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Mobile phones - emissions

What is an electromagnetic field?

Electromagnetic fields are present everywhere in our environment. They are produced by the local build-up of electric charges in the atmosphere, by the earth's magnetic field and by daylight itself.

Electromagnetic fields are generated by man-made sources. The most obvious of these are the use of higher frequency radio waves to transmit information and these include television and radio transmissions and mobile phone communications. But there are many other sources: communications by the emergency services, medical and factory equipment, remote controls, electronic car keys, shop security tag systems and baby monitoring devices for example. In fact, any household appliance using an electric current from the fridge to the vacuum cleaner will emit electromagnetic fields.

What are the different electromagnetic fields and how are they classified?

One of the main characteristics of an electromagnetic field is its frequency. All possible frequencies put together are called the "electromagnetic spectrum" and these sub-divide into two principal areas of ionising and non-ionising radiation.

Non-ionising radiation

At the lower end of the electromagnetic spectrum comprises the major elements of modern life including radio and TV, mobile phones, radar and satellite systems.

At this level there is not sufficient energy to provoke any changes at a molecular level. In particular conditions, however, a few functions of the human body are positively influenced by the action of electromagnetic fields that emit non-ionising radiation. This is the case when radio waves are used in orthopaedic applications to promote healing, and when microwavesare used to treat tumours.

Ionising radiation

Ionising radiation on the other hand, occurs in the region of very high frequencies in the spectrum, and where the power is elevated, could cause changes at molecular level. Examples are ultraviolet radiation, x-rays and gamma rays.

How are the emissions controlled?

Various regulations and guidelines apply to the construction and operation of radio base stations, the most relevant, as far as the public is concerned, relate to their safety. Guidelines for limiting exposure to radio frequency fields from radio base station antennas are made up of two parts: the first is based on established and proven science; the second part incorporates a safety factor. In this way, the guidelines come with built-in precautionary element. Installations comply with the precautionary INCIRP (International Commission on Non-Ionising Radiation Protection) public exposure guidelines as recommended by the European Union. The guidelines were set following a thorough review of science and took into consideration both thermal and non-thermal effects and all sectors of the population. The guidelines are frequency-dependent:

• at 900 MHz it is 4.5 W/m²
• at 1800 MHz it is 9 W/m²
• at 2100 MHz it is 10 W/m²

What do the experts say?

The scientific consensus is that, below guidelines, there is no evidence of any adverse effects from mobile phone technologies. This, after six or seven decades of research and many thousands of research projects. However, research continues in form of the Mobile Telecommunications and Health Research Project to which Vodafone, other operators and the government have committed a total of £7 million. The objective of the research is to investigate any gaps in the knowledge and provide evidence of the continuing validity of international guidelines. It is hoped that this continuing research will provide further reassurance to the public.

How does a mobile phone work?

Mobile phones are two way radios. When you talk into a mobile telephone, it picks up your voice and converts the sound to radio frequency energy, or radio waves. The radio waves travel through the air until they reach a receiver at a nearby base station. The base station then sends your call through the telephone network until it reaches the person you are calling. When you receive a call on your mobile the message travels through the telephone network until it reaches a base station close to your phone. The base station sends out radio waves that are detected by a receiver in your telephone, where the signals are changed back into voice or data. 

Depending on the equipment and operator, the frequency that each operator uses is 900 MHz, 1800 MHz or 2100 MHz.

Base stations are designed for a number of different purposes, such as to provide coverage to a wide area or to increase capacity in a heavily congested area. Base stations are divided into three 'cell' categories:

• macrocells - they are the main structure for mobile phone networks and work up to a 22-mile range
• microcells - they are used to improve the capacity of the main network, especially in areas where the volume of calls is high, such as in airports and shopping centres.  They emit less power than the macrocells and have a range of only a few hundred metres
• picocells - they are situated in buildings and give dedicated coverage and capacity to a very small area such as a particular floor in a building.

Associated documents:

  Frequently asked questions  (0.24 MB)
Factsheet on Mobile Phones  (0.03 MB)