Electromagnetic fields

Overhead power lines (alternating current) are the main source of constant, low frequency electrical and magnetic fields, commonly known as electrosmog. People living close to such extra high voltage power lines are more exposed to electrosmog than others.

Domestic appliances and electrical installations are further sources of electromagnetic radiation.

A differentiation is made between electrical fields and magnetic fields: magnetic fields are created by a moving electric charge or permanent magnets. In the area around electric wiring in a household they are variable (as opposed to earth's magnetic field).

When an electric charge move through the wire i.e when electricity flows, a magnetic field around is created around the wire. If, as with alternating current, the electric current constantly changes direction, the magnetic field changes in exactly the same rhythm.

One problem here is that magnetic fields are not easy to shield and penetrate house walls as easily as if they were made of fabric – the same is true for the human body.

If electric force fields are exerted on a body they cause a shift in electrical charge. The surface of the body is charged, but on the inside it remains practically field-free. Materials that conduct electricity can be easily used to to shield these kinds of electric fields and thereby prevent any health risks.

Power lines that are in operation have different effects depending on whether they are installed as overhead lines or underground cables. 

Underground cables do not create any electric fields. However, they do create a  measurable magnetic field that has higher strengths directly above the trench.

Overhead power lines, on the other hand, have a wider lateral variance. The long term effects and possible health risks have not yet been fully researched.

Links:

ICNIRP: Various studies

NIEHS (USA): Assessment of Health Effects from Exposure to Power-Line Frequency Electric and Magnetic Fields