Mitigation of Low-Frequency Magnetic Fields in Sweden
Paper i proceeding, 2013
The paper describes action to protect the general public and workers. Swedish authorities launched a precautionary principle to protect the general public against EMF in 1995, due to the research on childhood cancer and magnetic field exposure. This has led to actions to mitigate magnetic fields from new power lines and new train tracks.
In 2016 all EU countries will have implemented the EU directive on minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (electromagnetic fields). Only activities using very high currents will be affected by the low frequency magnetic field limits, such as welding.
In a research project EMFWELD we have developed a method to assess the limits for magnetic fields in the directive. Complex magnetic field can be assessed against the EU directive limits using weighting filters. The evaluation is performed in the time domain, which allows for arbitrary signal waveforms and can be applied for both action levels and exposure limit values. The strength of the induced electric field strength in the body induced by the source current can be described as a coupling factor. By using weighting filters and coupling factors the time and geometrical dependences can be treated separately, which considerably simplifies the assessment and makes it cost effective.