Electric and Magnetic Fields from Power Lines
- Scientific studies have not clearly shown whether exposure to EMF increases cancer risk.
Electric and magnetic fields, also known as electromagnetic fields (EMF), consist of waves of electric and magnetic energy moving together. These energy fields surround us all the time. The World Health Organization, an agency of the United Nations, classifies extremely low frequency electromagnetic fields as possibly carcinogenic to humans based on limited evidence showing an association with childhood leukemia. However, scientific studies have not consistently shown whether exposure to any source of EMF increases cancer risk. Scientists continue to conduct research on the possible health effects of exposure to EMFs in order to improve health risk assessments and protection programs.
About Electric and Magnetic Fields from Power Lines
Electromagnetic Radiation (EMR)
Electromagnetic radiation (EMR) consists of waves of electric and magnetic energy moving together through space. An example of electromagnetic radiation is visible light. Electromagnetic radiation can range from low to high frequency, which is measured in hertz, and can range from low to high energy, which is measured in electron volts. Wavelength, another term associated with electromagnetic radiation, is the distance from the peak of one wave to the next.
There are two general kinds of electromagnetic radiation: ionizing radiation and non-ionizing radiation. Ionizing radiation is powerful enough to knock electrons out of their orbit around an atom. This process is called ionization and can be damaging to a body’s cells. Non-ionizing radiation has enough energy to move atoms in a molecule around and cause them to vibrate, which makes the atom heat up, but not enough to remove the electrons from the atoms.
Electromagnetic Fields (EMF)
Electromagnetic fields associated with electricity are a type of low frequency, non-ionizing radiation, and they can come from both natural and man-made sources. For example, during a thunderstorm the base of a cloud will develop a negative charge while the upper portion of a cloud accumulates a positive charge. This separation of charge leads to an electric field which increases in strength (measured in volts per meter) as the electric potential between the base and upper region of the cloud increases. At the same time, positive charge may begin to pool at the surface of the earth. With sufficient strength, this electric field can lead to a discharge allowing the flow of electricity—the movement of electrons, or current—between the sky and the ground (i.e. lightning). The flow of current generates a magnetic field whose strength is proportional to increases in current (measured in teslas). The image below shows the range of frequencies for different forms of electromagnetic radiation found in the electromagnetic spectrum.
The waves from power lines and electrical devices have a much lower frequency than other types of EMR, such as microwaves, radio waves or gamma rays. However, a low frequency wave does not necessarily mean that it is low energy; a charging cable for a phone produces a low frequency, low energy electromagnetic field, while a high-tension power line can create a much higher energy electromagnetic field that is still low in frequency.
EMR associated with power lines is a type of low frequency non-ionizing radiation. Electric fields are produced by electric charges, and magnetic fields are produced by the flow of electrical current through wires or electrical devices. Because of this, low frequency EMR is found in close proximity to electrical sources such as power lines. As current moves through a power line, it creates a magnetic field called an electromagnetic field. The strength of the EMF is proportional to the amount of electrical current passing through the power line and decreases as you move farther away. Because of this property, the exposure to an electromagnetic field you would receive from a power line decreases with distance.
What You Can Do
If you are concerned about possible health risks from electric and magnetic fields, you can:
- Increase the distance between yourself and the source. The greater the distance between you and the source of EMF, the lower your exposure.
- Limit the time spent around the source. The less time you spend near EMF, the lower your exposure.