Issue 25, February 2008

An EMF, or Electromagnetic Field, is an invisible field of force caused by the presence of an electric current. This force field is made up of two components - an electric field and a magnetic field, hence EMF.

The electric field is proportional to the voltage, while the magnetic field is proportional to the current. The direction of the current and therefore that of the magnetic field changes 50 times per second (i.e. 50Hz).

An EMF is often loosely referred to as ‘radiation’, but you should not confuse this with nuclear radiation.  The radiation associated with an EMF is comprised of the electric and magnetic vibration that emanates from an oscillating electric charge. The EMF radiation has an associated energy component, whereby the higher the frequency of the radiation, the higher energy. Nuclear radiation is completely different and relates to particles and radiations emanating from an atomic nucleus due to radioactive decay and nuclear reactions. The types of nuclear radiation include alpha, beta, gamma and X-Ray.

The issue of chronic exposure to weak magnetic fields being equally harmless is unresolved. With prolonged exposure to weak electric fields however, (such as those found typically in a workplace) human studies have not yet shown evidence of adverse health effects. This is the same for acute (short-term) exposure, as there is no evidence to date that suggests magnetic fields cause immediate harm.

Electromagnetic fields have the greatest intensity close to their source, which then declines with distance. Hence in an office or home environment, electrical appliances which have high electromagnetic fields immediately around them, will indicate a much lower EMF value at distances greater than one metre away.

There are presently no Australian standards regulating exposure to electromagnetic fields. The National Health and Medical Research Council (NHMRC) issued interim guidelines on limits of exposure to 50/60 Hz electric and magnetic fields. These guidelines are aimed at preventing immediate health effects resulting from exposure to these fields:

• The environmental exposure limit (24 hours) is 1000 mG. Note that the earth’s magnetic field has a strength of about 500 mG (NB the Earth’s EMF does not change direction 50 to 60 times per second);

• The occupational exposure limit (whole working day) is 5000 mG.

Some computer monitors, electrical switchboards, microwave ovens and other electrical appliance are common sources of EMF radiation.  An EMF survey of your building will measure the extremely low frequency (ELF) EMF and ensure you meet the NHMRC guidelines.  

CETEC has expertise in conducting EMF surveys and in providing an risk assessments for your office building/s.  If you would like to discuss your EMF concerns you can call Dr Robert Schiller on (03) 9544 9111 or Dr Scott Bruce on (02) 9966 9211. or contact us via this form.

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