Electric and magnetic fields
Electricity is transmitted from a power plant to the consumer first by means of high-voltage transmission lines (in Finland 400, 220 and 110 kV), then by means of medium-voltage overhead lines and cables (50, 20 and 10 kV), and finally by means of low-voltage lines. Transmission lines cause an electric and magnetic field in their surroundings.
On 12 July 1999, the Council of the European Union published a recommendation of the limitation of exposure of population to electric and magnetic fields. The recommendation aims to protect the health of citizens against the direct health impacts of these fields. The recommendation is applied in particular to areas where people tend to stay for significant periods of time. The decree issued by the Finnish Ministry of Social Affairs and Health on 1 May 2003 is based on this recommendation.
The recommended values for exposure over a significant period of time, issued by the Ministry of Social Affairs and Health, are 100 μT (microtesla) for exposure to a magnetic field and 5 kV/m for exposure to an electric field. The recommended values for exposure over a non-significant period of time (such as berry picking, hunting, farming) are 500 μT for exposure to a magnetic field and 15 kV/m for exposure to an electric field. The Ministry of Social Affairs and Health published a guide concerning public exposure to low-frequency electric and magnetic fields in Finland (guidelines by the Ministry of Social Affairs and Health, ISSN 1236-116X; 2003:12), which contains an information package on the electric and magnetic fields involved in the electricity transmission and distribution system.
Transmission lines are designed and built so that the values given in the recommendation of the Council of the European Union and in the decree of the Ministry of Social Affairs and Health are not exceeded.
Potential health impacts
Some ‒ mainly epidemiological ‒ research studies have also dealt with the potential link between magnetic fields and health considerations, such as cancer diseases.
The Tampere University of Technology has drawn up a brochure (in Finnish) of the electric and magnetic fields of transmission lines and of their potential health effects.
Further information is also available on the website of the World Health Organization WHO.