Magnetic fields

When assessing the health-damaging effects of magnetic fields, it is important to distinguish between the static magnetic fields and the pulsating magnetic fields from radio frequency generators. From a work environment point of view, static magnetic fields of NMR devices are usually of the greatest importance.


  • The Danish Labor Inspection Authority uses the guideline limit values from WHO/ICNIRP as a starting point for an assessment of magnetic fields.
  • A limit value of 2 x 105 mT is recommended for the static magnetic fields of NMR devices. If this limit is exceeded, additional studies should be initiated to obtain a concrete assessment of the effect of the magnetic field in the body.
  • The Danish Working Environment Authority recommends that for pregnant women the limit value should be equal to the one recommended for the general population, which is 4 x 104 mT for static magnetic fields. For the sake of people with pacemakers, a 0.5mT safety zone is recommended.
  • Powerful magnetic fields can erase hard drives, destroy computer equipment, and powerfully attract magnetic objects.