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Home » Technical Services » Safe and Healthy Buildings » Magnetic field mitigation

Magnetic field mitigation

The Department of Public Works is committed to providing safe and productive working environments for its client agencies and all public sector workers in buildings that it owns and manages. In line with this commitment, the Department is continually seeking improvement in the quality of the indoor environment in these buildings.

Electric and magnetic fields are invisible forces to which humans are constantly exposed. These originate from both natural and man-made sources, and the strength of these forces can vary significantly with both time and situation.

While no conclusive links between low level, low frequency electric or magnetic fields and impacts on human health have been established, the Department has elected to take a prudent approach to this issue and has developed world leading guidelines for the management of magnetic fields in its office buildings. These guidelines were developed with the support of a Peer Review Group comprised of representatives from a number of the Department’s business areas plus external experts from Workplace Health and Safety Queensland, Queensland University of Technology and a representative of the Together Queensland Industrial Union of Employees.

In buildings, electric fields exist around any source of an electric voltage while magnetic fields are generated wherever an electric current is flowing through a wire or cable. The strength of these fields varies with the voltage level and the amount of current flowing respectively, and decreases with distance from the conductor. Electric fields are attenuated readily by many forms of physical barrier while magnetic fields require special screening for their control. Consequently it is the management of magnetic fields in the office environment that the Department has addressed in its document:

The Department has adopted the ‘as low as reasonably achievable’ (ALARA) principle as the basis for these Guidelines. Consequently the Guidelines establish a level of five micro-Tesla (µT), when averaged over the working day, as a target level that should not be exceeded at any location within an office building where an employee may be stationed for the greater part of the working day (e.g. office desks, work stations, customer service counters, etc). This is significantly below the level of 100 µT recommended as a limit for continuous exposure over 24 hours, and 500 µT for continuous exposure during a normal working day, by the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA).

It is important to note that in adopting the ALARA principle, the level of 5 µT is not a limit; rather it is a target that has been set with a view to keeping magnetic field intensities within the office environment as low as is reasonably possible.

The Department tested all those office buildings that it both owns and manages and which also house electricity sub-stations (electricity sub-stations carry large electric currents and so are, generally, the largest single source of magnetic fields in typical office buildings) in the greater Brisbane area in 2008 and 2009, and extended this testing to all such buildings across the State in 2010/11.

Summaries of the results of both the initial 2008, and subsequent 2009 and 2010/11, annual rounds of testing can be accessed via the links provided below. All measurements taken in areas accessed by general staff have been well below the ARPANSA recommended guidelines of 100 µT for continuous 24 hour exposure with a reading of 20 µT being the highest recorded. There were no instances where readings exceeded the targeted level under the Guidelines of 5 µT in permanently occupied work areas.

These test results have confirmed the expectation that the pattern of magnetic field intensity within any building is unlikely to vary significantly unless there has been a material change in the electrical load and/or a relocation of cables or heavy electrical equipment. Consequently in December 2011 the Peer Review Group endorsed a variation to the Guidelines whereby testing would be limited to new buildings at the time of commissioning and to existing buildings where major renovations or refits have been carried out.

While these Guidelines apply specifically to all office buildings that are both owned and managed by the Department, it is intended that they should also be applied to leased office accommodation as new leases are negotiated and existing leases come up for renewal.

Further consideration to the management of electric and magnetic fields in the office environment is given in the paper authored by Daniel Matheson as part of his internship with the Department of Public Works. At the time Mr. Matheson was a third year student in the University of Queensland’s Bachelor of Arts program, majoring in Economics and Peace and Conflict Studies.

Concerns in regard to electro-magnetic field levels in Mineral House (41 George Street, Brisbane) raised in May 2008, triggered an in-depth investigation. Reports resulting from this review include:




Last Updated 07/12/2012

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