Analysis of adult and child exposure to uniform plane waves at mobile communication systems frequencies (900 MHz-3 GHz)

The problem of adult and child exposure to uniform plane waves in the frequency range from 900 MHz to 3 GHz, employed by the fixed stations of the most widely used mobile communication systems, is investigated. Anatomically scaled models of a 7-year-old child, a 13-year-old child, and an adult were developed, starting from the visible-human dataset. The dosimetric analysis was performed using a parallel implementation of the finite-difference time-domain method. A uniform plane wave of either vertical or horizontal polarization was used as the incident field. The results showed that the whole-body averaged SARs are higher in the smaller (child) models. Specifically, for adult exposure to fields in compliance with reference levels promulgated by International Commission on Non-Ionizing Radiation Protection and IEEE-2005 guidelines, the resulting SAR values are lower than the basic restrictions, as expected. However, the basic restrictions are exceeded for child exposures between 1.8 and 2.4 GHz. A comparison between SAR values in child models, derived from accurate anatomical scaling and those using simple uniform scaling, showed that the anatomical models are required only for accurate local SAR evaluation at the organ level, but are not necessary for compliance assessments, where whole-body averaged SAR is generally the limiting parameter. Simple empirical formulas to relate the whole-body averaged SAR to body dimensions are proposed. Their validity was confirmed by considering results obtained in this paper and SAR results available in the literature. Finally, a comparison between the Federal Communications Commission and IEEE-2005 exposure guidelines is provided.