The incoming mail of our Company includes many letters addressed to the Sanitary Control Service. Our readers are eager to discuss the article “Mobile Communication is Safe” and the topic of cellular communication and sanitary safety. They write that interest surrounding this question is rapidly increasing. However, the number of qualitative and interesting articles in the mass media is too small to satisfy such interest. Articles are mainly published on scandal pages and their cognitive value is too small. This is the reason for the activity of our readers, as well as for the number and variety of their questions following the publication of our article. Still, there are some main issues, which our readers have asked to be discussed in detail. These questions include: the sources of the electromagnetic field around us, the biological impact of the electromagnetic field, safety issues, base stations and the principles of their operation and the impact of radio-frequencies on medical equipment. In this issue we will deal with some of those questions.    The electromagnetic field is characterized by its biological activity: by the reaction of living beings. Man has no special organ to detect the electromagnetic field. The only exception is an optical range: the light visible to a naked eye. With respect to biological impact, the spectrum of electromagnetic frequencies is divided into two parts.    The major part of the spectrum is the “non-ionizing” oscillation of the industrial and broadcast-band. The antennae used in cellular communication are the establishers of the “non-ionizing” electromagnetic field. Their biological effect is specified by the partial absorption of the energy of the electromagnetic field by the tissues of living beings, resulting in a rise in tissue temperature or warming. Taking into consideration the low power of transmitting antennae (up to 20 watts) and the acting sanitary norms, the real “warming effect” is insignificant and can only be detected by measurements taken by sensitive instruments.    The other part of the spectrum is the “ionizing” or radioactive (ultra-violet, X-ray and gamma) radiation, which is not used in mobile communications. This is only employed for medical (X-ray units) or industrial (gamma-sterilization) purposes.    The biological effect of “ionizing” rays results in the breaking of chemical bonds ionization, which damages the genetic material of cells and provokes a number of diseases.    All these clearly show the difference between “ionizing” and “non-ionizing” electromagnetic fields with respect to biological impact.    Scientists have discussed the literature dedicated to the biological impact of the electromagnetic field, in particular the frequency bands used in cellular communications, and have come to the unanimous conclusions that:  · the investigations undertaken to study the electromagnetic field are sufficient to work out the safety norms; · the exposure of the entire body to the electromagnetic field under a smaller than certain coefficient has no biological effect.

   In Georgia such a coefficient is the maximum acceptable level of the intensity of the electromagnetic field, which equals to 10 mW/cm2.
   This value stipulates a round-the-clock impact on population and provokes no changes in the human organism, irrespective of age or sex.
   This is one of the strictest limitations on the level of the electromagnetic field created by radioactive sources.

   It should be noted that measurements of the electromagnetic field are taken on a regular basis in the vicinity of MagtiCom base stations. The analysis of control measurements showed that the intensity of the electromagnetic field around the base station of our Company is 3-20 times less than the maximum acceptable level in Georgia. This is a good indication of the high quality of MagtiCom work in observing sanitary safety.

Electromagnetic Fields around us

   The electromagnetic environment in the everyday life of a human being is created by radio- and TV broadcasting stations, radio-communication means, radio-radars and systems of satellite communication. All these transmitting stations work within radio-frequency range. Control is exercised by the Supervisory Inspection of Sanitary Norms, in accordance with common normative bases.
   According to legislation in force, sanitary-protective and construction-limitation zones are specified around any radio-broadcasting object and the intensity of the electromagnetic field on the outer border of such a zone equals the maximum acceptable level.

Any radio and TV broadcasting station is a source of an electromagnetic field within the frequency range of 9 KHz to 1,000 MHz. The power of transmitting antennae reach 1 or 2 MW. Usually, the electromagnetic field of radio and TV broadcasting antennae has equal expansion in any direction.

Cellular base stations operate within the frequency band of 450-1,900 MHz with the power of transmitting antennae up to 20 watts. The question of cellular base stations will be discussed in detail in our next issue.
The antennae of radio-location stations have a narrow diagram of the electromagnetic field directed along the optical axis. The signal generated by radar completely differs from the electromagnetic field set up by any other source. This is related to the movement of an antenna in the space and the periodicity of the signal generated. That is why the quantity of electromagnetic fields set up by such sources is not constant on immovable objects. It always changes.

The system of satellite communication consists of an earth transceiving radio-station and a satellite in orbit. The antenna of satellite radio-stations usually looks like a dish. The electromagnetic field established by antennae of this type can be imagined as a clearly defined narrow beam with a certain part of the energy scattered directly close by the antenna.

Receiving antennae of satellite TV broadcasting are absolutely safe for human health, as they establish no electromagnetic field.

Recommendations relating to transmitting antennae are as follows:

· find out the sanitary-protective and construction-limitation zones at the Supervisory Inspection of Sanitary Norms;
· do not approach an antenna without having the necessary information on the sanitary-protective zone;
· do not touch the antenna.
 

 There are other sources of the electromagnetic field in our everyday life besides those from radio-frequency bands:

· a personal computer, in particular its monitor, is a source of electromagnetic field. Recommendations: purchase a monitor with a low electromagnetic field; ground the monitor and the computer; use additional means of protection (protective filter) to reduce the level of electromagnetic field; decrease the continuous and summary time of computer access according to sanitary recommendations.