Magnetic fields are generated by two sources: either the magnetic component of electromagnetic
radiation generating devices, or from magnetized metals. Exposure guidelines for the
magnetic field component of electromagnetic radiation are published by the International
Commission on Non-Ionizing Radiation Protection (ICNIRP) and the Institute of Electrical
and Electronics Engineers.
Working in Areas with Magnetized Fields
Magnetized metals generate static magnetic fields. The university follows the guidelines for static magnetic fields as published by the American Conference of Governmental Industrial Hygienists (ACGIH). Guidelines recommend that any area where strong magnetized metals can generate static magnetic flux densities great than 5 Gauss be marked. Individuals that are required to cross into the 5 Gauss field to work with the magnet should be evaluated for any metallic implants and cardiac pacemakers or defibrillators before accessing these areas.
Cardiac Pacemakers and Defibrillators
Some cardiac pacemakers and defibrillators have a built-in magnetic switch for a cardiologist to be able to turn the device on and or off during an examination utilizing a handheld magnet. If the individual with an installed pacemaker or defibrillator crosses into a high magnetic field, the magnetic switch may be activated and turn the device off. The ACGIH promulgates the 5 Gauss limit to afford an adequate level of protection from this happening to an individual with an implanted pacemaker or defibrillator.
Additionally, magnetized objects may be effected in fields above 5 Gauss. Magnets that generate a very high magnetic field can “pull” magnetized devices into the magnet, sometimes so strong that it will pull a magnetized object out of the hand (such as a handheld tool). Magnetic resonance imaging (MRI) devices that have very large bores for human diagnostic imaging are especially hazardous and precautions must be taken to ensure safety. MRI magnets can generate enough magnetic force to pull very large magnetized objects.
In order for a magnetic force to be applied, the magnetic object must be aligned with
the magnetic flux lines generated by the magnet. Someone can be “fooled” by this if
in a high magnetic flux field. A magnetic object they are holding may have no “pull”,
then just a slight turn may align the object with the magnetic flux and instantaneously,
a strong force is applied and the individual loses control of the object. The object
then becomes a projectile as it is pulled toward the magnet and hazardous to anyone
who may be in the path of travel.
If you are working with strong magnets, an evaluation by USC Radiation Safety staff should be conducted.