During the life of a person is always in range of the electromagnetic field (EMF) of the Earth. This field, called the background has a certain level at each frequency, which is not harmful to human health, and is considered normal. Natural electromagnetic waves with a frequency range covers from a few hundredths and tenths of Hertz to thousands of gigahertz.
Power lines, radio transmitters create a strong electromagnetic field, many times higher than the permissible level. To protect the rights were developed health standards (GOST 12.1.006-84 regulates the effects of electromagnetic radiation on humans), including those that prohibit the construction of residential and other facilities close to strong sources of electromagnetic radiation.