Environmental Management of Electromagnetic Fields

TYPES OF RADIATION

Electromagnetic radiation is classified into two major categories:

• Ionizing radiation

• Non-ionizing radiation (NIR)

Ionizing radiation:

Has sufficient energy to cause ionization:  removal of electrons from atoms or molecules.  Its interaction with matter may alter chemical reactions in the body, which may damage biological tissue, including effects on DNA (deoxy-ribonucleic acid), the human body’s genetic material. Gamma rays and x-rays are types of ionizing radiation.

Non-ionizing radiation:

Electromagnetic waves whose frequencies range from 0 Hz to approximately 3 x 1015 Hz, a frequency at which photon energy is equal to 2 x10-18 J or 12.4 eV, comparable to the bond energy of electrons with atoms, so that, below this frequency, electromagnetic waves do not have sufficient energy to break atomic bonds.

Non-ionizing electromagnetic radiation includes:  static fields (nuclear magnetic resonance), low frequency fields (electricity power networks, trains, etc.), radiofrequencies (telecommunications, surgical diathermy, etc.), microwave fields (telecommunications, radar, microwave ovens), infrared radiation (visible light), ultraviolet radiation, etc.

BIOLOGICAL AND HEALTH EFFECTS

The effects of electromagnetic fields have been studied since the 1950s.  The International Electromagnetic Field Project’s database (updated as of August 2006) indicates a total of 2462 studies of different types, of which its 2346 radiofrequency studies include 1137 on mobile telephony.

Table 02. Summary of study of radiofrequency electromagnetic fields

The above data was taken from the following World Health Organization web page:

http://www.who.int/peh-emf/emfstudies/studychart_criteria.cfm

From the outset, it is advisable to distinguish clearly between biological effects and health effects.  Biological effects are measurable physiological responses to exposure to electromagnetic fields that are not necessarily dangerous to health; whereas adverse health effects are biological effects outside the normal range of physiological compensation that are detrimental to human health or well-being.

MEASUREMENT AND EVALUATION OF EXPOSURE FROM BASE STATIONS AND OTHER TELECOMMUNICATION TRANSMISSION SYSTEMS

Measurements of the electromagnetic fields of mobile telephony are normally far-field, so that measurement of the electrical field is sufficient.

Measuring equipment and protocols

Instruments

The equipment that may be used to make measurements:

• Dipole, logarithmic periodic, and horn antennas, among others;

• Electromagnetic field analyzers and their respective probes and portable computers, to make broadband measurements to gain a general idea of electromagnetic field exposure;

• Spectrum analyzers, which, with their antennas, make detailed narrow band measurements of electrical field levels, enabling each source’s contribution to be determined;

• Portable computers, GPS, digital cameras, compasses, altimeters, and odometers.

Figure 01. (a) Electromagnetic field analyzer and its probe.  (b) Spectrum analyzer.

Protocol utilized

The measurement protocol to be utilized will depend on the country’s telecommunications administration.  In Peru’s case, the Ministry of Transportation and Communications (MTC) has adopted R.M. No. 613-2004-MTC/03, which basically applies to radio stations with emissions in the 9kHz- 300GHz range.

Victor Cruz
INICTEL