The EMF Directive takes two types of direct biophysical effect caused by electromagnetic fields into account. Firstly, these are thermal effects such as tissue heating caused by energy absorption, which occur with high frequencies. Strong high frequency fields can cause internal burns, leading to blindness in extreme cases, for example. Secondly, the EMF Directive considers effects such as muscle, nerve and sensory organ stimulation that can be caused by low frequencies. Such effects can cause optical illusions, for example.
In addition to this, the EMF Directive takes indirect effects into account, such as spark discharges and contact currents that can be induced by electromagnetic fields, interference with heart pacemakers or metallic implants, and the projectile risk from ferromagnetic objects – even a paperclip can become a dangerous missile in a strong static magnetic field.
The exposure level values (ELV), which are based on the actual field strengths within the human body, are mandatory for protection against biophysical effects. They cannot, however, be measured in practice. For this reason, the EMF Directive specifies so-called action levels (AL), which can be measured outside the human body. Human safety is adequately demonstrated as long as these action levels are not exceeded. This then automatically ensures compliance with the exposure level values.