Uncertainty in determining respect distance for electromagnetic fields by spatial interpolation of exposure indices

Exposure indices are significant quantities in the assessment of human exposure to electromagnetic fields, especially in the work environment, because they consider both the field spectrum and the frequency dependency of regulatory limits. Some measurement instruments available on the market allow to measure these indices, by expressing them as a percentage or unit value. In many situations, a parameter that allows to characterize the exposure and give synthetic and effective indications on risk assessment and risk reduction is the respect distance, i.e. the distance from the source beyond which the exposure index considered is less than 100% (or unity, depending on adopted standardization ). This definition implicitly assumes that a reference direction has been chosen so that, moving away from the source along it, the intensity of the exposure decreases with the distance itself. This work describes how the respect distance could be determined starting from exposure index measurements, thanks to a flexible interpolation method to be used in combination with different source models and that allows to propagate the uncertainty of each measurement on the result of the interpolation and therefore determine the uncertainty related to the respect distance.