231
Interaction of Extremely Low–Frequency Electromagnetic Fields
contents are up to 96 kHz for six razors, up to 3.4 kHz for three hair dryers, and up to
8.6 kHz for three drills. They examined, by IM, the coupling of the highly localized
magnetic fields with harmonic components with the induced current densities in the
1.31 cm resolution human head model. The averaged current densities were from about
2–27 μA/m 2 for the razor with highest contribution of 8 kHz, from 0.3 to 2.5 μA/m 2
for the hair dryer with 3.4 kHz, and from 0.8 to 5.8 μA/m 2 for the drill with 100 Hz.
The application to nonuniform magnetic fields for a transmission line can be found in
several papers (Dawson, Caputa, and Stuchly 1999a,b; Stuchly and Zhao 1996). In these
cases, the realistic human models based on working configurations are postured around
a transmission line, and it is speculated that the highest exposure level occurs for nonuniform magnetic fields such as working close to the conductor.
Nadeem et al. (2004) measured the magnetic fields from a spot welding machine
and calculated the induced body currents in a full three-dimensional human model
with 3-mm resolution obtained from the Visual Human Project in order to determine
whether the ICNIRP basic restriction is exceeded or not. The spot welding machine
had magnetic fields of up to 4 mT at the operator position and an almost 50 Hz waveform. They calculated the induced current densities using IM. The maximum induced
current densities at an operator position of 34 cm away from the machine were below
ICNIRP basic restriction. The basic restriction was exceeded if the operator was closer
to the machine. By applying the BEM, Park and Min (2008) calculated current densities induced inside a human body model with spheroids or cylinders with several
organs. This human body model was simulated for AC arc welder workers. The arc
welder of 200–300 A was used for simulation, with 1000 A applied to the worst case.
The condition for calculation was locating the human body model 1–20 cm away from
the power cable of the welder. The maximum current densities were calculated on the
surface of the heart, and when working within 15 cm, this value may exceed ICNIRP
basic restriction. The complex waveforms from the source of pulsed electric and magnetic fields in the working place was reviewed and analyzed (Cooper 2002; Crotti and
Giordano 2009; Jokela 2000, 2007).
Dawson, Caputa and Stuchly evaluated the dosimetry for live-line workers exposed
to 50 Hz magnetic fields from high-voltage transmission lines (Dawson, Caputa, and
Stuchly 2002a). The dosimetry includes the calculations of the electric fields and current densities induced in tissue and the current densities averaged over 1 cm 2 . Scenarios
include three worker postures for the twin and triple bundles, and four postures for the
quadruple bundle. The human models comprising cubic voxels with 3.6-mm edges were
derived from the basic upright body posture (Dawson, Moerloose, and Stuchly 1997a).
Three to four positions of the worker’s body have been simulated for each conductor bundle. The basic restriction of ICNIRP guidelines is 10 mA/m 2 for occupational exposure.
From calculation with each scenario, the current densities are exceeded only for some
exposure scenarios and a load of 1 kA per conductor. They pointed out that the highest exposure levels very close to the high-voltage transmission line are for nonuniform
magnetic fields in occupational scenarios (Stuchly and Dawson 2002) and introduced
the simplified method to estimate the induced electrical quantities for four nonuniform
magnetic field exposure scenarios by using quasistatic approximation techniques. In
two of four configuration scenarios, the conductors were separated by 45.72 cm with