Operation and placement of base stations
Data communication between the mobile phone and the base station is carried out using radio waves. The call or other information is transmitted from the mobile phone as a radio wave to the nearest base station and from there to the fixed network either directly or via a microwave link.
In cities and urban areas, so-called macro cell base stations serving a large area are often placed on the roofs or exterior walls of buildings. In sparsely populated areas, more base station masts are used. There can be base station antennas from several network operators in the same location. Base stations serving smaller areas are also used in mobile networks, for example to improve indoor coverage.
Several mobile network technologies are in use in Finland, the earliest of which was introduced in the early 1990s. With increased data transfer needs, new technologies have been introduced approximately every ten years. The 5G network, which was introduced most recently, already reaches the majority on Finns.
Among other things, information on the frequencies and coverage of mobile networks can be found on the website of Finnish Transport and Communications Agency (Traficom).
• Read more about mobile network frequencies and license holders
• Read more about mobile network coverage
General population is only minimally exposed to the fields generated by base stations
Radiation legislation specifies limit values for exposure to ensure the radiation safety of mobile networks. The values comply with the recommendation of the Council of the European Union (1999/519/EC), valid in most European countries. The heating of the tissues is the only scientifically verified effect of radio frequency fields. There is a large safety margin between the maximum exposure allowed by the limit values and potentially harmful heating of tissue.
The general population is only minimally exposed to the fields generated by base stations because the exposure diminishes rapidly as the distance to the antenna increases. The exposure limits of the general population can be exceeded approximately 10 m away from the antenna of a macro cell base station serving a large area. Outsiders must not have access to this area. In base stations that serve a small area, the transmission power is low, and the limit values are not necessarily exceeded even within arm’s reach.
A base station mounted on the roof or exterior wall of a building does not expose residents to fields to any appreciable extent, because the radio waves are mostly directed horizontally. Radio waves directed downwards, upwards, or backwards from the antenna are clearly weaker.
The introduction of the new 5G mobile network has sparked a discussion about radiation safety. However, based on the current information, there is no need to worry about the exposure caused by the 5G network. Below are arguments to support the view:
• The exposure limit values cover all frequencies of the 5G network.
• The transmission powers of 5G base stations are in the same category as in previous mobile technologies.
• 5G base stations have not significantly increased the population’s exposure.
• At most, the exposure is clearly lower than the limit values in places where the population has access.
The limit values are based on advanced scientific data
STUK ensures that the limit values are up to date and monitors the development of relevant research. STUK bases its views on literature surveys concerning the health effects of radio frequency fields, published by independent, international groups of experts (e.g. WHO, SCHEER/SCENIHR, ICNIRP). STUK also follows research articles published in international scientific journals regarding the topic to obtain the latest information.
International groups of experts contain comprehensive and multidisciplinary competence required to evaluate the health effects of radio frequency fields. Such groups review thousands of studies for their literature surveys and use predetermined quality criteria to evaluate the studies.
In some studies, biological effects have been observed in cell cultures, for example, but evidence of health effects other than those based on the heating of tissue has not been established. Based on the surveys, the limit values used in Finland are up to date.
Mobile network operators are responsible for complying with the limit values. Among other things, the operators must assess the population’s exposure to radio frequency fields before putting a new base station in service. The exposure must not exceed the limit values in any location freely accessible to general population.
STUK actively monitors the activities of operators. STUK intervenes in base station assembly if there is reason to suspect that the general population could be exposed to radio frequency fields that exceed the limit values.
STUK has measured the exposure levels of several base stations, for example in apartments and outdoor locations. All measurement results have been clearly lower than the limit values.
Government Decree 388/2016 (in Finnish)
Väestön altistuminen matkapuhelintukiasemien radiotaajuisille kentille Suomessa (General public’s exposure to radio frequency fields from base stations in Finland, in Finnish) (STUK-TR 16)
Tukiasema-antennien asentaminen (Installation of base station antennas, in Finnish) (STUK guides)
ICNIRP (International Commission for Non-Ionizing Radiation Protection), 1998, ICNIRP guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic fields (up to 300 GHz) (pdf)
ICNIRP (International Commission for Non-Ionizing Radiation Protection), 2020, ICNIRP guidelines for limiting exposure to electromagnetic fields (100 kHz to 300 GHz) (pdf)
SCENIHR/SCHEER, 2015, Opinion on potential health effects of exposure to electromagnetic fields (EMF) (pdf)
WHO, 2020, World Cancer Report 2020 (pages 88-89)