Radiofrequency (RF) Radiation: Satellite Dish, Radar, Power Line, and Miscellaneous
Is it safe to camp overnight (multiple nights) on the top of a large hill that also hosts a television antenna within about 100 feet horizontally from the base of the tower?
The Federal Communications Commission (FCC) regulates ambient radiofrequency (RF) fields in the areas surrounding broadcast antennas. The FCC adheres to the maximum permissible exposure guidelines published by the American National Standards Institute (ANSI) in its C95.1 standard. Areas in which the ambient RF fields exceed the maximum permitted exposure (MPE) for unrestricted occupancy by the public are required to be posted and fenced or otherwise restricted. This being the case, one would generally assume that if there are no postings or access restrictions near a specific tower, then the RF fields in the area meet the requirements and are safe for continuous occupancy.
Are there references or direct experience dealing with an association between tinnitus (ringing in the ear) and a previous exposure to microwave/radiofrequency radiation?
The only consistently repeatable finding of bioeffect from microwave radiation is heating (as in a microwave oven). This is the basis for the limitation of RF exposure in magnetic resonance imaging. In years past there were sporadic reports of other effects, including neurological. Most of these were in the Soviet literature. To the best of my knowledge, western scientists have been unable to duplicate these findings.
I was thinking of putting a satellite dish in my apartment. Is this dangerous to my health from the possible radiation that the dish might have?
A TV satellite dish is a passive device, that is, it does not emit any energy. The dish is a receiving device to capture signals from the satellite. Therefore there is no concern of radiofrequency exposure. However, because of the very weak signal from the satellite in space, it is important that there is no signal attenuation due to building materials. If you put it inside your apartment, the signal can be too weak and you may not get good reception.
What are the known health risks to microwave radiation such as that used on commercial aircraft weather radar? Assume everyday exposure 10 ft from the radome on the aircraft.
The nominal output of these systems is a few hundred watts of microwave power. In general, these systems are not operating when the aircraft is on the ground. However, there may be circumstances, especially during maintenance and testing, that ground personnel may be exposed to the X-band radiation emitted by the system. There is a large database of calculated and measured hazard distances of X-band systems. The power output of weather radar is many orders of magnitude lower than fire control radar. While fire control systems have the potential to overexpose personnel, it is a common misconception that any system found in the radome of an aircraft nose is dangerous.
In the X-band region, the Institute of Electrical and Electronics Engineers (IEEE) C95.1 Radiofrequency Radiation Standard (1999), as well as the American Conference of Governmental Industrial Hygienists, Threshold Limit Value (2000) has an exposure limit of 10 mW/cm2 for controlled (occupational) exposures, averaged over 6 minutes. For uncontrolled (essentially public areas), the IEEE has an exposure limit of 6.67 mW/cm2, with a slightly longer averaging time. Measurements made on a typical WXR-700 system by the United States Air Force in 1996 were unable to produce levels that are above either the controlled or uncontrolled limits recommended by IEEE. Therefore, in general, it is safe to assume that these systems are incapable of overexposing personnel to recommended standards in wide use both in the United States and the rest of the world.
My husband has neurofibromas on both his feet, which are growing larger and more painful. He also has prostate cancer. He is the first in his family with either one of these diseases and he feels that these were caused, in part at least, by working closely with radar equipment on navy ships during the Korean War. Is there any documentation of this?
The only proven biological injury from radar is the result of its very short wavelength radio waves, commonly called microwaves. Like microwave ovens, high exposures to radar emissions cause heating in exposed tissue. If the heating is sufficient, the tissue dies. Normal blood flow provides cooling, so long exposures in very close proximity to radar emissions are usually required for significant injury. Exceptions to this are the eyes and testes, where blood-flow cooling is weak. There have been several claims of other biological injuries from microwaves, including induction of cancer. However, none of these have been confirmed by independent research.
In 1996, the World Health Organization (WHO) established a program called the International EMF Project that is designed to review the scientific literature concerning biological effects of electromagnetic fields, identify gaps in knowledge about such effects, recommend research needs, and work towards international resolution of health concerns over the use of RF technology. The WHO maintains a website that provides extensive information on this project and about RF biological effects and research.
We are thinking about building a house near a "major power line." Is there any evidence that our children or we will develop an illness such as cancer? How far away do we have to be from the power line before we are considered at a "safe range"?
Potential health concerns about power lines were first raised in a 1979 study which associated increased risk of childhood leukemia with residential proximity to power lines. Since that initial study, numerous other investigations have attempted but failed to clarify whether observed associations between electromagnetic fields (EMFs) and various health effects were causal or coincidental. Some scientists have argued the physical impossibility of any health effect due to weak ambient levels of EMFs, while others maintain that the potential health risks should not be dismissed even though the evidence remains equivocal and contradictory.
There are no known health risks that have been conclusively demonstrated in relation to living near high-voltage power lines. But science is unable to conclusively prove that anything, including low-level EMFs, is completely risk free. Most scientists believe that exposure to the low-level EMFs near power lines is safe, but some scientists continue research to look for possible health risks associated with these fields. If there are any risks such as cancer associated with living near power lines, then it is clear that those risks are small.
Recently our electric utility put up some powerful cables along with higher poles. How can I find all the information that I need in order to be informed?
Your local electric utility company would be the best source of information on what exactly is being installed. Most companies have good information available on EMF facts and can answer questions about local concerns. Look for a consumer-information telephone number in your electric bill.
There are two general sources of information about EMF that you might be interested in pursuing:
- "Possible Health Effects of Exposure to Residential Electric and Magnetic Fields," Committee on the Possible Effects of Electromagnetic Fields on Biologic Systems, National Academy of Sciences/National Research Council.
- An excellent collection of questions and answers on health issues related to power lines from the Medical College of Wisconsin.
How can I find out how many Hz I am being exposed to from a corridor of high-power pylons near my condo? Also, would proximity to these pylons affect the amount and intensity of static electricity in my apartment?
In the United States the power system supplies 60 Hz electrical power. One Hz is one cycle per second. Electrical power in the United States uses alternating current that changes at a rate of 60 cycles per second. In some other countries the electrical power supply oscillates at 50 Hz. The 50-60 Hz is in a frequency range called extremely low frequency, or ELF. Electrical transmission lines do not affect static electricity in the home.
How far from high-voltage lines is it safe to live?
The National Academy of Sciences reports of reviews of possible health hazards of power-line EMF are available online. Two reports may be of interest to you: a 1997 Report and a 1999 Report.
The second, most recent, report is available for reading online. It presents a review of the results from the EMF-RAPID (Electric and Magnetic Fields Research and Public Information Dissemination) program, a national research program authorized by Congress in the Energy Policy Act of 1992. In the Executive summary the report concludes (in part): "The EMF-RAPID biological research contributed little evidence to support the hypothesis that a link exists between MF [magnetic fields] and cancer" and "The results of the EMF-RAPID program do not support the contention that the use of electricity poses a major unrecognized health danger."
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