Survey of Residential Power Frequency Magnetic Fields
There have been few studies measuring magnetic field levels in Australian homes. ARPANSA has conducted a survey of power frequency magnetic fields in approximately 300 randomly selected homes in metropolitan Melbourne. The results have been published in a scientific journal and titled Survey of residential power-frequency magnetic fields in Melbourne, Australia. A summary of the findings is provided below.
In 2004 ARPANSA conducted a pilot study of 26 homes in order to investigate different methods of carrying out a survey. The results of this are now available as Pilot Study of Residential Power Frequency Magnetic Fields in Melbourne . The aim of the full survey is to identify the distribution of residential magnetic field levels and determine the average magnetic field in Melbourne homes. It is expected that a study in Melbourne will provide data that is much more representative of Australia generally than the currently available results from overseas.
Magnetic fields within homes vary with location in the home and over time. The fields can come from sources outside the home, such as powerlines, or from wiring and appliances within the home. The actual strength of the field at a given location depends upon the type of electrical sources and their distance from the location of measurement. The survey collected data from 297 homes of volunteers between September 2005 and August 2007. Analysis of the information collected shows that:
- Time-averaged magnetic fields in the living room and the youngest child’s bedroom were 0.06 µT (0.6 mG) and 0.05 µT (0.5 mG), respectively.
- The majority of homes (~93%) had time-averaged fields below 0.2 µT (2 mG). Around 2% had fields greater than 0.4 µT (4 mG) and these were mainly due to close proximity (less than 50 metres) to high voltage transmission lines.
- Other factors associated with different magnetic field exposures included the proximity of the distribution powerline outside the home, other external electrical infrastructure (such as sub-stations and transformers) and the geographical location of the home in relation to housing density (i.e. homes in inner city suburbs tended to have higher magnetic fields).
- As expected from a survey relying on voluntary access to homes, there was evidence of some selection and self-selection bias in the survey. When corrections for these biases were applied, the residential magnetic fields were slightly lower than the measurements by approximately 5 %.
For further information on magnetic field measurements refer to the ARPANSA fact sheet titled
Measuring Magnetic Fields
Currently there is no evidence that exposure to electric fields is a health hazard (excluding electric shock). Whether exposure to magnetic fields is equally harmless remains a more open question. A large number of scientific studies performed on animals and cells have not found a health risk. Some studies of exposed populations, however, have suggested there might be a weak association between prolonged exposure to higher than normal level of magnetic fields and an increased risk of childhood leukaemia.
For further information on electric and magnetic fields and the possibility of adverse health effects refer to the ARPANSA fact sheet titled Electricity and Health.
For further information regarding the survey you can call ARPANSA’s toll-free number 1800 022 333 during business hours and ask to speak to Ken Karipidis.