Electric and Magnetic Fields

Electric and magnetic fields (EMFs) are part of our everyday environment. They are emitted by power lines and other electrically-powered systems that light, cool and heat our homes, provide our communications and entertainment and support other aspects of our modern lifestyle. EMFs also are produced naturally by the Earth.

For more than 30 years, scientists and researchers from universities, national laboratories, health agencies, the World Health Organization and other groups have conducted research activities into possible health effects of EMFs. According to this large body of research, there are no confirmed health risks caused by exposure to low-level EMFs.

What are EMFs?

The term “EMF” describes two invisible forces that surround any electrical device. Both types of fields weaken significantly as they extend further away from the source.

Electric fields are produced by voltage – the strength or ‘pressure’ with which an electric current flows. Electric fields can be weakened by solid objects such as vegetation, buildings or other structures. The strength of electric fields varies depending on the voltage of the power line.

Magnetic fields are produced by current – the movement of electrons through a conductor.

The EMFs associated with power lines and electrical devices are much weaker than those associated with other sources such as microwaves or radio waves; they are considered to be “extremely low frequency” fields at 60 Hertz (Hz). These EMFs, at the low end of the electromagnetic spectrum, are described as “non-ionizing” because they are not known to damage DNA or cells directly.

Health Studies and Concerns

Although researchers and scientists have heavily studied this issue since the 1970s, they have not confirmed that any adverse health effects have been caused by exposure to low-level EMFs.

  • After a recent review of scientific literature about the issue, the World Health Organization (WHO) called for continued research but concluded that, “…current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields.”
  • In 1997, a National Research Council committee studying the issue concluded, “…the current body of evidence does not show that exposure to these fields presents a human-health hazard. Specifically, no conclusive and consistent evidence shows that exposures to residential electric and magnetic fields produce cancer, adverse neurobehavioral effects, or reproductive and developmental effects.”
  • Similarly, in 1999, the National Institute of Environmental Health Sciences (NIEHS) reported to the U.S. Congress that, “No consistent pattern of biological effects from exposure to EMF had emerged from laboratory studies with animals or with cells.”
  • According to the National Cancer Institute: “No consistent evidence for an association between any source of non-ionizing EMF and cancer has been found, despite numerous epidemiologic studies and comprehensive reviews of scientific literature.”

This research has been performed through epidemiological, animal, biological and clinical studies.

Magnetic Field Exposure

Studies show that primary sources of EMF exposure can be found at home or at work. Median magnetic field strength, measured in milliGauss (mG), for common household items is shown in the first chart below.

Exposure levels vary considerably based on the model of appliance, distance from it and its use. For example, a hair dryer’s “high” setting produces a stronger magnetic field than its “low” setting. A dash means the measurement could not be distinguished from background measurements before the appliance was turned on.

Typical Magnetic Field Levels
Distance from source
6" 1' 2' 3'
Digital Clock 1 - - -
Electric Oven 9 4 - -
Hair dryer 300 1 - -
Microwave Oven 200 4 10 2
Refrigerator 2 2 1 -
Video Display Terminal (PCs with color monitors) 14 5 2 -
Washing Machine 20 7 1 -
Source: National Institute of Environmental Health Sciences

Magnetic fields surrounding everyday appliances can be stronger than fields near power lines, depending on distance from the source. This chart shows typical magnetic field strengths of overhead power lines.

Typical Magnetic Field Levels from Overhead Power Lines (60 Hz)
Distance from source
0' Right-of-Way Edge 100' 200' 300'
500 kV 86.7 29.4 at 65' 12.6 3.2 1.4
230 kV 57.5 19.5 at 50' 7.1 1.8 0.8
115 kV 29.7 6.5 at 50' 1.7 0.4 0.2
Source: National Institute of Environmental Health Sciences

Learn More

You can learn more about electric and magnetic fields by visiting these resources:

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