The Safety of ELF Fields Generated in the Ionosphere

The HAARP facility can be used to study techniques that use very low and extremely low frequencues for applications such as communication with deeply submerged submarines and geophysical exploration. The HF transmitter and antenna system at HAARP does not, itself, transmit any signals in the ELF frequency range. Instead these signals would be generated in the ionosphere, at an altitude of approximately 80 - 100 km.

The process of generating ELF within the ionosphere is very inefficient (the conversion efficiency is about 10-8). As a result, the level of ELF signal reaching the ground is extraordinarily small. Measurements of the ELF signal strength produced in the ionosphere by the HIPAS facility during a recent test, for example, showed field strengths on the order of 5 pT or 0.00005 milligauss (mg)[1]. This field strength is too weak to be detected with any commercially available instrument and is only useful for low data rate communications or for geophysical sensing applications where specialized correlating receivers can be employed.

The subject of ELF safety has received significant attention in the US and around the world, primarily because of concerns over the fields produced by High Voltage power lines, but also because of concerns over such common ELF sources as household appliances and video display terminals (VDTs). Concise summaries of some of these studies and additional information on radio frequency radiation (RFR) can be found at EMF Link operated by The EMF Clearinghouse.

Here are some comparisons between the signal levels that could be produced by ionospheric heating and some more common, day-to-day activities:

The Environmental Impact Process that was conducted during 1992 and 1993 for the HAARP project considered these and many other factors related to RFR health and safety. Measurements made between January and April, 1995 on the HAARP prototype in Gakona, have confirmed that the careful attention to RFR safety, inherent in the HAARP design, has been preserved. The conclusions presented in the final EIS document, published in July 1993, prior to beginning any construction of the HAARP facility, were that there would be no biological effects on humans or animals, and that conclusion remains valid today.

We have provided a stereogram to illustrate the point that ionospheric ELF fields are so weak that to detect them requires special processing methods. When you look at this stereographic image, you will see a great deal of "noise," in a direct analogy to the problem faced by ELF receivers which must be sophisticated enough to pick out a very weak signal in the presence of naturally occuring background noise or static. There is a message buried in this noise along with a picture that is even more difficult to see. The message is readable but only by using the special processing power provided by two eyes. You need to sit about an arm's length from the monitor to view this message (for safety reasons too!). Thanks to Tony Frazier-Smith of Stanford University for creating this image


[1] McCarrick, M. J., et al, "Excitation of ELF waves in the Schumann resonance range 
    by modulated HF heating of the polar Electrojet," Radio Science, Vol 25, Nr 6, 
    pp 1291-1298, Nov - Dec 1990.
[2] New Scientist, October 7,1995, p. 4

[3] Consumer Reports, May 1994.

[4] Baumann, S and Alagarsamy, S., Meeting abstract from Bioelectromagnetics Society, 
    12th Annual Meeting, 10-14 June, 1990.

[5] Bennett, William R. Jr., Health and Low Frequency Electromagnetic Fields, 
    Edwards Brothers, Inc: Ann Arbor, MI 1994. p. 95.



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Last updated July 17, 1998.