Posted By Jack What sort of environments are you talking about? Suggest as first step you contact NRPB: http://www.nrpb.org/

Posted By Paul Huber To add to the web sites quoted there is a very good US OSHA page on this subject at: www.osha-slc.gov/SLTC/radiofrequencyradiation/ (note you do need the - between osha and slc)

Posted By Jane Blunt Dear James You may need to distinguish between electric and magnetic fields. For some kinds of radiation, such as radio waves and light you get the two together. For applications such as the (I guess) electrolysis described above, you get essentially a magnetic field only. Magnetic fields are generated by the passage of electric currents, and a bar carrying a large current will have a correspondingly high magnetic field around it. Electric fields on the other hand are produced when there is a large potential difference (voltage), and so are quite large close to high tension distribution systems (pylons). I have visited an aluminium smelter where the current was 149000 amps, but the voltage was only around 4 V. There, the magnetic field was very large, but the electric field was almost non-existent. Welders work quite close to a high magnetic field - especially if they drape the welding cable over their shoulder. Fields do decay quite rapidly, and the decay depends a great deal on the shape of a source. Thus the field from a point source will decay more rapidly than the field from a long wire. There is an excellent scientific overview of the effects of magnetic fields 'Static and low frequency magnetic field effects: health risks and therapies' by Robert Adair, in Rep. Prog. Phys. vol 63, (2000) pages 415-454. The NRPB pages are well worth a look as mentioned above, as is the IEE site. I suggest you search 'field' or 'electromagnetic'. Jane