EMF: How close is too close?

E.M.F. Three little letters that strike terror into many hearts, but why?

EMF testing

Donna Shay, a Colorado citizen, asked Western to conduct an electric and magnetic field reading at her cabin that sits just outside a 115-kilovolt transmission line’s right-of-way. EMF readings determined about 1 milliGauss of exposure near her front door.

Mostly, it’s because we don’t understand electric and magnetic fields, or EMF.

The truth is people come into contact with these fields every day. EMFs occur naturally, like the magnetic field caused by currents deep inside Earth’s molten core. Manmade fields are also created by common appliances and equipment we depend on every day, like talking on a cell phone or heating up lunch in a microwave.

At Western, our high-voltage transmission lines and substations give off EMF, which sometimes concerns landowners with lines over and near their property. To help allay concerns, Western’s electrical engineers will test landowners’ EMF exposures from our transmission lines on request. Rocky Mountain Electrical Engineer Ron Padget is one such engineer who helps landowners determine the EMF exposure on their property. “They’ve heard about EMF, but they don’t know what it is,” he said. “So when I do a reading of their property, I let them know the physics of [EMF] and the fact that we don’t know if it’s dangerous or not.”

In fact, there is no official accepted “safe level” for EMF exposure; there is still considerable controversy and uncertainty surrounding the risks and long-term effects of EMF, but many sources defer to 1 milligauss.

There is also an important distinction between magnetic and electrical fields. Padgett explained, “Research shows electrical fields don’t have a harmful effect on humans, but researchers are still looking at the effects of magnetic fields.”

Electrical fields versus magnetic fields: What’s the difference?

Electric Field Magnetic Field
Produced by voltage (amount of energy) Produced by current (flow of energy)
Easily shielded (weakened) Not easily shielded (weakened)
Measured in volts per meter (V/m) Measured in milliGauss (mG)

The World Health Organization is also conducting long-term studies into the effects of EMF, and you can learn more about EMF at the WHO’s EMF Project website.

Go the distance

To reduce exposure to EMF, distance is the key.

“While magnetic fields are not easily shielded by objects or barriers like walls, roofs and trees; the exposure drops significantly the farther you are from the source creating EMF,” said Padget. “It’s the inverse of the square rule. If you’re twice as far away from the source (like a transmission line) you only get a quarter of the exposure; it drops off very quickly.”

For example, if your exposure standing directly under a 230-kilovolt transmission line is 64 mG, then when you walk 52 feet away your exposure is only 16 mG; and if you stand 116 feet away then your exposure is only 4 mG.

Common EMF sources

Electric stove EMF test

An EMF reader testing the magnetic field next to an electric stove clock displays 139.6 mG.

  • Electric blankets: Topping the list for worst EMF exposure is electric blankets because although the output is small, their close proximity to people increases EMF exposure. You’re unlikely to cuddle with your hairdryer or nap under a transmission line.
  • Wireless electronics (cell phones, etc)
  • Power Lines
  • TVs and computers
  • Electric clocks
  • Hairdryers
  • Electric razors
  • Kitchen appliances

Check out other EMF sources and their exposure levels at the Environmental Protection Agency’s “EMF in Your Environment” booklet.

Prudent avoidance

While you can’t prevent EMF, you can limit your exposure by using what what the EPA calls “prudent avoidance.” In addition to not wrapping up in a plugged-in electric blanket, you might:

  • Move your motor-driven electric clocks or other electrical devices (like cell phones) away from your bed.
  • Stand away from an operating microwave oven or other appliances that use a lot of electricity.
  • Sit away from the TV and at least an arm’s length away from the computer screen and processing unit.
  • Decide to use a safety razor instead of an electric one.

1 Comment

  • By Olivia jones, September 17, 2013 @ 6:00 am

    I would suggest EMF testing to all to be done in homes so as to be careful and prevent the radiation.

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