Electro-Magnetic Fields in the Workplace

Electric and magnetic fields are found wherever electric power is generated, transmitted or used. Until the last few decades, the natural background levels of electric and magnetic fields were extremely low. They have since dramatically increased. The industrialization and electrification of society have resulted in the exposure of people, animals and plants to a complex milieu of elevated EMF.

In modern office towers, usual sources include high voltage distribution lines, transformer vaults, electrical closets, switchgear rooms, computer equipment and lighting systems. The magnetic field component is present only when the current is flowing from a high voltage source. Its intensity increases with increased current flow and decreases rapidly with increasing distance from the source.

Possible Impacts of Elevated EMF

Health Effects Disruption of Computer Monitor Erasing of Data from Computer Hardware

There is concern over potential health effects associated with magnetic fields in the extremely low frequency (ELF) range of 3 – 3000 cycles per second (Hz). This, of course, includes 60 Hz, the power frequency in use in Canada, the USA and Mexico.

Epidemiological health studies carried out in the 1980’s claim to have identified an increased risk of leukaemia in children exposed to magnetic fields stronger than 2.5 milligauss (mG). Criticism of these studies has centered on a lack of scientific design. However, more sound studies carried out in Sweden appear to add support to the supposition that a risk does, in fact, exist. One study reported a four times higher rate of leukaemia in children exposed to magnetic fields greater than 3 mG. With adults, the results were less dramatic, but males exposed to similar levels had a three times higher incidence of chronic lymphocytic leukaemia.

Epidemiological studies of adult cancers in relation to occupational and residential exposure have shown some clear associations, but overall the results are mixed, with variation in both the strength of associations and in the cancer types noted. Studies, which evaluate non-cancer endpoints, such as adverse reproductive outcomes, suicide and depression, and developmental problems, have, with a few exceptions, produced negative results.

Among the medical community, the link between cancer and EMFs is not established with certainty. Consequently, there is no accepted health standards that pertain to human exposures to extremely low frequency EMF. Confronted with the risk uncertainty, many individuals have chosen to take a cautious approach and limit their exposure where possible, ie, “prudent avoidance”.

Experiences in office buildings have shown that EMF fields in the range of 25 mG may cause disruption of some electronic equipment such as computer monitors. They have also been known to cause data erasure from computer storage disks.

Where relocation of the source is not economic or is not possible, shielding can offer significant reduction in magnetic fields. Remediation of elevated EMF levels has been shown to be successful through shielding with Mu metal or low carbon steel.

These EMF contour maps, in units of milligauss (mG), illustrate measurements made at floor level and at 1.1 meter elevation during a recent assessment conducted by C5 Plus Ltd. and shows the impact of under-the-floor power lines in an office building.

For more information please contact us via e-mail or at our Calgary office - Telephone: 403-215-0040; Fax: 403-294-0959.