What Distance is Safe?
Michael’s Table of EMF Safety Distances — from Power Lines, Cell Towers, Many Other Sources (See Chart at Bottom of Page)
By MICHAEL R. NEUERT © 2012
The following table of Safe Distances from EMF Sources is offered below to help reduce your exposure to electromagnetic fields (EMFs). But the actual EMFs emitted from different sources can vary greatly, and the distances needed to reach a desired “safety level” are difficult to predict. For more accurate safety distances, on-site measurements with appropriate test meters are strongly advised.
The guidelines below are the minimum distances usually needed to reduce the EMFs down to the General Public Precautionary Levels. In many cases the distances needed will be less than is shown here — but in a few cases, a greater distance will be required. Therefore, it is always best to measure with the proper EMF test equipment to verify distances for your situation.
Individuals with a heightened sensitivity to electromagnetic fields — or other serious health issues such as chronic fatigue, cancer or Lyme Disease — may want to reduce their exposures even further, perhaps down to the much stricter EMF Hypersensitivity Advisory levels. For these concerns, consider doubling many of the distances shown in the table below. And perhaps most important, please listen to your own body, intuition and experience as your final guide.
Safe Distance from Power Lines…
It is difficult to predict a safe distance from power lines, because the EMFs can vary greatly depending upon the situation. The best advice is to measure with a gaussmeter to determine the actual levels of magnetic fields and the distance required in your particular case. (Special note: magnetic fields are particular EMF component most often linked to health effects in the studies. They are measured with special instruments called gaussmeters.)
The strongest magnetic fields are usually emitted from high voltage transmission lines — the power lines on the big, tall metal towers. To be sure that you are reducing the exposure levels to 0.5 milligauss (mG) or less, a safety distance of 700 feet may be needed. It could be much less, but sometimes more. You must test with a gaussmeter to be sure.
It’s even more difficult to predict a safe distance from neighborhood power distribution lines — the type typically found on wooden poles. For example, homes with a nearby transformer will sometimes have higher EMFs because the transformer is a hub and the power lines carry more electricity for a group of homes. The issue is complicated by the fact that there can be stray electricity flowing in the metal water service pipes of the neighborhood, increasing the magnetic fields from both the power lines and from the buried pipes!
Thus, there is no reliable safety distance for neighborhood power lines. In general, a magnetic field level of 0.5 mG will be reached somewhere between 10 and 200 feet from the wires. But you cannot tell by simply looking up at the power lines. You have to test on-site with a gaussmeter to be sure.
If the electrical power lines are installed underground, the magnetic fields may be just as strong, or even stronger. This is because the power lines could actually be closer to you when only buried a few feet down, rather than up 20 or 30 feet overhead. For neighborhoods with buried power lines, you must always test with a gaussmeter.
Power lines also emit electric fields. The electric fields from high voltage transmission lines (metal towers) can be very strong outside near the wires, and extend for over a thousand feet. However once inside the home, the building structure usually provides some shielding, and the electric fields from electrical wiring and cords will usually be much stronger than that from the power lines.
Safe Distance from Cell Towers…
It is also difficult to predict a safe distance from cell towers. For example, cell towers are designed to transmit most of their radio frequency (RF) energy horizontally. Some areas below the tower may have lower levels than locations farther away that are more in line with the vertical height of the antennas.
The exposure from a cell tower will depend on the type of antennas, the number of antennas, how much the antennas are actually being used, the time of day, etc. The distance needed to reduce exposures down to the General Public Precautionary Level of 0.010 microwatt per centimeter squared (μW/cm²) is often around a quarter of a mile (1320 feet) or more. Due to the uncertainty, on-site testing with a broadband RF test meter is strongly recommended.
A German study reported that people living within 400 meters (1312 feet) of cell towers had over 3 times the normal rate for new cancers (City of Naila 2004). In an Israeli study, the relative risk for cancer was about 4 times greater within 350 meters (1148 feet) of the cell tower (Wolf et al. 1997). Based on findings like these, a minimum safety distance of 1/4 mile (1320 feet) might be considered prudent.
And again, individuals with EMF hypersensitivity or other serious health issues may want to consider a much greater safety distance, perhaps a half mile, or even more.
Table of Safety Distances from Various EMF Sources…
The safety distances below are based on Michael Neuert’s actual EMF measurements in the San Francisco Bay Area over a 20 year period. The distances shown here are usually far enough away for the majority of cases, but may not be for all. Please always measure with a test meter to be sure. (See notes 1 – 4 at bottom of this page.)
Note 1 The General Public Precautionary Level is a precautionary guideline that I sometimes offer to my concerned clients who wish to be proactive with EMFs and protect their health. This guide is only a suggestion based on my own understanding of the EMF research literature and professional experience with clients for over 20 years. For example with magnetic fields, I suggest a safety level of 0.5 mG to provide a margin of safety below the 1.0 milligauss (mG) linked to childhood cancer in the studies. However, for sensitive individuals and those with serious health issues, even lower safety levels and thus greater distances may be appropriate. Please consult with your own health professional to help determine adequate safety levels for your own particular situation. For more information, please refer to our EMF Safety Guide page.
Note 2 The safety distance from an EMF source is simply the measured distance needed to reduce human exposures down to some desired safety level for most cases. But safety distances are difficult to predict because many factors can cause variations in the actual level of EMFs emitted, and thus variations in the actual safety distances needed. The distances shown here are likely to reduce the EMF exposures to the safety level shown at the top of the chart, for the majority of situations. In many cases, the actual distances needed will be less than shown in this chart — but in some cases an even greater distance may be needed. It is advisable to measure on-site with an EMF test meter to determine the actual safety distance.
Note 3 Individuals with heightened sensitivity to electromagnetic fields — or other serious health issue such as cancer, chronic fatigue or Lyme Disease — may wish to reduce their EMF exposures even further, perhaps down to the stricter EMF Hypersensitivity Advisory levels. For these kinds of health concerns, you might consider doubling the safety distances shown here. And most important, please listen to your own body, intuition and experience regarding safety levels and distances.
Note 4 The suggestions for safety distances in this chart are generally based on Michael Neuert’s professional on-site testing of the various EMF sources in the San Francisco Bay Area since 1992. Actual EMF emissions, and thus the corresponding safety distance, can vary greatly and are difficult to predict. To better determine actual safety distances, it is always advisable to measure the actual EMF levels with an appropriate EMF test meter whenever possible.