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
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 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.”

What is AEP doing?

AEP 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 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 also is 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 shares the results of these programs with customers and employees.

AEP'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 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.