Non-Ionising Radiation, or NIR, is emitted from various household products such as TV sets, AM/FM radios, Wireless Broadband, hair dryers, baby monitors, as well as mobile phones/base stations. It is produced through a combination of electric and magnetic fields. It is physical energy that moves in wave-like motion and does not change the structure of atoms. NIR is fundamentally different from ionizing radiation created by X-rays, gamma rays, and ultra-violet rays.

The Frequency of a radio signal is the number of cycles completed in one second by an electromagnetic wave, i.e. the number of cycles that pass a point in space in one second. It is expressed in Hertz (Hz) or a multiple of Hertz, e.g. kHz (kilohertz, 1,000 Hertz), MHz (MegaHertz, 1,000,000 Hertz) and GHz (GigaHertz, 1,000,000,000 Hertz). Modern broadcast radio is always expressed in frequency, for example 98FM and FM104 signify broadcasters transmitting at 98MHz and 104MHz respectively. In Dublin these stations can be found by turning the tuner on a radio to the numbers 98 or 104 on the FM broadcast radio band.

The Wavelength of a radio signal is the distance between the same points on consecutive cycles of the signal waveform. Wavelengths are usually expressed in metres. Broadcast radio stations used to give their radio dial locations in wavelength and the name of two common broadcast bands reflects this, the long wave and medium wave bands.

In radio, wavelength and frequency are directly related by the speed of light, if we know one we can find the other.

Radio bands are portions of the radio spectrum used to describe the upper and lower frequencies of the portions. Some examples are medium frequency band (MF) which contains, among other services, medium wave broadcast radio, and the very high frequency band (VHF) which contains broadcast television as does the ultra high frequency band (UHF). The frequency range of the MF band is 300kHz to 3MHz and the frequency range of the VHF band is 30MHz to 300MHz.

Common Names for the different portions of the electromagnetic spectrum are

Up to 300GHz – the radio spectrum, this contains all radio communications as well as sources such as RF welding, microwave ovens, etc.

Above that there is the infra-red portion. This can be used for communications, in a manner similar to the way light can. All warm bodies give off infra-red radiation.

Above that is the visible light spectrum.

Next is the ultra violet light spectrum; typical uses in industry are, curing adhesives and for sterilisation. Common sources are sunlight and welding. At frequencies below ultraviolet the radiation is non-ionising, i.e. unable to alter the structure of atoms or molecules. Above ultraviolet the radiation is ionising and precautions have to be taken to minimise or eliminate exposure. Many people express fear at the word radiation however this is usually due to confusion between ionising and non-ionising radiation, light bulbs radiate visible light but people don’t have any fear of this radiation.

Above the ultraviolet spectrum are x-rays and gamma rays.