Mobile phones rely on a network of base stations that send and receive calls and other mobile services such as video calling, wireless broadband and mobile TV. Base stations need to be located close to mobile phone users to provide good quality reception.
The International Commission on Non-Ionizing Radiation Protection (ICNIRP) has issued guidelines on levels of exposure to RF fields, including that from mobile phones and base stations. These guidelines have a large safety margin built into them.
Base stations are typically installed so that the public's exposure to RF fields typically hundreds, if not thousands of times below the safety guideline level.
In relation to radio frequency emissions and wireless technology and health, the general conclusion from the World Health Organization (WHO) is;
“Despite extensive research, to date there is no evidence to conclude that exposure to low level electromagnetic fields is harmful to human health”
WHO - About Electromagnetic Fields – Summary of Health Effects Key Point 6
In relation to base stations and health, the conclusion from the WHO is;
“Considering the very low exposure levels and research results collected to date, there is no convincing scientific evidence that the weak RF signals from base stations and wireless networks cause adverse health effects.”
WHO Fact sheet 304
Confirmed as current position in WHO RF and Health Presentation – ITU Workshop on EMF Turin May 2013
In 2009 and 2010, ICNIRP reaffirmed the EMF safety guidelines following a review of national and international EMF research and published scientific literature.
What is a base station and wireless network?
What do base stations look like?
How do mobile operators decide where to put base stations?
How many base stations are required in a given area?
What different types of base stations are there?
How strong are the environmental EMF levels near a base station?
Do base station EMF levels vary?
Should base stations be located near homes and schools?
Are base stations safe - is it safe to live near a base station?
Mobile Communications and Health Booklet
RF safety at base station and antenna sites
Wireless systems use a network of radio base stations to provide service for mobile phones and other wireless devices. Base stations send and receive low powered radio signals to and from mobile phones, and provide the connection to the main telephone network. A mobile network is usually configured in a cellular grid format.
Base stations need to be located close to mobile phone users to provide good quality reception.
Example wireless network with cellular grid overlay. Click here for a short animated explanation of how networks work (wmv)
Base stations usually consist of a small equipment cabinet or hut, and antennas mounted on a support structure.
The antenna support structure can vary considerably. Typical examples are:
- Light poles
- Towers or masts
Base station antennas are usually located on the most suitable structure in the area for example an existing building, tower or structure. Sometimes a new tower or mast is required if there are no existing structures. Each base station is connected to the main telephone network either via a microwave link using a small dish antenna, or via optical fibre cable.
To provide a good quality mobile service, base stations need to be located where people use their mobile phones. A mobile network is typically designed on a "cell grid" basis covering a geographic area. Base stations are located either in the centre of each cell or on the corner of a group of cells. The number of base stations required for a given area will depend on the terrain and number of people using mobile phones.
The radio signals that base station antennas transmit are primarily transmitted from the centre of the antenna outwards. This means that the antennas need to be placed in locations where there are no obstructions, such as building rooftops and masts.
In built-up and mountainous areas with many buildings, trees and obstructions, it is likely that more base stations will be required to provide service to the local community. In rural areas with fewer obstructions, less base stations will be required.
Mobile networks have a finite capacity which means the ability to cater for simultaneous phone calls. The more people using mobile phones, the more capacity is required and this usually means more base stations closer together. Mobile networks must be designed according to the local population and number of people using the network.
Base stations are broadly divided into the following categories
- Macro cells – towers, masts and poles providing wide are coverage
- Micro cells – small antennas at street level providing local area coverage
- Pico cells – very small antennas providing dedicated coverage spots
- In Building Systems – small antennas inside a building providing dedicated coverage
Base station transmitters use relatively low power and environmental EMF surveys conducted in many countries around the world have shown background EMF levels to be equally very low.
The World Health Organization has reviewed the background EMF levels from wireless systems and says,
"Recent surveys have shown that the RF exposures from base stations range from 0.002% to 2% of the levels of international exposure guidelines, depending on a variety of factors such as the proximity to the antenna and the surrounding environment. This is lower or comparable to RF exposures from radio or television broadcast transmitters"
Specifically on EMF levels in public areas the WHO says,
"Recent surveys have indicated that RF exposures from base stations and wireless technologies in publicly accessible areas (including schools and hospitals) are normally thousands of times below international standards."
Mobile networks are specifically designed to use the lowest possible power from base stations and mobile phones necessary to quality voice or data services. The network automatically adjusts the base station transmitter power according to how far away the mobile phone users are.
With the optimal network design, base stations are located close to mobile phone users and produce the lowest possible EMF.
The further away base stations are located from mobile phone users, the higher the power required resulting in higher EMF levels.
Today’s society relies on mobile phones working everywhere including at home, at school and at work. When base stations are located close to users, the transmitter power required by the mobile phone and the base station to communicate is relatively low. If base stations were located further away, the power required is generally higher, and this means a higher EMF.
Therefore to provide good reception and minimise EMF, base stations need to be located close to users and where we live.
Base stations operate at low power. Independent surveys demonstrate that the background EMF level in the community from base stations is very low, and similar to environmental EMF levels from broadcast radio and television.
The World Health Organization monitors scientific research into EMF and concludes,
“Considering the very low exposure levels and research results collected to date, there is no convincing scientific evidence that the weak RF signals from base stations and wireless networks cause adverse health effects”
In 2009 and 2010, the International Commission for Non Ionizing Radiation Protection (ICNIRP) reaffirmed the EMF safety guidelines following a review of national and international EMF research and published scientific literature.
The MMF and GSMA has prepared a document giving practical rf safety guidance for personnel working at base station and antenna sites. Click here to download.
Download the Mobile Communications and Health Booklet from the GSMA
Additional Information on Base Stations
Health Authority & Educational Resources
- RF & Health - A WHO Perspective 2013 - World Health Organization
- Base Stations & Wireless Networks - World Health Organization
- ICNIRP Review of RF Health Effects 2009 - International Commission for Non Ionizing Radiation Protection
- ICNIRP Review Note May 2010 - International Commission for Non Ionizing Radiation Protection
- Cellular Tower Safety - US Federal Communications Commission
- Mobile Phone Networks & Health - Australian Radiation Protection and Nuclear Safety Agency
- Base Station Emissions Audit - Australian Radiation Protection and Nuclear Safety Agency
- EMF in the Environment Video & Poster - Australian Radiation Protection and Nuclear Safety Agency
- Health Exposures from Base Stations - UK Health Protection Agency
- Base Stations and Early Childhood Cancer Study 2010 - Imperial College London & British Medical Journal
- Review of Health Effects from Exposure to RF from Base Stations - WHO Bulletin 2010
- Cell Phone Towers and Health - American Cancer Society (2013)
- Mobile Communication and Health Booklet - GSMA
- Mobile Networks and Health Booklet - MMF
- How Networks Operate - GSMA
- Base Station & Health Fact Pack - GSMA
- Small Cells & Health Brochure - GSMA, MMF, Small Cells Forum
- Reported Illness Clusters Near Base Stations - GSMA
- Locating Base Stations - Mobile Manufacturers Forum
- Exclusion Zones not Scientifically Sound - Mobile Carriers Forum
- In Building Coverage - Mobile Carriers Forum
- Antennas on Rooftops - Mobile Carriers Forum
- RF safety at base station and antenna sites - MMF and GSMA
- Mobile Networks in the Environment Video - Mobile Carriers Forum
- Implications of Lower Limits - GSMA / Mobile Manufacturers Forum