According to the industry-funded Electric Power Research Institute (EPRI) electromagnetic fields (EMFs) in residences generally range from 0.5 to 10 mG. However, a number of recent studies have found that most residences have readings below .5 mG. A large-scale Denver study showed magnetic fields to be below 1.82 mG for 90 percent of the homes, while 75 percent had fields below 1 mG.
This is the most controversial aspect of the EMF issue with some scientists saying more research is necessary to determine safe or dangerous levels. However a growing number of scientists have accepted that EMFs are a proven health risk. The levels cited by these scientists as a maximum safe level of exposure range from 1 mG (for example, Dr. Robert O. Becker) to 3 mG (for example, the Washington State Department of Health).
A study by the Electric Power Research Institute listed the primary sources of residential magnetic fields as:
Numerous studies have established that most high magnetic fields in houses are produced by nearby power lines. The fields from high-voltage transmission lines are greater and require greater distances before they drop off. Fields from distribution lines are lower and drop off sooner but are more pervasive within our communities. Transformer stations and pole/ground mounted transformers also emit EMFs.
Luciano Zafanella of EPRI states: "The two most common sources of magnetic fields in this country today are the power lines outside on the street and the home grounding system".
The simplest way is to avoid purchasing a home with high EMF levels. This can be determined indirectly by checking for the presence of EMF sources such as nearby transmission or distribution lines or transformer boxes close to the home. The first or second home from a pole/ground mounted step-down transformer will likely have high readings.
The EMF level can be determined directly by measuring the fields in the home. If you choose to measure the fields (or have them measured for you) the readings should be taken at a time of peak power usage - around supper time is best. Susan Sugarman in her book (cited below) sets forth a protocol for measuring EMFs on your property and in your home. A similar protocol is outlined in the Special Spring 1995 Issue of Network News, the newsletter of the EMR Alliance.
Often the utility company can use mitigation strategies to reduce EMF levels. These strategies include: reverse phasing of conductors; reconfiguration of lines to reduce magnetic fields; placing power lines on higher poles and towers or using different tower designs; employing wider rights-of-way; and balancing currents on distribution lines.
A study prepared by eight major New York State utilities showed that when a 345 kV transmission line is placed in steel pipe filled with oil and buried at a depth of five feet, the strength of the magnetic field measured one metre above the ground over the pipe is only about 1 mG during normal current flow, as compared with magnetic field strengths as high as 60 mG that can be measured at the edge of a 100 foot right-of-way for an overhead 345 kV transmission line.
Sometimes high EMF levels in the home can be a result of the way the electrical system is grounded to the municipal water system, especially if the water pipes and electrical power lines enter the home at opposite ends of the house. Even currents from your neighbours house may enter your home this way and contribute to high fields. It may be possible to make changes to the electric grounding system or the water system to eliminate these fields but anyone contemplating this should consult an electrician to ensure the changes comply with the electrical code.
Unusual wiring, such as having the positive and neutral wires of a circuit not running together can contribute to higher fields. Again, consult an electrician for possible solutions.
The Philadelphia Inquirier (June 3, 1994) reports that home safety inspections to detect electromagnetic fields (EMFs) are becoming more and more common, as homeowner concern about the potential health risks of EMF exposure increases. Independent consultants, who charge approximately $75 for spot tests and $150 or more for whole-house assessments, generally survey the home's exterior and interior with gaussmeters, prepare written reports, and offer literature on recent biomedical studies, hazards, and remediation methods. In addition, they may suggest specific solutions for lowering exposure to high EMF levels. EMF home surveys are playing an increasing role in home sales, as concerned buyers add EMF contingency clauses to purchase contracts, ensuring their right to cancel the deal if the survey finds unacceptably high EMFs. EMFs appear to be affecting home values, as location near a transmission line can sometimes reduce a home's value by as much as 20%. In some cases, buyers are refusing to even consider houses located near utility lines.
Susan Sugarman provides greater details of these electrical wiring problems in her book.
Ed Maxey (E. Stanton Maxey, M.D., retired) firstname.lastname@example.org provides the following advice on finding and resolving high EMF levels in your home:
A. Locate the problem
The source will be either from the wiring in your abode or from the distribution system in your area (external to the abode). If you have a milligauss meter it is relatively easy to find out which is the case.
B. Correct the problem
If the reading drops significantly with the breakers open it is likely that there is a ground fault in your building. The most common such fault is a bonding screw in the electrical panel itself. Electricians in this area have been installing such screws for many years at the insistence of building inspectors. They are a violation of the electric codes which prohibit any grounding connection on the load side of the service disconnect means. Such a fault was found in every unit of this condominium.
