Electric And Magnetic Fields


Electric and magnetic fields (EMF) occur in nature and wherever electricity flows.

Electric and magnetic fields are present in and around the earth. Thunderstorms produce EMF.

The earth’s magnetic field is the force that causes a compass to always point north. Magnetic fields also result from current or the flow of electricity in a wire; field strength increases as the current increases and decreases as distance from the wire increases.

Magnetic fields are measured in units called gauss or Tesla and typically are reported in thousandths of a gauss, milligauss (mG), or microTelsa.

Electric fields are produced by the presence of voltage or an electrical charge: the higher the voltage, the greater the electric field.

Electric fields are measured in volts per meter.

A lamp that is plugged in produces an electric field even while it is turned off. It will produce a magnetic field only when it is turned on.

Objects such as trees, shrubs and buildings can block electric fields. Magnetic fields, however, are not easily blocked and can pass through most objects.

The strength of both fields declines rapidly as the distance from the wire increases.

Because EMF can be found in nature and because our society relies on electricity, people are exposed to EMF much of the time.

Our Position on EMF

Electric and magnetic fields are everywhere. Virtually all human beings in industrialized countries are exposed to them most of the time. Electric and magnetic fields are produced by household wiring and appliances, as well as by all other electric equipment.

Electric and magnetic fields are created by electric lines needed to power our society. AEP Transmission is obligated to meet its customers’ needs by providing service that is reliable and economical and as safe as possible. We must design and operate our electric system in a manner consistent with all these obligations.

AEP Transmission and its parent companies have followed worldwide scientific study and developments related to EMF for decades. They have participated in EMF research through membership in trade associations and have communicated with customers and employees on the issue.

AEP Transmission’s parent company was among sponsors of the U.S. Department of Energy’s approximately $45 million EMF Research and Public Information Dissemination (RAPID) Program, which concluded that “scientific evidence suggesting that EMF exposures pose any health risk is weak.”

Scientific studies over the past several decades have explored the possibility of health effects from EMF. While some of the studies have indicated some statistical associations between EMF and certain health effects, the majority of research has found no such association. Significantly, laboratory research has not shown any causal relationship between EMF exposure and cancer, or any other adverse health effects.

This Retro Report video confirmed that, based on extensive laboratory experiments, EMF from power lines is not a public health threat.

Because the issue involves questions of public and employee health, AEP Transmission remains committed to participating in the EMF issue on a national and worldwide level and to serving as a resource to customers and employees regarding the EMF issue.

Questions And Answers About EMF

For general information about EMF – what they are, what causes them, whether they can be blocked or mitigated, etc. – please consult our answers to the following frequently asked questions.

What are electric and magnetic fields?

Commonly called EMF, electric and magnetic fields are invisible lines of force present in the natural environment and wherever electricity flows.

Sources of EMF include electric power lines, electrical wiring in homes and businesses, home appliances, office equipment, electric tools and hospital diagnostic equipment.

Electric fields are produced by voltage or electric charge. These types of fields are measured in volts per meter(V/m). The higher the voltage, the greater the electric field.

A lamp cord that is plugged in produces an electric field even if the lamp is not on.

Magnetic fields are created by the current or flow of electricity in a wire. As current increases, the field strength increases. When an appliance is turned on, the magnetic field is produced. The magnetic field is not present when the appliance is turned off.

Magnetic fields are measured in units called gauss or Tesla and typically are reported in milligauss or mircroTesla. Note: 1 guass = 1,000 milligauss (mG); 1mG= 0.1 mircroTesla.

Appliances produce EMF

Lamp off and on

How does nature produce EMF?

Electric and magnetic fields are present in and around the earth, which has a magnetic field strong enough to make a compass needle point north. This field averages approximately 500 mG at the earth's surface and is relatively static.

Unlike alternating current (AC) magnetic fields associated with power lines, static or direct current (DC) fields do not cause electrical charges to flow in stationary objects. Thunderstorm activity in the atmosphere is a source of naturally-occurring EMF. 

How does power frequency EMF (EMF associated with power lines and household appliances) compare with other sources of electromagnetic energy?

The electromagnetic spectrum covers a wide range of frequencies. These frequencies are expressed in hertz (Hz) or cycles per second.

Electrical current associated with power lines and household appliances is characterized by extremely low frequencies -- 60 Hz AC, meaning the direction of current alternates at a rate of 60 times per second.

Energy associated with x-rays, for example, is at the higher end of the electromagnetic spectrum.

Scientists generally agree that 60 Hz fields are not powerful enough to damage the body's genetic material or to directly cause cancer.

Electromagnetic spectrum (frequency in Hz)

Electromagnetic spectrum (frequency in Hz)

This chart illustrates some common sources of electromagnetic energy.

Is it possible to block EMF?

Electric fields are blocked by trees, shrubs, building materials and other objects. Magnetic fields, on the other hand, are not easily blocked and can pass through most objects.

The strength of both electric and magnetic fields declines rapidly with distance from the source.

