19 February 2010

“The City Is Full of Dizzy People”: Iran and Jamming

An article recently appeared in Iran’s Mardomsalari newspaper by a doctor challenging claims by the country’s Health Minister that the jamming of TV and radio broadcasts has no negative health impact on humans.

The Minister’s comment contradicted a statement by the head of Iran’s parliamentary health committee, who had previously noted such negative effects as fatigue, dizziness and nervous and mental health disorders. The comment also came after a university medical department head told a health conference that jamming had resulted in a rise in the number of patients suffering from infertility.

The Mardomsalari article’s author said “we cannot just ignore the effects of jamming waves on people.” He reported the number of patients coming to health clinics because of dizziness has increased. He noted many others simply don’t visit a doctor.

He then went on to say: “The city is full of dizzy people. I have seen people leaning against the wall to avoid falling.”

This doctor acknowledges “we have no right to say the epidemic of dizziness is related to radio frequency waves without proper proof. Maybe we are dealing with an unknown virus…”

But he argues that jamming needs to be considered as the source of the problem.

VOA signals to some places like Iran are jammed from time to time. We obviously don’t approve as jamming violates the notion of the free flow of information. Jamming is wrong. And if authorities anywhere knowingly endanger their citizens' health through jamming, that is clearly wrong, too.

One of VOA’s transmission experts tells me there are distinct similarities between exposure to the microwaves from microwave ovens and exposure to the frequencies like those used in jamming.

One link the expert gave me was to a Radio Frequency Safety guide from the U.S. Federal Communications Commission. One quote: “Biological effects that result from heating of tissue by RF [radio frequency] energy are often referred to as "thermal" effects. It has been known for many years that exposure to very high levels of RF radiation can be harmful due to the ability of RF energy to heat biological tissue rapidly. This is the principle by which microwave ovens cook food. Exposure to very high RF intensities can result in heating of biological tissue and an increase in body temperature. Tissue damage in humans could occur during exposure to high RF levels because of the body's inability to cope with or dissipate the excessive heat that could be generated. Two areas of the body, the eyes and the testes, are particularly vulnerable to RF heating because of the relative lack of available blood flow to dissipate the excess heat load.”

But let me conclude by noting that as in Iran, this is a topic of debate elsewhere. For its part, the World Health Organization says, “there is no convincing scientific evidence that the weak RF [radio frequency] signals from base stations... cause adverse health effects.”


Anonymous said...

The health impacts experienced may be due to nonthermal RF effects. The Federal Communications Commission has often conceded that it is "not a health and safety agency" and has been unable to incorporate nonthermal effects into its regulatory scheme.

The claim of "no convincing scientific evidence that the weak RF [radio frequency] signals from base stations... cause adverse health effects" is not relevant to jamming.

There is little possibility that jamming transmissions originate from "base stations" -- that is, cellular mobile network facilities that are the usual target of concern. The jamming is more likely from high power transmitters designed to disrupt broadcast reception.

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Nick said...

The analogy of RF signals to microwave cooking is not very relevant. Microwave ovens cook with microwaves at a frequency of 2.45 GHz. This frequency is readily absorbed by water, which is how the food is heated. Similarly, this frequency would be readily absorbed by human tissue (the thermal effects people speak of). However, communications bands, particularly AM / FM radio or VHF TV are much, much lower in frequency (around 0.1 GHz), and are not absorbed as efficiently by human tissue.
This is the basis for statements that RF signals are unlikely to cause adverse health effects from thermal heating.