You can confirm a grounding fault as follows. With the power restored again note the reading on the milligauss meter. Now turn on a heavy load 120 volt appliance at some distance from the meter. A microwave oven is a good bet. If the milligauss meter registers a significantly higher reading you have a ground fault. Such faults will generate fields from unbalanced currents in the wires/pipes in walls, ceilings and under the floors.
Removing the bonding screws in each unit of this condo significantly reduced the EMFs. An electrician should be contacted if you wish to remove the bonding screw.
Two additional grounding faults were found in this particular unit of the condominium. Each was nothing more than the bare wire ground in an electrical outlet being inadvertently bent so that it touched a return lug in the outlet. Correction consisted of separating the contact points with a screwdriver. DO NOT TRY THIS WITHOUT FIRST DISCONNECTING THE POWER!
A dentist brother had a problem with high EMFs in his home. The culprit was a single return wire the insulation of which was frayed allowing an electrical contact to the metal of an electrical outlet box. Correction was accomplished with several turns of electricians tape about the frayed spot.
In another case a lady had high EMFs from a distribution ground current running in a water pipe which ran the length of the home beneath the floor. A plumber removed an approximately two foot section of the copper pipe and spliced in a two foot section of plastic. The plastic pipe does not conduct electricity. This completely stopped the EMFs from the water pipe.
Utility companies like to cite appliance use when discussing EMFs -- mostly to confuse the issue. For the most part, magnetic fields from appliances are not a significant factor. Although some appliances have high fields they usually drop off within a short distance and the appliances are usually used only for a short period of time. For example the field within an electric oven is extremely high. However, if one was to keep one's head inside an electric oven when it is on for any length of time the EMFs would be the least of their worries.
However there are some appliances where magnetic fields may be a problem - electric blankets and water-bed heaters, hair dryers, black and white televisions and electric heat.
Studies have linked higher miscarriage rates to the use of electric blankets. Water-bed heaters emit similar fields. It is recommended that electric blankets be used to pre-heat the bed and not plugged in while you are in bed; although some newer models are being designed so that the fields cancel each other out. As well electric clocks with motors should not be placed on bedside tables.
Electric hair dryers and razors are two devices that emit high fields next to the head. Although used for short periods of time there are alternatives that pose no EMF risk. It is recommended by Dr. David Carpenter that children not use electric hair dryers. Children should also keep a reasonable distance from the screen while watching television - 42" is cited as a minimum distance - greater for large screen TVs.
Studies have linked electric heating coils embedded in the ceiling with cancer and miscarriages. As well, electric heaters, portable and baseboard, produce EMFs. Keep your distance from electric heaters and do not place a child's bed immediately beside an electric baseboard heater.
Also one should not needlessly stand beside a microwave oven while it is operating, not only to avoid EMFs but to avoid possible microwave leaks.
One way to challenge proposed new transmission lines in your neighbourhood is to take a two-pronged approach. First raise the health issue. But also question the need for the new lines in the first-place. Utility companies are notorious for over-forecasting future electricity needs. Often a proposal can be defeated by demonstrating there is no need for the power it will be carrying - and recent energy use trends support this argument.
Electromagnetic fields increase with the current in the power lines. Reduce energy consumption and you reduce the load and with that you reduce the fields. That is why Ellen Sugarman states: "Energy conservation policy holds the key to an immediate, sensible, inexpensive and safe resolution of the EMF public health question. Energy conservation is also the answer to everyone's concern about our continued ability, as a society, to produce all the energy we need."
Workers can be exposed to EMFs from the electrical system in their buildings and the equipment that they work with.
The National Institute for Occupational Safety and Health (United States) has made recommendations on reducing EMF exposure in the workplace. These include:
Electromagnetic field exposures from Video Display Terminals (VDTs) are a major concern among office workers as studies and anecdotal evidence have linked EMF exposure to increased health problems among pregnant workers. Some fourteen reproductive research studies conducted between 1984 and 1992 indicate various types of links between VDT usage and reproductive problems, ranging from higher miscarriage rates to birth defects.
The Canadian Centre for Occupational Health and Safety has recommended that office space be arranged so that workers not be exposed to emissions from the sides and backs of other people's computers.
Sweden has established a manufacturing standard for both ELF and VLF emissions from VDTs. the ELF radiation limit is 2.5 mG at 20 inches.
Low EMF computer monitors are now being marketed in North America as industry has recognized that it is a concern of consumers. Leading computer magazines recommend purchasing monitors that comply to the Swedish standard.
Recent concerns have been raised that electromagnetic fields from cellular phones and the transmission towers that serve them may pose a health risk.