Electricity is essential to daily life in developed countries. It is therefore important to describe Electromagnetic Fields (EMFs) for the purposes of their interaction with living beings:
- EMFs can be divided into static and low-frequency electric and magnetic fields, which include electricity transmission lines, household appliances and computers, and high-frequency or radiofrequency fields, which include radars, radio and television transmitters and mobile phones.
- Energy transmission and distribution lines (very high, high, medium and low voltage), transformer substations, domestic electrical installations and electrical appliances (such as irons, hairdryers, electric shavers, vacuum cleaners and toasters) are sources of environmental exposure to EMFs. At low frequencies (in the region of 50 Hertz, as in these cases), electric and magnetic fields can be considered separately and there is no real production of an electromagnetic wave.
- High frequencies (kilohertz, megahertz and gigahertz), especially radiofrequencies and particularly hyperfrequencies, have two types of use: they are sources of heat and act as carriers of information. The World Health Organization (WHO) distinguishes between sources of high and low capacity radiofrequencies. Examples of sources of high capacity include sound radiodiffusion and television transmitters, surveillance radars and air traffic control. Examples of sources of low capacity are cordless telephones, remote controls and microwave ovens.
- Within any living organism there are endogenous electrical currents which play an important role especially in neuromuscular activity.
- The effects of the external exposure of the human body and its cells to EMFs depend mainly on its frequency and magnitude or intensity. Compliance with the exposure limits recommended in national and international regulations helps to control the risks of exposure to EMFs which may be harmful to human health. Source: WHO, Ed. 2002 "Establishing a Dialogue on Risks from Electromagnetic Fields".