Typical magnetic field ranges (in mG)

Distance from appliance 6 " 1 ' 2 ' 4 '
Microwave ovens 100 - 300 1 - 200 1 - 30 * - 20
Electric ranges 20 - 200 * - 30 * - 9 * - 6
Refrigerators 4 - 100 * - 20 * - 10 * - 10
Clothes washers 4 - 100 1-30 * - 6 *
Clothes dryers 2 - 10 * - 3 * *
Fluorescent lamps 20 - 100 * - 30 * - 8 * - 4
Hair dryers 1 - 700 * - 70 * - 10 * - 1
Color televisions   * - 20 * - 8 * - 4
Analog clocks   1 - 30 * - 5 * - 3
Vacuum cleaners 100 - 700 20 - 200 4 - 50 * - 10
Copy machines 4 - 200 2 - 40 1 - 13 * - 4
Video display terminals 7 - 20 2 - 6 1 - 3 *
Electric blankets 1 - 40 (at 2")      
Note: the asterisk (*) indicates same as background fields.
Source: EMF In Your Environment, EPA 1992

Magnetic Field Comparison Charts PDF

How does EMF exposure vary throughout the day?

A person is routinely exposed to EMF from a large number of sources throughout the day. Electric and magnetic field exposure depends to a large degree on what a person is doing.

The chart illustrates how a person's exposure to EMF may fluctuate during a 24-hour period. It is important to note that no level of electric or magnetic field has been determined to be hazardous.

Example of 24-hour magnetic field exposure

24-hour magnetic field exposure

While asleep, this person's magnetic field exposure was less than 1 mG. During the day, exposure varied to a peak of about 20 mG. Average magnetic field exposure during this 24-hour period was 0.5 mG.

What type of EMF research is being done?

Electric and magnetic field research currently is focused on three main areas:

  1. Laboratory or basic science studies which look at effects of EMF on cells and tissue samples of humans and animals.
  2. Epidemiological studies which use statistics to determine whether an association exists between a disease and an environmental factor such as EMF exposure.
  3. Exposure assessment studies which look at the sources and amount of EMF exposure.

What has research shown?

Scientific studies over the past several decades have explored the possibility of health effects from EMF exposure. While some of the studies have indicated some statistical associations between EMF and certain health effects, the majority of research has found no such association. Significantly, laboratory research has not shown any causal relationship between EMF exposure and cancer, or any other adverse heath effects.

AEP Transmission’s parent company was among sponsors of the U.S. Department of Energy $45 million EMF Research and Public Information Dissemination (RAPID) Program which concluded that “scientific evidence suggesting that EMF exposures pose any health risk is weak.”

This Retro Report video further confirmed that, based on extensive laboratory experiments, EMF from power lines is not a public health threat.

What is AEP Transmission doing?

AEP Transmission’s parent company has been involved in the EMF issue by following worldwide scientific developments, participating in EMF research, sponsoring studies and communicating with customers and employees on the issue.

AEP Transmission’s parent company was a sponsor of the U.S. Department of Energy's $45 million EMF Research and Public Information Dissemination (RAPID) Program which concluded that “scientific evidence suggesting that EMF exposures pose any health risk is weak.”

AEP Transmission’s parent company is also a member of the Electric Power Research Institute, which sponsors and coordinates EMF laboratory, epidemiological and exposure studies.

In addition to monitoring and sponsoring research, AEP Transmission shares the results of these programs with customers and employees.

AEP Transmission’s overall responsibility is to continue providing safe and reliable electric service and a safe working environment for employees.

Can EMF measurements be taken in my home?

Upon request, an AEP Transmission representative will conduct EMF measurements at your home. However, the representative will not be able to interpret whether the field levels are safe or hazardous because no level of exposure has been determined to be unsafe.

Health Effects Of EMF

We all are aware of certain safety issues associated with electricity, such as electric shock. But some scientists also have raised questions about potential health effects caused by exposure to electric and magnetic fields (EMF). Researchers are trying to determine whether EMF can lead to cancer, particularly childhood leukemia or brain cancer. So far, studies have been inconclusive or have failed to link EMF to cancer.

Questions about health effects from EMF exposure first arose in the 1960s and 1970s with the use of higher transmission voltages in the U.S.

Early research focused on electric fields. Studies of electric fields overall have found no evidence of biological changes that could lead to health effects.

The research focus moved to magnetic fields when, in 1979, an epidemiological study suggested that magnetic fields might be linked to childhood cancers. Since then, while some statistical associations have been reported, no actual health effects have been demonstrated.

This Retro Report video further confirmed that, based on extensive laboratory experiments, EMF from power lines is not a public health threat.

AEP Transmission and its parent company are not health research experts and recommend that interested individuals review the expert information available at the links provided below. By providing these links, AEP Transmission is not endorsing the accuracy or quality of information, nor does it necessarily agree with any conclusions set forth by these sources.

EMF Research And Other Information

AEP Transmission takes any health and safety issue very seriously. Therefore, the company monitors scientific and technical developments and public policy related to EMF as part of its ongoing effort to provide a safe environment.

AEP Transmission itself does not actively conduct research on the health effects of EMF. However, through its membership in the Electric Power Research Institute (EPRI – the research organization for the electric utility industry), AEP Transmission’s parent company has sponsored and continues to sponsor research.

AEP Transmission’s parent company was among sponsors of the U.S. Department of Energy’s $45 million EMF Research and Public Information Dissemination (RAPID) Program.

Upon request, AEP Transmission will conduct measurements of EMF. However, interpretation of such measurements is impossible because no level of exposure has been determined to be unsafe.

You can obtain additional information about electric and magnetic fields at numerous websites. By providing the links below, AEP Transmission is not endorsing the accuracy or quality of nor does it necessarily agree with any conclusions set forth by these sources.

Please see Health effects of EMF for links to current reports on that specific topic.