The efficacy of different methods for informing the public about the rangedependency of magnetic fields from high voltage power lines

The AC electric and magnetic fields associated with high voltage power line s have become a concern as a possible health risk; In most cases the streng th of these fields decreases as the inverse square of the distance from the line. In earlier work, we found that laypeople do not understand how rapid ly field strength decreases with distance. Most believe that any high volta ge power line they can see is exposing them to strong fields. This paper co nfirms the earlier finding and explores a number of strategies which might be used in risk communications to correct this misperception. We found it r elatively easy to provide subjects with a better understanding of the range -dependency of magnetic field strength. Moreover, the quality of this acqui sition was apparently independent of the manner in which they were instruct ed. Such successful instruction is markedly different from the well-establi shed difficulty of teaching people about many qualitative domains, such as physics or ideas in probability. Clearly, while some erroneous beliefs are highly resistant to change, others can be altered quite readily. We suspect that an important distinction between knowledge about the range-dependency of power+frequency magnetic fields and less tractable topics involves the presence or absence of prior folk-theories or "mental models" of the domain .