WIRELESS COMMUNICATIONS

Controlling radiation to protect health

By Luiz Carlos Neves and Antonio Marini de Almeida

The boom in mobile telephony has triggered demand for more transparency in providing information to the public about the levels of electromagnetic radiation emitted by base stations of wireless communication systems. The long-term effects of electromagnetic radiation on human health are still under research. Nevertheless, a key question for many people worldwide is what controls are exercised over these radiation emissions.

To address this concern, Brazil has developed a system that allows local authorities in a city to manage radiation levels produced by telecommunication infrastructure and gives the public access to this information through the internet. The system also offers objective information to validate and improve the criteria for planning the expansion of mobile telecommunication infrastructure. This article highlights Brazil’s experience with this new approach to controlling electromagnetic radiation.

The example of Brazil

Telecommunication indicators for Brazil reveal just how important mobile technology has become: the five years between 2001 and 2005 saw a growth of 270 per cent in the number of mobile handsets. According to the Indicators 2006 report from Brazil’s National Regulatory Agency for Telecommunications (Agência Nacional de Telecomunicações — Anatel), by 2005 there were 86 million mobile subscribers nationwide, compared with 42 million fixed lines. This spectacular growth is associated with the significant expansion of the infrastructure for mobile telephony, including an increased number of radio base stations, antennas and towers installed in urban areas. Service providers try to optimize their investment by installing towers on small lots or in areas shared with residences, and even near schools. Increasingly, though, such changes to the environment have provoked reactions among local people regarding the location of radio towers, the impact on the landscape, and concerns about risks to human health.

Many Brazilian cities have now established rules that limit radio station installations in urban areas. Also, there is a national regulation establishing limits for electromagnetic emissions, based on the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. However, due to the lack of a device to demonstrate that the levels of radiation are within permitted limits in the vicinity of a radio tower, the number of lawsuits has risen. Alongside municipal laws to slow down installations, this significantly complicates expansion projects.

A page on the internet site of the monitoring system, showing data from one radio station on a street map of Americana. By clicking on the station icon, a new window appears with details of its name, address, owner and construction type

To deal with this situation, a research-and-development project was launched in 2004, financed by the Brazilian Telecommunications Technological Development Fund (Fundo para o Desenvolvimento Tecnológico das Telecomunicações — FUNTTEL), and conducted by the Center for Research and Development in Telecommunications (CPqD). The aim was to find a way to disseminate up-to-date, trustworthy information on wireless communications.

Designing a solution

The situation in Brazil, as well as experience in other countries, shows that more must be done to tell people about the effects of technology, and to make procedures for monitoring these effects more transparent and understandable. This is also the recommendation of the World Health Organization. The Brazilian public was not sufficiently informed about changes in their environment, and, often, people did not receive a satisfactory answer when they did ask for details of new installations. At the same time, technical complexities prevented local authorities from demonstrating that the relevant legislation was being obeyed and that existing radio stations were being properly controlled.

The answer was to create a system that people can trust to provide them with accurate information they can understand. For a developing country especially, the system had to satisfy the following requirements:

• Personnel without a background in telecommunications must be able to manage the system.
• It must be possible to evaluate the radiation emitted by a group of installations, and the changes that would be produced by a new installation before authorizing its implementation.
• Local residents must have access to the system and information on control of radiation limits, in clear, easily understood language.
• The technological resources employed must require a limited amount of investment and must be easily maintained.

Online monitoring made possible

The monitoring system that was developed in Brazil performs continuous measurements and simulations of the intensity of non-ionizing radiation (NIR) produced by base stations of wireless telecommunication systems. The system allows users to see, via the internet, a map of actual electromagnetic emissions in their city, or to examine simulations of the emissions from changes to the wireless network.

Known as CPqD NIR Monitoring, the system has an internet server and database, a map server, an interface to control remote radiation monitoring units, and diverse clients. The data regarding radiation levels are graphically illustrated on maps as percentages of the permitted radiation limit. The software modules were developed using open-source tools, in order to create a system with low investment needs.

A device was developed to allow remote measurements. It is composed of an electromagnetic field sensor and a control module that performs periodic measurements and transmits them to the system via the mobile phone network itself.

Pilot project in Americana

The system was tested in the city of Americana, in Brazil’s state of São Paulo, in order to validate and improve it. Technical data and information on the location of radio stations was obtained from the city’s authorities and from Anatel.

The layout of streets in Americana was obtained from a digital map that also includes information on railways, main highways, public squares, city districts and city landmarks. Photographs of the base stations for mobile communications were also provided. For each station, the system records its owner’s name and address, the geographical coordinates, technical characteristics of the antennas (model, gain, height, azimuth and mechanical tilt), frequency and power of each of the installed transmitters, number of carriers, and losses in the means of transmission. Effectiveness of this simulation process was proved through field measurements carried out at all base stations in the city of Americana.

Luiz Carlos Neves and Antonio Marini de Almeida, CPqD Telecom and IT Solutions, Telecommunications Research and Development Center, Campinas, São Paulo, Brazil

The system allows citizens to query existing installations in the city and to measure radiation emissions and simulated values of emissions by simply clicking a base station’s location on a familiar street map. Access to the online system was made public in December 2004, via the websites of the local government and of CPqD.

Thanks to the new system, public authorities in Americana now have better control over the radio stations installed in the city, and local people can obtain information about the levels of radiation. The system has contributed significantly to lessening conflicts among interested parties, regulatory bodies and service providers of mobile communications. Americana is now considering a change in its municipal legislation, which would establish criteria for the installation of base stations.

The radiation monitoring system developed in Brazil seems to have demonstrated a successful way of maintaining a balance between allowing the expansion of wireless access technologies, while enabling the community to exercise control over possible adverse effects of the use of certain technologies on a broad scale.