A transmission utility's experience of applying EMF exposure standards

Exposure standards for power-frequency electric and magnetic fields are often structured in terms of basic restrictions and investigation levels. For uniform exposures, investigation levels help the user operate within the standard without concern about exceeding the basic restriction. For non-uniform fields, however, numerical calculations of induced currents in the body may be necessary to determine compliance with the basic restriction. Utilities have strong incentives to apply exposure standards so that they do not impose unnecessary and unjustified constraints on their operations. They are therefore likely to be prepared to invest considerable effort in assessing compliance. However, the standards are based on round numbers, the values of tissue conductivity are not well characterized, and the calculations needed to apply the standards are still evolving. This suggests that, scientifically, this level of effort devoted to distinguishing compliant and non-compliant exposure scenarios is not justifiable.