Electric and Magnetic Fields and Health

INTRODUCTION

Valley Link is committed to supplying electricity in a responsible and safe manner. This commitment includes balancing environmental issues, aesthetics, land use, safety, project costs and customer preferences, and addressing concerns about electric and magnetic fields (EMF).

We recognize community members may have questions related to power lines. This interactive website provides information in an easy-to-understand format. Valley Link, like other utilities, relies on information from federal, state and international health agencies. When proposing new transmission lines, we include estimated EMF calculations as part of our regulatory filings. We also stay updated on the most current research to ensure we can quickly respond to emerging issues or concerns. Click here for links to reports from health experts.

INTRODUCTION

There has been on-going research on the potential health effects from EMF exposure since the late 1970s. Thousands of independent studies have been conducted on everything from household electrical sources, power lines operating at levels typically found in communities, to large machines operating in industrial settings.

INTRODUCTION

Health, scientific, and governmental organizations from around the globe have repeatedly evaluated this large body of research. To date, none of these organizations have concluded that EMF exposures cause or contribute to long-term adverse health effects.

INTRODUCTION

Electric and magnetic fields (EMF) are found wherever electricity is generated, transmitted, or used - such as power lines and everyday electronic appliances. EMF is constantly around us as part of our modern way of life.

WHAT ARE ELECTRIC AND
MAGNETIC FIELDS?

There are two types of fields associated with power lines and any other devices that carry or use electricity: electric fields and magnetic fields.

WHAT ARE ELECTRIC AND
MAGNETIC FIELDS?

Buildings, trees, shrubbery, fences, and other conductive materials significantly reduce electric fields. Also, electric and magnetic field intensity decreases as distance from the source increases.

WHAT ARE ELECTRIC AND
MAGNETIC FIELDS?

Electric fields are produced by the voltage, or electrical pressure, on lines or in wiring. Electrical field strength increases as the voltage on power lines increases.

WHAT ARE ELECTRIC AND
MAGNETIC FIELDS?

Magnetic fields are produced by the flow of current through electrical wires. Magnetic strength increases as the current flowing through power lines increases. The strength of magnetic fields is not directly affected by voltage. Magnetic field intensity quickly decreases as distance increases.

WHAT ARE ELECTRIC AND
MAGNETIC FIELDS?

The levels of electric and magnetic fields may be modified by their interaction with fields emitted from adjacent power lines.

MEASURING EMF

Electric fields are measured in volts per meter (V/m). Voltage is the pressure of the electricity flowing through the wires.

Electric fields are produced any time voltage is present; including when objects are plugged in, but not turned on.

Magnetic fields are measured in milligauss (mG) and are present only when the object is turned on.

For both electric and magnetic fields, the strength decreases rapidly with increasing distance from the source.

MEASURING EMF

Electric fields are significantly reduced by vegetation and building materials. Strength decreases rapidly with increasing distance from the source.

MEASURING EMF

Unlike electric fields, magnetic fields are not typically reduced by other objects. Like electric fields, the strength decreases rapidly with increasing distance from source.

Click here to explore exposure levels in the home, or click here to explore typical EMF levels from power lines.

WHAT DOES RESEARCH TELL US ABOUT EMF?

Thousands of studies have been conducted on everything from household electrical sources, power lines operating at levels typically found in communities, to large machines operating in industrial settings.

WHAT DOES RESEARCH TELL US ABOUT EMF?

Health, scientific, and governmental organizations from around the globe have repeatedly evaluated this large body of research. This research includes epidemiological studies, in vivo studies, and in vitro studies.

WHAT DOES RESEARCH TELL US ABOUT EMF?

Studies that observe humans are called epidemiological studies.

WHAT DOES RESEARCH TELL US ABOUT EMF?

Laboratory studies of animals are called in vivo studies.

WHAT DOES RESEARCH TELL US ABOUT EMF?

Studies of isolated cells and tissues are called in vitro studies.

ADDITIONAL HOUSEHOLD ITEMS

Distance from Source

	1 Foot	2 Feet	4 Feet
Microwave	40mG	10mG	2mG
Blender	10mG	2mG	--mG
Drill	30mG	4mG	--mG
Washer	7mG	1mG	--mG

Source: EMF Electric and Magnetic Fields Associated with the Use of Electric Power, National Institute of Environmental Health Sciences, 2002
Click Here to View Source

TRANSMISSION LINES

Distance from Source

Source: Electric and magnetic field are representative values provided by American Electric Power.

DISTRIBUTION LINES

Distance from Source

	0 Foot	50 Feet	100 Feet	200 Feet
Magnetic Fields	20mG	--mG	--mG	--mG

Source: EMF Electric and Magnetic Fields Associated with the Use of Electric Power, National Institute of Environmental Health Sciences, 2002
Click Here to View Source

UNDERGROUND LINES

Undergrounding power lines may make electric field readings negligible; however, it does not eliminate magnetic fields. Magnetic field strength associated with underground lines will vary based on several factors, such as: proximity, voltage, and various mitigation methods. Some methods include phasing orientation and sub-surface composition.

Source: EMF Electric and Magnetic Fields Associated with the Use of Electric Power, National Institute of Environmental Health Sciences, 2002
Click Here to View Source

DOES VALLEY LINK CALCULATE POWER LINE EMF LEVELS?

Yes. Exposure to magnetic fields is calculated using the annual average amount of current flowing through the lines.

DOES VALLEY LINK CALCULATE POWER LINE EMF LEVELS?

Throughout the year, the level of current fluctuates because of weather, temperature, load, etc. Average load is the most accurate way to estimate EMF exposure.

DOES VALLEY LINK CALCULATE POWER LINE EMF LEVELS?

When submitting applications for proposed facilities to Virginia State Corporation Commission (SCC), Valley Link includes EMF calculations.

DOES VALLEY LINK CALCULATE POWER LINE EMF LEVELS?

Valley Link sites and designs its facilities using accepted conservative practices to minimize any impact of EMF levels while balancing environmental, aesthetic and cost factors. This approach is consistent with recommendations of the U.S. National Institute of Environmental Health Sciences and the WHO.

DOES VALLEY LINK CALCULATE POWER LINE EMF LEVELS?

Adding more transmission lines in a right of way doesn’t necessarily increase EMF levels. EMF fields which interact with other fields may counteract one another. Valley Link also designs its lines, where practicable, to reduce effective EMF emissions. Adding separate EMF levels associated with various transmission lines near one another is NOT an accurate method to estimate EMF levels from multiple lines.