t follow the NEC correctly. It can result in unbalanced currents which cause high magnetic fields, usually over a large part of the house; all the outlets and appliances usually still work, and the magnetic fields are invisible. If a gaussmeter shows high fields, then turning off the main breaker for the house will determine whether the high fields are coming from wiring inside the house. Correcting wiring problems can be very time consuming and expensive. We offer a DVD and book to help electricians regarding this problem.
In large buildings, proximity to rooms with electric panels or to cables in walls or floors that carry large currents can also result in high magnetic fields. In any house or building the magnetic fields can vary depending on the appliances in use.
Proximity to overhead power lines also increases magnetic fields for nearby houses, sometimes hundreds of feet away. Exposure will depend on distance, and the amount of current carried by the power line which can vary with season and time of day. The Swedish National Energy Department issued an advisory warning that schools, playgrounds, and day-care centers should not be sited near power lines, and that children should not be subjected for long periods every day to magnetic fields over 3.0 mG.
What do ELF, RF, EMF, and EMR mean?
“ELF” means “Extremely Low Frequency” so it includes fields from alternating current (AC) home wiring, power lines, and most appliances.
“RF” means “Radio Frequency” such as from cell phones, cell towers, radio and TV towers.
“EMF” means “Electromagnetic Fields” which includes both ELF and RF fields.
“EMR” means “Electromagnetic Radiation” which includes both ELF and RF fields, as does the term “non-ionizing radiation”.
What types of EMFs are there? “EMFs” usually refers to one or more of the following:
(a) Magnetic fields from building wiring, appliances, and power lines. These are at the alternating current (AC) ELF frequencies of 50 Hz and 60 Hz, and up to a few KHz. These travel through walls.
(b) Radio Frequency (RF) electromagnetic fields. These have higher frequencies from 3 KHz up to many GHz. These are described at FAQ about RF fields . RF also includes microwave frequencies and microwave energy.
(c) Sometimes EMFs can also refer to the electric fields at lower frequencies. These are stopped by many types of walls including wood, brick, and aluminum. Also, most of the concern and epidemiological research has been in regards to the magnetic fields and the RF fields. The electric field is also more difficult to measure accurately since it is changed by nearby conductive objects including the person's body making the measurement.
Which meter should I use?
(c)
For (b) above you can use the E-100 accessory with the MSI-95. However, most people don’t bother with measuring the electric field for the reasons stated above.
For (b) above you can use the E-100 accessory with the MSI-95. However, most people don’t bother with measuring the electric field for the reasons stated above. What units are most often used to measure EMFs and electromagnetic field strength?
(a)Magnetic field in milligauss (mG) or microtesla (uT) (1 mG = 0.1 uT).
Magnetic field in milligauss (mG) or microtesla (uT) (1 mG = 0.1 uT). (b)RF field in Watts per square meter (W/m2) or similar units
RF field in Watts per square meter (W/m2) or similar units(c)Electric field in Volts per meter (V/m)
Electric field in Volts per meter (V/m) What about the earth’s magnetic field? That is a static magnetic field which people have lived in for millions of years. It is not the same as ELF magnetic fields which have only recently become widespread at high levels since man-made AC electrical power has been in use.
Will these gaussmeters measure magnets? No, the AC or ELF gaussmeters like the Bell-4180, Bell-4190, and MSI-95 will not be able to measure magnets or the earth’s magnetic field. The Bell-5170 and Bell-5180 are used to measure magnets.
Why do we recommend triple-axis gaussmeters? Triple-axis gaussmeters like the Bell-4180 or Bell-4190 are easier to use, much faster, and result in more accurate measurements. They offer much better accuracy than cheaper gaussmeters which cost under $200, especially since the cheaper gaussmeters are single-axis and need to be rotated in various directions which is hard to read and often result in large errors due to not rotating the single-axis meter to the correct orientation.
To buy or rent the Bell-4180 gaussmeter go to: Bell-4180
Email other questions to: info@magneticsciences.com
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