Various medical and industrial equipment types with electric fields having frequencies in the range 13 to 40 MHz have a long history. The relative simplicity of the generators and applicators (i.e. the assembly which is adapted for the treatment) have led to equipment manufacturing by many small companies having insufficient knowledge about human exposure hazards. The international regulations on maximum allowed exposure are not well-developed and mainly concern limits of the measured electric field, so-called reference levels, which are set to low values considered to be safe under all possible conditions. – Quite some scientific work on the field characteristics has been carried out since the 1970’s, the goal in many cases having been to motivate further research grants rather than assisting industry in improving safety by proposing more detailed regulations. In particular, researchers have used the electric field strengths as measured, without consideration of the field curvature and decay rate from the equipment, and by also using a too simplistic approach to the “power flux density” of the field emission. – As a consequence of the above, it is estimated that over 90 % of today’s operational equipment does not fulfill these simple regulations. In spite of that, very few incidents or accidents are reported. – New ongoing work by the International Electrotechnical Commission (IEC; committee 27) is now explaining this. The work is based on advanced numerical modelling of typical kinds of equipment and humans in different postures of arms and hands. Some results will be demonstrated and indicate that from five to more than twenty times stronger fields can be accepted under conditions of limited direct access to the energised equipment parts such as electrodes and rails, and proper design of the system grounding.