Electromagnetic Fields
All of us depend on electricity to meet basic needs such as heating, cooling and lighting our homes. We also depend on electricity to meet the transportation, communication, commercial, recreational, industrial and health care requirements of our society. Wherever we make use of electricity, power frequency electric and/or magnetic fields (EMF) are present.
Magnetic Fields
Magnetic fields are created whenever there is a flow of electric current. This can also be thought of as the flow of water in a garden hose. As the amount of current flowing increases, the level of magnetic field increases. Magnetic fields are measured in milliGauss (mG). The level of magnetic fields from electrical appliances in homes can be as high as or higher than the magnetic fields near outdoor power lines, although the fields from most household appliances diminish rapidly with distance from the appliance. Magnetic field strength from power lines depend on many factors including the design of the line, the amount of current the line carries, and the distance away from the line.
Electric Fields
An electric field occurs wherever a voltage is present. Electric fields are created around appliances and wires wherever a voltage exists. You can think of electric voltage as the pressure of water in a garden hose – the higher the voltage, the stronger the electric field strength. Electric field strength is measured in volts per meter (V/m). The strength of an electric field decreases rapidly as you move away from the source. Electric fields can also be shielded by many objects, such as trees or the walls of a building.
Research on EMF – How It Affects You
You may have questions about whether there are adverse health effects from exposure to power frequency EMF. Over the past 30 years, there have been many scientific studies conducted on power frequency EMF. According to extensive reviews conducted by leading public health agencies such as the World Health Organization (WHO) and the U.S. National Institute of Environmental Health Sciences (one of the U.S. National Institutes of Health), this large body of research does not show that exposure to power frequency EMF causes adverse health effects in humans or animals. In the view of WHO, " Based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields."
There are two principal types of studies that have been conducted on power frequency EMF: laboratory studies and epidemiology studies.
Laboratory Studies
involve exposing cells, tissues and animals to EMF under controlled conditions in the laboratory. Many laboratory studies have examined whether cells exposed to EMF show significant permanent damage to the structure of DNA or chromosomes that could lead to the development of cancer. Other studies have examined whether adverse health effects are found in animals exposed to power frequency EMF for their entire lives. The reviews conducted by leading public health agencies, such as WHO and NIEHS have found that the laboratory studies do not show that exposure to power frequency EMF causes adverse effects in cells or animals.
Epidemiology Studies
look for statistical associations between the incidence of disease and specific conditions or exposures. Some epidemiology studies have reported a weak statistical association between estimates of EMF exposures and some cancers, such as childhood leukemia, while other epidemiology studies have not found such an association. Leading public health agencies, such as WHO and NIEHS have found that at most these epidemiology studies can be interpreted as showing a "possible" but inconclusive relationship between EMF and childhood leukemia, and that the relationship is weak and lacks support from the laboratory research. As noted by WHO, "Despite extensive research, to date there is no evidence to conclude that exposure to low level electromagnetic fields is harmful to human health."
Exposure Limits
Neither the U.S. government nor the State of Washington has established exposure standards for public exposure to power frequency EMF. Two international organizations, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute of Electrical and Electronic Engineers (IEEE), have developed exposure guidelines. For power frequency (60 Hz) magnetic fields ICNIRP recommends public exposures not exceed 2,000 milliGauss (mG) and the IEEE recommends a maximum of 9,040 mG.
| Established EMF exposure limits |
|---|
| International Commission on Non-Ionizing Radiation Protection |
2,000 mG1 |
| Institute of Electrical and Electronic Engineers |
9,040 mG |
| 1In November 2010, ICNIRP updated its guidelines. These new guidelines replace the prior exposure guidelines ICNIRP issued in 1998; the new exposure guidelines have more than doubled from 833 mG to 2,000 mG. See “ICNIRP Statement – Guidelines for Limiting Exposure to Time-Varying Electric and Magnetic Fields (1 Hz to 100 kHz)” and “Fact Sheet on the Guidelines for Limiting Exposure to Time-Varying Electric and Magnetic Fields (1 Hz to 100 kHz)” at www.icnirp.org. |
PSE's Approach
At PSE, safety is always our top priority. We rely on the findings of the reputable, international and national scientific and public health organizations and agencies that have reviewed the research on EMF. We understand that you may have concerns about EMF. We work to address those concerns by:
- Following all applicable federal, state, county and city rules, regulations and standards when constructing power facilities for the safe and reliable delivery of electric service;
- Remaining informed about important developments in EMF research;
- Sharing accurate and objective information about EMF with our customers;
- Providing magnetic field measurements upon request in homes.
If you are interested in more information about EMF, you may want to try some of the following sources:
Download more information
PSE's EMF brochure
Contact Us
425-456-2522 or 1-888-225-5773.