Sources of non-ionising radiation
Non-ionising radiation is radiation that does not cause changes to the molecular structure of living tissue, as is the case with ionising radiation such as gamma and X-rays. However, it can increase core body temperature, causing thermal damage to exposed sensitive body tissue such as the skin and eyes and localised limb heating. Its effects also focus on areas where there is a high water content and low blood flow, such as in the muscles and testes.
First responders may need to gain access and work near non-ionising sources of radiation such as radio frequency (RF) antennae that may be potentially hazardous to health. The antennae may be on freestanding masts or located on buildings.
Radio frequency (RF) is the term used to describe the part of the electromagnetic spectrum that can be used for radio communications. Electromagnetic waves emit from a power source, usually from an antenna that concentrates the energy in a beam or radiated pattern, and they usually lie in the infrared region.
Emissions present the greatest risk in the direction of the maximum gain from the antenna, which is generally to the front or within a sector. Many different types of antenna exist and it should be assumed that all unknown antennae are potentially hazardous. Non-ionising radiation affects the body in differing ways depending on wavelength, frequency and energy levels. The effects depend on:
- Distance from the source
- Time exposed
- Power level
Site owners must position antennae so that no member of public can be exposed to power levels in excess of those stipulated in the guidelines from the International Commission for Non-Ionising Radiation Protection, and employers are required to protect any workers or visitors to such sites. The telecoms industry categorises sites as 'controlled', 'restricted' and 'general public'.
This is a secure compound with access strictly controlled by the operator. Access is given only to those authorised, trained in radio frequency (RF) safety, wearing RF monitoring equipment or with established safe systems of work such as power isolation.
These are controlled by a thirdparty provider and normally situated on building rooftops, lamp posts and other structures. Access is granted to non-operator third parties for maintenance. Antennae in restricted sites must be positioned so they are 'occupationally safe by position', with calculated exclusion zone warning signs at all access points.
These occupy sites where it is reasonable to expect the public may gain access near the antennae, such as on rooftops or areas where members of the public carry out day-to-day activities.
Broadcasting installations operate at very high power levels, have strict controls, require a system of work to be in place and followed, and will have signage that identifies the radio frequency (RF) hazard. All visitors to these sites must have RF monitors or access will be declined.
The operation of surgical implants such as pacemakers and metallic implants such as pins or plates may be disrupted by radio frequency (RF) transmissions, causing them to heat up.
Many types of antenna are used:
Panel-shaped sector antenna (mobile phone communications).
Pole-shaped Omni antenna (mobile phone communications)
Knowledge and understanding
|Sources of non-ionising radiation||
Understand all associated hazard knowledge
- Control measureAdopt defensive tactics until the utility system is isolated
- Control measureConsider adherence to local restrictions and signage